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Antimicrobial peptides are promising alternatives to antibiotics to treat bacterial and fungal infections, especially drug-resistant clinical pathogens. Antimicrobial peptides (AMPs) were synthesized and antimicrobial activity was assayed. The antibacterial mechanism, ATP production, ROS generation and molecular mechanism were determined. Biofilm inhibition assay was performed in planktonic bacterial cells and biofilm degradation assay was performed using mature biofilm. The synthesized AMP2 was subjected to in vitro and in vivo analysis to analyze the safety. The synthesized peptides AMP1, AMP2, AMP3 and AMP4 exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria. The MIC values ranged from 1.5 ± 0.25–12.5 ± 1.25 µM and the MFC values range from 2.25 ± 0.12–25 ± 1.25 µM. F. solani showed fewer MFC values than other fungal strains. Time kill assay was performed and the AMP2 killed about 70 % of Acinetobacter baumannii at 1 × MIC concentration within 10 min incubation and killed 97 % of bacteria at 1 × MBC concentration within 15 min. The antimicrobial peptide AMP2 was highly effective against planktonic A. baumannii and L. monocytogenes. The tested AMP2 showed less toxicity to cell lines and Zebrafish. Antimicrobial peptides have potential antimicrobial properties against Gram-positive and Gram-negative bacteria. The in silico studies of these antimicrobial peptides are useful for eradicating drug-resistant bacteria. [ABSTRACT FROM AUTHOR]

Phycoerythrin (PE) is a phycobiliprotein holding great potential as a high-value food colorant and medicine. Deep eutectic solvent (DES)-based ultrasound-assisted extraction (UAE) was applied to extract B-PE by disrupting the resistant polysaccharide cell wall of Porphyridium purpureum. The solubility of cell wall monomers in 31 DESs was predicted using COSMO-RS. Five glycerol-based DESs were tested for extraction, all of which showed significantly higher B-PE yields by up to 13.5 folds than water. The DES-dependent B-PE extraction efficiencies were proposedly associated with different cell disrupting capabilities and protein stabilizing effects of DESs. The DES-based UAE method could be considered green according to a metric assessment tool, AGREEprep. The crude extract containing DES was further subjected to aqueous two-phase system, two-step ammonium sulfate precipitation, and ultrafiltration processes. The final purified B-PE had a PE purity ratio of 3.60 and a PC purity ratio of 0.08, comparable to the purity of commercial products. • COSMO-RS predicted the solubility of microalgal cell wall components in DESs. • High solubility-predicted DESs could disrupt the resistant cell wall effectively. • PGly-based UAE of cells could produce the B-PE extract the most efficiently. • PGly-based UAE method was considered green based on AGREEprep evaluation. • High-purity B-PE was obtained from DES extract by ATPS, followed by ASP and UF. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sodium pyrophosphate and thermal hydrolysis had synergistic effects. • Proposed combined pretreatment doubled short-chain fatty acid yield. • Hydrolysis and acidification were enhanced while methanation was inhibited. • Macellibacteroides sp. and Romboutsia sp. were enriched. The slow breakdown of sludge is the primary obstacle hindering the conversion of waste-activated sludge to short-chain fatty acids (SCFAs) by anaerobic fermentation. This study proposed a novel method incorporating sodium pyrophosphate and thermal hydrolysis (SP-TH) for sludge pretreatment and evaluated its effectiveness regarding SCFA production. The combined pretreatment of SP at 0.4 g/g of total suspended solids and TH at 140 °C enhanced SCFA production from 2,169 ± 208 to 4,388 ± 184 mg chemical oxygen demand/L. SP strips extracellular polymeric substances, and the subsequent TH decomposes cells in the sludge, thus promoting sludge hydrolysis. SP-TH pretreatment promoted SCFA accumulation by enhancing enzyme activity and enriching acidifying bacteria. This study demonstrated that SP-TH pretreatment can effectively promote acid production from sludge, providing a new avenue for organic matter recovery through sludge anaerobic fermentation pretreatment. [ABSTRACT FROM AUTHOR]

Microalgae and cyanobacteria are photosynthetic and unicellular organisms that contain considerable amounts of proteins, lipids, carbohydrates, and polyunsaturated fatty acids, among others, with applications in the cosmetic, pharmaceutical, and food industries. These microorganisms can accumulate protein up to 70 % of total biomass depending on the microalgal strain, hence they have been regarded as an alternative protein source for the future. Microalgal proteins have important applications such as emulsifying, foaming, and gelation properties, which are important for the determination of quality and texture of foods. Some microalgal peptides possess important bioactivity with many health-benefit effects. Therefore, to maximize the production of proteins from microalgae and cyanobacteria, many protein extraction procedures have been studied to increase the economic return. They have been tested towards higher protein yields at low energy cost, the preservation of protein native properties, and lower cell debris. This later is fundamental to facilitate the subsequent purification processes so that the overall cost can be reduced. The aim of this work is to review some cell disruption processes for the extraction of protein from microalgae and cyanobacteria, considering that this step is crucial for the overall process due to the high rigidness of microalgal cell covering, which can hamper the release of proteins. It also aims at reviewing the purification techniques after cellular disruption, from conventional to more recent approaches, and finally addresses the antioxidant, antidiabetic, antihypertensive, antibacterial and other bioactive properties of microalgal protein hydrolysates and peptides. [Display omitted] • Evaluation of mechanical and non-mechanical cell disruption methods for microalgal protein release. • Assessment of protein isolation procedures. • Techno-functional properties of microalgae-derived proteins are discussed. • Bioactivity properties of protein hydrolysates and peptides from microalgal proteins are addressed. [ABSTRACT FROM AUTHOR]

Alternative nutrient sources for fish feed are currently of high interest. Feed ingredients with suitable lipid contents and valuable amounts of essential fatty acids are especially needed to relieve the usage of fish oil and maintain high product quality of fish from aquaculture. Microalgae contain promising nutrient contents and suitable fatty acid profiles that cover dietary requirements of fish. Nutrient digestibility, however, can be hindered by their rigid cell wall. Therefore, in the presented study, the microalgae species Isochrysis galbana and Tetraselmis chui were processed by freeze-drying and centrifugal milling to evaluate their nutrient and fatty acid digestibility in fish nutrition. For T. chui , an additional treatment with enzyme supplementation was tested. Test diets contained 70% of a fish meal based reference diet and 30% of the respective microalgae meal, as well as titanium dioxide as an inert marker to calculate apparent digestibility coefficients (ADC). Rainbow trout (Oncorhynchus mykiss) were fed for 14 days and faeces were collected via manual stripping. The ADCs of Kjeldahl nitrogen (∼ 64–79%), nitrogen-free extracts (∼ 40–54%) and energy (∼ 52–66%) were not significantly different between the algae species, but I. galbana inclusion resulted in reduced lipid digestibility (∼ 57% to 77%), which was linked to the high content of saturated fatty acids. The fatty acid ADCs were higher for T. chui except for arachidonic acid (20:4 n-6) and lauric acid (12:0). Mechanical or enzyme-treating processing did not increase nutrient and fatty acid digestibility for the microalgae used in this trial, and sole freeze-drying sufficiently ensured nutrient availability. The high digestibility of nutrients and, particularly, polyunsaturated fatty acids of I. galbana and T. chui underscore their potential as fatty acid and nutrient sources in fish feed. • Isochrysis galbana and Tetraselmis chui are promising fatty acid sources for fish. • Lipid and fatty acid digestibility is lower for I. galbana than for T. chui. • Freeze-drying sufficiently provided nutrient availability for these microalgae. [ABSTRACT FROM AUTHOR]

High-intensity ultrasonication is an emerging technology for plant protein isolation and modification. In this study, the potential of temperature-controlled ultrasonication to enhance the recovery of functional proteins from potato trimmings was assessed. Different ultrasound energy levels [2000–40,000 J/g fresh weight (FW)] were applied during protein extraction at pH 9.0. True protein yields after ultrasonication significantly increased (up to 91%) compared to conventional extraction (33%). Microstructural analysis of the extraction residues showed more disrupted cells as ultrasonication time increased. Ultrasound treatments (10,000 and 20,000 J/g FW) increased the protein yield without affecting the foaming and air-water interfacial properties of protein isolates obtained after isoelectric precipitation (pH 4.0). However, proteins obtained after extended ultrasonication (40,000 J/g FW) had significantly slower early-stage adsorption kinetics. This was attributed to ultrasound-induced aggregation of the protease inhibitor fraction. In conclusion, ultrasonication shows potential to help overcome some challenges associated with plant protein extraction. [Display omitted] • Ultrasonication significantly increases the protein recovery from potato trimmings. • Temperature-controlled ultrasonication causes disruption of cellular structures. • The impact on the foaming properties of the isolated proteins is limited. • Potato protease inhibitors aggregate during extended ultrasonication. • Interfacial adsorption of isolated proteins is slower after extended ultrasonication. [ABSTRACT FROM AUTHOR]

Microalgae have potentially beneficial effects on animal health and nutritional value when added to feed. Crucial hereby is that intracellular bio-active molecules are released in the intestinal tract. Digestibility of Chlorella vulgaris and its impact on total digestibility of broiler feed is a first step in assessing its characteristics as feed supplement. Different methods could be used to increase the digestibility of the algae. Among other, pulsed electric field (PEF) and freezing to disrupt autotrophic (A) and heterotrophic (H) Chlorella vulgaris cells was assessed to increase their availability followed by in-vivo trials. In these trials effect of algae type (A and H) and effect of PEF-processing was evaluated on the apparent nutrient digestibility. Pulsed electric field showed to have a disruption efficiency of 83.90% and 79.20% for heterotrophic and autotrophic C. vulgaris respectively. Freezing C. vulgaris only showed efficiencies ranging from 3.86 to 11.58%. In the in-vivo trials, microscopic counting of intact C. vulgaris cells showed an increase in digested intact C. vulgaris cells of PEF-processed C. vulgaris compared to nonprocessed cells ranging from 12.16% to 15.20%. Autotrophic C. vulgaris had a higher digestibility compared to heterotrophic C. vulgaris , with an increase of 7.29, 9.44, and 17.29% in digestibility of C. vulgaris in the 1, 2, and 5% feed respectively. Feeds with PEF-processed C. vulgaris showed no significant increase in digestibility compared to nonprocessed C. vulgaris supplemented feeds. The 5% C. vulgaris feeds showed lower fat digestibility than the 1 and 2% and control feeds. Protein digestibility was lower for all C. vulgaris feeds compared to the control feed. There was a significant linear decreasing effect (P < 0.001) for all digestibility parameters. Except for crude ash digestibility, which first lowered for the 1 and 2% feeds, but then increased at 5% inclusion. Considering this study, including low dosages of 1 and 2% of C. vulgaris in broiler feed does not compromise its digestibility. [ABSTRACT FROM AUTHOR]

A wide range of conventional and non-conventional technologies have been employed to extract a wide range of bioactive compounds from the complex matrices of seaweeds. Green extraction technologies are increasingly employed to improve extraction efficiencies. The objective of this review was to outline various approaches employed for the extraction of bioactives from seaweeds. This review covers various pretreatment methods generally employed prior to extraction, and their combinations with conventional and green extraction technologies. Novel technologies which can be employed with or without pretreatments to improve existing processes are also discussed. The role of pretreatments is of utmost importance and have significant impacts on the quality and quantity of target compounds. Combinations of different cell disruption technologies and extraction methods can enhance the extractability of compounds with higher purity and contribute towards improved process efficiency. • Comprehensive assessment of pre-treatment technologies. • Novel extraction techniques for bioactives from seaweeds. • Mechanism of pre-treatment and extraction techniques. • Factors influencing extraction of bioactives from seaweeds. [ABSTRACT FROM AUTHOR]

Freshwater green microalgae are a source of valuable industrial products. Owing to the lipid accumulating nature of these organisms, it is among the most promising solutions to meet carbon neutral hydrocarbon fuel needs for future transportation. However, there are many technical hurdles that need to be overcome before their commercial viability. One of the challenges is getting cellular lipids out from the cell because of the sturdy algal cell wall. Several chemical, physical, thermal, and biological techniques have been tested and reported so far, but all the methods are either energy intensive, not scalable, product damaging, slow or less effective. Photocatalysis is a promising field with emerging green solutions to many environmental problems and has only scarcely been studied so far for algal cell disruption. In this study Ag 3 PO 4 –TiO 2 photocatalyst was used for pre-treatment of Chlorella vulgaris (UTEX-26) cells in the presence of UV and visible light. Results showed an increase of ∼8% in lipid quantity compared to raw cells with 5 and 30 min of UV and visible light pre-treatment, respectively at a catalyst dose of 500 mg L−1 at pH 3. The Attenuated Total Reflection - Infra Red (ATR-IR) analysis of bio-oil revealed that no significant change in lipid quality occurred due to photocatalytic pre-treatment. The pre-treatment experiments also resulted in simultaneous harvesting of the cells, thus further reducing the energy needs of the process. The technique for algal cell wall disruption using Ag 3 PO 4 –Titania composites for lipid yield enhancement has not been reported to date. [ABSTRACT FROM AUTHOR]

The yield and quality of lipids extracted from microalgal biomass are critical factors in the production of microalgae-based biodiesel. The green microalga Chlorella homosphaera , isolated from Beira Lake, Colombo, Sri Lanka was employed in the present study to identify the effect of chlorophyll removal and cell disruption methods on lipid extraction yield, fatty acid methyl ester (FAME) profile and quality parameters of biodiesel; including cetane number (CN), iodine value (IV), degree of unsaturation (DU) and high heating value (HHV). In the first section of this study, chlorophyll was removed from dry microalgae biomass prior to lipid extraction. Through the analysis of FAME profiles, it was observed that chlorophyll removal yielded biodiesel of enhanced quality, albeit with a lipid loss of 44.2% relative to the control. In the second section of the study, mechanical cell disruption strategies including grinding, autoclaving, water bath heating and microwaving were employed to identify the most effective method to improve lipid recovery from chlorophyll-removed microalgae biomass. Autoclaving (121 °C, 20 min sterilization time, total time 2 h) was the most effective cell disruption technique of the methods tested, in terms of lipid extraction yield (39.80%) and also biodiesel quality. Moreover, it was observed that employing cell disruption subsequent to chlorophyll removal has a significant impact on the FAME profile of microalgae-based biodiesel, and consequently served to increase HHV and CN although IV and DU did not vary significantly. [ABSTRACT FROM AUTHOR]

Industrial scale microalgal cell disruption requires low cost, high efficiency and structural conservation of biomolecules for biorefinery. Many cultivated microalgae have thick walls and these walls are barriers for efficient cell disruption. Until recently, despite the high biodiversity of microalgae, little attention has been paid to thin-wall microalgal species in the natural environment for the production and recovery of valuable biomolecules. Instead of developing high power cell disruption devices, utilization of thin-wall species would be a better approach. The present paper describes a simple device that was assembled to evaluate the viability and effectiveness of biomolecule extraction from both thin- and thick-wall species as a proof of concept. This device was tested with high-pressure gases including N 2 , CO 2 plus N 2 , and air as the disruption force. The highest nitrogen pressure, 110 bar, was not able to disrupt the thick-wall microalgal cells. On the other hand, the thin-wall species was disrupted to different degrees using different pressures and treatment durations. In the same treatment duration, higher nitrogen pressure gave better cell disruption efficiency than the lower pressure. However, in the same pressure, longer treatment duration did not give better efficiency than the shorter duration. High pressure CO 2 treatments resulted in low soluble protein levels in the media. The best conditions to disrupt the thin-wall microalgal cells were 110 bar N 2 or air for 1 min among these tests. In these conditions, not only were the disruption efficiencies high, but also the biomolecules were well preserved. • The high biodiversity of microalgae implies many thin-wall species exist. • A device was assembled to break thin- and thick-wall algal cells using high pressure gases. • The efficiency of breaking the thin-wall cells was 100% using 110 bar N 2 or air but not for the thick-wall cells. • Cell wall thickness and thermo-tolerance are critical in microalgal screening. [ABSTRACT FROM AUTHOR]

Cell disruption is a basic yet often overlooked step in the extraction of valuable substances from plants. A simple and easily applicable method is presented to assess cell membrane stability as an integral part of phytoextraction by measuring electric conductivity (EC) and calculating the Index of Injury (Id). In this paper, a wide range of industrially applicable methods is evaluated including mechanical disruption, heat, a combination of both, extreme pH-values, application of microwaves, ultrasound and pulsed electric field (PEF). Moreover, the approach via Id is compared to an alternative method using HPLC analysis of a marker substance to show the method's limitations as well as to provide further applications of this basic system. For the feedstock used, heavy mechanical processing such as grinding, temperatures above 50 °C as well as acidic condition below pH 2.5 were equally potent methods for complete cell disruption. Alternatively, moderate mechanical treatment like chopping or cutting could be combined with temperatures above 40 °C for maximal cell damage. Although PEF application showed merely moderate effects applied alone, it may be combined with mechanical pre-treatment in order to achieve high cell disruption at low temperatures, making it ideal for the extraction of thermolabile compounds. [ABSTRACT FROM AUTHOR]

• Production of branched-chain fatty acids enriched lipid (81% of total FA) without any supplementation in medium. • Use of food-waste hydrolysate as substrate. • Scalable cell lysis method followed by solvent extraction for lipid isolation. • Energy efficient lipid isolation method. Oxidation stability and cold flow properties of biodiesel can be improved by using lipid with enriched branched-chain fatty acid (BCFA) as a feedstock. A halophilic bacterium was utilized for the production of BCFA enriched lipid from acid hydrolysate of food-waste. The maximum reducing sugar obtained by hydrolysis of wheat bran, rice bran, mango peel, and orange peel were 64.52 ± 0.57, 38.7 ± 0.58, 55.64 ± 1.14, 36.29 ± 0.54 g/L, respectively. On assessing these hydrolysates as feedstock for growth of halophilic bacterium Lentibacillus salarius NS12IITR at 10 g/L reducing sugar concentration, wheat bran hydrolysate was found to be best in-terms of sugar consumption (92%), lipid production (0.70 ± 0.029 g/L) and maximum branched-chain fatty acid methyl ester (FAME) (81 ± 4.72% of total FAME). At 20 g/L of reducing sugar concentration of wheat bran hydrolysate, the biomass and lipid yields were almost doubled. Efficient lipid extraction from cell, involving thermolysis at 85 °C and pH 2 along with osmotic shock resulted in isolation of 69% of total lipid. [ABSTRACT FROM AUTHOR]

• Anthocyanin degradation caused colour change in blackberries affected reversion. • Cell disruption and decompartmentalisation occurred in affected drupelets. • Affected drupelets lost skin firmness relative to unaffected drupelets. • Acylated anthocyanins were less readily degraded than non-acylated. Red drupelet reversion (RDR) is a physiological disorder causing individual or groups of drupelets on blackberries that are black at harvest to turn red during postharvest cool storage. The objectives of this study were to examine and quantify the physiochemical changes occurring in flesh affected by RDR. Drupelets were classified as 'fully black', 'partially red', or 'fully red'. The total anthocyanin concentration in black, partially, and fully red drupelets was 1841 mg kg−1, 1064 mg kg−1 and 769 mg kg-1 fresh weight respectively. Anthocyanins containing acylated or disaccharide sugar moieties were more stable than anthocyanins with non-acylated monosaccharide sugar moieties. The pH of partially red (3.05) and fully red drupelets (3.01) was lower than black drupelets (3.32). Firmness of partially red (1.90 N) and fully red drupelets (1.77 N) was lower than that of fully black drupelets (2.39 N). Examination by light and electron microscopy showed cell disruption, separation, and loss of integrity in the upper mesocarp of affected drupelets. Electrolyte leakage over 24 h was significantly higher from partially red (84.8%) and fully red (90.0%) than fully black drupelets (64.9%). The data are consistent with RDR in blackberries arising from mechanical damage that causes cell decompartmentalisation and subsequent anthocyanin degradation. [ABSTRACT FROM AUTHOR]

Algae species like Schizochytrium sp. are resilient photosynthetic factories that produce large quantities of fatty acids that can be converted to biodiesel. These lipids must be extracted from the raw biomass before they can be used as biofuel feedstocks or other bioproducts such as hydrogen. In this paper, hydrogen production by steam reforming of schizochytrium algae oil are studied. The effects of continuous microwave and intermittent microwave, freezing and thawing times of different mass fractions, time of alkali heat and other factors on the ratio of cell disruption and ultrasonic-assisted ethanol extraction are considered. The results show that the highest lipid yield can reach by ultrasonic-assisted ethanol extraction from the schizochytrium algae which are pretreated by alkali heat method. The hydrogen production from steam reforming of the lipids, which are extracted by ethanol with ultrasonic-assisted from algae after alkali thermal pretreated is proposed. • Hydrogen produced by steam reforming of Schizochytrium algae oil. • Algae oil extracted by ethanol with ultrasonic-assisted from pretreated algae. • Algae pretreated by potassium hydroxide at 60 °C. [ABSTRACT FROM AUTHOR]

Abstract Protic Ionic Liquids (PILs) with their labile protons are expected to simultaneously disrupt and exudate lipids from microalgae, crucial for efficient biodiesel production. A survey study with a battery of ten carboxylate PILs with lactam and ammonium cations was conducted with dried and dewatered marine Nannochloropsis oculata and Chlorella salina microalgae. The results showed that the formate and hexanoate PILs in comparison to acetate PILs could efficiently catalyse simultaneous near-complete cell disruption and lipid extraction from dewatered microalgae. The ability of PIL to handle dewatered microalgae avoids the energy-intensive drying step used in other conventional methods. The maximum lipid recovery of 134.9 and 85.4‰ was recorded with butyrolactam hexanoate treated N. oculata and C. salina respectively. The lipid profile showed the predominant presence of C 16 and C 18 fatty acids and comparable with lipid profile obtained with conventional Bligh & Dyer method. The PILs were also found to favourably inhibit lipases which likely promote lipolysis in wet microalgal lipid samples. The PIL extracted lipids were found to have reduced pigments, favoured for reducing the number lipid/biodiesel purification steps. Highlights • Marine N. oculata and C. salina microalgae were processed for lipid recovery with ten different carboxylate-PILs. • PILs exhibited enhanced lipid recoveries from dewatered microalgae than dried microalgae. • Hexanoate and formate PILs exhibited enhanced lipid recovery compared to acetate PILs. • The PILs exhibited varying degrees of lipase inhibition and recovered less-pigmented lipids. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydrodynamic cavitation technology was used for cell disruption. • Selective recovery of periplasmic enzyme using hydrodynamic cavitation. • Combined strategy enhances the energy efficiency up to 63.19 times. • Pretreatment prior to cell disruption enhance selective release up to 4.79 times. Abstract Cell disruption is a crucial step in the recovery of intracellular products and has a huge impact on further downstream processing steps and associated cost. The non-selective recovery of intracellular product by conventional method is the major cause for the higher cost of bioproducts. Hydrodynamic cavitation is an emerging technology for the selective recovery of intracellular product at the cell disruption stage. In the present study, the hybrid strategy for the large-scale cell disruption has been developed using hydrodynamic cavitation with different pretreatment strategies such as exposure to the acidic stress, hypoosmotic acidic stress condition and reducing agent. The maximum enzyme recovery of 55.78U/ml and selectivity of 495U/mg were obtained at an optimized pretreatment of hypoosmotic acidic stress (3.6 pH, 0.05 M, 12 h) and reducing agent (2 mM Dithiothreitol, 2 h) followed by the cell disruption using hydrodynamic cavitation. The pretreatment prior to cell disruption by hydrodynamic cavitation increases the selectivity up to 4.79 times and energy efficiency up to 63.19 times as compared to high pressure homogenizer as a conventional method for the cell disruption. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Comparison of imidazolium ionic liquids (ILs) for disruption of H. pluvialis cyst. • Co-extraction of lipid and astaxanthin using room-temperature IL/water mixtures. • Very high astaxanthin recoveries (>99%) by IL pretreatments and hexane extractions. Abstract Energy-saving, high-efficiency cell disruption is a critical step for recovery of thermolabile antioxidant astaxanthin from Haematococcus pluvialis cyst cells of rigid cell-wall structure. In this study, as room-temperature green solvents, 10 types of 1-ethyl-3-methylimidazolium ([Emim])-based ionic liquids (ILs) were compared and evaluated for their abilities to disrupt H. pluvialis cyst cells for astaxanthin/lipid extraction. Among the 10 ILs tested, 3 [Emim]-based ILs with HSO 4 , CH 3 SO 3 , and (CF 3 SO 2) 2 N anions were selected based on astaxanthin/lipid extraction performance and synthesis cost. When pretreated with IL/water mixtures, intact cyst cells were significantly torn, broken or shown to release cytoplasmic components, thereby facilitating subsequent separation of astaxanthin/lipid by hexane. However, excess IL pretreatments at high temperature/IL dosages and longer incubation times significantly deteriorated lipid and/or astaxanthin. Under optimized mild conditions (6.7% (v/v) IL in water solution, 30 °C, 60 min), almost complete astaxanthin recoveries (>99%) along with moderate lipid extractions (∼82%) could be obtained. [ABSTRACT FROM AUTHOR]

Abstract A major step in microalgal biodiesel production is lipid extraction, which is mostly done using the conventional chloroform-methanol solvent system. The objective of the present work was to optimise the process of pretreatment of an indigenous Chlorella sp. KA-24NITD (Chl -24). Various physical cell disruption methods were combined with the optimised solvent system along with chemical (Dimethyl sulfoxide) and enzymatic (cellulase and pectinase) pretreatments of wet and dry biomass for lipid yield enhancement. Optimisation was done by Taguchi Orthogonal Array L9 (34). Under optimised conditions, subsequent experimental runs showed that the optimum lipid yield of about 38.59% was obtained when wet biomass was enzymatically pretreated with pectinase and cellulase in the ratio 1:2 along with the combination of the physical process. Thus enzymatic pretreatment proved to be more efficient than chemical pretreatment showing significant results by improving lipid yield, which suggests that Chl -24 could be a potent candidate for biodiesel production. Graphical abstract Image 1 Highlights • Indigenous Chlorella sp. NITDKA lipid extraction optimised by Taguchi L9 method. • Optimised lipid yield from dry biomass was about 1.2 times that from wet biomass. • Increased lipid yield by combining enzymatic and physical treatments of biomass. • Lipid extraction from wet biomass consumed 5 times less energy than for dry biomass. [ABSTRACT FROM AUTHOR]

Highlights • Lysozyme was immobilized on an extrudate-shaped Na-Y zeolite for enzymatic lysis. • A simple cell disruption and protein recovery in a recirculating packed bed reactor. • Disruption yield of 93% and released protein content of 400 μg/ml was achieved. • Separation of immobilized lysozyme and released protein is not needed. Abstract Carrier-based immobilization has been developed to improve the functional properties of enzymes and promote the employment of enzymatic lysis in downstream processing without the necessity to separate the lysis enzyme after processing. In this study, lysozyme was immobilized on an extrudate-shaped Na-Y zeolite and was used for the disruption of Micrococcus lysodeikticus in a recirculating packed bed reactor. The factors influencing immobilization process, namely, liquid velocity and initial concentration of lysozyme solution, were studied aiming to improve the amount of immobilized lysozyme. Additionally, the key process parameters of cell disruption operation using lysozyme-zeolite complex in recirculating packed bed reactor, including the volume of M. lysodeikticus suspension, liquid velocity and operating temperature, were further investigated for their effects on the efficiency of cell disruption. Under the optimal conditions (50 ml of 2.0 mg/ml cell suspension, liquid velocity of 500 cm/h, and operating temperature of 25 °C), the system successfully achieved cell disruption yield of 93% and released protein content of approximately 400 μg/ml. Besides, the system demonstrated its reusability by acquiring released protein content of 250 μg/ml after 12 successive cycles of operation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Halophylic fungi cell disruption with SC CO 2 or homogenization method. • Extremozymes with high catalytic activities after exposure of fungi cell suspension to SC CO 2. • High protein concentration in fungi cell suspension after the treatment with SC CO 2. Abstract Trimatostroma salinum, Wallemia ichthyophaga, Hortaea werneckii and Phaeotheca triangularis are halophilic fungi, which can thrive in a wide range of salinity (0%–32% NaCl). They present a source of valuable bio-active compounds, enzymes and proteins interesting for environmental management, food, textile and pharmaceutical industry. Enzymes from these fungi, e.g. amylases, cellulases, lipases, and proteases, which possess so called polyextremophilicity (they are thermostable, tolerant to a wide range of pH, less susceptible to denaturation and tolerant to high salt concentrations) present a novel catalytic alternative for biotechnological applications. To release enzymes from halophilic fungi cells, a conventional method using mechanical homogenizer (rotor-stator homogenizer) and a novel method using supercritical technology were applied. Very high protein concentration in all halophilic fungi cell suspensions after the treatment with SC CO 2 were detected. Obtained results also show very high activities of protease, α-amylase, β -glucosidase and cellulase after the treatment of each halophilic fungi cell suspension by SC CO 2. Using SC CO 2 as a medium for cell disruption offers additional benefits regarding performance of a biochemical reaction and bioseparation in the same medium leading in integration of all three processes into a single step. Besides, integration of processes presents important advantage in industrial processes from an economic point of view. Enzymes from extremophiles namely possess improved properties and can be used at harsh conditions where non-extremophilic enzymes may deactivate. Therefore, extremozymes from T. salinum , W. ichthyophaga, H. werneckii and P. triangularis are as high-pressure tolerant enzymes suitable for many industrial applications, which could be performed also in non-aqueous media like SC CO 2. [ABSTRACT FROM AUTHOR]

Abstract Considering the phosphorus (P) reserve state and its value, recovery of P from microalgae has become a popular topic. In this study, an integrated system of a hydrothermal process for microalgae cell disruption to release P and magnesium modified hydrochar adsorption to capture P was set up. Emission scanning electron microscopy with Energy Dispersive X-ray spectroscopy and Three-Dimensional Excitation Emission matrix spectroscopy with parallel factor analysis were applied to evaluate the P release process from microalgae and found the optimal breaking-wall condition (P release 90.5%, hydrothermal digestion mixture of H 2 O 2 and NaOH at 348 K). Parallel factor analysis showed there was a close relationship between P and humic-like substance. Hydrochar loaded with magnesium exhibited a strong affinity for P, with maximum capacity 89.61 mg/g at 318 K. The P adsorption fitted pseudo-second-order kinetic and Langmuir models. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were applied to reveal the mechanism of hydrochar modification and adsorption. It showed that Mg is loaded on the surface of hydrochar by electrostatic attraction and electron transfer with the carboxylic acid. P absorption was reached through anion exchange. Graphical abstract Unlabelled Image Highlights • Cell disruption process was explored by 3D-EEM with PARAFAC and SEM for Scenedesmus dimorphus. • 90.5% P release by hydrothermal process with NaOH and H 2 O 2 for 13.01 kWh/kg input-energy • The adsorption process was explored and 89.61 mg/g P-recovery capacity was obtained at 318 K. • The Mg loading and P recovery ways on MHC were explored by XPS and FTIR. [ABSTRACT FROM AUTHOR]

Lipid extraction directly from the wet oleaginous microorganisms for biodiesel production is preferred as it reduces the energy input for traditional processes which require extensive drying of the biomass prior to the extraction. The high water content (≥80% on cell dry weight) in the wet biomass hinders the extraction efficiency due to the mass transfer limitation. This limitation can be overcome by pretreating wet biomass prior to the lipid extraction using pressurized gas that can be used alone or combined with other pretreatments to disrupt the cell wall. In this review, an extensive discussion on different pretreatments and the subsequent lipid extraction using these pretreatments is presented. Furthermore, a detailed account of the cell disruption using pressurized gas (e.g., CO 2 ) treatment for microbial cell lysing is also presented. Finally, a new technique on lipid extraction directly from wet biomass using the combination of pressurized CO 2 and microwave pretreatment is proposed. [ABSTRACT FROM AUTHOR]

A wide variety of nutritious products and biofuels can be produced from microalgae. Their applications span across various sectors such as food, medical, and energy industries. Microalgal cell disruption is a crucial aspect in the production processes as it facilitates the extraction of bio-products stored within them. One of the commonly extracted compounds from microalgae is lipids, which constitute a high percentage of their composition. In this study, we conducted ultrasonic pre-treatment on two different microalgae species, namely Chlorella vulgaris and Nannochloropsis oculata. The pre-treatment involved ultrasonic frequencies of 37 and 80 kHz, exposure times of 10, 15, and 20 min, and extraction times of 2, 3, and 4 h. By utilising ultrasonic frequencies, we induced acoustic cavitation to break the microalgae cell walls and extract lipids. The experimental design followed a Response Surface Methodology (RSM) to evaluate the effect of ultrasonication pretreatment parameters on lipid extraction. In comparison to previously published studies, our findings indicate that higher frequencies of ultrasonication lead to increased lipid extraction from microalgae. The highest lipid yield achieved in our study was 11.54% for Chlorella vulgaris and 17.91% for Nannochloropsis oculata , using the input factors of 80 kHz frequency, 20 min of running time, and 4 h of extraction time. Our results contribute to the existing body of knowledge by demonstrating the efficacy of ultrasonic pre-treatment in lipid extraction from microalgae. By providing a quantitative comparison with previous studies, this study highlight the novel aspects of work and its potential implications for the production of biofuels and other valuable products from microalgae. • Ultrasonication pre-treatment on microalgae Chlorella vulgaris and Nannochloropsis oculata was found to be effective. • Lipid yield was transesterified into biodiesel using solvents CH 3 OH and concentrated H 2 SO 4. • Response surface methodology was used to optimise the Lipid efficiency. • Maximum lipid efficiency of 11.54% for Chlorella vulgaris and 17.91% for Nannochloropsis oculata was achieved. [ABSTRACT FROM AUTHOR]

• Hydrodynamic cavitation (HC) is a highly effective, low-cost, and eco-friendly process. • The working principle of hydrodynamic cavitation is explained. • The recent applications of HC technique for food processing are discussed. • Application of HC for cell disruption and selective enzyme release has been discussed. • The HC processed foods showed improved physicochemical properties and bioactive stability. • The HC technology can be considered as a green technology for large-scale food processing applications. Hydrodynamic cavitation (HC) is the process of bubbles formation, expansion, and violent collapse, which results in the generation of high pressures in the order of 100–5000 bar and temperatures in the range of 727–9727 °C for just a fraction of seconds. Increasing consumer demand for high-quality foods with higher nutritive values and fresh-like sensory attributes, food processors, scientists, and process engineers are pushed to develop innovative and effective non-thermal methods as an alternative to conventional heat treatments. Hydrodynamic cavitation can play a significant role in non-thermal food processing as it has the potential to destroy microbes and reduce enzyme activity while retaining essential nutritional and physicochemical properties. As hydrodynamic cavitation occurs in a flowing liquid, there is a decrease in local pressure followed by its recovery; hence it can be used for liquid foods. It can also be used to create stable emulsions and homogenize food constituents. Moreover, this technology can extract food constituents such as polyphenols, essential oils, pigments, etc., via biomass pretreatment, cell disruption for selective enzyme release, waste valorization, and beer brewing. Other applications related to food production include water treatment, biodiesel, and biogas production. The present review discusses the application of HC in the preservation, processing, and quality improvement of food and other related applications. The reviewed examples in this paper demonstrate the potential of hydrodynamic cavitation with further expansion toward the scaling up, which looks at commercialization as a driving force. [ABSTRACT FROM AUTHOR]

One of the critical challenges in releasing protein from microalgae is to effectively disrupt their rigid thick cell walls. This study could provide some guidance on the implementation of a simple, cost-effective and scalable cell disruption in a downstream processing of microalgal industry for the recovery of protein from microalgae. The effects of solvent types, alkalis, and ultrasonication in disrupting microalgal cell wall and protein solubility were studied. It was found that alkaline treatment played a key role in cell disruption and protein solubilisation. From the industrial perspective, water is an excellent choice of extractive solvent due to low-cost, safety, and scalability. Among all the tested methods, the combination of both alkaline and ultrasonication treatment demonstrated the greatest cell disruption efficiency and was thus suggested to be use at large scale. [ABSTRACT FROM AUTHOR]

Pulsed Electric Fields (PEF) and High Pressure Homogenization (HPH) are promising and scalable cell disruption technologies of microalgae cells. In this work, the permeabilization degree, morphological properties, and extractability of intracellular compounds from microalgae Chlorella vulgaris suspensions (1.2%, w/w) were investigated as a function of PEF treatment at different electric field strengths (10–30 kV/cm) and total specific energy input (20–100 kJ/kg), in comparison with the more disruptive HPH treatment (150 MPa) at different number of passes (n P  = 1–10). The conductivity and the particle size analyses, as well as the SEM images, clearly showed that PEF induces the permeabilization of the cell membranes in an intensity-dependent manner, without producing any cell debris, whereas HPH treatment causes the total disruption of the algae cells into small fragments. Coherently with the lower permeabilization capability, PEF promoted the selective extraction of carbohydrates (36%, w/w, of total carbohydrates), and low molecular weight proteins (5.2%, w/w, of total proteins). On the other hand, HPH induced the undifferentiated release of all the intracellular content, resulting in a 1.1 and 10.3 fold higher yields than PEF, respectively of carbohydrates and protein. These results suggest that, in a multi-stage biorefinery, PEF could represent a suitable cell disruption method for the selective recovery of small-sized cytoplasmic compounds, while HPH should be placed at the end the cascade of operations allowing the recovery of high molecular weight intracellular components. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effectiveness of extrusion on cell disruption of a marine alga Nannochloropsis oceanica with a single-screw extruder for the production of intracellular valuables. The effect of operating parameters including feed moisture (15–24%) and screw rotation speed (300–450 rpm) was also determined. Experimental results demonstrated that extrusion was effective in algal cell disruption indicated by direct observation of cell break-up through scanning electron microscope (SEM) and significant increases up to 94.3% and 68.7% in lipid and sugars yield, respectively between treatments and the control (no treatment). It was found that feed moisture (15%) generally improved cell disruption efficiency due to longer residence time of biomass in the extruder. Increasing screw rotation speed from 300 to 450 rpm tended to enhance cell disruption because of stronger shear forces on algae. However, the effectiveness was restricted by residence time of biomass in the extruder because a faster screw rotation speed resulted in a higher biomass flow rate. Thus, the optimal cell disruption was not always achieved at the fastest screw rotation speed; instead, it appeared at the levels depending on specific evaluation indicators (around 350 rpm), therefore the optimal conditions for algal cell disruption were obtained at about 15% of feed moisture and 350 rpm of screw rotation speed. This study also confirmed that extrusion was beneficial for the production of more valuables including polyunsaturated fatty acids (PUFA) and essential amino acids (EAA) from microalgae, for example up to 74.3% increase of PUFA and 20.5% increase of EAA after extrusion compared to the control. [ABSTRACT FROM AUTHOR]

Due to the rigid cell wall of Chlorella species, it is still challenging to effectively extract significant amounts of protein. Mass methods were used for the extraction of intracellular protein from microalgae with biological, mechanical and chemical approaches. In this study, based on comparison of different extraction methods, a new protocol was established to maximize extract amounts of protein, which was involved in ethanol soaking, enzyme digest, ultrasonication and homogenization techniques. Under the optimized conditions, 72.4% of protein was extracted from the microalgae Chlorella pyrenoidosa , which should contribute to the research and development of Chlorella protein in functional food and medicine. [ABSTRACT FROM AUTHOR]

The microalgae-based biorefinement process has attracted much attention from academic and industrial researchers attracted to its biofuel, food and nutraceutical applications. In this paper, recent developments in cell-disruption and lipid-extraction methods, focusing on four biotechnologically important microalgal species (namely, Chlamydomonas , Haematococcus , Chlorella , and Nannochloropsis spp.), are reviewed. The structural diversity and rigidity of microalgal cell walls complicate the development of efficient downstream processing methods for cell-disruption and subsequent recovery of intracellular lipid and pigment components. Various mechanical, chemical and biological cell-disruption methods are discussed in detail and compared based on microalgal species and status (wet/dried), scale, energy consumption, efficiency, solvent extraction, and synergistic combinations. The challenges and prospects of the downstream processes for the future development of eco-friendly and economical microalgal biorefineries also are outlined herein. [ABSTRACT FROM AUTHOR]

To examine the possibility of better utilizing Chlorella vulgaris biomass including its carbohydrate as well as lipid contents, it was investigated whether cell disruption for lipid extraction could render the remaining microalgal residue (MR) suitable for enzymatic saccharification, possibly due to the disruption of cell wall structures. The C. vulgaris biomass was subjected to lipid extraction with different cell disruption methods (autoclaving, microwave irradiation, osmotic shock, and sonication), and recovered MRs were hydrolyzed using an enzyme produced from Trichoderma koningiopsis KUC21269 in this study. The enzyme was produced on-site with a highly simplified medium of barley straw, an agricultural byproduct. As a result, the saccharification rate of MR treated with microwave was more than twice that of the control group, and microwave irradiation appeared to be a promising method for both lipid extraction and subsequent saccharification. Our results suggested that both lipids and carbohydrates in C. vulgaris can be utilized by applying proper cell disruption method and a fungal enzyme produced on-site using an agricultural byproduct, respectively. This study revealed the high potential of C. vulgaris as an integrated bio-resource for both lipids and glucose, which can be converted to biodiesel and bioethanol, providing clues for overcoming hurdles in economically feasible biofuel production using microalgae. [ABSTRACT FROM AUTHOR]

In this study, ozone was used as a pretreatment method to improve the yield in enzymatic saccharification of microalgal carbohydrates by increasing the disruption of microalgal cells. Different ozone doses (0.25–2.0 g O 3 g −1 dry weight biomass (DWB)) were applied to the algal suspensions before the enzymatic hydrolysis process, which was performed at various enzyme concentrations, enzymatic hydrolysis times and biomass concentrations. The highest glucose yield obtained was 80.6% (w/w) of total carbohydrates under the conditions of 2.5 g L −1 biomass concentration and 4 h hydrolysis time for 0.5 g O 3 g −1 DWB ozone dose and 1.2 mL −1 g −1 DWB enzyme concentration. In addition to ozone pretreatment, the same algal culture was subjected to acid, alkaline and ultrasonic pretreatments. It was observed that application of ozone increased the glucose yield much higher than the other three pretreatment methods, indicating its great potential in production of bioethanol from microalgae. [ABSTRACT FROM AUTHOR]

Demand for food production has increased due to population growth. The negative environmental impact of animal agriculture necessitates the search for alternatives to animal protein-based products. Potential health benefits from micronutrient-rich seaweeds have attracted significant attention for further research. This encourages the use of seaweed as an alternative protein-rich source. However, traditional seaweed protein extraction presents drawbacks because of energy and water-intensive treatments and poor extraction yield, which limit their application. There is an urge for cost-effective, novel, and sustainable technologies for seaweed protein extraction at the right techno-economics. Thus, this review article discusses the economic potential of seaweed proteins and identifies the traditional technologies applied to extract seaweed protein and their limitations. A detailed analysis of novel methods that could potentially be utilized to extract and enrich seaweed protein is presented. Various protein quantification/qualification approaches reported in the literature have been thoroughly assessed to compare their advantages and disadvantages. Technologies like the pulsed electric field, ultrasound- and microwave-assisted extraction, high-pressure processing, and subcritical-water extraction have huge potential to extract protein from seaweed sustainably yet are relatively under-explored. More research is required to develop further insights on the process-quality inter-relationship of these technologies for improved seaweed protein extraction. Essential amino acid index, protein digestibility corrected amino acid score, and digestible indispensable amino acid score are the best approaches to evaluate seaweed protein quality for human consumption. However, reported studies have barely covered these aspects, including seaweed protein's sensorial quality. • Alternative protein and sustainable protein shift • Eco-innovative protein extraction • Cell disruption and protein isolation • Seaweed protein quantification • Food processing and novel technologies [ABSTRACT FROM AUTHOR]

Cell disruption to break the rigid algal cell wall was essential to improve the utilization of resources enriched in microalgae. This study aimed to compare the effects of alkali, ultrasound, and the synergistic effect of ultrasonic and alkali on microalgae disruption and preliminarily investigated the synergistic disruption mechanism. The effect of the above methods on the disruption of microalgal cells was quantified by measuring protein and TOC release. Under the optimized conditions of the UA method (initial pH: 12.0, sound intensity: 6 W/mL, 40 min), the protein release was 360.42 mg/g TS, which were 5.6 and 7.1 times higher than those of alkali and ultrasound, respectively. EEMs spectroscopy showed that org-N compounds were mainly released during UA treatment of Chlorella pyrenoidosa (C. pyrenoidosa), with soluble microbial by-product-like compounds predominating. With free radical detection and particle size analysis, it was found that nutrient release occurred mainly during the microalgal bloom dispersion and individual microalgal micro-fragmented phases. The practical applicability of the synergistic strategy was also investigated. Microalgal hydrolytic acidification after UA pretreatment was suitable for VFAs production. Compared to the blank group, the peak VFAs production (392.5 mg COD/g VSS) increased by 200 % and the time reduced from 11 days to 9 days. These results indicated that synergistic disruption pretreatment was expected to improve the performance of microalgal biomass hydrolytic acidification. [Display omitted] • Ultrasonic-alkali (UA) was more suitable for cell disruption. • Protein release in UA were 5.6 and 7.1 times higher than that of alkali and ultrasound. • Physical effects were the main contributor to microalgal disruption. • Nutrient release occurred mainly during the microalgal micro-fragmented phases. • UA disruption pretreatment was suitable for microalgal hydrolytic acidification. [ABSTRACT FROM AUTHOR]

Spirulina platensis is considered an alternative and excellent source of protein [46–63% dry basis (DB)], having protein levels comparable to meat and soybeans. Thus, it can be considered an adequate ingredient to supply the necessity of this compound in the food industry. Its carbohydrates (8–14% DB) may also be a useful food ingredient or a potential source of bioenergy. Thus, extracting these compounds from the microalgae biomass will maximize its exploitation. Sonication can completely or partially degrade the microalgal cell wall, providing a useful technique to extract the protein and carbohydrate. This study used a sequential strategy of experimental design (fractional factorial design and central composite rotatable design) to evaluate the protein and carbohydrate extraction from S. platensis defatted biomass using ultrasonic waves and mechanical agitation, under alkaline conditions. The optimal conditions for protein and carbohydrate co-extraction were established by selecting and maximizing the variables that significantly influenced the extraction. The optimized percentages recovery from the extraction process yielded 75.76% protein and 41.52% carbohydrate at 33–40 min sonication and 40–55 min agitation. The protein fraction may be further concentrated and purified for use in food formulations, and the carbohydrates may be a useful feedstock for bioethanol production. [ABSTRACT FROM AUTHOR]

High-pressure jet devices (HPJDs) support high throughput and are cost-effective in reducing excess activated sludge. We aimed to identify the dominant mechanism among frictional shear, collision, and cavitation on bacterial cell disruption and intercellular substances eluted by an HPJD. An HPJD was modified to disassociate these three mechanisms so that they could be analyzed separately. Gram-negative and Gram-positive bacteria ( Escherichia coli and Bacillus subtilis , respectively) were subjected to treatment by the modified HPJD device. Frictional shear, collision, and cavitation were found to damage 11.12 ± 1.12%, 11.97 ± 1.12%, and 23.70 ± 2.35% of E. coli cell and 5.2 ± 1.57%, 7.81 ± 1.09%, and 28.54 ± 3.45% of B. subtilis cell, respectively. The application of atomic force microscopy (AFM) displayed different morphological changes of E. coli and B. subtilis cells induced by frictional shear, collision, and cavitation. Frictional shear and collision deformed E. coli cells but not severely B. subtilis cells, merely increasing the cell surface roughness. In contrast, cavitation directly contributed to implosion of B. subtilis cells, resulting in higher concentrations of released intracellular DNA, polysaccharide and protein than those by frictional shear and collision. Despite the distinct cell disruption mechanisms, cavitation commonly provided the most intense effect on cell disintegration and the release of intracellular components for both E. coli and B. subtilis . [ABSTRACT FROM AUTHOR]

The toughness of microalgal cell walls makes lipid extraction and large-scale biodiesel production difficult. This study investigated the enzymatic hydrolysis of algal cell walls, in which the enzymes were produced by eight biomass-degrading bacterial strains. The bacteria were first cultured in mineral salt medium containing 5% (w/v) wheat bran and various lignocellulolytic enzymes, including exoglucanases (CMCase), endoglucanases (FPase), xylanase, and laccase were monitored in order to obtain an enzymatic extract. All the strains showed marked CMCase activity, with a range of 3.0–6.9 U ml −1 after incubation for 2–5 d. Some strains also produced FPase, xylanase, and laccase. The enzymatic extract was directly added to fresh algae culture at a ratio of 1:3 (v/v) for 48 h. All the bacterial enzymatic extracts significantly disrupted algal cell walls, according to the enhancement of reducing sugar content in the culture. The lipid extraction yield was markedly increased by 10.4–43.9%, depending on the bacteria strains used. Due to its high reducing sugar production and lipid extraction efficiency, Bacillus sp. K1 was selected for a time-course experiment. Maximum lipid yield was obtained after 24 h of incubation at the room temperature, with about 40% of the cells were disrupted. These results showed that enzymes produced by biomass-degrading bacteria can weaken and disrupt cell walls and components of algae and facilitate the release of lipids from algae. [ABSTRACT FROM AUTHOR]

In this study, the microalga Nannochloropsis gaditana was subjected to acid catalysed steam explosion treatment and the resulting exploded material was subsequently fractionated to separate the different fractions (lipids, sugars and solids). Conventional and vibrational membrane setups were used with several polymeric commercial membranes. Two different routes were followed: 1) filtration + lipid solvent extraction and 2) lipid solvent extraction + filtration. Route 1 revealed to be much better since the used membrane for filtration was able to permeate the sugar aqueous phase and retained the fraction containing lipids; after this, an extraction required a much lower amount of solvent and a better recovering yield. Filtration allowed complete lipid rejection. Dynamic filtration improved permeability compared to the tangential cross-flow filtration. Best membrane performance was achieved using a 5000 Da membrane with the dynamic system, obtaining a permeability of 6 L/h/m 2 /bar. [ABSTRACT FROM AUTHOR]

Microalgae has potential as a biofuel feedstock and as a source of valuable bioproducts for a variety of food, feed, nutraceutical, and pharmaceutical industries due to high yields of proteins, starch, and lipids. However, several challenges are associated with bioproduct extraction from microalgae. The complexity of microalgae cell walls necessitates use of energy intensive disruption methods, but current chemical or mechanical techniques can degrade economically valuable bioproducts. Therefore, disruption methods that target microalgae cell walls are essential, such as enzymatic biomass pretreatment for the release of specific biomolecules. Aqueous enzymatic pretreatment can preserve valuable bioproducts while permitting high levels of cell disruption. In this study, we optimized harvesting times that maximized protein yields in nitrogen depleted cultures and promoted lipid accumulation in the microalgae Chlamydomonas reinhardtii . Furthermore, an aqueous enzymatic assisted extraction (AEAE) treatment was developed. Four lytic enzymes were tested for their ability to permeate C. reinhardtii cell walls. Autolysin treatment was chosen as preferred cell disruption method. Treated cells were visualized by TEM imaging. TEM images and cell counts confirmed cell permeability (100%) and further cell lysis (50%) and product release when cells were treated with autolysin for 24 h. Biomass was also subjected to lipid and protein extraction after autolysin treatment and yields were compared to other mechanical and chemical extraction methods. Protein extractability was significantly enhanced by the autolysin pretreatment when compared to sonication pretreatment. Solvent extraction accompanied with autolysin biomass pretreatment significantly enhanced lipid extractable yields as compared to only solvent extraction and solvent plus sonication extraction. [ABSTRACT FROM AUTHOR]

Protic ionic liquids (PILs) with their ability to host labile protons and form hydrogen bonds are likely to be efficient catalyst for bioprocessing. This is one of the first reports investigating PIL-assisted microalgal cell disruption and lipid extraction. The applicability of several PILs with butyrolactam, caprolactam, propylammonium and hydroxypropylammonium cations in combination with formate, acetate and hexanoate anions for cell disruption and lipid extraction from fresh water Chlorella and Chlorococcum sp. have been evaluated in this study. The investigations were performed with de-watered wet microalgae under ambient temperatures and hence do not require any energy intensive drying and/or processing steps. The PILs with formate and hexanoate anions when compared with conventional pre-treatment techniques: sonication, microwave and cellulase provided better microalgal cell disruption efficiencies. The FESEM analysis for the Butyrolactam hexanoate (BTH) treated cells show extensive pattern of microalgal cell disruption. The fluorescence imaging analysis coupled with culturing experiments indicates a near-complete disruption and loss in viability of the PIL-treated microalgal cells. The lipid yield from the formate and hexanoate anions-PILs was statistically comparable and/or higher to the Bligh & dyer control method. Among the PILs, BTH recorded 1.86 and 1.72 folds higher lipid yields than the control method with Chlorella and Chlorococcum sp. respectively. The lipids show predominance of C 16 and C 18 fatty acids similar to lipid profile obtained with the control method. Furthermore, the PILs were also found to have a beneficial role in reducing the chlorophyll pigments in the final lipid product. Overall, the results show PILs with formate and hexanoate anions can be utilized for a relatively energy efficient, one-step cell disruption and lipid extraction process from wet microalgae. [ABSTRACT FROM AUTHOR]

Marine microorganisms represent a rich source of enzymes with the potential industrial application. In this study, we screened novel thraustochytrids for a range of enzymatic activities. The similarity between isolates based on enzyme activities was investigated using cluster analysis. Thraustochytrids were observed to possess different enzymatic activities, however, we focused on lipase activity. Two strains AMCQ-4b27 (34 IU/g) and AMCQS1-9 (36 IU/g) exhibited highest intracellular lipase activity among the isolates. To extract lipase, four different cell disruption methods such as bead vortexing, grinding, sonication and homogenization, were evaluated for their efficiency on lipase extraction yields and quality. Sonication was found to be the best method for enhancing lipase extraction yields from Thraustochytrium sp. AMCQ-4b27 (0.903 IU/μg) and Schizochytrium AMCQS1-9 (1.44 IU/μg). [ABSTRACT FROM AUTHOR]

Microalgae are promising sources of lipids for applications in food, fuel, pharmaceutics and cosmetics. However, these lipids are also subject to lipolysis reactions during processing and storage. Especially during wet biomass storage, substantial amounts of free fatty acids (FFA) are formed, which has negative effects on flavor and nutritional value and can cause downstream processing problems in biodiesel production. This study contributes to a better understanding of the underlying processes leading to lipolysis by focusing on cell wall differences between species. Therefore, in a first phase, a comparison was made between the lipolytic stability of Nannochloropsis oculata and T-Isochrysis lutea , two species reported to have substantial differences in cell wall structure and strength. Nannochloropsis appeared to be stable during the first days of wet storage, while in T-Isochrysis , lipolysis started immediately after harvest. In a second experiment, the influence of cell disruption by high pressure homogenization (HPH) on lipolytic stability during wet storage of Nannochloropsis was investigated. It was observed that the HPH treatment induced lipolysis, as the FFA content was rapidly increasing immediately after the treatment, in contrast to the control sample, in which the FFA content was constant during the first days of storage. The integrity of the microalgal cell was thus found to play a crucial role in lipid stability during short-term post-harvest wet storage. [ABSTRACT FROM AUTHOR]

Many studies have focused on the possibility of applying graphene oxide as an effective drug delivery system, but also as an effective tool for a thermally-responsive system. Thus, the main aim of the study was to evaluate the cellular response of the MCF-7 cell line to covalently and non-covalently conjugated graphene oxide with hydroxycamptothecin (GO-HCPT) and the effect of an 8-h rotating magnetic field (RMF) exposure. The objective of this novel approach is to use graphene oxide platform not only as a drug delivery system, but also as an effective tool for a thermally-responsive system. The present study analyzed the effect of nanocomposites and RMF on the activity of MCF-7 cells and revealed that mitochondrial metabolism was significantly reduced in the cells incubated under all tested RMF parameters. In all tested variants of c-GO-HCPT concentrations and RMF inductions, cell viability was reduced by approximately 10–50% (data from WST-1 assay) for cells incubated with nanocomposite for 24 h and 70–90% for cells incubated with nanocomposite for 48 h. The observed LDH leakage was higher for cells exposed to c-GO-HCPT for longer incubation time. In the case of nc-GO-HCPT, the relative viability was reduced by 10–30%, respectively to the sample concentration and magnetic induction value for 48-h incubation. The data obtained in the NR assays after 24 h confirmed slightly higher cytotoxic co-effect of nc-GO-HCPT with cellular metabolism reduced by 90–98%. The concentration of nanomaterials also influenced mitochondrial metabolism. Both tested nanomaterials, c-GO-HCPT and nc-GO-HCPT, and RMF affected effectively the metabolism and viability of the cells, but not in a dose-dependent manner. A small difference in cellular response was observed in the presence of non-covalent and covalent GO-HCPT, with a slightly higher cytotoxicity effect of nc-GO-HCPT, visible 24 h after the experiment. These findings could have potential clinical application, including targeted tumor chemotherapy and thermal ablation. [ABSTRACT FROM AUTHOR]

A simultaneous cell disruption and lipid extraction method is developed for microalgal biodiesel production using a triethylamine/methanol solvent system. Individually, the pure solvents, i.e. triethylamine and methanol, do not exhibit significant enhancement in lipid extraction, but a 3:7 (v/v) triethylamine/methanol mixture exhibits the highest lipid extraction, corresponding to 150% of the conventional chloroform/methanol (2:1, v/v) solvent extraction. This extraction is equivalent to 92.5% of the total lipids, even when extracted from a wet microalgal biomass with a water content of 80%. The cell surfaces of the microalgae are significantly disrupted without using additional cell disruption reagents and without requiring energy-intensive equipment. The lipid mass transfer coefficient is 1.6 times greater than that of the chloroform/methanol solvent system. It is clearly demonstrated that triethylamine and methanol cooperate well for the cell disruption and lipid extraction. [ABSTRACT FROM AUTHOR]

Laccases belong to multicopper oxidases and are widespread in nature. Currently, mainly fungal laccases are applied in biotechnological processes. One reason for this is that fungal laccases are much better studied. Compared to fungal laccases, bacterial laccases possess some advantageous characteristics like high stability at elevated temperatures and alkaline pH values. Intracellular recombinant expression of bacterial laccases in E. coli makes however downstream processing more complex and time-consuming compared to extracellular expression of fungal enzymes. Here, we demonstrate that cell disruption by cell thermolysis is an efficient and simple method for the isolation and partial purification of recombinant bacterial laccases. Three different laccases, Tth from Thermus thermophilus , CotA from Bacillus subtilis and Ssl1 from Streptomyces sviceus , were used to compare cell disruption by cell thermolysis with sonication and high-pressure homogenization, with and without subsequent heat treatment. Cell thermolysis resulted in high laccase activities per gram of cell wet weight and in the highest specific activities of the laccases. For example, specific activity of Tth laccase after cell thermolysis was 469-fold higher than after sonication. Furthermore, high decolorization activity towards indigo carmine and alizarin red S of these laccases, isolated via cell thermolysis, demonstrate their potential for technical applications. [ABSTRACT FROM AUTHOR]

The aim of this research was to optimize the energy recovery in the form of biodiesel and biogas from ubiquitous Spirulina platensis microalgae. Investigations were undertaken to select appropriate cell disruption technique, organic solvent for lipid recovery and catalyst for transesterification reaction for biodiesel production from Spirulina platensis . Based on energy considerations, osmotic shock was the most suitable cell disruption technique which recorded highest lipid recovery yield of 8.9% when chloroform/methanol (1:2 v/v ) was used as solvent. The extracted lipid from Spirulina platensis was esterified into Fatty Acid Methyl Esters (biodiesel) using sulfuric acid as the catalyst with conversion up to 79.5%. Under these conditions, biodiesel yield of 7.1 % (based on biomass weight) was obtained. Investigations also brought out that the lipid-extracted residue can be used as feedstock for biogas production with the average methane yield of about 290 ml/gVS. [ABSTRACT FROM AUTHOR]

Biofuel from marine microalgae is an attractive green sustainable product because marine microalgae absorb greenhouse gases (GHG) such as carbon dioxide during photosynthesis and microalgae based biofuel are free from sulphur during fuel combustion. The main obstacle for biodiesel production from marine microalgae is the high cost due to many downstream stages involved such as harvesting, dewatering, drying, extraction, separation and transesterification processes. In order to address these issues, the one step process is introduced where lipids are directly extracted and transesterified from wet biomass and processed using simultaneous cooling and microwave heating transesterification (SCMH) which is a green technology since microwave heating consumes only one third of the conventional heating energy and the cooling effect promotes more microwave penetration to the reaction mixture. This one step biodiesel production via SCMH was then benchmarked against the conventional one step process using the water bath heating and microwave assisted transesterification. The results revealed one step SCMH produced higher biodiesel production (75%) than water bath (13.46%) and microwave method (15.39%). The biodiesel production via SCMH was almost 5 times higher than the other methods. Biodiesel properties and cell disruption produced from SCMH method were also better than the other two methods. [ABSTRACT FROM AUTHOR]

A mild biorefinery process was investigated on the microalga Nannochloropsis gaditana , to obtain an enriched fraction of water soluble proteins free from chlorophyll. After harvesting, a 100 g.L −1 solution of cells was first subjected to cell disruption by either high-pressure homogenization (HPH) or enzymatic treatment (ENZ). HPH resulted in a larger release of proteins (49%) in the aqueous phase compared to the Alcalase incubation (35%). In both cases, an ultrafiltration/diafiltration (UF/DF) was then performed on the supernatant obtained from cell disruption by testing different membrane cut-off (1000 kDa, 500 kDa and 300 kDa). After optimising the process conditions, the combination of ENZ → UF/DF ended in a larger overall yield of water soluble proteins (24.8%) in the permeate compared to the combination of HPH → UF/DF (17.4%). A gel polarization model was implemented to assess the maximum achievable concentration factor during ultrafiltration and the mass transfer coefficient related to the theoretical permeation flux rate. [ABSTRACT FROM AUTHOR]

The goal of this study was to reveal the mechanism of bacterial cell disruption by a high-pressure jet device (HPJD) for the reduction of excess sludge produced during wastewater treatment. Escherichia coli and Bacillus subtilis , representative Gram-negative and Gram-positive bacteria respectively, were subjected to HPJD treatment followed by observation of the damaged cells with epifluorescence microscopy and atomic force microscopy (AFM), as well as spectrophotometric quantification of the released intracellular polymeric compounds. The AFM observations demonstrated that the types of cell damage incurred by E. coli and B. subtilis were distinct. B. subtilis showed modest cell disruption comprising partial damage, i.e. , the formation of pores and cracks on the cell envelope. In contrast, E. coli showed more extensive damage, i.e. , cell cleavage and lysis, in addition to the partial damages observed for B. subtilis . The damaged cells of both bacterial species also exhibited leakage of intercellular compounds such as DNA, proteins and polysaccharides. This loss of intracellular macromolecules resulted in increased cell surface roughness and decreased cell diameter and elasticity, irrespective of the bacterial species tested. The results demonstrated that the degree of cell damage inflicted by HPJD treatment is dependent on the cell wall and membrane structure of the bacterial species. In summary, we propose multiple possible mechanisms of cell disruption resulting from HPJD treatment. [ABSTRACT FROM AUTHOR]

Carotenoids have been receiving increasing attention due to their potential health benefits. Microalgae are recognized as a natural source of carotenoids and other beneficial byproducts. However, the production of micro-algal carotenoids is not yet sufficiently cost-effective to compete with traditional chemical synthetic methods and other technologies such as extraction from plant based sources. This review presents the recent biotechnological developments in microalgal carotenoid production. The current technologies involved in their bioprocessing including cultivation, harvesting, extraction, and purification are discussed with a specific focus on downstream processing. The recent advances in chemical and biochemical synthesis of carotenoids are also reviewed for a better understanding of suitable and economically feasible biotechnological strategies. Some possible future directions are also proposed. [ABSTRACT FROM AUTHOR]