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Phospholipids are distinctive, adaptable molecules that are crucial to numerous biological systems. Additionally, their various architectures and amphiphilic characteristics support their unrivaled crucial functions in scientific and industrial applications. Due to their enormous potential for use in the fields of medicine, food, cosmetics, and health, structured phospholipids, which are modified phospholipids, have garnered increased attention. Traditional extraction methods, however, are pricy, resource-intensive, and low-yielding. The process of enzyme-catalyzed conversion is effective for producing several types of structured phospholipase. However, most frequently employed catalytic procedures involve biphasic systems with organic solvents, which have a relatively large mass transfer resistance and are susceptible to solvent residues and environmental effects due to the hydrophobic nature of phospholipids. Therefore, the adoption of innovative, successful, and environmentally friendly enzyme-catalyzed conversion systems provides a new development route in the field of structured phospholipids processing. Several innovative catalytic reaction systems are discussed in this mini-review, including aqueous-solid system, mixed micelle system, water-in-oil microemulsion system, Pickering emulsion system, novel solvent system, three-liquid-phase system, and supercritical carbon dioxide solvent system. However, there is still a glaring need for a thorough examination of these systems for the enzymatic synthesis of structural phospholipids. In terms of the materials utilized, applicability, benefits and drawbacks, and comparative effectiveness of each system, this research establishes further conditions for the system's selection. To create more effective biocatalytic processes, it is still important to build green biocatalytic processes with improved performance. Key points: • The latest catalytic systems of phospholipase D are thoroughly summarized. • The various systems are contrasted, and their traits are enumerated. • Different catalytic systems' areas of applicability and limitations are discussed. [ABSTRACT FROM AUTHOR]

Phospholipids are distinctive, adaptable molecules that are crucial to numerous biological systems. Additionally, their various architectures and amphiphilic characteristics support their unrivaled crucial functions in scientific and industrial applications. Due to their enormous potential for use in the fields of medicine, food, cosmetics, and health, structured phospholipids, which are modified phospholipids, have garnered increased attention. Traditional extraction methods, however, are pricy, resource-intensive, and low-yielding. The process of enzyme-catalyzed conversion is effective for producing several types of structured phospholipase. However, most frequently employed catalytic procedures involve biphasic systems with organic solvents, which have a relatively large mass transfer resistance and are susceptible to solvent residues and environmental effects due to the hydrophobic nature of phospholipids. Therefore, the adoption of innovative, successful, and environmentally friendly enzyme-catalyzed conversion systems provides a new development route in the field of structured phospholipids processing. Several innovative catalytic reaction systems are discussed in this mini-review, including aqueous-solid system, mixed micelle system, water-in-oil microemulsion system, Pickering emulsion system, novel solvent system, three-liquid-phase system, and supercritical carbon dioxide solvent system. However, there is still a glaring need for a thorough examination of these systems for the enzymatic synthesis of structural phospholipids. In terms of the materials utilized, applicability, benefits and drawbacks, and comparative effectiveness of each system, this research establishes further conditions for the system's selection. To create more effective biocatalytic processes, it is still important to build green biocatalytic processes with improved performance. Key points: • The latest catalytic systems of phospholipase D are thoroughly summarized. • The various systems are contrasted, and their traits are enumerated. • Different catalytic systems' areas of applicability and limitations are discussed. [ABSTRACT FROM AUTHOR]

Chitosan derivates with varying degrees of polymerization (DP) have attracted great concern due to their excellent biological activities. Increasing the abundance of chitosanases with different degradation modes contributes to revealing their catalytic mechanisms and facilitating the production of chitosan derivates. However, the identification of endo-chitosanases capable of producing chitobiose and D-glucosamine (GlcN) from chitosan substrates has remained elusive. Herein, an endo-chitosanase (CsnCA) belonging to the GH46 family was identified based on structural analysis in phylogenetic evolution. Moreover, we demonstrate that CsnCA acts in a random endo-acting manner, producing chitosan derivatives with DP ≤ 2. The in-depth analysis of CsnCA revealed that (GlcN)3 serves as the minimal substrate, undergoing cleavage in the mode that occupies the subsites − 2 to + 1, resulting in the release of GlcN. This study succeeded in discovering a chitosanase with distinctive degradation modes, which could facilitate the mechanistic understanding of chitosanases, further empowering the production of chitosan derivates with specific DP. Key points: • Structural docking and evolutionary analysis guide to mining the chitosanase. • The endo-chitosanase exhibits a unique GlcN-producing cleavage pattern. • The cleavage direction of chitosanase to produce GlcN was identified. [ABSTRACT FROM AUTHOR]

In this study, we proposed a reliable and sustainable technique for the clean utilization of shrimp wastes, which can yield a solid inoculant of Bacillus subtilis OKF04 containing micronutrients at low cost without the risk of contamination. Study of the culture conditions revealed that the head of shrimp Litopenaus vannamei and the wheat bran acted as suitable substrates for the growth of B. subtilis OKF04. With 60% initial moisture content, 30 °C culture temperature, and 5 % inoculation amount, followed by 48 hours of fermentation and 0.5% soluble starch added during the drying process (50°C for 6 h), a solid B. subtilis OKF04 inoculant with a spore amount of 2.4×1010 CFUg−1 and a high amino acid content was obtained. The solid B. subtilis OKF04 inoculant was applied to cultivate pakchoi under pot experiment. As the result, of adding to, the size of stems and leaves, nutritional composition, and physiological activity of pakchoi were significantly (P<0.05) enhanced by solid B. subtilis OKF04 inoculant. B. subtilis OKF04 also significantly (P <0.05) increased the soil's nutrient content and improved its microbial composition. Furthermore, pakchoi cultivated with a low dose of solid B. subtilis OKF04 inoculant (0.05 g kg−1 soil) resulted in the best results. This study provides a new method for the preparation of microbial inoculants with solid waste shrimp heads. [ABSTRACT FROM AUTHOR]

A novel chitinase gene of 888 bp from Streptomyces bacillaris was cloned and expressed in Escherichia coli BL21. The purified recombinant enzyme (SbChiAJ103) was identified as the first microbial-derived family 19 endochitinase that showed exochitinase activity. SbChiAJ103 exhibited the substrate preference for N-acetylchitooligosaccharides with even degrees of polymerization and the capability to specifically hydrolyze colloidal chitin into (GlcNAc)2. Mono-methyl adipate was employed as a novel linker for the efficient covalent immobilization of chitinase on magnetic nanoparticles (MNPs). The immobilized SbChiAJ103, SbChiAJ103@MNPs, exhibited superior pH tolerance, temperature stability, and storage stability than free SbChiAJ103. Even after incubation at 45 °C for 24 h, SbChiAJ103@MNPs could retain more than 60.0% initial activity. As a result, the enzymatic hydrolysis yield of SbChiAJ103@MNPs increased to 1.58 times that of free SbChiAJ103. Moreover, SbChiAJ103@MNPs could be reused by convenient magnetic separation. After 10 recycles, SbChiAJ103@MNPs could retain almost 80.0% of its initial activity. The immobilization of the novel chitinase SbChiAJ103 paves the way to the efficient and eco-friendly commercial production of (GlcNAc)2. Key points: • The first microbial GH19 endochitinase with exochitinase activity was reported. • Mono-methyl adipate was first employed to immobilize chitinase. • SbChiAJ103@MNPs showed excellent pH stability, thermal stability, and reusability. [ABSTRACT FROM AUTHOR]

Chitosanase, a glycoside hydrolase (GH), catalyzes the cleavage of β-1,4-glycosidic bonds in polysaccharides and is widely distributed in nature. Many organisms produce chitosanases, and numerous chitosanases in the GH families have been intensely studied. The reported chitosanases mainly cleaved the inter-glucosamine glycosidic bonds, while substrate specificity is not strictly unique due to the existence of bifunctional or multifunctional activity profiles. The promiscuity of chitosanases is essential for the different pathways of biomass polysaccharide conversion and understanding of the chitosanase evolutionary process. However, the reviews for this aspect are completely unknown. This review provides an overview of the promiscuous activities, also considering the substrate and product specificity of chitosanases observed to date. These contribute to important implications for the future discovery and research of promiscuous chitosanases and applications related to biomass conversion. Key points: • The promiscuity of chitosanases is reviewed for the first time. • The current review provides insights into the substrate specificity of chitosanases. • The mode-product relationship and prospect of promiscuous chitosanases are highlighted. [ABSTRACT FROM AUTHOR]

Chitosanase could cleave β-1,4-linkage of chitosan to produce chitooligosaccharides (COS) with diverse biological activities. However, there are many limitations on the use of free chitosanase in industrial production. Enzyme immobilization is generally considered a valuable strategy in industrial-scale applications. In this study, the chitosanase Csn-BAC from Bacillus sp. MD-5 was immobilized on Fe3O4-SiO2 magnetic nanoparticles (MNPs) to enhance its properties, which could be recovered easily from reaction media using magnetic separation. The activities of Csn-BAC immobilized with MNPs (MNPs@Csn-BAC) were determined with temperature and pH, and the thermal- and pH-stabilities, respectively. The reusability of the MNPs@Csn-BAC was determined in repeated reaction cycles. Immobilization enhanced the thermal and pH stability of Csn-BAC compared with the free enzyme. After eight reaction cycles using MNPs@Csn-BAC, the residual enzyme activity was 72.15%. Finally, the amount of COS released by MNPs@Csn-BAC was 1.86 times higher than that of the free Csn-BAC in the catalytic performance experiment. The immobilized Csn-BAC exhibits broad application prospects in the production of COS. [ABSTRACT FROM AUTHOR]

Saxitoxin (STX), one of the most toxic paralytic shellfish poisons discovered to date, is listed as a required item of aquatic product safety inspection worldwide. However, conventional detection methods for STX are limited by various issues, such as low sensitivity, complicated operations, and ethical considerations. In this study, an aptamer-triplex molecular switch (APT-TMS) and gold nanoparticle (AuNP) nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive detection of STX. An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS. Specific binding between the aptamer and STX triggered the opening of the switch, which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3′,5,5′-tetramethylbenzidine. Under optimized conditions, the proposed aptasensor showed high sensitivity and selectivity for STX, with a limit of detection of 335.6 pmol L−1 and a linear range of 0.59–150 nmol L−1. Moreover, good recoveries of 82.70%–92.66% for shellfish and 88.97%–106.5% for seawater were obtained. The analysis could be completed within 1 h. The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers. [ABSTRACT FROM AUTHOR]

Plectasin is a promising and potent antimicrobial peptide isolated from the fungus Pseudoplectania nigrella which has been heterologously expressed in various hosts. In this study, a four-copy cassette of plectasin was constructed via 2A peptide assembly to further increase its expression level in recombinant Pichia pastoris. The yeast transformant 4Ple-61 harboring four-copy cassette of plectasin could secrete 183.2 mg/L total protein containing 60.8% of plectasin at the flask level within 120 h, which was 2.3 times higher than that of the yeast transformant Ple-6 carrying one-copy cassette of plectasin. Western blot confirmed the significant peptide expression level in the transformant 4Ple-61. Furthermore, it yielded as high as 426.3 mg/L total protein within 120 h during a 5-L fermentation. The purified plectasin shows superior stability and good antimicrobial activity against conventional Staphylococcus aureus ATCC 26,001 and some food-borne antibiotic-resistant S. aureus strains with the MICs ranging from 8 to 32 μg/mL. Therefore, the strategy based on 2A peptide assembly can enhance the expression of plectasin and further expand its application prospect. Key points: • A yeast transformant 4Ple-61 with four-copy cassette of plectasin was constructed. • The plectasin level yield by the transformant 4Ple-61 was boosted by 2.3 times. • The plectasin showed good activity against food-borne antibiotic-resistant S. aureus. [ABSTRACT FROM AUTHOR]

Okadaic acid (OA) is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning (DSP). Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analysis. In this study, a label-free colorimetric aptasensor was constructed for visual and rapid detection of OA in shellfish. To exploit the binding capability of the anti-OA aptamer, the inherent molecular recognition mechanism of aptamer and OA was studied, based on molecular docking, fluorescent assay, and biolayer interferometry. Consistent results showed that the stem-loop near the 3' terminal of the aptamer exhibit dominate binding capacity. Based on the revealed recognition information, the aptamer was thus rationally utilized and combined with AuNPs and cationic polymer polydiallyl dimethyl ammonium chloride (PDDA) for the development of the label-free colorimetric aptasensor, in which the 3′ terminal was thoroughly exposed to OA. The aptasensor provided robust performance with a linear detection range of 100–1200nmol L−1, a limit of detection of 41.30nmol L−1, recovery rates of 91.6%–106.2%, as well as a high selectivity towards OA in shellfish samples. The whole detection process can be completed within 1 h. To our best knowledge, this is the first time that the anti-OA aptamer was thoroughly studied, and a label-free colorimetric aptasensor was rationally designed in this way. This study not only provides a rapid detection method for highly sensitive and specific detection of OA, but also serves as a reference for the design of efficient aptasensors in the future. [ABSTRACT FROM AUTHOR]

Hydrogel has high water content and structural similarity with natural extracellular matrix. So it has been widely studied and applied in the field of biomedicine. In order to further develop multifunctional hydrogels, we prepared mixed gels with anti-ultraviolet properties. This study found that the addition of polysaccharides and polyphenols was beneficial to the rheological, mechanical properties, and biological activity of the protein. Chitosan (CS) could significantly improve the viscoelasticity, hardness, gel strength, thermal stability and crystallinity of gelatin. Interestingly, the addition of gallic acid (GA) could not only provide significant cross-linking effect, improve gel properties and microstructure, but also improve the UV resistance of the mixed gel. [ABSTRACT FROM AUTHOR]

Brown algae is one of the three major types of marine algae and includes approximately 2000 species. It is widely distributed in various seas around the world. Brown algae contain a plethora of active substances, such as polysaccharides, polyphenols, omega-3 fatty acids, and carotenoids. Laminarin, a type of storage carbohydrate found abundantly in brown algae, is mainly formed by glucose monomers linked by β-1,3-glucosidic bonds and partial β-1,6-glucosidic bonds. Laminarin and laminarin oligosaccharides, which contain 2–10 saccharide units, have extensive biological activities, such as antitumor, antioxidant, anti-inflammatory, and prebiotic properties. Moreover, both laminarin and laminarin oligosaccharides can be considered as ideal substrates for bioethanol production because they are composed of abundant glucose residues. Therefore, brown algae-derived laminarin and laminarin oligosaccharides have various potential applications in the food, medicine, cosmetics, and bioenergy fields. This paper reviews the preparation methods of laminarin and laminarin oligosaccharides, as well as their biological activities and potential applications. [ABSTRACT FROM AUTHOR]

Sodium alginate (SA) limits its application due to its low stability and poor performance. This study explored the synergy between SA and gum ghatti (GG) to improve the performance of biodegradable SA film. In this study, the chemical structure, rheological properties, morphology, thermal stability, and physical properties of the films were evaluated. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy analysis (FTIR-ATR) revealed that hydrogen bonds are established between SA and GG, as well as strong electrostatic interactions. scanning electron microscopy and X-ray diffraction confirmed that SA has good compatibility with GG. Differential scanning calorimetry data demonstrated the excellent thermal properties of the SA/GG blend films. The film with an SA/GG ratio of 5:1 exhibited an elongation at break (EB), tensile strength (TS) and water vapor permeability (WVP) of 15.27% and 34.11 MPa and 7.19 × 10−11 g/(m s Pa), respectively. In addition, the light barrier properties of the blend film were improved 65.17%. Thus, there is a strong interaction between SA and GG to improve the properties of the blend films. SA/GG blend films offer wide application prospects as packaging materials and biomaterials in food industries. [ABSTRACT FROM AUTHOR]

Lycopene is a dark red carotenoid belonging to C40 terpenoids and is widely found in a variety of plants, especially ripe red fruits and vegetables. Lycopene has been shown to reduce the risk of prostate cancer, other cancers, and cardiovascular disease. It is one of the most widely used carotenoids in the healthcare product market. Currently, commercially available lycopene is mainly extracted from tomatoes. However, production of lycopene from plants is costly and environmentally unfriendly. To date, there have been many reports on the biosynthesis of lycopene by microorganisms, providing another route for lycopene production. This review discusses the lycopene biosynthetic pathway and natural and engineered lycopene-accumulating microorganisms, as well as their production of lycopene. The effects of different metabolic engineering strategies on lycopene accumulation are also considered. Furthermore, this work presents perspectives concerning the microbial production of lycopene, especially trends to construct microbial cell factories for lycopene production. Key points: • Recent achievements in the lycopene biosynthesis in microorganisms. • Review of lycopene biosynthetic metabolism engineering strategy. • Discuss the current challenges and prospects of using microorganisms to produce lycopene. [ABSTRACT FROM AUTHOR]

Red algae represents an important marine bioresource. One high-value utilization of red algae is the production of agaro-oligosaccharides which have many positive biological effects. However, the lack of an efficient production route seriously limits the application of agaro-oligosaccharides. In this study, we established a green route that combines chemical liquefaction and enzymatic catalysis for the efficient production of agaro-oligosaccharides, and we used the production of neoagarotetraose (NA4) as an example. Agarose (150 g L−1) liquefaction by citric acid was controlled with respect to two targets: a 100% liquefaction rate and a high average degree of polymerization (> 4) of the liquesced agaro-oligosaccharides, which were then catalyzed by β-agarase into an oligosaccharides mixture with a high concentration of NA4 (30.8gL−1) in a 1-L reaction volume. After purification, we obtained 25.5g of NA4 with a purity of 92%. This work establishes an easy route for the efficient production of pure agaro-oligosaccharides from agarose. [ABSTRACT FROM AUTHOR]

Thermal activity and stability are important characteristics for proteases applied in the detergent, pharmaceutical, food, and other green industries. With the intent to discover thermostable novel proteases, we constructed a fosmid metagenomic library from marine sediments in the East China Sea and isolated a clone endowed with high proteolytic activity from this library. Sequence analysis of the positive subclones allowed the identification of a coding region of 1254 bp related to protease activity. The unrooted phylogenetic tree and alignment results revealed that the sequence might be derived from Anaerolineaceae bacterium and encodes a new member of the peptidase S8A subfamily with the typical catalytic triad Asp119/His150/Ser325. The fusion protein, named pF1AL2, was expressed in Escherichia coli and showed a molecular weight of 35 kDa. pF1AL2 was active in the pH range of 5.0–11.0 with an optimal pH at 10.0 and had high stability under alkaline conditions, retaining more than 95% of its activity after 24 h at pH 11.0. The optimal temperature of pF1AL2 was 80 °C, and it retained nearly 80% of its activity after 6 h at 70 °C, showing great thermal activity and stability. In addition, the enzyme had great salt tolerance (the residual activity when kept in 3 M NaCl was 40%). Its thermal activity and stability, along with its halotolerance and pH-tolerance, indicate the high potential value of pF1AL2 in industrial applications. The exploitation of pF1AL2 could lay the foundation for the development and utilization of proteases with special features from marine resources by a metagenomic strategy. Key points: • A novel protease, pF1AL2, from marine sediments, was screened out by a metagenomic strategy. • The protease pF1AL2 analyzed in silico, cloned, and characterized. • pF1AL2 had an optimal temperature of 80 °C and retained nearly 80% of activity after 6 h at 70 °C. • pF1AL2 had great tolerance for high-temperature and acid, alkaline, and high salt environments. [ABSTRACT FROM AUTHOR]

The industrial processing of shrimp produces massive quantities of solid waste that is a notable source of animal protein, chitin, carotenoids, and other bioactive compounds that are not appropriately utilized. In the present study, chitin and protein extraction from shrimp head with autolysis and fermentation using Bacillus licheniformis were investigated. The results showed that when shrimp heads were autolyzed with a natural pH at 50°C for 4 h, the total amino acid nitrogen in the supernatant was 5.01 mg mL−1. Then, when a 50% (v/m) inoculum of the hydrolysate was incubated at 60°C for 10 h, a deproteinization rate of 88.3% could be obtained. The fermented supernatant was processed into a dry protein powder, while the residues were demineralized by 10% citric acid for chitin. The recovered protein powder contained 5.5% moisture, 11.5% ash, and 66.7% protein, while the chitin contained 3.5% moisture, 2.1% ash, and 3.1% protein. In addition, amino acids, minerals, heavy metals, the degree of acetylation, microstructure, and Fourier-transform infrared (FT-IR) spectroscopy results were analyzed. Furthermore, the statistics of the large scale trial after treatment with 20 kg of shrimp heads were analyzed. Thus, this work made the shrimp waste utilization environmentally sound and valuable. [ABSTRACT FROM AUTHOR]

The biochemical composition of the turbot skin was investigated. The moisture level of the skin was found to be 51.4%. Based on dry matter content, there were relatively high protein (82.1%) and lipid (13.1%) concentrations in the turbot skin. Mineral element analysis revealed that the turbot skin had high Ca content (2069.0 mg kg−1), and the concentrations of toxic heavy metals Hg and Pb were less than 0.005 mg kg−1, which indicates that the turbot skin is a safe resource for collagen production. The sodium do-decyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that acid-soluble collagen (ASC) extracted from the turbot skin was type-I collagen. The imino acid content of the ASC was 241.6 per 1000 amino acids, which suggests a relatively high denaturation temperature. The Fourier transform infrared (FTIR) spectra of ASC reflected a highly stable structure, and the measured denaturation temperature of ASC was 29.5°C, which is higher than those from many temperate fishes. ASC was the most soluble at pH 4.0, and when the pH values were below or above 4.0, the solubility decreased rapidly. The ASC exhibited a relatively high solubility when NaCl concentration was lower than 2%. These results show that turbo skin can be employed as a source for producing collagen with high quality. [ABSTRACT FROM AUTHOR]

AgWH50C, an exo-β-agarase of GH50 isolated from Agarivorans gilvus WH0801, plays a key role in the enzymatic production of neoagarobiose, which has great application prospect in the cosmetics and pharmaceutical industry. In contrast, the poor thermostability becomes the main obstructive factor of glycoside hydrolase (GH) family 50 agarases, including AgWH50C. Herein, based on the AgWH50C crystal structure, we designed several mutants by a multiple cross-linked rational design protocol used thermostability predicting softwares ETSS, PoPMuSiC, and HotMuSiC. To our surprise, the mutant K621F increased its relative activity by as much as 45% and the optimal temperature increased to 38 °C compared to that of wild-type, AgWH50C (30 °C). The thermostability of K621F also exhibited a substantial improvement. Considering that the gelling temperature of the agarose is higher than 35 °C, K621F can be used to hydrolyze agarose for neoagarobiose production. [ABSTRACT FROM AUTHOR]

To systematically study multi-stage countercurrent process for Antarctic krill protein extracting and to optimize the multi-stage countercurrent technology, the solubility of Antarctic krill proteins after multi-step dissolution was explored firstly; multi-step extraction was investigated; and then multi-stage countercurrent system for protein extraction was carried out. In single step extraction, krill-to-water ratio and pH were chosen as 1:10 and 12.5 respectively, in order to extract more protein. In the multi-step dissolution process, the protein solubility of aqueous solution at pH 12.5 was 33.0 ± 0.8 mg/mL. Multi-step cross-flow processing testified the feasibility of multi-stage countercurrent assumption. Three-stage countercurrent method using krill-to-water ratio 1:10 extracted, 95.1 ± 0.6% protein from krill, where almost the same water as previous works. The total recovery yield of 67.9 ± 1.6% was achieved after precipitation at pH 4.5. [ABSTRACT FROM AUTHOR]

β-Galactosidases have a wide application in the food and pharmaceutical industries. Recently, β-galactosidase was also found to participate in agar degradation. In this study, the second reported agarolytic β-galactosidase was found in the marine bacterium Agarivorans gilvus WH0801 and characterized. The β-galactosidase named AgWH2A (83 kDa) exhibited good activities under optimal hydrolysis conditions of pH 8.0 and 40 °C. AgWH2A could cleave the first D-galactose of agarooligosaccharides from its nonreducing end to produce neoagarooligosaccharides, but could not act on the neoagarooligosaccharides. AgWH2A has great potential in the comprehensive utilization of marine red algae. [ABSTRACT FROM AUTHOR]

Time-temperature indicators (TTIs) are convenient intuitive devices that are widely used to predict food quality. The aim of this study is to develop a new simple device which can be attached to food packages as a quality indicator for turbot sashimi. In this study, a solid TTI based on the reaction between tyrosinase and tyrosine was developed. The Arrhenius behavior of this enzymatic TTI was studied. The kinetics of the tyrosinase-based TTI was investigated in the form of color change from colorless to dark black induced by the enzymatic reaction. The mathematical formula for the color alterations as a function of time and temperature was established. The longest indication time for the developed TTI was 50 hours at 4°C. The activation energy of the tyrosinase-based TTI was 0.409 kJ mol. The suitability of the tyrosinase-based TTI was validated for turbot sashimi using total plate count. The feasibility of using this TTI as a quality indicator for turbot sashimi was assessed based on the activation energy and indication time. Therefore, the tyrosinasebased TTI system developed in this study could be used as an effective tool for monitoring the quality changes of turbot sashimi during the distribution and storage. [ABSTRACT FROM AUTHOR]

Protease is wildly used in various fields, such as food, medicine, washing, leather, cosmetics and other industrial fields. In this study, an alkaline protease secreted by Micrococcus NH54PC02 isolated from the South China Sea was purified and characterized. The growth curve and enzyme activity curve indicated that the cell reached a maximum concentration at the 30th hour and the enzyme activity reached the maximum value at the 36th hour. The protease was purified with 3 steps involving ammonium sulfate precipitation, ion-exchange chromatography and hydrophobic chromatography with 8.22-fold increase in specific activity and 23.68% increase in the recovery. The molecular mass of the protease was estimated to be 25 kDa by SDS-PAGE analysis. The optimum temperature and pH for the protease activity were 50°C and pH 10.0, respectively. The protease showed a strong stability in a wide range of pH values ranging from 6.0-11.0, and maintained 90% enzyme activity in strong alkaline environment with pH 11.0. Inhibitor trials indicated that the protease might be serine protease. But it also possessed the characteristic of metalloprotease as it could be strongly inhibited by EDTA and strongly stimulated by Mn. Evaluation of matrix-assisted laser desorption ionization/time-of-flight MS (MALDI-TOF-TOF/MS) showed that the protease might belong to the peptidase S8 family. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus, a marine pathogen, is a causative agent of gastroenteritis in humans after consumption of contaminated seafood. In recent years, infections with V. parahaemolyticus have become an increasingly frequent factor in microbial food poisoning; therefore, it is urgent to figure out ways to control Vibrio parahaemolyticus. Endolysins, lytic enzymes encoded by bacteriophages, have been regarded as a therapeutic alternative to antibiotics in control of bacterial growth and have been successfully utilized in various areas. Here, we report the full genome sequence of the novel phage qdvp001, which lyses Vibrio parahaemolyticus 17802. The qdvp001 genome consists of a 134,742-bp DNA with a G+C content of 35.35 % and 227 putative open reading frames. Analysis revealed that the qdvp001 open reading frames encoded various putative functional proteins with a putative endolysin gene (ORF 60). No holin genes were identified in qdvp001. ORF 60 was cloned and expressed. The results showed that the purified endolysin Lysqdvp001 had a high hydrolytic activity toward Vibrio parahaemolyticus and a broader spectrum compared to that of the parental bacteriophage qdvp001. Thus, purified endolysin Lysqdvp001 has a potential to be used as an antibacterial agent in the future. [ABSTRACT FROM AUTHOR]

Twelve kinds of strains were isolated from deep-sea mud which can use Antarctic krill powder as the sole carbon/nitrogen source. These strains were identified by 16s rDNA sequence analysis and grouped into eight different genera, including Bacillus, Shewanella, Psychrobacter, Klebsiella, Macrococcus, Aeromonas, Acinetobacter, and Saccharomyces. After fermentation of Antarctic krill powder using these strains, bioactive compounds including total phenolics, free amino acids, and enzyme activities were investigated. Meanwhile, antioxidant activities of the fermentation liquors were also detected. Results showed that bioactive compounds could be effectively produced through fermentation process by these strains, of which three strains ( Bacillus subtilis OKF04, Macrococcus caseolyticus OKF09, and Aeromonas veronii OKF10) could produce more than 650 mg/L total phenolics or 2000 mg/L total free amino acids. In terms of enzyme activities, almost all of the strains showed protease activity and amylase activity, but only Bacillus cereus OKF01 and Bacillus megaterium OKF05 performed lipase activity and chitinase activity, respectively. All of the fermentation liquors showed antioxidant activity, within which Bacillus megaterium OKF05, Macrococcus caseolyticus OKF09, and Aeromonas veronii OKF10 displayed it more prominently. These results demonstrate that the Antarctic krill powder could be effectively converted by microorganisms isolated from deep-sea mud for production of bioactive compounds mixture. [ABSTRACT FROM AUTHOR]

Biochemical characteristics of fast fermented fish sauce made by adding anchovy juice during the process of low salt, solid state fermentation were investigated using 3 different techniques (A: adding anchovy juice in the process of making koji, B: adding anchovy juice in the process of fermentation, and C: not adding anchovy juice). After fermentation under optimized conditions, the amino nitrogen contents of sauces A and B were 7.50 and 7.73 mg/mL after two weeks, respectively. Chemical analysis suggested that the amounts of amino nitrogen and reducing sugar, degree of hydrolysis (DH), DPPH radical-scavenging activity, total acidity, and total amino acid in sauce B were higher than those in sauce A. Volatile odorant analysis and sensory evaluation showed that sauce B was superior to sauce A. Adding anchovy juice during the process of fermentation is a good way to produce a fish sauce with a good flavor and nutrition value. [ABSTRACT FROM AUTHOR]

agWH50C, a novel β-agarase gene, was cloned from Agarivorans gilvus WH0801 by degenerate PCR and nested PCR. The gene agWH50C comprized a 2,223-bp, encoding a protein of 740 amino acids. Sequencing results demonstrated that AgWH50C shared 45 % sequence identity with a well characterized β-agarase, Aga50D, from Saccharophagus degradans 2-40. The mature agarase was expressed in Escherichia coli and purified by affinity chromatography. The optimum pH and temperature for AgWH50C activity were 6.0 and 30 °C. The K and V values for agarose were 12.55 mg/ml and 1.17 U/mg. Analysis of the hydrolysis products using linear ion trap mass spectrometry, Fourier transform-nuclear magnetic resonance spectrometry and thin-layer chromatography confirmed that the reaction product of AgWH50c was α-neoagarobiose alone. Therefore, our novel agarase has the potential for industrial applications to produce neoagarobiose as well as provides a key β-agarase for fermentation of agar biomass. [ABSTRACT FROM AUTHOR]

A new production bioprocess for sea cucumber rice wine (SCRW) was established. The traditional production technology of Chinese rice wine was combined with addition of sea cucumber hydrosylates. The optimal enzymatic conditions of sea cucumber and the fermentation process of SCRW were determined. The weight of sea cucumber enzymatic hydrolysates was 2.5% of millet while cooking the millet. SCRW contained abundant free amino acids (30 total at 1,681.216 mg/L), oligosaccharides (4 total at 10,999.380 mg/L), total phenols (658.850 mg/L), and mineral elements (9 total at 1,911.353 mg/kg), and an antioxidant activity, all of which were higher than for control rice wine (CRW). Galactosamine and glucuronic acid, both sea cucumber polysaccharides, were present in SCRW, but not in CRW. [ABSTRACT FROM AUTHOR]

Antioxidative activities were found in the culture supernatant of Bacillus licheniformis OPL-007 using shrimp head waste (SHW) as the sole carbon and nitrogen source. After optimizing fermentation conditions, some bio-active substances were determined from the broth. The contents of total phenols, polysaccharides, reducing sugars, free amino acids, and organic acids were 888.80, 402.74, 85.88, 2,061.79, and 5,426.74 mg/l, respectively. Moreover, the fermentation liquid was found rich in eight essential amino acids and non-protein amino acids. The antioxidant activity of the culture supernatant, in terms of the scavenging activity of DPPH radicals, reducing power, and metal chelating ability, was monitored, and the fermentation liquid showed a strong antioxidant capacity. The results indicate that bio-deproteinization of SHW by B. licheniformis OPL-007 can increase its antioxidant activity, and SHW has the potential application in the production of functional foods. [ABSTRACT FROM AUTHOR]

Fermentation of shrimp head was conducted using Streptococcus thermophilus to produce antioxidant and recover chitin. Fermentation conditions were found to be 10% shrimp head concentration, 5% glucose concentration, 1.2%(v/v) inoculum size, and 64 h of incubation time at 42°C to attain an initial pH of 5.00 with response surface method optimization and the actual deproteinization rate obtained was 93.59%. Antioxidant activity in the supernatant fluid increased greatly during fermentation, the DPPH radical scavenging ability of the culture supernatant was about 98.70%. The concent-ration of astaxanthin, phenolic compounds, and free amino acid in the culture supernatant was 1.774 μg/mL, 589.69 μg gallic acid equivalents/mL, and 796.978mg/mL, respectively. Comparison of the FT-IR spectra and X-ray diffraction (XRD) analysis among commercial chitin (CTa), chitin prepared by the S. thermophilus fermentation (CTb), and chitin prepared by chemical treatments (CTc) demonstrated that CTb had the highest degree of deacetylation. [ABSTRACT FROM AUTHOR]

Dextran has already been widely applied in food, pharmaceutical, and chemical industries. In this study, a novel intracellular dextran dextrinase (DDase, EC 2.4.1.2) from Gluconobacter oxydans DSM-2003 exhibiting catalytic activity to synthesize dextran from maltodextrin was purified to homogeneity by ultrasonic cell disruption, ion exchange chromatography, and gel filtration. This procedure showed 187.5-fold purification from the cell-free extract with 41.9 % yield. And the apparent molecular weight was estimated to be 62 kDa by SDS-PAGE. It was different from the reported literatures, which found that the molecular weight of intracellular and extracellular DDase of G. oxydans ATCC-11894 was 300 and 152 kDa, respectively. Otherwise, it showed different physicochemical characteristics (optimal temperature and pH, thermal, pH stability, effect of metal ions) from the DDase of G. oxydans ATCC-11894. This indicated that DDase of G. oxydans DSM-2003 was a novel one compared to the reported literatures. [ABSTRACT FROM AUTHOR]

Neoagaro-oligosaccharides derived from agarose have been demonstrated to possess a variety of biological activities, such as anti-bacteria and anti-oxidative activities. In this study, we mainly explored the inhibitory effects and the mechanisms of neoagaro-oligosaccharide monomers against LPS-induced inflammatory responses in mouse macrophage RAW264.7 cells. The results indicated that neoagaro-oligosaccharide monomers especially neoagarotetraose could significantly reduce the production and release of NO in LPS-induced macrophages. Neoagarotetraose significantly suppressed the expression and secretion of inducible nitric oxide synthase (iNOS) and proinflammatory cytokines such as TNF-α and IL-6. The inhibition mechanisms may be associated with the inhibition of the activation of p38MAPK, Ras/MEK/ERK and NF-κB signaling pathways. Thus, neoagarotetraose may attenuate the inflammatory responses through downregulating the MAPK and NF-κB signaling pathways in LPS-stimulated macrophages. In summary, the marine-derived neoagaro-oligosaccharide monomers merit further investigation as novel anti-inflammation agents in the future. [ABSTRACT FROM AUTHOR]

Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly’s distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) − (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme’s active cleft.Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly’s distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) − (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme’s active cleft.Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly’s distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) − (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme’s active cleft.Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly’s distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) − (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme’s active cleft.Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly’s distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) − (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme’s active cleft.Graphical abstract: Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly’s distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) − (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme’s active cleft. [ABSTRACT FROM AUTHOR]