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The global seaweed market is expected to reach USD 17.8 billion by 2032, fuelled by growing demand for sustainable and healthy food solutions and expanding applications in agriculture and aquaculture. However, this rapid growth poses significant challenges, particularly in managing diseases that often establish themselves in intensive macroalgal culture facilities. Red rot disease, Olpidiopsis, and green spot disease often affect marine macroalgae species of high commercial interest, as seen in Pyropia/Porphyra as has already happened for "ice-ice" malaise on Kappaphycus, causing huge economic losses. These diseases are caused by infectious agents that find their place in extreme environmental conditions, such as those characterized by sudden changes in temperature and pollution. Despite technological advances aimed at monitoring the well-being of cultivated seaweed, discrepancies between regions' technological capabilities and species vulnerability exacerbate management difficulties. This review provides an overview of diseases prevalent among marine algae, their impact on aquaculture, and the effectiveness of currently adopted treatments. This study highlights the need to improve disease management strategies and highlights the importance of understanding host–pathogen interactions in order to mitigate future epidemics. [ABSTRACT FROM AUTHOR]

The removal of pollutants, including heavy metals, from the aquatic environment is an urgent problem worldwide. Actively developing nanotechnology areas is becoming increasingly important for solving problems in the field of the remediation of aquatic ecosystems. In particular, methods for removing pollutants using nanoparticles (NPs) are proposed, which raises the question of the effect of a combination of NPs and heavy metals on living organisms. In this work, we investigated the role of CuO-NPs in changing the toxicity of Cd and Pb salts, as well as the bioaccumulation of these elements in a culture of the microalga Desmodesmus communis. It was found that CuO-NPs at concentrations of 10, 100, and 1000 µg L−1 had no effect on the viability of microalgae cells. On the 14th day of the experiment, Cd at a concentration of 1 mg L−1 reduced the viability index by 30% and, when combined with CuO-NPs, by 25%, i.e., CuO-NPs slightly reduced the toxic effect of Cd. At the same time, in this experiment, when CuO-NPs and Cd were used together, the level of oxidative stress increased, including on the first day in mixtures with 1 mg L−1 Cd. Under the influence of Pb, the cell viability index decreased by 70% by the end of the experiment, regardless of the metal concentration. The presence of CuO-NPs slightly reduced the toxicity of Pb in terms of viability and reactive oxygen species (ROS). At the same time, unlike Cd, Pb without NPs caused ROS production on the first day, whereas the addition of CuO-NPs completely detoxified Pb at the beginning and had a dose-dependent effect on mixtures at the end of the experiment. Also, the introduction of CuO-NPs slightly reduced the negative effect of Pb on pigment synthesis. As a molecular mechanism of the observed effects, we prioritized the provocation of oxidative stress by nanoparticles and related gene expression and biochemical reactions of algae cells. Analysis of the effect of CuO-NPs on the Cd and Pb content in microalgae cells showed increased accumulation of heavy metals. Thus, when algae were cultured in an environment with Cd and CuO-NPs, the Cd content per cell increased 4.2 times compared to the variant where cells were cultured only with Cd. In the case of Pb, the increase in its content per one cell increased 6.2 times when microalgae were cultured in an environment containing CuO-NPs. Thus, we found that CuO-NPs reduce the toxic effects of Cd and Pb, as well as significantly enhance the bioaccumulation of these toxic elements in the cells of D. communis microalgae. The results obtained can form the basis of technology for the nanobioremediation of aquatic ecosystems from heavy metals using microalgae. [ABSTRACT FROM AUTHOR]

Most studies of terrestrial bryophytes as natural substrates for photosynthetic microorganisms have been performed in the polar regions, where bryophytes are an important part of the ecosystem. As they remain green throughout the year, bryophytes may also be an ideal substrate for epiphytic organisms in temperate regions. The present study investigated the colonization potential and diversity of microalgae on selected plant species in riparian forest and spruce monoculture in a temperate region. It examines whether the presence of algae is related to substrate humidity, the micromorphology of gametophyte or the seasonal availability of substrate. The taxonomic diversity of algae was studied. Cyanobacteria and green algae were cultured on BG-11 agar medium, while diatoms were identified in permanent diatomaceous slides. The alpha- and beta-diversity indices were calculated, and the communities were compared using Bray-Curtis distances and multidimensional correspondence analyses. Our findings indicate that the largest number of alga species were diatoms; however, their presence was only observed in riparian forest and was associated with high humidity. Both aerophilic and freshwater taxa were noted, the latter carried by water from nearby aquatic ecosystem. Green algae were present in both phytocoenoses and humidity appears to have no substantial effect on the degree of colonization; their diversity was low and the group consisted of terrestrial taxa. In two bryophytes growing at the highest humidity, cyanobacteria were only identified in culture. The key factor influencing the degree of microalgae colonization was the humidity of the substrate, which was related to the distance from water. [ABSTRACT FROM AUTHOR]

Simple Summary: Seaweed aquaculture plays an important role in global food supply, but single-species intensive seaweed aquaculture has problems related to simple industrial structure and risk susceptibility. Therefore, there is an urgent need to establish a series of large-scale seaweed rotational culture models to address the current industrial challenges in algae culture. The culture of macroalgae is mainly affected by environmental factors such as water temperature and light. In this study, we constructed a rotational culture model by carrying out experiments with three species of macroalgae, observing in situ their photosynthetic activity responses to different temperature and light conditions. The results of this study can provide a theoretical basis for the establishment of large-scale rotational aquaculture, which can effectively improve the ecological and economic value of macroalgae aquaculture. Seaweed farming has made outstanding contributions to food supply and the restoration of the ecological environment despite the limitations in production and ecological effects due to the current intensive farming of single algae species. These limitations can be overcome by selecting suitable algal species based on their physiological characteristics and by constructing a large-scale seaweed rotation model. This study carried out a trial culture in aquaculture sea areas, and performed in situ monitoring of the environmental conditions and physiological characteristics of Saccharina japonica, Hizikia fusiformis, and Gracilariopsis lemaneiformis. Additionally, a comparative analysis of the three macroalgae at different times was conducted to determine their response characteristics to environmental factors. The results showed that: (1) The three macroalgae had varying light tolerance. The effective quantum yield of Hizikia fusiformis and Gracilariopsis lemaneiformis remained unchanged during the changes in light environment, while that of Saccharina japonica first decreased and then recovered. (2) The relative electron transport rates of the three macroalgae were significantly different under different temperature conditions. Hizikia fusiformis and Saccharina japonica exhibited the highest relative electron transport rates (70.45 and 106.75, respectively) in May (20.3 °C). Notably, Gracilariopsis lemaneiformis demonstrated good growth and exhibited the highest relative electron transport rate (93.07) in September (27.5 °C). These findings collectively support the feasibility of establishing a macroalgae rotation model. Based on the combined environmental conditions of the seas in Shandong, Zhejiang, and Fujian, a macroalgae rotation model was proposed. The application of this model in the construction of artificial seaweed farms in marine ranches can provide a stable output of large-scale seaweed production and ecological benefits. [ABSTRACT FROM AUTHOR]

Advances in fermentation technology, genetic engineering, and enzyme application technology have increased the use of enzymes. Enzymes can be produced by utilizing a source of microorganisms such as bacteria. Proteolytic bacteria or protease enzyme-producing bacteria are found in foods or plants that contain protein such as the brown seaweed Hydroclathrus sp. This study aimed to obtain protease-producing bacterium associated with marine algae Hydroclathrus sp. from waters around Hoga Island of Wakatobi District and identify the organism based on its 16S rRNA gene sequence. Isolation of bacteria from algae samples was carried out with nutrient agar (NA) media, while proteolytic bacteria selection was carried out on skim milk agar (SMA) media. The bacterial isolates producing proteolytic-clear zone on SMA media were then identified targeting the 16S rRNA gene using the PCR (Polymerase Chain Reaction) method with 27F-1492R primers. Based on the isolation results, there were 3 unique colonies of bacteria that could be cultured from algae samples and coded HIHA-1 to HIHA-3 (HIHA stands for Hoga Island Hydrolathrus macroalgae). The selection process for protease-producing bacteria on SMA media resulted in 1 isolate of proteolytic bacteria, namely HIHA-1. Molecular identification by PCR on HIHA-1 isolate resulted in a single DNA band on the electrophoresis gel sized ~1500bp. The sequencing results showed a DNA sequence with the size of 1421bp sharing the highest similarity with the bacterium Exiguobacterium aestuarii strain TF-16 (homology level of 99,93%). In conclusion, the proteolytic bacterial isolate HIHA-1 associated with marine brown algae Hydroclathrus sp. was obtained and identified as Exiguobacterium aestuarii strain HIHA-1. [ABSTRACT FROM AUTHOR]

Photosynthetic protists, known as microalgae, are key contributors to primary production on Earth. Since early in evolution, they coexist with bacteria in nature, and their mode of interaction shapes ecosystems. We have recently shown that the bacterium Pseudomonas protegens acts algicidal on the microalga Chlamydomonas reinhardtii. It secretes a cyclic lipopeptide and a polyyne that deflagellate, blind, and lyse the algae [P. Aiyar et al., Nat. Commun. 8, 1756 (2017) and V. Hotter et al., Proc. Natl. Acad. Sci. U.S.A. 118, e2107695118 (2021)]. Here, we report about the bacterium Mycetocola lacteus, which establishes a mutualistic relationship with C. reinhardtii and acts as a helper. While M. lacteus enhances algal growth, it receives methionine as needed organic sulfur and the vitamins B1, B3, and B5 from the algae. In tripartite cultures with the alga and the antagonistic bacterium P. protegens, M. lacteus aids the algae in surviving the bacterial attack. By combining synthetic natural product chemistry with high-resolution mass spectrometry and an algal Ca2+ reporter line, we found that M. lacteus rescues the alga from the antagonistic bacterium by cleaving the ester bond of the cyclic lipopeptide involved. The resulting linearized seco acid does not trigger a cytosolic Ca2+ homeostasis imbalance that leads to algal deflagellation. Thus, the algae remain motile, can swim away from the antagonistic bacteria and survive the attack. All three involved genera cooccur in nature. Remarkably, related species of Pseudomonas and Mycetocola also act antagonistically against C. reinhardtii or as helper bacteria in tripartite cultures. [ABSTRACT FROM AUTHOR]

Growing algae on anaerobic digestate could decrease the algal production cost while reducing nutrient pollution. In past work, we developed a successful biological pretreatment for digestate that enables rapid algal growth on digestate without dilution. The objective of this work was to test the effectiveness of this pretreatment in outdoor algae cultures over a year-long timeframe. The study was conducted in semi-continuous, replicated bubble column photobioreactors in Auburn, AL, USA. Algae could grow successfully in pretreated digestate during the fall, spring, and summer, achieving average growth rates of 30, 42, and 66 mg L-1 d-1, respectively. Although the cold temperatures in winter suppressed algal growth, external heating was not required to keep the cultures alive. For two weeks during the summer, the system was challenged with 100% digestate that did not undergo pretreatment, and the algal community suffered a culture collapse with a significant (p < 0.001) decrease in productivity compared to the previous batches in which pretreatment was used. Nitrogen, phosphorus, and sulfur removal were observed during robust algal growth. There was no nitrification in the photobioreactors during the initial 200 days, but evidence of nitrification emerged during the summer and persisted into the fall. Nitrospirae were detected by 16S rRNA sequencing, proving that nitrifying bacteria could adapt to high ammonium (462 - 1502 mg/L). The eukaryotic community was dominated by Coelastrum (>90%) in the cold season, and the dominance transitioned to Chlorella in the warm season (>95%) based on 18S rRNA sequencing. The low relative abundance of cyanobacteria showed that green algae were the favored photosynthetic organisms in the system. [ABSTRACT FROM AUTHOR]

Shrink film is a thin sheet of polystyrene plastic that shrinks to 25–40% of its original size when heated. This study investigated the shrinkage factor of the film at different temperatures and baking times to determine the optimal fabrication recipe for shrink film microfluidic device production. Additionally, this study characterized the properties of shrink film, including minimum possible feature size and cross-section geometries, using manual engraving and the CAMEO 4 automated cutting machine. The optimal shrinkage factor ranged from 1.7 to 2.9 at 150 °C and a baking time of 4 min, producing the ideal size for microfluidic device fabrication. The X- and Y-axes shrank ~2.5 times, while Z-axis thickened by a factor of ~5.8 times. This study achieved a minimum feature size of 200 microns, limited by the collapsing of channel sidewalls when shrunk, leading to blockages in the microchannel. These findings demonstrate the feasibility and versatility of using shrink film as a cost-effective and efficient material for the rapid fabrication of microfluidic devices. The potential applications of this material in various fields such as the medical and biomedical industries, bacteria and algae culture and enumeration are noteworthy. [ABSTRACT FROM AUTHOR]

A unicellular cyanobacterium, strain VI4D9, was isolated from thermophilic microbial mats thriving in a hot spring of the Ahousaht territory of Vancouver Island, Canada, and characterized using optical and electron microscopy, genome sequencing and cultivation approaches. The cells were elongated rods (5.1 µm in length and 1.2 µm in width, on average). Their UV visible absorption spectra revealed that they contain chlorophyll a, phycocyanin and carotenoids. Transmission electron microscopy showed the presence of thylakoids concentrated on one side of the cells. The strain grew within a temperature range of 37–50°C, with an optimum growth at 45°C. Its genome had a size of 3 049 282 bp and a DNA G + C content of 51.8 mol%. The cells contained numerous intracellular spherical granules easily visible under scanning electron microscopy. Energy dispersive X-ray spectroscopy revealed that these granules were made of Ca-, Ba- and Sr-containing carbonates. A phylogenetic 16S rRNA gene tree robustly placed this strain as sister to several environmental sequences and the described species Gloeomargarita lithophora, also characterized by the possession of intracellular carbonate inclusions. We consider strain VI4D9 to represent a new Gloeomargarita species based on its marked phenotypic differences with G. lithophora, notably, its thermophilic nature and different thylakoid organization, therefore we propose the name Gloeomargarita ahousahtiae sp. nov. The type strain is VI4D9 (Culture Collection of Algae and Protozoa strain 1472/1; Laboratorio de Algas Continentales Mexico strain LAC 140). Gloeomargarita ahousahtiae is the second species described within the recently discovered order Gloeomargaritales. Gloeomargarita ahousahtiae is a new thermophilic cyanobacterium. Growth temperature and thylakoid morphology differentiate G. ahousahtiae and G. lithophora. All described Gloeomargaritales synthesize intracellular carbonate inclusions. [ABSTRACT FROM AUTHOR]

Glycerol is a carbon source that produces good biomass under mixotrophic conditions. Enhancing the composition of culture media in algae biomass production improves growth rates, biomass yield, nutrient utilization efficiency, and overall cost-effectiveness. Among the key nutrients in the medium, nitrogen plays a pivotal role. Urea can be effectively used as a nitrogen source and is considered a low-cost form of nitrogen compared to other sources. Urea metabolism releases some CO2 in photosynthesis, and magnesium plays a major role in urea uptake. Magnesium is another key nutrient that is key in photosynthesis and other metabolic reactions. To maximize glycerol consumption in the mixotrophic system and to obtain high biomass and lipid productions, the variations in MgSO4·7H2O and urea concentrations were evaluated in the growth medium of the microalgae. A response surface methodology (RSM) using a central composite design (CCD) was designed to maximize glycerol consumption at the initial cellular growth rates (up to four days). The magnesium and urea supply varied from 0.3 to 1.7 g L−1. Response surface methodology was utilized to analyze the results, and the highest glycerol consumption rate, 770.2 mg L−1 d−1, was observed when C. vulgaris was grown at 1.7 g L−1 urea, 1.0 g L−1 MgSO4·7H2O. Using the optimal urea and magnesium concentrations with acetate, glucose, and glycerol as carbon sources, the same lipid content (10% average) was achieved on day 4 of mixotrophic C. vulgaris culture. Overall, the results show that mixotrophic growth of C. vulgaris using urea with an optimum magnesium concentration yields large amounts of fatty acids and that the carbon source greatly influences the profile of the fatty acids. [ABSTRACT FROM AUTHOR]

Abstract Phycobiliproteins (PBPs), one of the functional proteins from algae, are natural pigment–protein complex containing various amino acids and phycobilins. It has various activities, such as anti-inflammatory and antioxidant properties. And are potential for applications in food, cosmetics, and biomedicine. Improving their metabolic yield is of great interest. Microalgaes are one of the important sources of PBPs, with high growth rate and have the potential for large-scale production. The key to large-scale PBPs production depends on accumulation and recovery of massive productive alga in the upstream stage and the efficiency of microalgae cells breakup and extract PBPs in the downstream stage. Therefore, we reviewed the status quo in the research and development of PBPs production, summarized the advances in each stage and the feasibility of scaled-up production, and demonstrated challenges and future directions in this field.

Non-concentrated algae storage can bridge the period between algae harvesting and processing while avoiding the stress conditions associated with the concentration step required for concentrate storage. This study aimed to examine organic matter losses during the non-concentrated storage of Microchloropsis gaditana at pilot-scale. Algae cultures (400–500 L) were stored for up to 12 days either at an 8 °C target temperature or at 19 °C as the average temperature. The centrifugation yield of stored algal cultures decreased from day 5 or day 8 onwards for all storage conditions. After 12 days, the centrifugation yields were between 57% and 93% of the initial yields. Large differences in centrifugation yields were noted between the algae batches. The batch-to-batch difference outweighed the effect of storage temperature, and the highest yield loss was observed for the 8 °C cooled algae batch. The analysis of stored algae before and after centrifugation suggested that the decreasing yields were not related to respiration losses, but rather, the decreasing efficiency with which organic matter is collected during the centrifugation step. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Biotecnología is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microalgal-biofilm culture has the advantages of less water requirement and higher lipid productivity. For efficient lipid production in an aerial phase condition, it is ideal to simultaneously induce microalgal biofilm growth and lipid accumulation. Biomass production and lipid accumulation in the aerial microalga Coccomyxa subellipsoidea KGU-D001 were investigated in the logarithmic growth phase. Initially, the alga was cultured in three different conditions: in liquid phase using Bold's basal medium (BBM), and in the aerial phase in the presence or absence of BBM. In aerial phase conditions with nutrients (i.e., BBM), biomass production was prioritized over cell proliferation until approximately the 7th day of culture. In the liquid phase conditions, the ratio of total organic carbon to total nitrogen (C/N) in cells was almost constant during the culture period. However, in both aerial phase conditions, the C/N ratio increased during the culture period, more so in the absence of nutrients. The total fatty acid content also increased throughout the culture period. Then, algal cells were cultured for a 17-day culture; there would be a growth period of 10 days followed by a lipid accumulation period of 7 days. In such cultures in the presence of BBM, the biomass and lipid productivities (388 and 94.2 mg/m2/day) were both significantly higher in the aerial phase than in the liquid phase during the lipid production period. C. subellipsoidea can produce lipids even during growth if the CO2 supply is efficient and the C/N ratio is high. [ABSTRACT FROM AUTHOR]

The rotifer Epiphanes brachionus spinosa occurs in shallow temporary waters with hydroperiods up to several months in the Chihuahuan Desert (U.S.A. and Mexico). Clonal populations from one such habitat were initiated from stem females hatched from fertilised resting eggs in flooded dried sediment, and cultured with the alga Cryptomonas erosa at 19°C in a photoperiod (L:D 16:8). Experiments show that the rotifer has: (1) a morphological response to the predatory rotifer Asplanchna, with which it can co‐occur; and (2) an early and constant propensity for sex and resting‐egg production during population development.Stem females, and females from later generations, have two posterior spines. Measurements of live juveniles and adults indicate that spine length increases isometrically during postnatal growth.Presence of live Asplanchna brightwellii, or its kairomone in Asplanchna‐conditioned medium, significantly increase spine length. In one clone, spine lengths of juvenile Epiphanes from cultures with or without live Asplanchna were, respectively, c. 40 and c. 27 μm. In that clone, spine lengths of adult Epiphanes in cultures with or without Asplanchna kairomone were, respectively, c. 54 and c. 37 μm. In another clone, these spine lengths were, respectively, c. 44 and c. 36 μm. Asplanchna‐induced spine elongation may act as a mechanical defence against capture and ingestion by the predator.Sexual reproduction in E. brachionus spinosa populations is initiated soon after populations develop from stem females and then continues at a rate allowing both population growth by female parthenogenesis and production of resting eggs. Resting eggs hatched after 6–12 days at 19°C. Stem females were amictic (producing daughters parthenogenetically) but produced some daughters that were mictic (producing haploid males parthenogenetically or fertilised resting eggs). In subsequent generations tested 2–7 weeks after hatching of stem females, amictic females from three clonal populations produced similar proportions of mictic daughters (mean c. 0.25) when cultured singly in large volumes (15 and 40 ml) or a small one (1.5 ml).Mictic‐female production is probably automatic and controlled by an endogenous mechanism, rather than specifically induced by crowding or some other environmental factor. Early and continuous sexual reproduction assures production of resting eggs throughout short and unpredictable hydroperiods. [ABSTRACT FROM AUTHOR]

This study examined the potential for green microalgae to produce lipid that could be used for biodiesel production from wastewater substrate. Green microalgae has the potential to be used in the production of biodiesel because it accumulates 5.3211 g of lipid in 39.2246 g of centrifuged and oven-dried algae biomass, accounting for 13.57% of its dry cellular weight. This was obtained with wastewater substrate under open-culture growth conditions. The wastewater substrate contained phosphate, nitrate, nitrite, ammonia, and sulfate at relatively optimal concentrations for culturing algae. The algae assimilated 95% of these nutrients on average for growth until the stationary phase was reached in 13 days. The most rapid cell doubling time observed was 192 h, and the maximum biomass production rate observed was 0.00057 mg/mg/day, reaching a peak algae weight fraction of 0.00926 mg/mg in 13 days. This study also examined and presented the scale-up of growing green microalgae in an open raceway culture system for obtaining maximum lipid yield from a wastewater substrate. The cost-benefit analysis of designing and building such a system was also presented in this study. The open raceway system described and modeled in this study measured 8 m * 3 m * 0.6 m and had a capacity of 10,000 liters, yielding 0.45 kg of biocrude lipid for each cycle of green microalgae culture harvested. [ABSTRACT FROM AUTHOR]

Phycobiliproteins (PBPs), one of the functional proteins from algae, are natural pigment–protein complex containing various amino acids and phycobilins. It has various activities, such as anti-inflammatory and antioxidant properties. And are potential for applications in food, cosmetics, and biomedicine. Improving their metabolic yield is of great interest. Microalgaes are one of the important sources of PBPs, with high growth rate and have the potential for large-scale production. The key to large-scale PBPs production depends on accumulation and recovery of massive productive alga in the upstream stage and the efficiency of microalgae cells breakup and extract PBPs in the downstream stage. Therefore, we reviewed the status quo in the research and development of PBPs production, summarized the advances in each stage and the feasibility of scaled-up production, and demonstrated challenges and future directions in this field. [ABSTRACT FROM AUTHOR]

Benzo[a]pyrene (B[a]P) is an environmentally ubiquitous, persistent, and carcinogenic pollutant belonging to the polycyclic aromatic hydrocarbons (PAHs) family. Several methods have been employed to follow PAH degradation by bacteria. However, there is very scarce information about microalgae as bioremediation species. In this work, we investigated the protein profile for B[a]P degradation by the Selenastrum capricornutum algae culture extract employing high-performance liquid chromatography (HPLC) in size exclusion chromatography mode (SEC) and electrophoresis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]). We evaluated the degradation of crude extracts (CEs) and SEC fractions, and we found the presence of trace levels of 4, 5-dihydrodiolbenzo[a]pyrene (4,5-dB[a]P) and 7,8-dihydrodiolbenzo[a]pyrene (7,8-dB[a]P) in cis geometry as B[a]P degradation products. SEC chromatographic profile comparison of CEs and SEC fractions, both exposed to B[a]P along with the corresponding controls, allowed us the identification of molecular weights (MWs) of a multi-component system involved in the B[a]P biodegradation through protein over-production. Electrophoresis analysis showed several protein components, with MWs between 10 and 250 kDa, where two subunits of 38.15–41.97 and 82.73 ± 3.15 kDa suggested the presence of multi-component di-oxygenases in the early stages of B[a]P biodegradation by S. capricornutum cultures. This work extends the knowledge of the biodegradation process of high molecular PAHs by microalgae. [ABSTRACT FROM AUTHOR]

Microalgae are considered to have great potential as a source of biodiesel. Currently, algae culture has three different trophic modes, i.e., autotrophic, heterotrophic, and mixotrophic, but not all kinds of algae are suitable for heterotrophic and mixotrophic cultivation. In this study, Parachlorella kessleri TY, screened from the soil of Shanxi Province, was heterotrophically and mixotrophically treated with glucose as an organic carbon source, and the physiological and biochemical levels of its growth and lipid accumulation were measured. The results showed that the highest biomass and biomass productivity (1.53 g·L−1 and 218.57 mg·L−1d−1) were attained by P. kessleri TY under mixotrophic cultivation. In comparison, the lowest (0.55 g·L−1 and 78.57 mg·L−1d−1) were attained under heterotrophic culture. Furthermore, heterotrophic and mixotrophic conditions could accumulate more lipids (total lipid contents: 39.85% and 42.92%, respectively), especially the neutral lipids. Additionally, the contents of fatty acids suitable for use as biodiesel raw materials in both heterotrophic and mixotrophic cultures increased, especially the content of C18:1. Moreover, due to the lower biomass of heterotrophic cultivation compared with that from mixotrophic cultivation, the total lipid productivity of heterotrophic conditions decreased. In summary, the conditions of mixotrophic cultivation are more conducive to the accumulation of lipids in P. kessleri TY. [ABSTRACT FROM AUTHOR]

This paper depicts characteristics of degradation of walls of bioreactors made of polymethylmethacrylate (PMMA) which was used to culture algae. The degradation processes take place stimulated by lighting of external surface and interaction with cultured species on internal surface. Results presented are representative for degradation of a bioreactor tube after the 4-year cultivation of Chlorella sp. Microscopic observations, roughness and transmission tests showed that changes have occurred on the inner surface. The result of use is a decrease in transmission and an increase in roughness. Microscopic observations showed that particles remained after culture, especially in cracks. [ABSTRACT FROM AUTHOR]

In recent decades, the worldwide production of microalgae has been carried out on an industrial scale. In recent years, the market for natural products has grown because of changes in consumer preferences for more natural products. The objective of this study was to demonstrate the hepatoprotective capacity of fucoxanthin extract obtained from an industrial culture of the microalgae Phaeodactylum tricornutum (Culture Collection of Alga and Protists in Scotland). The microalga was grown in an artificial and natural seawater mixture (1:9), using Walne's culture medium in columns and raceway photobioreactors (RWP) inside a greenhouse. The carotenoid content in the tested systems continued to increase from day 5 of the culture, when the stationary phase was reached. The final biomass powder contained 4.9 mg (2.59%) of pure fucoxanthin. The possible hepatoprotective activity of fucoxanthin was then studied in the HepG2 cell line for 24 h in culture, and compared with the cytotoxicity of methotrexate (MTX). In conclusion, the active ingredient showed hepatoprotective activity against MTX in the human hepatocyte cell line HEPG-2 at a concentration of 0.25 mg/mL. The current results also suggest that it has beneficial properties for liver health and is a suitable ingredient for all types of nutraceutical products. [ABSTRACT FROM AUTHOR]

The objective of this research was to isolate and identify lactic acid bacteria living in the digestive tract of the queen scallop Aequipecten opercularis and further test it as a probiotic culture on the growth of the bivalve during one month in captivity. Classic microbiological techniques (API and MALDI TOF) were used and four different strains of Lactiplantibacillus and one Lactococcus were identified and further analyzed, namely: Lactiplantibacillus plantarum I, Lactiplantibacillus plantarum 1, Lactiplantibacillus plantarum 2, Lactococcus lactis, and Lactiplantibacillus brevis. The isolated cultures were further tested for the highest antimicrobial activity towards the most common marine pathogens and survival at different temperatures and pH levels. The strain Lactiplantibacillus plantarum I had the best results, with the highest antimicrobial activity (77–85% pathogen growth inhibition) and the best safety standards showing no antibiotic resistance, and no ability to synthesize biogenic amine and degrade red blood cells. Considering all the abovementioned characteristics, the strain Lpb. plantarum I was further tested on the growth and health status of the bivalve Aequipecten opercularis during a month of cultivation in captivity. The results showed that the incorporation of Lpb. plantarum I led to a decrease in the quantity of test microorganisms in the bivalve and an increase in both the growth rate weight and growth rate length of the queen scallop A. opercularis. Furthermore, the scallops fed with the algae culture + Lpb. plantarum I gained significantly higher meat yield (33.15 ± 2.63%) compared with the control scallops fed only with the algae culture (29.66 ± 2.87%). To conclude, the results from this research indicate that including Lpb. plantarum I as a dietary supplement could enhance growth performance and serve as a feasible approach to reduce pathogen levels while cultivating A. opercularis in captivity. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Environmental Protection is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to improve the protein content and yield of heterotrophic microalgal cultivation and establish a simple, economical, and efficient method for microalgal protein production using the novel green alga, Graesiella emersonii WBG-1, which has not been previously reported for heterotrophic cultivation. Through batch heterotrophic cultivation of this alga, we observed that glucose was the optimal carbon source, while it could not use sucrose as a carbon source. Biomass production and protein content were significantly reduced when sodium acetate was used as the carbon source. Compared with nitrate, protein content increased by 93% when urea was used as the nitrogen source. Cultivation temperature had a significant impact on biomass production and protein content. The optimal conditions were glucose as the carbon source at an initial concentration of 10 g/L, urea as the nitrogen source at an initial concentration of 1.62 g/L, and a culture temperature of 35 °C. On the second day of batch cultivation, the highest protein content (66.14%) was achieved, which was significantly higher than that reported in heterotrophic cultures of Chlorella and much higher than that reported for specially established technologies aimed at increasing the protein content, such as two-stage heterotrophic, heterotrophy–dilution–photoinduction, and mixotrophic processes. These results demonstrate the great potential of the heterotrophic cultivation of G. emersonii WBG-1 for protein production. [ABSTRACT FROM AUTHOR]

If mass cultivation of photoautotrophic microalgae is to gain momentum and find its place in the new "green future", exceptional optimizations to reduce production costs must be implemented. Issues related to illumination should therefore constitute the main focus, since it is the availability of photons in time and space that drives synthesis of biomass. Further, artificial illumination (e.g., LEDs) is needed to transport enough photons into dense algae cultures contained in large photobioreactors. In the present research project, we employed short-term O2 production and 7-day batch cultivation experiments to evaluate the potential to reduce illumination light energy by applying blue flashing light to cultures of large and small diatoms. Our results show that large diatom cells allow more light penetration for growth compared to smaller cells. PAR (400–700 nm) scans yielded twice as much biovolume-specific absorbance for small biovolume (avg. 7070 μm3) than for large biovolume (avg. 18,703 μm3) cells. The dry weight (DW) to biovolume ratio was 17% lower for large than small cells, resulting in a DW specific absorbance that was 1.75 times higher for small cells compared to large cells. Blue 100 Hz square flashing light yielded the same biovolume production as blue linear light in both the O2 production and batch experiments at the same maximum light intensities. We therefore suggest that, in the future, more focus should be placed on researching optical issues in photobioreactors, and that cell size and flashing blue light should be central in this. [ABSTRACT FROM AUTHOR]

Snow algae blooms often form green or red coloured patches in melting alpine and polar snowfields worldwide, yet little is known about their biology, biogeography, and species diversity. We investigated eight isolates collected from red snow in northern Norway, using a combination of morphology, 18S rRNA gene and internal transcribed spacer 2 (ITS2) genetic markers. Phylogenetic and ITS2 rRNA secondary structure analyses assigned six isolates to the species Raphidonema nivale, Deuterostichococcus epilithicus, Chloromonas reticulata , and Xanthonema bristolianum. Two novel isolates belonging to the family Stichococcaceae (ARK-S05-19) and the genus Chloromonas (ARK-S08-19) were identified as potentially new species. In laboratory cultivation, differences in the growth rate and fatty acid profiles were observed between the strains. Chlorophyta were characterized by abundant C18:3 n -3 fatty-acids with increases in C18:1 n -9 in the stationary phase, whilst Xanthonema (Ochrophyta) was characterized by a large proportion of C20:5 n -3, with increases in C16:1 n -7 in the stationary phase. In a further experiment, lipid droplet formation was studied in C. reticulata at the single-cell level using imaging flow cytometry. Our study establishes new cultures of snow algae, reveals novel data on their biodiversity and biogeography, and provides an initial characterization of physiological traits that shape natural communities and their ecophysiological properties. [ABSTRACT FROM AUTHOR]

In this article, we focus on a periodic resource allocation problem applied on a dynamical system which comes from a biological system. More precisely, we consider a system with N$$ N $$ resources and N$$ N $$ activities, each activity use the allocated resource to evolve up to a given time T>0$$ T>0 $$ where a control (represented by a given permutation) will be applied on the system to reallocate the resources. The goal is to find the optimal control strategies which optimize the cost or the benefit of the system. This problem can be illustrated by an industrial biological application, namely, the optimization of a mixing strategy to enhance the growth rate in a microalgal raceway system. A mixing device, such as a paddle wheel, is considered to control the rearrangement of the depth of the algae cultures, hence the light perceived at each lap. We prove that if the dynamics of the system is periodic, then the period corresponds to one reallocation whatever the order of the involved permutation matrix is. A nonlinear optimization problem for one reallocation process is then introduced. Since N!$$ N! $$ permutations need to be tested in the general case, it can be numerically solved only for a limited number of N$$ N $$. To overcome this difficulty, we introduce a second optimization problem which provides a suboptimal solution of the initial problem, but whose solution can be determined explicitly. A sufficient condition to characterize cases where the two problems have the same solution is given. Some numerical experiments are performed to assess the benefit of optimal strategies in various settings. [ABSTRACT FROM AUTHOR]

Due to their extensive application potential in biopharmaceuticals, nutraceuticals, and renewable energy, microalgae have recently drawn considerable attention worldwide. Biofuels, bioactive medicinal products, and food ingredients are made from microalgae, a renewable, sustainable, and economic resource. A number of microalgae species have shown remarkable pharmacological and biological properties that have made them useful as value-added products. The cost, renewable nature, and environmental concerns of biofuels make them a perfect substitute for liquid fossil fuels. As well as carbohydrates, lipids, and other bioactive metabolites, microalgae convert atmospheric CO2 into useful products. There are some limitations and challenges to overcome before microalgae can be upgraded from pilot stage to industrial scale, though they are feasible sources of bioenergy and biopharmaceuticals in general. Enhancing microalgae growth rate and product synthesis is the most challenging and crucial issue, as is dewatering algae cultures, pretreating biomass, and optimizing fermentation processes. Various bioactive compounds as well as microalgae advantages for biofuel production are discussed in this review. [ABSTRACT FROM AUTHOR]

Microalgae absorb various nutrients (nitrogen and phosphorus) in wastewater, providing bioproduct production and ensuring sustainability in wastewater treatment. The use of waste biomass becomes more effective with immobilized algae biomass usage. This study aims to investigate the removal of ammonium nitrogen (NH4+-N) and phosphate (PO43−) in wastewater taken from the outlet of the primary settling unit of the domestic wastewater treatment plant using immobilized Chlorella Vulgaris pure algae culture. A batch reactor setup was used in the laboratory-scale study. The removal rates of NH4+-N and PO43− were evaluated with the effects of different environmental (luminous photoperiod:24-h (h), 16/8 h), chemical (pH: 7.5, 8.0, 8.5 and nitrogen:phosphorus (N:P): 21.4, 18.7, 16.7) and shape factors (bead diameter: 3.4, 5.3 mm) using wastewater samples taken from the presettlement outlet of a typical domestic wastewater treatment plant. pH 8.5 and 24-h luminous photoperiod conditions, the use of 5.3 mm diameter immobilized beads, and the addition of excess phosphate concentration to obtain a nutrient ratio of 16 N:P have increased the NH4+-N and PO43− removal rates and algal biomass growth rate. As a result, in the batch reactor using immobilized Chlorella vulgaris algae biomass, 83% NH4+-N and 95% PO43− removal rates were achieved in domestic wastewater in approximately 20 h. [ABSTRACT FROM AUTHOR]

Microalgae consist of unicellular algal species that can produce and accumulate a wide variety of biomolecules. In order to maintain a high cell density in a continuous phototrophic culture of algae, the nutrient can serve as the most important factor in enhancing cell density. In this study, the effect of different concentrations of nutrients on the cell density of microalga Nannochloropsis sp. cultured in the mega plastic box (with 50 L capacity) was investigated. Four groups of treatment with four replicates were tested: group A (including 5 g L-1 of ferric chloride, ammonium phosphate, and Urea), group B (including 10 g L-1 of ferric chloride, ammonium phosphate, and urea), group C (including 15 g L-1 of ferric chloride, ammonium phosphate, and urea), and group D (including 15 g L-1 of ferric chloride, ammonium phosphate, and urea with 40 g L-1 of cow manure). Results revealed that group C and group D achieved maximum density on day three as 86.39×106 cell mL-1 and 85.59×106 cell mL-1, respectively, which were significantly (p≤0.05) higher than the cell density of groups A (58.01×106 cell mL-1) and group B (70.67×106 cell mL-1). Additionally, the increasing specific growth rate (SGR) of Nannochloropsis sp. cultured was obtained in group D at 0.308 day-1 after the culture period. From the result of the study, it is concluded that the concentrations of 15 g L-1 ferric chloride, ammonium phosphate, and urea (group C) and 15 g L-1 ferric chloride, ammonium phosphate, and urea combined with 40 g L-1 cow manure (group D) are capable of increasing cell density growth of microalga Nannochloropsis sp. cultured in a mega plastic box. [ABSTRACT FROM AUTHOR]

Photosynthetic hydrogen production from microalgae is considered to have potential as a renewable energy source. Yet, the process has two main limitations holding it back from scaling up; (i) electron loss to competing processes, mainly carbon fixation and (ii) sensitivity to O2 which diminishes the expression and the activity of the hydrogenase enzyme catalyzing H2 production. Here we report a third, hitherto unknown challenge: We found that under anoxia, a slow-down switch is activated in photosystem II (PSII), diminishing the maximal photosynthetic productivity by three-fold. Using purified PSII and applying in vivo spectroscopic and mass spectrometric techniques on Chlamydomonas reinhardtii cultures, we show that this switch is activated under anoxia, within 10 s of illumination. Furthermore, we show that the recovery to the initial rate takes place following 15 min of dark anoxia, and propose a mechanism in which, modulation in electron transfer at the acceptor site of PSII diminishes its output. Such insights into the mechanism broaden our understanding of anoxic photosynthesis and its regulation in green algae and inspire new strategies to improve bio-energy yields. H2 generation from Chlamydomonas reinhardtii cultured under anoxia is found to be limited by activation of a slow-down switch in photosystem II that modulates electron transfer at the acceptor site of this photosystem following light exposure. [ABSTRACT FROM AUTHOR]

The objective of this work was to investigate the potential of pumpkin rind and seed on antidiabetic and anti-inflammatory activities and the underlying mechanism. Therefore, this work was carried out to determine the antidiabetic activity using inhibitory activities of pumpkin rind and seeds extracts on α - glucosidase and the anti-inflammatory activity via inhibitory activity on nitric oxide production. And also, the potential of the pumpkin rind and seeds on culture of Chlorella ellipsoidea was determined. Determination of inhibitory activity on α - glucosidase was performed using α - glucosidase assay, while the Griess assay was employed for the inhibition on Nitric oxide (NO) -production. The pumpkin seed extract inhibited α - glucosidase more potent than the pumpkin rind extract (IC50 of 321.36 vs. 326.18 µg/mL). However, the activities of the extracts were less potent than that of Acarbose (IC50 of 317.26 µg/mL). Application of the extracts at the highest concentration, 500 µg/mL, the pumpkin seed extract displayed the inhibition of NO production higher than the pumpkin rind extract did (18.01 ± 1.57 % vs. 14.99 ± 1.94 %). Study on the effects of pumpkin rind and seeds on C. ellipsoidea culture revealed that the optimum media was the 7th medium (NPK+ mixture of pumpkin seed water and Blue-Green Medium (BG- 11), 1:4) which generated the growth of C. ellipsoidea for 28 days with the Optical Density (OD) value of 1.43 ± 0.01 followed by BG-11 medium OD value of 1.41 ± 0.02) and the 3rd medium (NPK+ mixture of pumpkin rind water and BG-11, 1:1, OD value of 1.32 ± 0.01), respectively. The chemical contents of C. ellipsoidea cultured in 7th medium contained 54.25 ± 0.06 % protein, 15.95 ± 0.87 % carbohydrates, 9.35 ± 0.05 % fat, and 20.30 ± 0.33 % ash, meanwhile 53.37 ± 0.77 % protein, 12.83 ± 0.62 % carbohydrates, 17.80 ± 0.23 % fat, and 23.30 ± 1.33 % ash in the 3rd medium. The results obtained from this investigation indicate that pumpkin rind and seeds not only can be exploited for the antidiabetic and anti-inflammatory components but also can be applied instead of the conventional medium for the culture of C. ellipdoidea. Therefore, bio-waste from pumpkin could be potentially utilized as the source of natural antidiabetic inhibitors, anti-inflammatory drugs and the effective components of C. ellipdoidea culture media. [ABSTRACT FROM AUTHOR]

The cultivation of algae either in open raceway ponds or in closed bioreactors could allow the renewable production of biomass for food, pharmaceutical, cosmetic, or chemical industries. Optimal cultivation conditions are however required to ensure that the production of these compounds is both efficient and economical. Therefore, high‐frequency analytical measurements are required to allow timely process control and to detect possible disturbances during algae growth. Such analytical methods are only available to a limited extent. Therefore, we introduced a method for monitoring algae release volatile organic compounds (VOCs) in the headspace above a bioreactor in real time. This method is based on ion mobility spectrometry (IMS) in combination with a membrane inlet (MI). The unique feature of IMS is that complete spectra are detected in real time instead of sum signals. These spectral patterns produced in the ion mobility spectrum were evaluated automatically via principal component analysis (PCA). The detected peak patterns are characteristic for the respective algae culture; allow the assignment of the individual growth phases and reflect the influence of experimental parameters. These results allow for the first time a continuous monitoring of the algae cultivation and thus an early detection of possible disturbances in the biotechnological process. [ABSTRACT FROM AUTHOR]

Dynamic light regimes strongly impact microalgal photosynthesis efficiency. Finding the optimal way to supply light is then a tricky problem, especially when the growth rate is inhibited by overexposition to light and, at the same time, there is a lack of light in the deepest part of the culture. In this paper, we use the Han model to study the theoretical microalgal growth rate by applying periodically two different light intensities. Two approaches are considered depending on the period of the light pattern. For a large light period, we demonstrate that the average photosynthetic rate can be improved under some conditions. Moreover, we can also enhance the growth rate at steady state as given by the PI-curve. Although, these conditions change through the depth of a bioreactor. This theoretical improvement in the range of 10–15% is due to a recovery of photoinhibited cells during the high irradiance phase. We give a minimal value of the duty cycle for which the optimal irradiance is perceived by the algae culture under flashing light regime. [ABSTRACT FROM AUTHOR]

Increases in algal growth have been reported in rivers, reservoirs, and other water resources worldwide, including Korea. Algal overgrowth can result in algal bloom, which has several negative impacts, such as ecosystem degradation and economic losses. Mitigation measures employed in Korea include an algal warning system and survey-based water quality forecast systems. However, these methods are time-consuming and require sample collection from the site. On the other hand, remote sensing techniques that use chlorophyll a are unable to distinguish between different types of algal species. In this paper, we aimed to identify a classification technique based on remote sensing methods that can be used to distinguish between blue-green algae and green algae. We acquired and prepared an algal culture solution and used a hyperspectral sensor to obtain an algae spectrum. Thereafter, we measured the absorption and emission spectra of blue-green and green algae and distinguished them using the instantaneous slope change of the spectrum. The absorption spectra for green algae showed two peaks at 417–437 nm and 661–673 nm, whereas those of blue-green algae showed three peaks at 449–529 nm, 433–437 nm, and 669–677 nm. The results of this study could form a basis for developing mitigation measures for algal overgrowth. [ABSTRACT FROM AUTHOR]

Monitoring and estimating the density of microalgae in a closed cultivation system is a critical task in culturing algae since it allows growers to optimally control both nutrients and cultivating conditions. Among the estimation techniques proposed so far, image-based methods, which are less invasive, nondestructive, and more biosecure, are practically preferred. Nevertheless, the premise behind most of those approaches is simply averaging the pixel values of images as inputs of a regression model to predict density values, which may not provide rich information of the microalgae presenting in the images. In this work, we propose to exploit more advanced texture features extracted from captured images, including confidence intervals of means of pixel values, powers of spatial frequencies presenting in images, and entropies accounting for pixel distribution. These diverse features can provide more information of microalgae, which can lead to more accurate estimation results. More importantly, we propose to use the texture features as inputs of a data-driven model based on L1 regularization, called least absolute shrinkage and selection operator (LASSO), where their coefficients are optimized in a manner that prioritizes more informative features. The LASSO model was then employed to efficiently estimate the density of microalgae presenting in a new image. The proposed approach was validated in real-world experiments monitoring the Chlorella vulgaris microalgae strain, where the obtained results demonstrate its outperformance compared with other methods. More specifically, the average error in the estimation obtained by the proposed approach is 1.54, whereas those obtained by the Gaussian process and gray-scale-based methods are 2.16 and 3.68, respectively [ABSTRACT FROM AUTHOR]

Macroalgal cultures are currently of great interest worldwide. Although along the Romanian Black Sea coast, there is no tradition in this sense, currently, a major interest in developing this direction exists, taking into consideration that the overexploitation of wild seaweed resources involves the disturbance of the marine environment, with implications that can sometimes be irreversible. Porphyra and Pyropia species (also known as nori algae) are considered the world's most valuable mariculture algal products due to their high nutritional value and multiple active principles, considered unique representatives of marine algae. Considering these aspects, attention was focused on the only nori species from the Romanian Black Sea coast, namely, Pyropia leucosticta. The species was cultivated in controlled laboratory conditions for 5.5 months by manipulating its reproductive elements. The aim was to establish a simple, low-cost method by avoiding the complicated conchocelis phase of the species; therefore, reproduction and further species development were achieved by collecting the released neutral spores and isolating them in culture vessels, ensuring, at the same time, proper nutrient conditions, using sterile enriched seawater and mimicking ambient conditions. At the end of the experiment, specimens of almost 80−90 mm were obtained, making this method suitable for obtaining ex situ P. leucosticta blades on the Romanian Black Sea shore. [ABSTRACT FROM AUTHOR]

The cellular mechanisms responsible for the regulation of nutrient exchange, immune response, and symbiont population growth in the cnidarian–dinoflagellate symbiosis are poorly resolved. Here, we employed liquid chromatography–mass spectrometry to elucidate proteomic changes associated with symbiosis in Breviolum minutum, a native symbiont of the sea anemone Exaiptasia diaphana ('Aiptasia'). We manipulated nutrients available to the algae in culture and to the holobiont in hospite (i.e., in symbiosis) and then monitored the impacts of our treatments on host–endosymbiont interactions. Both the symbiotic and nutritional states had significant impacts on the B. minutum proteome. B. minutum in hospite showed an increased abundance of proteins involved in phosphoinositol metabolism (e.g., glycerophosphoinositol permease 1 and phosphatidylinositol phosphatase) relative to the free-living alga, potentially reflecting inter-partner signalling that promotes the stability of the symbiosis. Proteins potentially involved in concentrating and fixing inorganic carbon (e.g., carbonic anhydrase, V-type ATPase) and in the assimilation of nitrogen (e.g., glutamine synthase) were more abundant in free-living B. minutum than in hospite, possibly due to host-facilitated access to inorganic carbon and nitrogen limitation by the host when in hospite. Photosystem proteins increased in abundance at high nutrient levels irrespective of the symbiotic state, as did proteins involved in antioxidant defences (e.g., superoxide dismutase, glutathione s-transferase). Proteins involved in iron metabolism were also affected by the nutritional state, with an increased iron demand and uptake under low nutrient treatments. These results detail the changes in symbiont physiology in response to the host microenvironment and nutrient availability and indicate potential symbiont-driven mechanisms that regulate the cnidarian–dinoflagellate symbiosis. [ABSTRACT FROM AUTHOR]

As the severity of extreme precipitation events increases with global climate change, so will episodic pulses of contamination into lotic systems. Periphytic algae represents bioindicator species in most freshwater systems due to their rapid accumulation of toxicants; therefore, it is vital to understand how accumulation in this group differs across temporally variable exposure regimes. The ability to rapidly accrue contaminants has additional implications for the trophic transfer of metals to primary consumers. While dietary toxicity has been studied in algivorous consumers, techniques used to prepare contaminated periphytic algae for consumption have not been compared. This study used a modified subcellular fractionation method to compare the partitioning of zinc (Zn) in periphyton cultures exposed for various durations (cultured in the presence of Zn and 15 min, 24 h, and 48 h exposures). Three exposure groups were additionally depurated over a period of 24 h in order to compare retention of Zn, an important aspect of preparing diets used in dietary toxicity studies. The results not only provide evidence for increased retention by periphytic algae cultured in the presence of Zn but reveal relationships among treatments and subcellular partitioning that suggest time-dependent accumulation and detoxification. These relationships suggest that episodic exposure of periphytic algae to contaminants may pose a greater risk than that of chronic regimes. Based on these results, we additionally advocate for culturing periphytic algae in the presence of contamination to produce a more reliable diet for dietary exposure testing in algivorous organisms. [ABSTRACT FROM AUTHOR]

Contamination of microalgae cultures can reduce their productivity and affect the quality of biomass and valuable bioproducts. In this article, after having isolated and identified for the first time the filamentous fungus Penicillium citrinum from heterotrophic cultures of the red polyextremophilic microalga Galdieria sulphuraria, we investigated the biological and metabolic significance of this alga-fungus association. In the same medium, both organisms grow better in each other's presence than separately. Both cell density and cell size of G. sulphuraria increase in co-cultures compared to pure alga cultures. In co-cultures, despite very severe growth conditions, the load of P. citrinum increases compared to pure fungus cultures. Optical microscope images have shown physical contact between cells of P. citrinum hyphae and G. sulphuraria which, however, retain their morphology and cell wall intact. GC–MS-based metabolomics analysis of metabolites excreted in the culture medium shows that pure cultures of the fungus and alga and co-cultures of alga plus fungus can be easily differentiated based on their metabolic products. Indeed, a richer assortment of extracellular metabolites (comprising both products of primary and secondary metabolism) is a distinct feature of co-cultures compared to both pure alga and pure fungus cultures. [ABSTRACT FROM AUTHOR]

Skeletonema costatum is a dominant species in the spring phytoplankton composition of the Romanian Black Sea coastal waters. The species was isolated during a spring bloom and maintained in laboratory conditions for the past 10 years. The biomass was obtained by culturing the species in growth medium for diatoms under continuous light and shaking for four days. The biomass was harvested by vacuum filtration and lyophilized. The tannic acid content was determined by the HPLC method in the methanolic extract of S. costatum biomass. The tannic acid content was 0.46% (4.6 mg tannic acid/g biomass). Also, the chromatogram showed the presence of other separate, but unidentified organic compounds, which may contribute to its therapeutic potential. Our results justify further research to highlight S. costatum antioxidant and antimicrobial activity. [ABSTRACT FROM AUTHOR]

Microalgae are commonly cultivated using photobioreactors (PBRs). To investigate Chlorella vulgaris productivity, a 2.5‐L airlift photobioreactor (AL‐PBR) with vertical and incline baffles was newly developed using computational fluid dynamics (CFD), particle image velocimetry (PIV) methods, and dark/light cultures. A significant increase in cell density and lipid accumulation rate (LAR) in the AL‐PBR was observed. Hydrodynamic stresses including velocity fluctuation, pressure drop, looped bubble swarm, and vorticity magnitude were quantified in algae cultures, suggesting that microvortices induced light and CO2 distribution regulated the algae plastid metabolism in the exponential phase of growth. This study provides a fundamental practice to the scale‐up of bioreactors. [ABSTRACT FROM AUTHOR]

The disease burden of neurodegenerative diseases is on the rise due to the aging population, and neuroinflammation is one of the underlying causes. Spirulina platensis is a well-known superfood with numerous reported bioactivities. However, the effect of S. platensis Universiti Malaya Algae Culture Collection 159 (UMACC 159) (a strain isolated from Israel) on proinflammatory mediators and cytokines remains unknown. In this study, we aimed to determine the anti-neuroinflammatory activity of S. platensis extracts and identify the potential bioactive compounds. S. platensis extracts (hexane, ethyl acetate, ethanol, and aqueous) were screened for phytochemical content and antioxidant activity. Ethanol extract was studied for its effect on proinflammatory mediators and cytokines in lipopolysaccharide (LPS)-induced BV2 microglia. The potential bioactive compounds were identified using liquid chromatography-mass spectrometric (LC-MS) analysis. Ethanol extract had the highest flavonoid content and antioxidant and nitric oxide (NO) inhibitory activity. Ethanol extract completely inhibited the production of NO via the downregulation of inducible NO synthase (iNOS) and significantly reduced the production of tumor necrosis factor (TNF)-α and interleukin (IL)-6. Emmotin A, palmitic amide, and 1-monopalmitin, which might play an important role in cell signaling, have been identified. In conclusion, S. platensis ethanol extract inhibited neuroinflammation through the downregulation of NO, TNF-α and IL-6. This preliminary study provided insight into compound(s) isolation, which could contribute to the development of precision nutrition for disease management. [ABSTRACT FROM AUTHOR]

In the field of industrial microalgae production, the introduction of parasitic contaminants is an often-neglected topic, but one that represents a major risk with potentially significant financial implications. So far, no successful strategy exists to maintain a long-term stable cultivation environment in industrial photobioreactors. To create a strategy for preventing and controlling parasitic contamination, methods from synthetic ecology were used, replacing monocultures with mixed-biocoenoses. The goals were the identification of microbiotic ecosystems of potentially symbiotic bacteria and the utilization of synergistic effects between bacteria and algae to stabilize cultures. The final aim was to combine the findings with abiotic factors influencing the infections. As model organisms, the microalga Coelastrella vacuolata (formerly Scenedesmus vacuolatus) and the parasitic contaminant Amoeboaphelidium protococcarum were chosen. For this case, a correlation between infection rate and the chlorophyll a fluorescence in the culture was found. Algal co-cultures with specific bacteria were tested using the protecting effects of antiphytopathogenic, extracellular substances. This led to the bacterium Pseudomonas protegens and the naturally antipathogenic phenol 2,4-diacetylphloroglucinol (DAPG). Co-cultures with DAPG-producing P. protegens effectively inhibited the infection even though no quantifiable amounts of DAPG were found in the culture. Furthermore, abiotic influences on the infection process were identified, resulting in the implementation of a light–dark-cycle with induced anaerobic conditions in the dark phase. With these findings, conditions that inhibit the growth of parasitic contaminants could now be introduced preventively within standard cultivation procedures. [ABSTRACT FROM AUTHOR]

Global pork production has an annual growth of approximately 2.1%, and its economic and environmental impact are related with the treatment of waste in the production chain. There is little evidence of research advances to generate alternatives for using these wastes. The lack of research related to microalgae cultivation using digestate produced by porcine residues generates negative environmental impact, inadequate and inefficient technologies, low recovery and use of waste and loss of value and competitiveness in the market. The available literature focuses mainly on the treatment of anaerobic digestion liquid effluents for the removal of components, but not on the generation of value-added products. Therefore, there is a need to collect the available information, analyze it and propose other new methodologies. This article presents the information obtained from conducting a systematic review of the literature with a bibliometric and a comparative analysis; achieving an analysis of the temporal and geographical distribution, the main topics, the most influential players, the degree of maturity of the research and different strategies collected for microalgae-based swine manure digestate treatment. In this way, it was possible to capture an overview of the current state of the development of research focused on the use of digestate for the cultivation of microalgae, visualizing important aspects as the evolution of publications, identifying China and USA as the main players in research, biomass and wastewater as potential topics also Spirulina, Astaxanthin and beta-carotene as the main products based on microalgae. Thus, achieving an structure, organized and synthesized landscape of scientific and technological knowledge available for the proposal of investigations that allow the use of anaerobic digestion liquid effluents as cultivation medium for microalgae.

The functional state of an enrichment culture of a green alga Coelastrella multistriata (Trenkwalder) Kalina et Puncochárová in the course of 60-day cultivation was studied. The concentrations of chlorophylls a, b, and c, total carotenoids, protein, vitamins A and E were determined. The rates of lipid peroxide oxidation in the cells of C. multistriata strain MZ–Ch23 were determined using the concentrations of peroxidation products reacting with 2-thiobarbituric acid. The concentrations of these products were determined in the algal biomass on days 15, 25, and 60 of cultivation in the BBM medium, as well as after initiation of peroxide oxidation with Fe2+. Among the photosynthetic pigments, the highest content (14.82 mg/g dry biomass) was shown for chlorophyll a during the exponential growth phase. The total amount of carotenoids was comparable to the values for other studied Coelastrella strains, 0.74–4.21% of the dry biomass. Strain MZ–Ch23 was shown to accumulate high concentrations of retinol (170.49–586.09 µg/L of the algal culture) and protein (141.81–212.38 mg/L). While during all phases of the cultivation C. multistriata cells exhibited low concentrations of the products of lipid peroxide oxidation (0.005–0.015 nmol/mg protein), initiation of peroxide oxidation increased the concentration of TBA-active products up to 0.187 nmol/mg protein on day 60. Cultivation in BBM medium for 25 days proved to be the optimal strategy for obtaining C. multistriata biomass enriched with secondary metabolites and resistant to peroxide oxidation. This resulted in significant amounts of the biomass with high levels of carotenoids, protein, and vitamin A. [ABSTRACT FROM AUTHOR]

Oleaginous microalgae represent potential feedstocks for the sustainable production of lipids thanks to their ability to accumulate triacylglycerols (TAGs). TAG accumulation in several algal species is strongly induced under specific conditions such as nutrient deprivation and high light which, however, also negatively impact growth. Genetic modification of lipogenic pathways can potentially enhance TAG accumulation without negatively affecting growth, avoiding the trade-off between biomass and lipid productivity. In this study, the phospholipid: diacylglycerol acyltransferase (PDAT), an enzyme involved in membrane lipid recycling, was overexpressed in the seawater alga Nannochloropsis gaditana. PDAT overexpression induced increased TAG content in actively growing algae cultures while no effects were observed in conditions naturally stimulating strong lipid accumulation such as high light and nitrogen starvation. The increase of TAG content was confirmed also in a strain cultivated in industrially relevant conditions even though PDAT overexpression, if too strong, the gene overexpression becomes detrimental for growth in the longer term. Results overall suggest that genetic modulation of the PDAT gene represents a promising strategy to increase microalgae lipid content by minimizing negative effects on biomass productivity. • PDAT was overexpressed in Nannochloropsis gaditana. • Overexpression induced accumulating of triacylglycerols. • Increased lipids accumulation was confirmed in long term photobioreactors cultures. • Strong overexpression showed negative impact on growth, only visible on long term. [ABSTRACT FROM AUTHOR]