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Cosmopolitan Gram-negative cyanobacteria may affect human and animal health by contaminating terrestrial, marine and freshwater environments with toxins, such as lipopolysaccharide (LPS). The cyanobacterial genus Scytonema (S) produces several toxins, but to our knowledge the bioactivity of genus Scytonema LPS has not been investigated. We recently reported that cyanobacterium Oscillatoria sp. LPS elicited classical and alternative activation of rat microglia in vitro. Thus, we hypothesized that treatment of brain microglia in vitro with either cyanobacteria S. javanicum or S. ocellatum LPS might stimulate classical and alternative activation with concomitant release of superoxide anion (O2−), matrix metalloproteinase-9 (MMP-9), cytokines and chemokines. Microglia were isolated from neonatal rats and treated in vitro with either S. javanicum LPS, S. ocellatum LPS, or E. coli LPS (positive control), in a concentration-dependent manner, for 18 h at 35.9 °C. We observed that treatment of microglia with either E. coli LPS, S. javanicum or S. ocellatum LPS generated statistically significant and concentration-dependent O2−, MMP-9 and pro-inflammatory cytokines IL-6 and TNF-α, pro-inflammatory chemokines MIP-2/CXCL-2, CINC-1/CXCL-1 and MIP-1α/CCL3, and the anti-inflammatory cytokine IL-10. Thus, our results provide experimental support for our working hypothesis because both S. javanicum and S. ocellatum LPS elicited classical and alternative activation of microglia and concomitant release of O2−, MMP-9, cytokines and chemokines in a concentration-dependent manner in vitro. To our knowledge this is the first report on the toxicity of cyanobacteria S. javanicum and S. ocellatum LPS to microglia, an immune cell type involved in neuroinflammation and neurotoxicity in the central nervous system.

Biosynthesis of the leukotriene A (LTA) class of epoxide is a lipoxygenase-catalyzed transformation requiring a fatty acid hydroperoxide substrate containing at least three double bonds. Here, we report on biosynthesis of a dienoic analog of LTA epoxides via a different enzymatic mechanism. Beginning with homolytic cleavage of the hydroperoxide moiety, a catalase/peroxidase-related hemoprotein from Anabaena PCC 7120, which occurs in a fusion protein with a linoleic acid 9R-lipoxygenase, dehydrates 9R-hydroperoxylinoleate to a highly unstable epoxide. Using methods we developed for isolating extremely labile compounds, we prepared and purified the epoxide and characterized its structure as 9R,10R-epoxy-octadeca-11E,13E-dienoate. This epoxide hydrolyzes to stable 9,14-diols that were reported before in linoleate autoxidation (Hamberg, M. 1983. Autoxidation of linoleic acid: Isolation and structure of four dihydroxy octadecadienoic acids. Biochim. Biophys. Acta 752: 353–356) and in incubations with the Anabaena enzyme (Lang, I., C. Go¨bel, A. Porzel, I. Heilmann, and I. Feussner. 2008. A lipoxygenase with linoleate diol synthase activity from Nostoc sp. PCC 7120. Biochem. J. 410: 347–357). We also prepared an equivalent epoxide from 13S-hydroperoxylinoleate using a “biomimetic” chemical method originally described for LTA4 synthesis and showed that like LTA4, the C18.2 epoxide conjugates readily with glutathione, a potential metabolic fate in vivo. We compare and contrast the mechanisms of LTA-type allylic epoxide synthesis by lipoxygenase, catalase/peroxidase, and chemical transformations. These findings provide new insights into the reactions of linoleic acid hydroperoxides and extend the known range of catalytic activities of catalase-related hemoproteins.

Cyanobacteria exhibit biological rhythms as an adaptation to the daily light-dark (diel) cycle. Light is also crucial for bacteriophages (cyanophages) that infect cyanobacteria. As the first step of infection, the adsorption of some cyanophages to their host cells is light-dependent. Moreover, cyanophage replication is affected by light intensity and possibly the host cell cycle. Photosynthesis and carbon metabolism genes have been found in cyanophage genomes. With these genes, cyanophages may affect the host metabolic rhythm. Field studies suggest that cyanophage infection of cyanobacteria in aquatic environments is synchronized directly or indirectly to the light-dark cycle. These discoveries are beginning to reveal how the daily light-dark cycle shapes the interaction of cyanophages and cyanobacteria, which eventually influences matter and energy transformation in aquatic environments.

Microplastics are ubiquitous environmental contaminants, and concern about microplastics functioning as vectors for coexisting environmental contaminants has been increasing. In this study, we evaluated the potential of microplastics as a vector for microcystins (MCs) in an aquatic environment. Six microplastics—polyvinylidene chloride, polystyrene, polyamide-6 (PA-6), polyvinyl chloride, poly(ethylene terephthalate), and polyethylene—were used in the experiments, and the PA-6 microplastics showed strong affinity toward the cyanotoxin microcystin-leucine arginine (MC-LR) with an adsorption efficiency of 89.5 ± 0.1 %. The adsorption of MC-LR onto PA-6 microplastics was well described by the pseudo-first-order kinetics and Langmuir isotherm models, and the adsorption was considered to be driven mainly by polar–polar interactions. The maximum adsorption capacity (q m) of MC-LR onto PA-6 microplastics was estimated to be 85.64–129.05 μg per g of PA-6 microplastics. Coexisting ions of NaCl, MgSO 4 , KH 2 PO 4 , CaCO 3 , and Na 2 HPO 4 marginally affected the adsorption of MC-LR onto the PA-6 microplastics. However, water-quality parameters of conductivity and total-nitrogen content in environmental freshwaters influenced the adsorption of MC-LR onto PA-6 microplastics. The adsorption capability of PA-6 microplastics was evaluated using extracellular MCs (i.e., MC-LR, MC-YR, MC-RR, and total MCs) released from Microcystis aeruginosa cells during their growth. [Display omitted] • PA-6 microplastics can act as a vector for MC-LR in aquatic environments. • MC-LR adsorption by PA-6 microplastics was well fitted by the Langmuir isotherm. • Polar interaction was involved in the adsorption of MC-LR onto PA-6 microplastics. • Conductivity and T-N content in freshwaters influenced adsorption ability of PA-6. • PA-6 microplastics adsorbed extracellular MCs produced by Microcystis aeruginosa. [ABSTRACT FROM AUTHOR]

The aim of the current study was to optimize the cultivation conditions of Anabaena sp. which was designed by response surface methodology (RSM) executing central composite designs (CCD). The effect of some parameters such as pH, light intensity, and the level of phosphorus and nitrogen was stimulated and 13 conditions were suggested for Anabaena cultivation. After cultivation, their proteins were extracted according to the suggested conditions. Then, the extracted protein of Anabaena was enzymatically hydrolyzed and classified based on the degree of hydrolysis (DH). Based on the results, the highest DH (19.28 %) was found in the hydrolysate obtained from cultivation treatment number 11 (N/P = 4, pH = 7, temperature = 45 °C). Sephadex G25 filtration gel chromatography was then used to purify this hydrolysate. 5 fractions with high absorbance were separated for antioxidant and antibacterial activity evaluation, which were named F14, F15, F16, F17, and F-18. According to the results, F15 showed the strongest antioxidant activity (90.66 %) against DPPH free radicals (p < 0.05). These fractions also showed dose-dependent antibacterial properties against Escherichia coli and Staphylococcus aureus pathogens. A significant difference was seen against E. coli , but not against S. aureus , at the highest concentrations used. This investigation contributes to introducing Anabaena as a cost-effective rich source of protein. Furthermore, these hydrolyzed proteins have antibacterial and antioxidant properties for industrial use. [Display omitted] • Anabaena was successfully cultured in an optimal condition designed by RSM. • Protein was hydrolysate from Anabaena by Alcalase and ultrasound technique. • Protein hydrolysate indicated acceptable antioxidant activity. • Protein hydrolysate exhibited desirable antibacterial activity against E. coli and S. aureus. [ABSTRACT FROM AUTHOR]

Cyanobacterium Nostoc sp. can be considered as an interesting microorganism for the ability of excretion buffering compounds. With respect to possible applied potential of this strain, this ability has been studied under limited irradiance. Soil samples were collected from paddy-fields during one year. At the first step, different acidities (pHs 5,7,9) were studied under limited carbon dioxide condition. Results showed that in all treatments, organism tends to enter logarithmic phase of growth until third day, but acidic condition cause sharp decline on growth after this. Highest specific growth rate belong to alkaline condition (pH 9). For the next step, two alkaline condition near to pH 9 (pHs 8.5 and 9.5), were selected to compare. Results showed that specific growth rate was significantly less than pH 9, and even continuous aeration couldn’t be able to enlarge specific growth rate. Pigment composition can be rearranged at different acidities and phycobilisome systems cause viability and growth under acidity fluctuations and limited irradiance in addition of low carbon dioxide concentration. Ammonium liberation showed the highest rate at pH 5 and day two too.

The freshwater cyanobacterium Oscillatoria BTCC/A 0004 excretes pink pigment containing lipoproteins with molecular weights of about 10 kDa. This pigment has surfactant properties with strong emulsification activity toward several hydrocarbons. This extracellular metabolite was suspected as toxin or allelochemical in their habitat. In this study, I investigated the effect of co-cultivation of Oscillatoria with Anabaena variabilis on the pigment excretion to explore the physiological roles of this pigment in its natural environment. The dead or viable cells and medium of A. variabilis were added into Oscillatoria cultures. Results showed that co-cultivation of free viable cells of A. variabilis enhanced the excretion of pigment without effect on the cell growth. Co-cultivation with viable cells in separated method and dead cells did not influenced the pigment production. The addition of A. variabilis medium was slightly increased the excretion of the pigment. Those results indicated that direct contact with A. variabilis caused Oscillatoria released a certain signaling compound.

Cyanobacterium Nostoc sp can be considered as a potent strain both from antibacterial production ability and agricultural using at the future. So it seems logical to characterize this strain ecophysiologically include acclimation to salt stress. Soil samples were collected from paddy-fields during one year. Isolation and purification were done after soil colonization in BG0-11 medium. Inoculation of Nostoc sp. was done under 2 uE.m-2.s-1 illuminations, 28oC temperature, and without aeration. At the first step, wide ranges of sodium chloride salinities (25%, .5% and 1%) were treated. Results showed that specific growth rate, reach to maximum at 0.5% salinity and though at other salinities survival could be remained but naturally at lower levels using DIC concentration system. The ammonium liberation showed the highest rate at 0.25% salinity condition, both in aeration and limited carbon dioxide conditions. This ability can be considered as a outstanding character from applied aspect.

The effect of limited continuous irradiance and photoperiods on survival, growth and heterocyst frequencies of cyanobacterium Fischerella ambigua collected from paddy-fields of Golestan province have been studied at laboratory condition. After soil collection and culture, sample were isolated, purified, and incubated under 2μEm-2s-1 continuous irradiance with no carbon dioxide addition. The photoperiods were 2, 4, 6, 8 hours darkness each day. Survival, growth and heterocyst frequencies were studied in each treatment using optical density and chlorophyll measurements. Results showed that this cyanobacterium can survive under relatively short times of darkness (2 and possibly 4hours). The highest specific growth rate was related to 2hours dankness daily. 6 and 8hours darknesses cause relative similar results. 8hours darkness daily showed the highest degree of stress and cause sharp drop in growth. Chlorophyll production and morphological behaviors of aggregations showed unpredictable irregular fluctuations independent of photoperiods. We saw highest amount of heterocyst frequency and better regular patterns of heterocyst production at continuous irradiance but correlation between growth and heterocyst production differ completely at this condition.

A novel biosurfactant, 2-acyloxyethylphosphonate, was isolated from waterblooms of Aphanizomenon flos-aquae. Its structure was elucidated by chemical degradation and HRFABMS, GC/EI-MS and 1D- and 2D-NMR spectral analyses. The surfactant contained one mole of 2-hydroxyethylphosphonate and one mole of fatty acid, with hexadecanoic acid accounting for 84.1% of the total fatty acid content. The structure was confirmed by synthesis of 2-oleoyloxyethylphosphonate from ethylene oxide, phosphorus acid and oleic acid chloride. Considering the isolated surfactant molecule as hexadecanoyloxyethylphosphonic acid (mw. 364), the critical micelle concentration (CMC) was about 22 mM.

The cyanobacterium Pseudanabaena sp. FACHB 1277, a 2-methylisoborneol (2-MIB) producer isolated from Xionghe Reservoir, was identified by molecular biological methods based on the 16S rDNA sequence. Pseudanabaena sp. FACHB 1277 is a planktonic freshwater species with relatively high 2-MIB per cell density value (7.76 × 10 ng cell) and specific growth rate (0.25 ± 0.01 d). The effects of temperature and light intensity on 2-MIB production of Pseudanabaena sp. FACHB 1277 were investigated. Of the six temperatures tested, 10, 15, 20, 25, 30, and 35 °C, the maximum total 2-MIB per cell density and minimum cell density were observed at 10 °C, while the total 2-MIB and dissolved 2-MIB (including extracellular and dissolved intracellular 2-MIB) increased with increasing temperature. Among the six tested light intensities (10, 25, 40, 55, 70, and 85 μmol photons m s), the minimum total 2-MIB per cell density and maximum cell density were observed at 25 μmol photons m s. The total 2-MIB and extracellular 2-MIB increased with light intensity increasing from 10 to 40 μmol photons m s, while no significant increase was observed when the light intensity was higher than 40 μmol photons m s. The maximum intracellular 2-MIB (including dissolved and bound) occurred at 25 μmol photons m s. The present study indicates that increasing temperature could favor the conversion of bound intracellular to dissolved 2-MIB, while increasing light intensity stimulates the release of dissolved intracellular 2-MIB into the environment. [ABSTRACT FROM AUTHOR]

Cyanobacterial oxygenic photosynthesis transformed the early Earth's biosphere and resulted in complex aerobic life forms. During the course of evolution, cyanobacteria retained many genes that responded to specific environmental cues. Our study shows that microaerobic treatment did not significantly alter the functionality of photosystem II complex in Synechococcus sp. strain PCC 7002. Surprisingly, no changes in the induction levels of psbA genes, especially in D1' isoform, were recorded. This finding is important as signals an atypical behaviour of D1' isoform from Synechococcus sp. PCC 7002 to microaerobic stress as compared to other cyanobacterial strains. [ABSTRACT FROM AUTHOR]

Cyanobacteria are successful in diverse habitats due to their adaptation strategies. Their mechanisms to cope with individual stresses have been studied. However, the response to combined stress conditions as found in nature remains unclear. With this aim, we studied the dual effect of 24h-osmotic and 3h-UV irradiation on the cyanobacterium Calothrix BI22. Our approach included the study of redox homeostasis, oxidative damage, reactive oxygen species production-consumption processes and photosynthetic activity. Superoxide in vivo determination with confocal image processing showed the highest accumulation under UV. However, no lipoperoxidation occurred due to a high SOD activity. This cyanobacterium was less prepared to cope with the osmotic stress assayed. Under this condition, O 2 photoevolution decreased abruptly and oxidative damage was produced by reactive species other than superoxide. In this situation the cellular control of the amount of ROS failed to prevent oxidative damage and photosynthesis was seriously disturbed in spite of maximum quantum photosynthetic efficiency remained unchanged. Calothrix BI22 presented the more severe oxidative damage when both stressors were applied. The osmotic stress disentangled the mechanisms developed by this cyanobacterium to deal with 3h-UV irradiation alone. [ABSTRACT FROM AUTHOR]

To estimate the combined effects of elevated CO and temperature on microalgae, three typical and worldwide freshwater species, the green alga Scenedesmus acuminatus, the diatom Cyclotella meneghiniana, and the cyanobacterium Microcystis aeruginosa, as well as mixes of these three species were continuously cultured in controlled environment chambers with CO at 390 and 1000 ppm and temperatures of 20, 25, and 30 °C. CO and temperature significantly affected the production of microalgae. The cell productivity increased under elevated CO and temperature. Although the green alga dominated in the mixed culture within all CO and temperature conditions, rising temperature and CO intensified the competition of the cyanobacterium with other microalgae. CO affected the extracellular polymeric substances (EPS) characteristics of the green alga and the cyanobacterium. Elevated CO induced the generation of humic substances in the EPS fractions of the green alga, the cyanobacterium, and the mixed culture. The extracellular carbohydrates of the diatom and the extracellular proteins of the cyanobacterium increased with elevated CO and temperature, while the extracellular carbohydrates and proteins of the green alga and the mixes increased under elevated CO and temperature. There were synergistic effects of CO and temperature on the productivity and the EPS of microalgae. Climate change related CO and temperature increases will promote autochthonous organic carbon production in aquatic ecosystems and facilitate the proliferation of cyanobacteria, which potentially changes the carbon cycling and undermines the functioning of ecosystems. [ABSTRACT FROM AUTHOR]

Filamentous cyanobacterium (strain 10C-PS) isolated from a fresh water body of Bilaspur, Chhattisgarh, India is being described as new species of the polyphyletic genus Scytonema. Phenotypic, molecular and phylogenetic characterization was performed and the combined results validated the strain as a new species. Careful observations of the filaments, presence of a distinctly textured sheath throughout the length of the trichome, differences in the shape and dimensions of the vegetative cells, and heterocytes provided reliable morphological signals that the strain differed from rest of the closely related species. Sequencing of the 16S rRNA gene showed 96.89% sequence similarity with Scytonema hofmanni PCC 7110 while rbcl and psbA sequencing showed 95% and 92% similarities with Scytonema hofmanni PCC 7110 and Nostoc sp. PCC 7524 respectively while the nifD gene sequence similarity was found to be 96% with Scytonema hofmanni PCC 7110. The PC-IGS region was sequenced and concatenated cpcB, IGS and cpcA regions indicated 97% closest similarity with Scytonema sp. PCC 7110 and Scytonema bohnerii Ind24. Subsequent phylogenetic analyses gave a strong pattern of distinct clustering in case of all the molecular markers. The phenotypic, genetic and phylogenetic observations prove conclusively that the strain 10C-PS is a new species in the genus Scytonema with the name proposed being Scytonema bilaspurensis. [ABSTRACT FROM AUTHOR]

Biological production of silver nanoparticles (SNP) has recently received considerable attention because of their therapeutic applications. The present study reports the production and characterization of spherical-thermostable SNP from Spirulina platensis. Wet biomass harvested from optimized logarithmic-phase culture was used for production of SNP in 1, 3, or 5 mM silver nitrate solution. Formation and concentration of spherical SNP was highest when S. platensis was treated with 3 mM silver nitrate. Fourier transform infrared spectra of SNP indicate that vanillin, coumarins, tannins, amide, and glycogen may act as stabilizing agents for bioreduction. The crystalline nature of the produced SNP was evidenced from X-ray diffractometer analysis. Weight loss of SNP occurred at 210°C, 310°C, and 510°C as shown by thermogravimetric analysis. This study shows that S. platensis may be used as an efficient tool for production of spherical, crystalline, and thermostable SNP. [ABSTRACT FROM AUTHOR]

The halotolerant cyanobacterium Anabaena sp was grown under NaCl concentration of 0, 170 and 515 mM and physiological and proteomic analysis was performed. At 515 mM NaCl the cyanobacterium showed reduced photosynthetic activities and significant increase in soluble sugar content, proline and SOD activity. On the other hand Anabaena sp grown at 170 mM NaCl showed optimal growth, photosynthetic activities and comparatively low soluble sugar content, proline accumulation and SOD activity. The intracellular Na content of the cells increased both at 170 and 515 mM NaCl. In contrast, the K content of the cyanobacterium Anabaena sp remained stable in response to growth at identical concentration of NaCl. While cells grown at 170 mM NaCl showed highest intracellular K/Na ratio, salinity level of 515 mM NaCl resulted in reduced ratio of K/Na. Proteomic analysis revealed 50 salt-responsive proteins in the cyanobacterium Anabaena sp under salt treatment compared with control. Ten protein spots were subjected to MALDI-TOF-MS/MS analysis and the identified proteins are involved in photosynthesis, protein folding, cell organization and energy metabolism. Differential expression of proteins related to photosynthesis, energy metabolism was observed in Anabaena sp grown at 170 mM NaCl. At 170 mM NaCl increased expression of photosynthesis related proteins and effective osmotic adjustment through increased antioxidant enzymes and modulation of intracellular ions contributed to better salinity tolerance and optimal growth. On the contrary, increased intracellular Na content coupled with down regulation of photosynthetic and energy related proteins resulted in reduced growth at 515 mM NaCl. Therefore reduced growth at 515 mM NaCl could be due to accumulation of Na ions and requirement to maintain higher organic osmolytes and antioxidants which is energy intensive. The results thus show that the basis of salt tolerance is different when the halotolerant cyanobacterium Anabaena sp is grown under low and high salinity levels. [ABSTRACT FROM AUTHOR]

ContextArthrospira(Spirulina)platensis(SP) is a cyanobacterium which has attracted attention because of its nutritional value and pharmacological properties. It was previously reported that SP reduces oxidative stress in the hippocampus and protects against damaging neurobehavioural effects of systemic kainic acid (KA). It is widely known that the systemic administration of KA induces neuronal damage, specifically in the CA3 hippocampal region. ObjectiveThe present study determines if the SP sub-chronic treatment has neuroprotective properties against KA. Materials and methodsMale SW mice were treated with SP during 24 d, at doses of 0, 200, and 800 mg/kg, once daily, and with KA (35 mg/kg, ip) as a single dose on day 14. After the treatment, a histological analysis was performed and the number of atrophic neuronal cells in CA3 hippocampal region was quantified. ResultsPretreatment with SP does not protect against seizures induced by KA. However, mortality in the SP 200 and the SP 800 groups was of 20%, while for the KA group, it was of 60%. A single KA ip administration produced a considerable neuronal damage, whereas both doses of SP sub-chronic treatment reduced the number of atrophic neurons in CA3 hippocampal region with respect to the KA group. DiscussionThe SP neurobehaviour improvement after KA systemic administration correlates with the capacity of SP to reduce KA-neuronal death in CA3 hippocampal cells. This neuroprotection may be related to the antioxidant properties of SP. ConclusionSP reduces KA-neuronal death in CA3 hippocampal cells. [ABSTRACT FROM AUTHOR]

Marine biofouling, which leads to significant operational stress and economic damage on marine infrastructures, is a major problem in marine related industries. Currently, the most common way to avoid marine biofouling involves the use of biocidal products in surface coatings. However, the need for environmentally friendly antibiofouling compounds has increased rapidly with the recent global prohibition of harmful antifoulants, such as tributyltin (TBT). In particular, periphytic diatoms have been shown to contribute significantly to biofilms, which play an important role in biofouling. Therefore, inhibiting the proliferation of fouling diatoms is a very important step in the prevention of marine biofouling. In this study, we developed a new, rapid, accurate, and convenient growth inhibition assay using the XTT colorimetric method to prevent the growth of the fouling periphytic diatom, Nitzschia amabilis Hidek. Suzuki (replaced synonym, Nitzschia laevis Hustedt). The feasibility of this method was verified by determining the growth inhibition activities of two standard photosynthetic inhibitors, DCMU and CuSO 4 . However, neither inhibitor had any cytotoxic activities at the range of concentrations tested. Moreover, this method was applied by screening and purification of herbicidic but non-cytotoxic compounds from cyanobacteria extracts. Our results demonstrate the utility of this newly established growth inhibition assay for the identification of marine anti-biofouling compounds. [ABSTRACT FROM AUTHOR]

Microalgae mass cultivation is limited by light availability due to effects of absorption and reflection. These effects can only partially be coped with by increasing the photon-flux density. Further inhibitive effects, especially during outdoor cultivations, are described by photoinhibition and photosaturation. Therefore, moving the cells towards the light source and away from it in a distinct mode by convective mass transfer is the method of choice to cope with these inhibitive effects. Hereby, the utilization of culture-flow directing installations, e.g. static mixers, within photobioreactors can be of great benefit. The thermophilic model organism Thermosynechococcus elongatus BP-1 was cultivated in flat-panel airlift photobioreactors with and without static mixers in order to show their positive influence on growth kinetics. Optimal nitrate and carbon concentrations were 2000 mg L − 1 NO 3 − , 0.04 g L − 1 Na 2 CO 3 combined with 6.3% v/v CO 2 . It was shown that photobioreactors with static mixers increase volumetric productivity by a factor of 3.4 and final biomass concentration by a factor of 2.0. A maximum productivity of 2.9 g DW L − 1 d − 1 was demonstrated, to the knowledge of the authors the highest to be reported for the cyanobacterium T. elongatus BP-1. [ABSTRACT FROM AUTHOR]

Synechococcus elongatus cells were immobilized in alginate beads, and the effects of increasing the cross-linker concentration from 2 to 4 % CaCl were evaluated, as well as the effects of coating the beads with either glycerol or poly(ethylene glycol) methyl ether methacrylate (PEGMA)-not previously reported for immobilized microalgae-to improve the holding time of the immobilized cells. S. elongatus cells remain metabolically active after coating with glycerol or PEGMA. There is an inverse relation between the glycerol concentration and the chlorophyll a content for the alginate beads cross-linked with 2 % CaCl. PEGMA diminishes the rate of liberation of cells as its concentration increases, although results suggest the ability of S. elongatus to degrade PEGMA, which increases the growth rate of the liberated cells, because of PEGMA being used as carbon source. [ABSTRACT FROM AUTHOR]

The new paradigm is to view wastes as resources for sustainable development. In this regard, the feasibility of poultry waste and CO utilization for cultivation of a filamentous nitrogen-fixing cyanobacterium, Nostoc muscorum Agardh, was investigated for production polyhydroxyalkanoates, the biodegradable polymers. This cyanobacterium showed profound rise in biomass yield with up to 10 % CO supply in airstream with an aeration rate of 0.1 vvm. Maximum biomass yield of 1.12 g L was recorded for 8 days incubation period, thus demonstrating a CO biofixation rate of 0.263 g L day at 10 % ( v/ v) CO-enriched air. Poultry litter (PL) supplementation also had a positive impact on the biomass yield. The nutrient removal efficiency of N. muscorum was reflected in the significant reduction in nutrient load of PL over the experimental period. A maximum poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) [P(3HB- co-3HV)] copolymer yield of 774 mg L (65 % of dry cell wt.), the value almost 11-fold higher than the control, was recorded in 10 g L PL-supplemented cultures with 10 % CO supply under the optimized condition, thus demonstrating that N. muscorum has good potential for CO biomitigation and poultry waste remediation while simultaneously producing eco-friendly polymers. [ABSTRACT FROM AUTHOR]

Natural organic matters (NOMs), omnipresent in natural water, challenge the toxicity assessment of pollutants to aquatic organisms due to their complex interactions with chemicals and organisms. Here, we investigated the combined toxicity of one solid NOM (black carbon, BC) or one soluble NOM (humic acid, HA) with antibiotics, roxithromycin (RTM) or gatifloxacin (GAT), to the cyanobacterium Synechocystis sp.. The NOMs alleviated the toxicity of RTM and GAT to Synechocystis sp., and BC had greater alleviation effects than HA due to its stronger adsorption to antibiotics. Antibiotics disturbed the photosynthesis of Synechocystis sp. significantly, which were also mitigated by BC and HA. Proteomic analysis showed that BC up-regulated the pathway of ribosome and photosynthetic antenna protein. GAT down-regulated the pathways of ABC transporter and oxidative phosphorylation. RTM interfered the pathway of porphyrin and chlorophyll metabolism. Furthermore, the addition of BC reduced the number of differentially expressed proteins caused by antibiotics, corroborating its mitigation effects on the toxicity of antibiotics. The disturbance of HA on the pathway of ABC transporters inhibited the internalization of RTM, thus decreasing its toxicity. This study underscores the significance of NOMs in mediating the toxicity of organic pollutants to aquatic organisms in natural waters. [Display omitted] • Natural organic matters (NOMs) mitigated antibiotic toxicity through adsorption. • Back carbon showed greater antagonistic effects with antibiotics than humic acid. • NOMs reduced the interference of antibiotics on photosynthesis of Synechocystis sp. • Back carbon mitigated antibiotic toxicity through strong adsorption. • Humic acid reduced antibiotic toxicity by wrapping cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • TCL-1 presented 21.98 ± 1.52 mg/L/h CO 2 fixation rate in 30 L flat panel photobioreactor. • TCL-1 generated higher lipid content (49.91 %) than carbohydrate (24.22 %). • Accumulated phycocyanin by TCL-1 was dominated by C-phycocyanin (98.10 ± 6.67 mg/g). • Extraction with glucose provided heat and photo-damage protection to phycocyanin. Cultivation of Cyanobacteria is preferable for CO 2 fixation process due to its efficiency and production of beneficial byproducts like phycocyanin. In this study, Thermosynechococcus sp. CL-1 (TCL-1) was cultivated in a 30 L flat panel photobioreactor using a 3-fold-modified Fitzgerald medium with 113.2 mM dissolved inorganic carbon. The highest CO 2 fixation rate of 21.98 ± 1.52 mg/L/h was followed by higher lipid content (49.91 % dry weight content or %dwc) than the generated carbohydrate (24.22 %dwc). TCL-1 also potentially produced phycocyanin that was dominated by C-phycocyanin (98.10 ± 6.67 mg/g) along with a lower amount of allophycocyanin and phycoerythrin under extraction using various types of solvent. Stability of phycocyanin extract was further examined during storage under various temperatures and light illuminations. Extraction with 36 % glucose solvent presented a protective effect to phycocyanin from heat and photo-damage which was proven by the kinetics study of phycocyanin degradation in this study. [ABSTRACT FROM AUTHOR]

The food industry is a high consumer of polymer packing materials, sealing materials, and engineering components used in production equipment. Biobased polymer composites used in the food industry are obtained by incorporating different biogenic materials into the structure of a base polymer matrix. Renewable resources such as microalgae, bacteria, and plants may be used as biogenic materials for this purpose. Photoautotrophic microalgae are valuable microorganisms that are able to harvest sunlight energy and capture CO 2 into biomass. They are characterized by their metabolic adaptability to environmental conditions, higher photosynthetic efficiency than terrestrial plants, and natural macromolecules and pigments. The flexibility of microalgae to grow in either low-nutrient or nutrient-rich environments (including wastewater) has led to the attention for their use in various biotechnological applications. Carbohydrates, proteins, and lipids are the main three classes of macromolecular compounds contained in microalgal biomass. The content in each of these components depends on their growth conditions. In general, proteins represent 40-70% of microalgae dry biomass, followed by carbohydrates (10-30%) and lipids (5-20%). A distinctive feature of microalgae cells is the presence of light-harvesting compounds such as photosynthetic pigments carotenoids, chlorophylls, and phycobilins, which are also receiving growing interest for applications in various industrial fields. The study comparatively reports on polymer composites obtained with biomass made of two species of green microalgae: Chlorella vulgaris and filamentous, gram-negative cyanobacterium Arthrospira . Experiments were conducted to reach an incorporation ratio of the biogenic material into the matrix in the 5-30% range, and the resulting materials were characterized by their mechanical and physicochemical properties.

The bottom-up constructed artificial cells help to understand the cell working mechanism and provide the evolution clues for organisms. The energy supply and metabolism mimicry are the key issues in the field of artificial cells. Herein, an artificial cell containing cyanobacteria capable of light harvesting and carbon dioxide fixation is demonstrated to produce glucose molecules by converting light energy into chemical energy. Two downstream "metabolic" pathways starting from glucose molecules are investigated. One involves enzyme cascade reaction to produce H 2 O 2 (assisted by glucose oxidase) first, followed by converting Amplex red to resorufin (assisted by horseradish peroxidase). The other pathway is more biologically relevant. Glucose molecules are dehydrogenated to transfer hydrogens to nicotinamide adenine dinucleotide (NAD + ) for the production of nicotinamide adenine dinucleotide hydride (NADH) molecules in the presence of glucose dehydrogenase. Further, NADH molecules are oxidized into NAD + by pyruvate catalyzed by lactate dehydrogenase, meanwhile, lactate is obtained. Therefore, the cascade cycling of NADH/NAD + is built. The artificial cells built here pave the way for investigating more complicated energy-supplied metabolism inside artificial cells., (© 2022 Wiley-VCH GmbH.)

A new antibacterial 3-monoacyl- sn -glycerol, nostochopcerol ( 1 ), was isolated from a cultured algal mass of the edible cyanobacterium Nostochopsis lobatus MAC0804NAN. The structure of compound 1 was established by the analysis of NMR and MS data while its chirality was established by comparison of optical rotation values with synthetically prepared authentics. Compound 1 inhibited the growth of Bacillus subtilis and Staphylococcus aureus at MIC of 50 μg/mL and 100 μg/mL, respectively., (Copyright © 2023, Oku et al.)

Cyanobacterial expansion is harmful to the environment, the ecology of Lake Baikal and the economy of nearby regions and can be dangerous to people and animals. Since 2011, the process of colonisation of the lake with potentially toxic cyanobacteria belonging to the genus Tychonema has continued. An understanding of the mechanism of successful expansion of Tychonema requires scrutiny of biological and genomic features. Tychonema sp. BBK16 was isolated from the coastal zone of Lake Baikal. The morphology of BBK16 biofilm was studied with light, scanning electron and confocal microscopy. The biofilm is based on filaments of cyanobacteria, which are intertwined like felt; there are also dense fascicles of rope-like twisted filaments that impart heterogeneity to the surface of the biofilm. Genome sequencing, intergenomic comparisons and phylogenetic analyses indicated that Tychonema sp. BBK16 represent a new species related to planktic cyanobacterium Tychonema bourrellyi , isolated from Alpine lentic freshwater. Genome investigation revealed the genes possibly responsible for the mixotrophic lifestyle. The presence of CRISPR-Cas and restriction modification defence mechanisms allowed to suggest the existence of phages infecting Tychonema sp. BBK16. Analysis of CRISPR spacers and prophage-derived regions allowed to suggest related cyanophages. Genomic analysis supported the assumption that mobile elements and horizontal transfer participate in shaping the Tychonema sp. BBK16 genome. The findings of the current research suggest that the aptitude of Tychonema sp. BBK16 for biofilm formation and, possibly, its mixotrophic lifestyle provide adaptation advantages that lead to the successful expansion of this cyanobacterium in the Baikal's conditions of freshwater lake environments.

The influence of cultivation methods and postharvesting treatment on protein profiles of green freshwater microalgaeChlorella kessleri, Scenedesmus quadricauda, andChlorellasp. and cyanobacteriumSpirulina platensiswere evaluated. The comparison of protein profiles in algal biomass originated from the autotrophic cultivation in an outdoor open circulating cascade-type cultivation apparatus in thin-layer, a solar photobioreactor, and from the heterotrophic cultivation regime in a fermenter. All tested algae contained protein bands in the area between 14.3–27 and 70–116 kDa. Protein profiles revealed much higher heterogenity in the area between 30–70 kDa. [ABSTRACT FROM PUBLISHER]

Aims: Cyanobacteria have been used as sustainable bioresource producers for foods, feeds and other valuable natural products. However, selection of a new species (other than Arthrospira), with advantageous properties for alimentary purposes, continues to be a challenge due to potential toxicity and low biomass productivity. In this study, we report a valuable filamentous cyanobacterium isolated from Korea. Methods and Results: Morphological and phylogenetic analyses demonstrated that the isolate belongs to the genus Leptolyngbya, and consequently designated Leptolyngbya sp. KIOST-1. Interestingly, Leptolyngbya sp. KIOST-1 possessed numerous advantageous characteristics for biomass production, similar to Arthrospira. The isolate readily propagated in SOT medium with efficient biomass productivity, and its optimum growth was observed at 30°C under alkaline and saline conditions. Moreover, more than half of the cellular components in Leptolyngbya sp. KIOST-1 were composed of protein, with approx. 40% of essential amino acids. Most importantly, no significant cytotoxicity was detected in the isolate. Conclusions: Leptolyngbya sp. KIOST-1 has a number of advantageous characteristics for alimentary purposes due to its efficient productivity, high protein content and lack of potential cytotoxicity. Significance and Impact of the Study: Leptolyngbya sp. KIOST-1 may be considered a potential candidate for industrial biomass production, similar to Arthrospira. [ABSTRACT FROM AUTHOR]