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The synthesis and biosynthesis of the complex saxitoxin (STX) structure have garnered significant interest. Previously, we hypothesized that the tricyclic skeleton of STX originates from the monocyclic precursor 11‐hydroxy‐IntC'2 during biosynthesis, although direct evidence has been lacking. In this study, we identified conditions to synthesize a proposed tricyclic biosynthetic intermediate, 12,12‐dideoxy‐decarbamoyloxySTX (dd‐doSTX), along with its 6‐epimer (6‐epi‐dd‐doSTX) and a bicyclic compound, in a single step from di‐Boc protected 11‐hydroxy‐IntC'2. The reaction mechanism involves successive aza‐Michael addition of a guanidino amine to the conjugated olefin. Notably, both dd‐doSTX and 6‐epi‐dd‐doSTX were detected in a toxin‐producing cyanobacterium, suggesting that the biosynthetic enzymes may generate these compounds via similar mechanisms. [ABSTRACT FROM AUTHOR]

The interplay between cancer and bacteria is a complex and evolving area of study, with certain bacteria implicated in both cancer onset and elicitation of chemoresistance. Combining nanoparticle-based photodynamic therapy (PDT) with antibiotics is a powerful strategy to overcome bacteria-induced chemoresistance in tumors. This synergistic approach enhances targeting and killing of both cancer cells and bacteria with a prompting immune response. In this study, we have synthesized uniform spherical shaped, self-assembled chlorophyll-rich, fluorescent, and photosensitive nanocarriers (named algosomes), derived from cyanobacterium, Spirulina platensis. These algosomes specifically target cancer cells due to an abundance of polyunsaturated fatty acids (PUFA) which are taken up more by the cancer cells to maintain cell membrane phospholipids to support their rapid growth and survival and exhibit tumor suppression via PDT due to integrated chlorophyll. Additionally, they serve as an excellent drug delivery system for antibiotics, enhancing the antibacterial activity against multidrug-resistant bacteria. Comprehensive biocompatibility evaluations on L929 cell lines, hemocompatibility tests, and in ovo biocompatibility studies in zebrafish embryos validated the safety of algosomes for potential clinical applications. In vitro findings demonstrated that algosomes in response to near-infrared (NIR) light kill cancer cells by inducing oxidative stress and mitochondrial damage, which leads to apoptosis in skin and colon cancer. Photoresponsive algosomes also impede cell migration following treatment, a crucial factor in preventing metastasis. Furthermore, the antibacterial and antihemolytic effect of antibiotic-loaded algosomes against multidrug resistant Escherichia coli and Staphylococcus aureus was quantified. This nanocarrier addresses the complex interplay of bacterial infections and cancer within a single nanoplatform, offering a promising solution to combat these dual challenges. Continued research and clinical development of this combination therapy hold promise for more effective and comprehensive cancer treatments. [ABSTRACT FROM AUTHOR]

Azolla, also known as "green gold" or "super plant," is a nitrogen-fixing pteridophyte found in temperate and tropical freshwater ecosystems. This free-floating aquatic fern, native to Asia, Africa, and the Americas, thrives in diverse aquatic habitats, including swamps, ditches, lakes, and shallow rivers. It generates full biomass in a relatively short period of time. It acts as a nitrogen biofertilizer and boosts rice productivity. Beyond its role in agriculture, Azolla serves as a versatile resource, finding applications in livestock feed, human nutrition, hydrogen fuel production, biogas generation, pest control, and water purification. Notably, Azolla exhibits hyperaccumulation capabilities for various heavy metal contaminants and can effectively absorb ammonium and phosphorous from wastewater. Moreover, it possesses antimicrobial properties and a rich array of phytochemical compounds, promising multifaceted benefits in diverse fields. This review highlights the vast potential of Azolla, emphasizing its suitability for extensive research and development in food, feed, and fodder applications, as well as household cultivation and utilization. To fully harness the myriad advantages offered by Azolla and promote sustainability across various sectors, further exploration and investigation into its untapped applications remain imperative. Azolla holds the key to addressing numerous environmental, agricultural, and industrial challenges, paving the way for a more sustainable and resource-efficient future. [ABSTRACT FROM AUTHOR]

Wastewater from different sources with excessive nutrient loading, which is a major contributor to eutrophication, can be a promising medium alternative for microalgae cultivation with effective removal of NH4+-N, PO43--P and organic matter. In this study, three groups of synthetic wastewater (SWW), an ammonium-rich stream (60 to 250 mg L-1 NH4+) containing a specific type of organic matter, such as petroleum effluent (SWW1: 300 mg L-1 glucose and 10 mg L-1 phenol), molasses wastewater (SWW2: 600 mg L-1 glucose), and agro-industrial wastewater (SWW3: no organic matters) were used for growing Chlorella sp. and for investigating its potential for nutrient removal as well as the production of biomass and lipid. The findings showed that Chlorella sp. grown in SWW2 (i.e., the auto/mixotrophic culture with 14 days) served as efficient feedstock for lipid production, and showed the maximum lipid content and yield of 53 % DCW and 188 mg L-1, respectively. Additionally, the maximum removal of 76 % NH4+-N was observed under this condition. Higher removal of NH4+-N with 100 % efficiency was seen in Chlorella sp. under SWW1 and SWW3 conditions. However, under SWW2 the cells had higher NH4+ uptake rate than that under SWW1 and SWW3, resulting in highest biomass productivity in SWW2 grown cells. The spent media after Chlorella sp. cultivation were used for growing the N2-fixing cyanobacterium Fischerella muscicola TISTR 8215 for the production of hydrogen. Among different spent media, F.muscicola TISTR 8215 cultivated in SWW1 spent medium obtained from 7-day Chlorella sp. cultivation had the highest hydrogen production of 200.8 µmol H2 mg-1 chlorophyll a. Overall, the present study employed biorefinery approach using the microalga biomass as feedstock for lipid production with subsequent utilization of spent medium for growing the cyanobacterium for enhanced production of hydrogen. [ABSTRACT FROM AUTHOR]

The use of various artificial dyes in the preparation of cosmetics for over half a century has led to an increase in cancer diseases in humans. On the other hand, the excessive use of synthetic antibiotics available on the market, which have been used for treating humans and animals for over half a century, has significantly reduced the efficacy of many antibiotics due to the development of bacterial resistance. In contrast, phycoerythrin (PE) as a natural pigment possesses potential antioxidant and antimicrobial properties. Therefore, this article aims to use PE to create soap and cosmetic lipsticks that not only ensure consumer health but also avoid the harmful effects of chemical compounds present in cosmetic products. In the present study, PE extracted from the cyanobacterium Aliinostoc oryzae was microencapsulated with chitosan and added to the formulation of solid soap and lipstick. All standard tests were performed at intervals of 1, 5, 10, 15, 20, 25, and 30 days and compared with controls. The percentage change in the hardness of lipsticks enriched with PE was significantly higher than the control (p ≤ 0.05), while the amount of force required during use was significantly lower than the control (p ≤ 0.05). In soaps enriched with PE, the moisture reduction trend over time was steeper in soaps without PE. Additionally, the antioxidant activity and insoluble substances in alcohol in PE-enriched soaps were significantly higher than the control sample, while the percentage of lipid compounds and the unsaponifiable matter of free alkali in the control sample were significantly higher than the Soap + PE sample (p ≤ 0.05). Over time, the L* color component of all enriched products decreased significantly, while the a*, b*, and ΔE color components increased significantly (p ≤ 0.05). Moreover, the total microbial population, inhibition zone diameter, and peroxide index in enriched products were significantly lower than the control. Overall, the enriched products did not cause any skin sensitivity, and color changes and stability remained consistent over time. All these results confirm the claim that chitosan-coated PE, as an effective additive, has significant efficacy in cosmetic products.

Sacran is a supergiant cyanobacterial polysaccharide that forms mesogenic supercoil rods that exhibit liquid crystalline (LC) gels at deficient concentrations of around 0.5 wt%, and has several bioactive stimuli-responsive functions. Here, we attempted to form oriented microfibers of sacran by electrospinning, following structural analyses of the sacran rods. A heterogeneous acid-hydrolysis method using a protonated cation-exchange resin was adopted to examine the short-time exposition of concentrated acid to sacran rods. From the supernatant, the oligomeric fraction that was soluble in water and methanol was isolated. The oligomeric fraction had a main sugar ratio of α-Glc:β-Glc:α-Xyl:β-Xyl:α-Rha of 2:5:1.5:1.5:4 (Glc:Xyl:Rha = 7 (=4 + 3):3:4), and it was speculated that the sacran structure includes rhamnoglucan and xyloglucan (4:3), which are generally rigid enough to exhibit LC. To make oriented microfibers of LC sacran, solubility testing was performed on sacran to find good new solvents of polyhydroxy alcohols such as ethylene glycol, 1,2-propanediol, and glycerol. The oriented film was prepared from a sacran aqueous solution where calcium compound particles deposited on the film are different from polyhydroxy alcohol solutions. Although sacran could not form microfibers by itself, polymer composite microfibers of sacran with poly(vinyl alcohol) were prepared by electrospinning. Cross-polarizing microscopy revealed the molecular orientation of the microfibers. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui 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.)

Ultraviolet (UV) A radiation (315–400 nm) is the predominant component of solar UV radiation that reaches the Earth’s surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5–15 W m−2 (15–46 µmol photons m−2 s−1) UV-A and 4.35 W m−2 (20 μmol photons m−2 s−1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%–30% and 15%–56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography–mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides. IMPORTANCE Ultraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315–400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy. [ABSTRACT FROM AUTHOR]

Environmental variation has a significant impact on how organisms, including cyanobacteria, respond physiologically and biochemically. Salinity and ultraviolet radiation (UVR)-induced variations in the photopigments of the rice-field cyanobacterium Nostochopsis lobatus HKAR-21 and its photosynthetic performance was studied. We observed that excessive energy dissipation after UVR is mostly caused by Non-Photochemical Quenching (NPQ), whereas photochemical quenching is important for preventing photoinhibition. These findings suggest that ROS production may play an important role in the UVR-induced injury. To reduce ROS-induced oxidative stress, Nostochopsis lobatus HKAR-21 induces the effective antioxidant systems, which includes different antioxidant compounds like carotenoids and enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). The study indicates that Nostochopsis lobatus HKAR-21 exposed to photosynthetically active radiation + UV-A + UV-B (PAB) and PAB + NaCl (PABN) had significantly reduced photosynthetic efficiency. Furthermore, maximum ROS was detected in PAB exposed cyanobacterial cells. The induction of lipid peroxidation (LPO) has been investigated to evaluate the impact of UVR on the cyanobacterial membrane in addition to enzymatic defensive systems. The maximal LPO level was found in PABN treated cells. Based on the findings of this research, it was concluded that salinity and UVR had collegial effects on the major macromolecular components of the rice-field cyanobacterium Nostochopsis lobatus HKAR-21. [ABSTRACT FROM AUTHOR]

The cyanobacterial strain Cyanobacterium sp. IPPAS B-1200 isolated from Lake Balkhash is characterized by high relative amounts of myristic (30%) and myristoleic (10%) acids. The remaining fatty acids (FAs) are represented mainly by palmitic (20%) and palmitoleic (40%) acids. We expressed the genes for lysophosphatidic acid acyltransferase (LPAAT; EC 2.3.1.51) and Δ9 fatty acid desaturase (FAD; EC 1.14.19.1) from Cyanobacterium sp. IPPAS B-1200 in Synechococcus elongatus PCC 7942, which synthesizes myristic and myristoleic acids at the level of 0.5–1% and produces mainly palmitic (~60%) and palmitoleic (35%) acids. S. elongatus cells that expressed foreign LPAAT synthesized myristic acid at 26%, but did not produce myristoleic acid, suggesting that Δ9-FAD of S. elongatus cannot desaturate FAs with chain lengths less than C16. Synechococcus cells that co-expressed LPAAT and Δ9-FAD of Cyanobacterium synthesized up to 45% palmitoleic and 9% myristoleic acid, suggesting that Δ9-FAD of Cyanobacterium is capable of desaturating saturated acyl chains of any length. [ABSTRACT FROM AUTHOR]

Leptolyngbya sp. KIOST-1 has been proposed as a candidate species for use as a protein supplement due to its high protein content and absence of cytotoxicity. The species has also garnered attention due to the photosynthetic pigments it possesses. However, limited information is available on its cultivation. Therefore, this study was conducted to identify the optimal culture medium and fundamental physiological properties of Leptolyngbya sp. KIOST-1 under various culture conditions. In this study, SOT (Society of Toxicology) medium was confirmed as the optimal culture medium for Leptolyngbya sp. KIOST-1 growth. The biomass production, protein content, and photosynthetic pigment content of Leptolyngbya sp. KIOST-1 were significantly higher in SOT medium. The use of this medium allowed for scaling up from laboratory (10 mL) to pilot (200 L) conditions and industrial-scale outdoor conditions (10,000 L), with the biomass containing over 66% protein. The phytochemical composition of Leptolyngbya sp. KIOST-1 cultured at laboratory and industrial-scales was discovered in this study. Furthermore, we observed that reducing the carbon and nitrogen sources to 1/5 of those supplied by the optimal medium did not significantly affect biomass production, and Leptolyngbya sp. KIOST-1 demonstrated favorable growth capabilities in a salinity range of 10–50 psu and at pH levels of 8.3 to 10.3. The results of this study demonstrate the suitability of Leptolyngbya sp. KIOST-1 for various industrial applications and its adaptability to large-scale cultivation. [ABSTRACT FROM AUTHOR]

The northern part of James Ross Island is the largest deglaciated area in the Antarctic Peninsula region with a unique ecosystem created during the Late Glacial. This research aims to evaluate the degree of contamination of the locality with toxic metals (As, Hg, Cd, and Pb) through bioindicators in the aquatic environment—colonies of cyanobacteria and algae. For this purpose, bottom lake sediments of Big Lachman Lake were studied for contents of Fe, As, Hg, Cd, Pb, Cr, Co, Ni, Cu, and Zn, as well as samples of cyanobacterial mat, in which Fe, As, Hg, Cd, and Pb were determined. Metal contents were determined by means of inductively coupled plasma optical emission spectrometry and atomic absorption spectrometry. The contents of metals in sediments did not differ from the usual values in the area of the Antarctic Peninsula. The bioaccumulation of metals in cyanobacterial mat was evaluated by calculating enrichment factors (the calculation to Fe as a reference element). According to this method, moderate pollution of Big Lachman Lake was confirmed for Hg and Cd. [ABSTRACT FROM AUTHOR]

Cyanobacteria, a group of microalgae are the potent organism having the ability to survive in the copper rich environment and recently gained too much attention for their profuse proliferation in such water bodies. Amongst the members of cyanobacteria, the current study was conducted on Leptolyngbya sp. GUEco1015, collected from hydrocarbon rich water bodies of Assam, India. Morphological images of treated samples showed a remarkable damage in the cell surface as well as the organelles over the control. Biochemical results revealed a significant increase of enzymatic and non-enzymatic antioxidants during oxidative damage of Cu2+. But, ascorbate in 1.2 ppm (p

Carbon acquisition, assimilation and storage in eukaryotic microalgae and cyanobacteria occur in multiple compartments that have been characterised by the location of the enzymes involved in these functions. These compartments can be delimited by bilayer membranes, such as the chloroplast, the lumen, the peroxisome, the mitochondria or monolayer membranes, such as lipid droplets or plastoglobules. They can also originate from liquid–liquid phase separation such as the pyrenoid. Multiple exchanges exist between the intracellular microcompartments, and these are reviewed for the CO2 concentration mechanism, the Calvin–Benson–Bassham cycle, the lipid metabolism and the cellular energetic balance. Progress in microscopy and spectroscopic methods opens new perspectives to characterise the molecular consequences of the location of the proteins involved, including intrinsically disordered proteins. [ABSTRACT FROM AUTHOR]

Sacran is a supergiant cyanobacterial polysaccharide that forms mesogenic supercoil rods that exhibit liquid crystalline (LC) gels at deficient concentrations of around 0.5 wt%, and has several bioactive stimuli-responsive functions. Here, we attempted to form oriented microfibers of sacran by electrospinning, following structural analyses of the sacran rods. A heterogeneous acid-hydrolysis method using a protonated cation-exchange resin was adopted to examine the short-time exposition of concentrated acid to sacran rods. From the supernatant, the oligomeric fraction that was soluble in water and methanol was isolated. The oligomeric fraction had a main sugar ratio of α-Glc:β-Glc:α-Xyl:β-Xyl:α-Rha of 2:5:1.5:1.5:4 (Glc:Xyl:Rha = 7 (=4 + 3):3:4), and it was speculated that the sacran structure includes rhamnoglucan and xyloglucan (4:3), which are generally rigid enough to exhibit LC. To make oriented microfibers of LC sacran, solubility testing was performed on sacran to find good new solvents of polyhydroxy alcohols such as ethylene glycol, 1,2-propanediol, and glycerol. The oriented film was prepared from a sacran aqueous solution where calcium compound particles deposited on the film are different from polyhydroxy alcohol solutions. Although sacran could not form microfibers by itself, polymer composite microfibers of sacran with poly(vinyl alcohol) were prepared by electrospinning. Cross-polarizing microscopy revealed the molecular orientation of the microfibers.

Copyright of Salud, Ciencia y Tecnología is the property of Fundacion Salud, Ciencia y Tecnologia 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.)

Cyanobacteria and their interactions with phytopathogenic fungi in soil-less potting mixes is a less explored aspect in the protected cultivation of crops, as fungal diseases often bring about serious losses. The nursery of tomato was raised with A. laxa amended /unamended soil-less substrate mixes [P:C, perlite: cocopeat (1:1); C:V, cocopeat: vermiculite (1:1); P:C:V, perlite: cocopeat: vermiculite: (1:1:1)]. Preliminary investigation of percent germination of tomato seeds in the different media with the treatments illustrated the differential influence of the media, and Anabaena laxa amended treatments showing highest values, including those challenged with F. solani. To further understand the nature of such interactions in the rhizosphere, transplantation of 30 d-old seedlings was undertaken in mesocosm experiments deploying soil-less substrate mixes (P:C, C:V, P:C:V) challenged with /without Fusarium solani or Rhizoctonia solani. Significant increases of 10–46% were recorded in the total soil polysaccharides and dehydrogenase activity with F. solani, and in IAA with R. solani, compared to control. Among the treatments, T4 (A. laxa ± Fs) showed an almost 60% increase in terms of nitrogen and organic carbon content. This illustrated that A. laxa effectively interacted with both fungi and improved the nutrient availability in the media; interestingly, F. solani exhibited a growth stimulatory role. Cyanobacterium-fungal interactions led to better growth of tomato plants, illustrating that A. laxa amendment can be a promising option, particularly, in P:C:V, as media for developing robust and disease-free nurseries. [ABSTRACT FROM AUTHOR]

Recently, concern on several environmental issues including the pollutant discharge and high concentration of CO 2 have gained high interest due to its impact on ecosystem and global warming effect, respectively. Implementation of photosynthetic microorganism carries out numerous advantages including high efficiency of CO 2 fixation, the great endurance under extreme conditions and generation of valuable bioproducts. Thermosynechococcus sp. CL-1 (TCL-1), a cyanobacterium, has the ability to perform CO 2 fixation and accumulation of various byproducts under extreme conditions like high temperature and alkalinity, presence of estrogen, or even using swine wastewater. This study aimed to assess TCL-1 performance under various endocrine disruptor compounds (bisphenol-A, 17-β-estradiol/E2, and 17-α-ethynilestradiol/EE2), concentrations (0–10 mg/L), light intensities (500–2000 µE/m2/s), and dissolved inorganic carbon/DIC levels (0–113.2 mM). Addition of E2 content even until 10 mg/L carried out insignificant biomass growth interruption along with the improvement in CO 2 fixation rate (79.8 ± 0.1 mg/L/h). Besides the influence of E2, application of higher DIC level and light intensity also enhanced the CO 2 fixation rate and biomass growth. The highest biodegradation of E2 at 71% was achieved by TCL-1 in the end of 12 h cultivation period. TCL-1 dominantly produced protein (46.7% ± 0.2%), however, production of lipid and carbohydrate (39.5 ± 1.5 and 23.3 ± 0.9%, respectively) also could be considered as the potential source for biofuel production. Thus, this study can provide an efficient strategy in simultaneously dealing with environmental issues with side advantage in production of macromolecules. [Display omitted] • The highest TCL-1 CO 2 fixation rate achieved with 10 mg/L E2 addition. • 71.0% estrogen biodegradation occurred in 10 mg/L initial E2 concentration. • The highest protein productivity reached to 42.4 mg/L/h. • The highest lipid productivity (19.6 ± 1.5 mg/L/h) was achieved under 3 mg/L of E2. [ABSTRACT FROM AUTHOR]

An excess of reactive oxygen species (ROS) can cause severe oxidative damage to cellular components in photosynthetic cells. Antioxidant systems, such as the glutathione (GSH) pools, regulate redox status in cells to guard against such damage. Dehydroascorbate reductase (DHAR, EC 1.8.5.1) catalyzes the glutathione-dependent reduction of oxidized ascorbate (dehydroascorbate) and contains a redox active site and glutathione binding-site. The DHAR gene is important in biological and abiotic stress responses involving reduction of the oxidative damage caused by ROS. In this study, transgenic Synechococcus elongatus PCC 7942 (TA) was constructed by cloning the Oryza sativa L. japonica DHAR (OsDHAR) gene controlled by an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible promoter (Ptrc) into the cyanobacterium to study the functional activities of OsDHAR under oxidative stress caused by hydrogen peroxide exposure. OsDHAR expression increased the growth of S. elongatus PCC 7942 under oxidative stress by reducing the levels of hydroperoxides and malondialdehyde (MDA) and mitigating the loss of chlorophyll. DHAR and glutathione S-transferase activity were higher than in the wild-type S. elongatus PCC 7942 (WT). Additionally, overexpression of OsDHAR in S. elongatus PCC 7942 greatly increased the glutathione (GSH)/glutathione disulfide (GSSG) ratio in the presence or absence of hydrogen peroxide. These results strongly suggest that DHAR attenuates deleterious oxidative effects via the glutathione (GSH)-dependent antioxidant system in cyanobacterial cells. The expression of heterologous OsDHAR in S. elongatus PCC 7942 protected cells from oxidative damage through a GSH-dependent antioxidant system via GSH-dependent reactions at the redox active site and GSH binding site residues during oxidative stress.

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.

Abstract Background Along with the fast development and urbanization in developing countries, the waterbodies aside the growing cities become heavily polluted and highly eutrophic, thus leading to the seasonal outbreak of cyanobacterial bloom. Systematic isolation and characterization of freshwater cyanophages might provide a biological solution to control the awful blooms. However, genomic sequences and related investigations on the freshwater cyanophages remain very limited to date. Results Following our recently reported five cyanophages Pam1~Pam5 from Lake Chaohu in China, here we isolated another five cyanophages, termed Pan1~Pan5, which infect the cyanobacterium Pseudanabaena sp. Chao 1811. Whole-genome sequencing showed that they all contain a double-stranded DNA genome of 37.2 to 72.0 kb in length, with less than half of the putative open reading frames annotated with known functions. Remarkably, the siphophage Pan1 encodes an auxiliary metabolic gene phoH and constitutes, together with the host, a complete queuosine modification pathway. Proteomic analyses revealed that although Pan1~Pan5 are distinct from each other in evolution, Pan1 and Pan3 are somewhat similar to our previously identified cyanophages Pam3 and Pam1 at the genomic level, respectively. Moreover, phylogenetic analyses suggested that Pan1 resembles the α-proteobacterial phage vB_DshS-R5C, revealing direct evidence for phage-mediated horizontal gene transfer between cyanobacteria and α-proteobacteria. Conclusion In addition to the previous reports of Pam1~Pam5, the present findings on Pan1~Pan5 largely enrich the library of reference freshwater cyanophages. The abundant genomic information provides a pool to identify novel genes and proteins of unknown function. Moreover, we found for the first time the evolutionary traces in the cyanophage that horizontal gene transfer might occur at the level of not only inter-species, but even inter-phylum. It indicates that the bacteriophage or cyanophage could be developed as a powerful tool for gene manipulation among various species or phyla.

A cyanobacterium producing β-glucosidase was isolated from Lake Pamvotis located in Ioannina in Greece. This microorganism, named Pamv7, was identified as Pseudanabaena sp. using phylogenetic characterization. The high-throughput BiologMicroPlate™ method, used for the rapid assessment of heterotrophic potential, indicates that Pseudanabaena sp. metabolizes a wide range of organic substrates such as amino acids, carbohydrates, and carboxylic acids. When the strain grows in a culture medium containing cellobiose as a carbon source, it produces a significant amount of intracellular β-glucosidase. The effect of cellobiose concentration, nitrogen source, and nitrogen concentration of the growth medium, as well as the temperature of the culture, on biomass and β-glucosidase by Pseudanabaena sp., was studied. Biomass and β-glucosidase production by the strain in a lab-scale bioreactor at optimal conditions (10 g/L cellobiose, 1.5 g/L yeast, and 23 ± 1 °C) reached 2.8 g dry weight/L and 44 U/L, respectively. The protein and lipid content of the produced cyanobacterium biomass were 23% and 43 w/w, respectively. This study is the first report of β-glucosidase production by a cyanobacterial strain and concomitant high production of microalgae biomass, making Pseudanabaena sp. a promising microorganism in the field of enzyme biotechnology.

Sodium dodecyl sulfate (SDS) accumulation in nature impart detrimental effects on various lifeforms as it truncates cellular proteins. The present study exhibited SDS bioremediation ability of cyanobacterium Fischerella sp. lmga1. Phylogeny across cyanobacterial phyla depicted uneven distribution and abundance of SdsA1 hydrolase (characterised for SDS hydrolysis in Pseudomonas aeruginosa PA01) in Microcystis spp. and Fischerella spp. Further, Fischerella sp. lmga1, was administered with 200 µM SDS to validate not only the bioremediation capability but also the physiological adjustments during SDS hydrolysis. The preliminary effect of SDS was harsh, as the cyanobacterial growth was significantly reduced along with subsequent decline in photopigment, chlorophyll a fluorescence and carbohydrate. Nevertheless, drastic rejuvenation upon 8th day of treatment and increment in photosynthetic capacity suggested the resilience of lmga1 against SDS. Further, about 50% removal of SDS with highest degradation rate was observed on 10th day of treatment, followed after substantial increment in the expression of sdsA1 on 8th day. Interestingly, the Fourier-transform infrared (FTIR) depicted homeostasis in the carbon allocation pattern or membrane lipid dynamics during SDS removal, indicating the endurance of lmga1. Although, the peak intensity at 1077 cm−1 reduced on day 4 corresponded to DNA damage, yet increased peak intensity on 8th day ascertained damage repair. Molecular docking of SdsA1 hydrolase of Fischeralla thermalis CCME 5301 with SDS depicted low binding energy of -4.3 kCal mol−1, thereby endorsing stable binding. Thus, this study corroborated the application of lmga1 for removal of surfactant as it displayed commendable resilience and SDS removal capability. [ABSTRACT FROM AUTHOR]

Progress in phylogenomic analysis has led to a considerable re-evaluation of former cyanobacterial system, with many new taxa being established at different nomenclatural levels. The family Geminocystaceae is among cyanobacterial taxa recently described on the basis of polyphasic approach. Within this family, there are six genera: Geminocystis, Cyanobacterium, Geminobacterium, Annamia, Picocyanobacterium, and Microcrocis. The genus Geminocystis previously encompassed two species: G. herdmanii and G. papuanica. Herein, a new species G. urbisnovae was proposed under the provision of the International Code of Nomenclature for algae, fungi, and plants (ICN). Polyphasic analysis was performed for five strains from the CALU culture collection (St. Petersburg State University, Russian Federation), and they were assigned to the genus Geminocystis in accordance with high 16S rRNA gene similarity to existing species, as well as because of proximity to these species on the phylogenetic trees reconstructed with RaxML and Bayes methods. Plausibility of their assignment to a separate species of the genus Geminocystis was substantiated with smaller cell size; stenohaline freshwater ecotype; capability to complementary chromatic adaptation of second type (CA2); distinct 16S rRNA gene clustering; sequences and folding of D1-D1' and B box domains of the 16S-23S internal transcribed spacer region. The second objective pursued by this communication was to provide a survey of the family Geminocystaceae. The overall assessment was that, despite attention of many researchers, this cyanobacterial family has been understudied and, especially in the case of the crucially important genus Cyanobacterium, taxonomically problematic. [ABSTRACT FROM AUTHOR]

Synechocystis sp. PCC 6803 (hereafter: Synechocystis) is a model organism for studying photosynthesis, energy metabolism, and environmental stress. Although known as the first fully sequenced phototrophic organism, Synechocystis still has almost half of its proteome without functional annotations. In this study, by using co-fractionation coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), we define 291 multi-protein complexes, encompassing 24,092 protein–protein interactions (PPIs) among 2062 distinct gene products. This information not only reveals the roles of photosynthesis in metabolism, cell motility, DNA repair, cell division, and other physiological processes, but also shows how protein functions vary from bacteria to higher plants due to changes in interaction partners. It also allows us to uncover the functions of hypothetical proteins, such as Sll0445, Sll0446, and Sll0447 involved in photosynthesis and cell motility, and Sll1334 involved in regulation of fatty acid biogenesis. Here we present the most extensive PPI data for Synechocystis so far, which provide critical insights into fundamental molecular mechanisms in cyanobacteria.

Abstract Background As important producers using photosynthesis on Earth, cyanobacteria contribute to the oxygenation of atmosphere and the primary production of biosphere. However, due to the eutrophication of urban waterbodies and global warming, uncontrollable growth of cyanobacteria usually leads to the seasonal outbreak of cyanobacterial blooms. Cyanophages, a group of viruses that specifically infect and lyse cyanobacteria, are considered as potential environment-friendly agents to control the harmful blooms. Compared to the marine counterparts, only a few freshwater cyanophages have been isolated and genome sequenced to date, largely limiting their characterizations and applications. Results Here, we isolated five freshwater cyanophages varying in tail morphology, termed Pam1~Pam5, all of which infect the cyanobacterium Pseudanabaena mucicola Chao 1806 that was isolated from the bloom-suffering Lake Chaohu in Anhui, China. The whole-genome sequencing showed that cyanophages Pam1~Pam5 all contain a dsDNA genome, varying in size from 36 to 142 Kb. Phylogenetic analyses suggested that Pam1~Pam5 possess different DNA packaging mechanisms and are evolutionarily distinct from each other. Notably, Pam1 and Pam5 have lysogeny-associated gene clusters, whereas Pam2 possesses 9 punctuated DNA segments identical to the CRISPR spacers in the host genome. Metagenomic data-based calculation of the relative abundance of Pam1~Pam5 at the Nanfei estuary towards the Lake Chaohu revealed that the short-tailed Pam1 and Pam5 account for the majority of the five cyanophages. Moreover, comparative analyses of the reference genomes of Pam1~Pam5 and previously reported cyanophages enabled us to identify three circular and seven linear contigs of virtual freshwater cyanophages from the metagenomic data of the Lake Chaohu. Conclusions We propose a high-throughput strategy to systematically identify cyanophages based on the currently available metagenomic data and the very limited reference genomes of experimentally isolated cyanophages. This strategy could be applied to mine the complete or partial genomes of unculturable bacteriophages and viruses. Transformation of the synthesized whole genomes of these virtual phages/viruses to proper hosts will enable the rescue of bona fide viral particles and eventually enrich the library of microorganisms that exist on Earth. Video abstract

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 CO2 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. [ABSTRACT FROM AUTHOR]

Tissue engineering strategies using cell‐laden constructs have shown promising results in the treatment of various types of damaged tissues. However, inadequate oxygen delivery to the macroscale 3D cell‐constructs for regenerating skeletal muscle tissue has remained a multiplex issue owing to the pivotal factors including cell metabolism and several regulatory intercellular pathways that eventually influence various cellular activities and determines cell phenotype. To overcome this issue, a photosynthetic cyanobacterium (Synechococcus elongatus) is employed in a methacrylated gelatin bioink. Furthermore, to effectively induce cell alignment in the bioink, in situ electric field stimulation is used in a bioprinting system to fabricate cell‐laden scaffolds for regenerating skeletal muscle tissue. Owing to the synergistic effects of the bioactive microenvironment that rescues cells from hypoxic conditions and activations of voltage‐gated ion channels, highly aligned, multi‐nucleated myofibers are obtained as well as significant upregulation (7–10‐fold) of myogenic‐related genes compared with conventionally prepared cell‐constructs. In addition, in vivo studies using a mouse volumetric muscle loss model demonstrate considerable restoration of muscle functionality and regeneration. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Along with the fast development and urbanization in developing countries, the waterbodies aside the growing cities become heavily polluted and highly eutrophic, thus leading to the seasonal outbreak of cyanobacterial bloom. Systematic isolation and characterization of freshwater cyanophages might provide a biological solution to control the awful blooms. However, genomic sequences and related investigations on the freshwater cyanophages remain very limited to date. Results: Following our recently reported five cyanophages Pam1~Pam5 from Lake Chaohu in China, here we isolated another five cyanophages, termed Pan1~Pan5, which infect the cyanobacterium Pseudanabaena sp. Chao 1811. Whole-genome sequencing showed that they all contain a double-stranded DNA genome of 37.2 to 72.0 kb in length, with less than half of the putative open reading frames annotated with known functions. Remarkably, the siphophage Pan1 encodes an auxiliary metabolic gene phoH and constitutes, together with the host, a complete queuosine modification pathway. Proteomic analyses revealed that although Pan1~Pan5 are distinct from each other in evolution, Pan1 and Pan3 are somewhat similar to our previously identified cyanophages Pam3 and Pam1 at the genomic level, respectively. Moreover, phylogenetic analyses suggested that Pan1 resembles the α-proteobacterial phage vB_DshS-R5C, revealing direct evidence for phage-mediated horizontal gene transfer between cyanobacteria and α-proteobacteria. Conclusion: In addition to the previous reports of Pam1~Pam5, the present findings on Pan1~Pan5 largely enrich the library of reference freshwater cyanophages. The abundant genomic information provides a pool to identify novel genes and proteins of unknown function. Moreover, we found for the first time the evolutionary traces in the cyanophage that horizontal gene transfer might occur at the level of not only inter-species, but even inter-phylum. It indicates that the bacteriophage or cyanophage could be developed as a powerful tool for gene manipulation among various species or phyla. [ABSTRACT FROM AUTHOR]

Biologically synthesized metal-oxide nanoparticles (NPs) are in focus for their multifarious applications. In the current study, the green synthesis of copper oxide NPs (CuO NPs) is achieved using the fresh biomass of Cylindrospermum stagnale after its molecular characterization. Physical characterization of CuO NPs by several analytical techniques including UV–Vis analysis, FT-IR spectroscopy, SEM and TEM microscopy revealed spherical shaped crystalline CuO-NPs capped by functional groups of cyanobacterium biomolecules with slight aggregation. CuO NPs were found significantly antimicrobial against pathogens with MICs of 1.5, 2.4, 1.7, 2.5, and 0.6 mM against Candida albicans, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Escherichia coli, respectively. Moreover, cyanobacterium-capped CuO NPs were cytotoxic against HepG2 cell line and effective against larvae of Aedes ageypti, Anopheles subpictus Grassi and Culex quinquefasciatus. The synthesized CuO NPs were effective due to their high surface area and fairly small size 12.21 nm. Due to adequate biological activities of cyanobacterium CuO NPs even at lower concentrations, we prospect these NPs for clinical applications. [ABSTRACT FROM AUTHOR]

The toxicity of polycavernoside E and its structurally related macrolides, akunolides A, B, and C, was evaluated in mice. These compounds were recently isolated from the marine cyanobacterium Okeania sp. collected in Okinawa, Japan. The minimal toxicity of polycavernoside E was estimated as 0.81 mg/kg by intraperitoneal injection, whereas those of akunolides A–C were >13 mg/kg. Owing to the considerable toxicity of polycavernoside E, the occurrence of this cyanobacterium should be considered in seaweed production environments. [Display omitted] • The toxicity of polycavernoside E and akunolides A, B, and C was evaluated in mice by intraperitoneal injection. • The minimal lethal dose of polycavernoside E was estimated as 0.81 mg/kg. • The minimal lethal dose of akunolides was estimated as more than 13 mg/kg. • Occurrence of polycavernoside producing marine cyanobacterium Okeania sp. should be monitored. [ABSTRACT FROM AUTHOR]

Leptolyngbya sp. KIOST-1 has been proposed as a candidate species for use as a protein supplement due to its high protein content and absence of cytotoxicity. The species has also garnered attention due to the photosynthetic pigments it possesses. However, limited information is available on its cultivation. Therefore, this study was conducted to identify the optimal culture medium and fundamental physiological properties of Leptolyngbya sp. KIOST-1 under various culture conditions. In this study, SOT (Society of Toxicology) medium was confirmed as the optimal culture medium for Leptolyngbya sp. KIOST-1 growth. The biomass production, protein content, and photosynthetic pigment content of Leptolyngbya sp. KIOST-1 were significantly higher in SOT medium. The use of this medium allowed for scaling up from laboratory (10 mL) to pilot (200 L) conditions and industrial-scale outdoor conditions (10,000 L), with the biomass containing over 66% protein. The phytochemical composition of Leptolyngbya sp. KIOST-1 cultured at laboratory and industrial-scales was discovered in this study. Furthermore, we observed that reducing the carbon and nitrogen sources to 1/5 of those supplied by the optimal medium did not significantly affect biomass production, and Leptolyngbya sp. KIOST-1 demonstrated favorable growth capabilities in a salinity range of 10–50 psu and at pH levels of 8.3 to 10.3. The results of this study demonstrate the suitability of Leptolyngbya sp. KIOST-1 for various industrial applications and its adaptability to large-scale cultivation.

Global warming and climate instability have spurred interest in using renewable carbon resources for the sustainable production of chemicals. Cyanobacteria are ideal cellular factories for carbon-negative production of chemicals owing to their great potentials for directly utilizing light and CO 2 as sole energy and carbon sources, respectively. However, several challenges in adapting cyanobacterial technology to industry, such as low productivity, poor tolerance, and product harvesting difficulty, remain. Synthetic biology may finally address these challenges. Here, we summarize recent advances in the production of value-added chemicals using cyanobacterial cell factories, particularly in carbon-negative synthetic biology and emerging trends in cyanobacterial applications. We also propose several perspectives on the future development of cyanobacterial technology for commercialization. Excessive CO 2 emissions are one of the most widely discussed challenges in the 21st century. Carbon-negative production of value-added chemicals by cyanobacterial cell factories has been considered a top priority for solving such problems. Emerging synthetic biology tools, such as clustered regularly interspaced short palindromic repeats (CRISPR)/cpf1, riboswitch, and metabolic network reprogramming circuits, have accelerated the industrial applications of cyanobacterial cell factories. The synthesis of a range of biochemicals has been demonstrated in cyanobacteria; however, low product titers are the biggest barrier to commercialization of cyanobacterial biotechnology. To further increase production and meet industry demands, attention needs also be given to the integration of polymer biosynthesis with flocculation by cyanobacteria, thereby bypassing this unsolved problem. Recent efforts are underway to characterize and develop high-value-added applications of cyanobacteria in biomedicine, power production, and human habitation on Mars. [ABSTRACT FROM AUTHOR]

The efficacy of low-frequency ultrasound pulses in cell disaggregation of Chroococcidiopsis sp. aggregates has been studied as a possible strategy to improve the productivity and operation of the cultures. The modulation of the ultrasound pulses allowed to almost disaggregate most of the cyanobacterial aggregates completely while retaining cellular viability in terms of photosynthetic efficiency. In this study we used a strain isolated from the endolithic habitat of the Atacama Desert, the driest desert in the world due to the extremely scarce rainfall, low level of relative humidity and extremely high incident solar radiation. To survive these conditions and reduce the cell exposure to the incident UV radiation, Chroococcidiopsis sp. grows in the form of aggregates, diminishing the associated photo-oxidative damage. However, this adaptation strategy can reduce the availability of both light and nutrients to the growing cells. This study showed that the low-frequency ultrasound pulses were efficient in disaggregating Chroococcidiopsis sp. aggregates, improving light and nutrient availability to the cells. Our results revealed also that the modulated use of ultrasound pulses resulted in a decreased cell sedimentation velocity which becomes advantageous at large scale. The length of the ultrasound pulses can be optimized to achieve complete disaggregation of the aggregates without affecting cell viability. The preservation of cell viability is considered an advantage for eventual large-scale production as disaggregating of the aggregates can result in more homogeneous cultures with less energy needed to perform mechanical agitation. Additionally, our results indicated an improved growth of cyanobacterium in disaggregated cultures. [ABSTRACT FROM AUTHOR]

A cyanobacterium producing β-glucosidase was isolated from Lake Pamvotis located in Ioannina in Greece. This microorganism, named Pamv7, was identified as Pseudanabaena sp. using phylogenetic characterization. The high-throughput BiologMicroPlate™ method, used for the rapid assessment of heterotrophic potential, indicates that Pseudanabaena sp. metabolizes a wide range of organic substrates such as amino acids, carbohydrates, and carboxylic acids. When the strain grows in a culture medium containing cellobiose as a carbon source, it produces a significant amount of intracellular β-glucosidase. The effect of cellobiose concentration, nitrogen source, and nitrogen concentration of the growth medium, as well as the temperature of the culture, on biomass and β-glucosidase by Pseudanabaena sp., was studied. Biomass and β-glucosidase production by the strain in a lab-scale bioreactor at optimal conditions (10 g/L cellobiose, 1.5 g/L yeast, and 23 ± 1 °C) reached 2.8 g dry weight/L and 44 U/L, respectively. The protein and lipid content of the produced cyanobacterium biomass were 23% and 43 w/w, respectively. This study is the first report of β-glucosidase production by a cyanobacterial strain and concomitant high production of microalgae biomass, making Pseudanabaena sp. a promising microorganism in the field of enzyme biotechnology. [ABSTRACT FROM AUTHOR]

The cyanobacterium strain Synechococcus cedrorum SAG 88.79 stock culture has fungal contamination stated by the Sammlung von Algenkulturen der Universität Göttingen itself. In this recent work, this particular fungal strain was isolated, identified, and morphologically characterised. The fungal strain AGSC12 belongs to the species Cyphellophora olivacea, with respect to the sequence similarity, phylogeny, and morphology of the strain. Colony morphology and growth capability were examined on SMA, EMMA, PDA, MEA, YEA, and YPA plates. Growth of the colonies was the most successful on YPA plates, followed by PDA and MEA containing plates. Surprisingly, the AGSC12 strain showed extreme tolerance to NaHCO3, albeit it, is is considered a general fungistatic compound. Moreover, positive association between the AGSC12 and SAG 88.79 strains was revealed, as the SAG 88.79 strain always attained higher cell density in co-cultures with the fungus than in mono-cultures. Besides, a taxonomic note on the SAG 88.79 strain itself was also stated. [ABSTRACT FROM AUTHOR]

Implementation of outdoor photobioreactors has been challenged by an extremely oversaturated daily peak of solar irradiance. This study aims to understand the role of column size and paranet shading as well as to investigate the most convenient light control in outdoor cyanobacterial culture. The photobioreactor (PBR) consisted of plastic columns with a diameter of 12.74 cm (PBRd-20) and 31.85 cm (PBRd-50) laid outdoors and inclined at 158.22° upwards against solar radiation, while paranet shading was provided at 0%, 50%, 70%, and 90% shading capacity. A semi-continuous culture of cyanobacterium Arthrospira (Spirulina) platensis was conducted for 6 weeks with weekly monitoring of the growth parameter as well as the proximate and pigments content, while the daily irradiance and culture maximum temperature were recorded. The result shows that the column diameter of 12.74 cm had a lethal risk of 44.7% and this decreased to 10.5% by widening the column diameter to 31.85 cm. This lethal risk can be eliminated by the application of a paranet at a 50% reduction level for the column diameter of 31.85 cm and a 70% reduction level for the column diameter of 12.74 cm. The highest culture productivity of 149.03 mg/(L·day) was achieved with a PBRd-20 with 50% shading treatment, but a PBRd-50 with 90% shading treatment led to an increase in the protein and phycocyanin content by 66.7% and 14.91%, respectively. [ABSTRACT FROM AUTHOR]

Cyanobacteria are photosynthetic bacteria, widely studied for the conversion of atmospheric carbon dioxide to useful platform chemicals. Isoprene is one such industrially important chemical, primarily used for production of synthetic rubber and biofuels. Synechocystis sp. PCC 6803, a genetically amenable cyanobacterium, produces isoprene on heterologous expression of isoprene synthase gene, albeit in very low quantities. Rationalized metabolic engineering to re-route the carbon flux for enhanced isoprene production requires in-dept knowledge of the metabolic flux distribution in the cell. Hence, in the present study, we undertook steady state 13C-metabolic flux analysis of glucose-tolerant wild-type (GTN) and isoprene-producing recombinant (ISP) Synechocystis sp. to understand and compare the carbon flux distribution in the two strains. The R-values for amino acids, flux analysis predictions and gene expression profiles emphasized predominance of Calvin cycle and glycogen metabolism in GTN. Alternatively, flux analysis predicted higher activity of the anaplerotic pathway through phosphoenolpyruvate carboxylase and malic enzyme in ISP. The striking difference in the Calvin cycle, glycogen metabolism and anaplerotic pathway activity in GTN and ISP suggested a possible role of energy molecules (ATP and NADPH) in regulating the carbon flux distribution in GTN and ISP. This claim was further supported by the transcript level of selected genes of the electron transport chain. This study provides the first quantitative insight into the carbon flux distribution of isoprene-producing cyanobacterium, information critical for developing Synechocystis sp. as a single cell factory for isoprenoid/terpenoid production. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) radiation generates cyclobutane pyrimidine dimer (CPD) photoproducts in the DNA of skin cells, causing photoaging and non-melanoma skin cancer. Photoproducts can be repaired by the CPD-photolyase enzyme. The main source of CPD-photolyase is the cyanobacterium Synechococcus sp, from which a protein extract containing the enzyme is obtained, encapsulated, and included in skincare products. Thus, this work focused on the production (induction and recovery) of CPD-photolyase from the cyanobacterium Synechococcus leopoliensis. For this, variation in culture light conditions and extraction by Aqueous Two-Phase System (ATPS) were evaluated. Results showed an increase in specific CPD-photolyase activity during the stationary growth phase. Induction of CDP-photolyase under high light intensity and UVA irradiation was obtained. During downstream bioprocessing, centrifugation harvesting method preserves the enzyme activity, whereas the autoflocculation decreases it drastically. ATPS was used for the first time in the extraction of CPD-photolyase, allowing a one-step extraction from the biomass. The best ATPS condition was 15% PEG1000/18% phosphate (pH 7.0), where CPD-photolyase was partitioned to the PEG phase using both protein extract and wet biomass. Moreover, this ATPS also extracted c-phycocyanin in the PEG phase, which has important bioactivity properties and could complement skincare products based on CPD-photolyase. Overall, this bioprocess was successfully able to produce a CPD-photolyase rich PEG solution with an activity yield of 27.5 ± 2.6 mM h−1 g−1 dry biomass, ~ 5.5 times higher than in the protein extract. This PEG solution can be used for further CPD-photolyase purification or directly for skincare product development. [ABSTRACT FROM AUTHOR]

Microalgae are active producers of various compounds, including toxic substances. However, their metabolism is very diverse and insufficiently known. We demonstrate an approach that includes growing a new strain of cyanobacterium Leptolyngbya sp. (IPPAS B-1204) on an isotopically labeled medium (D 2 O) and evaluating the metabolomic composition of these microorganisms after deuterium uptake. Despite the low resolution of the GC-MS method, the interpretation of the obtained spectra allowed us to find out not only the amount of the embedded isotope label but also to assume the position in the structure where the label is embedded. We present the results of reliably detecting more than 30 compounds with isotope labels belonging to various classes of biological compounds produced by this cyanobacterium, revealing the metabolic pathways of entry of this label. We also demonstrate that the synthesis of unsaturated fatty acids is suppressed under the growth on D 2 O medium. In addition, we found an isotopic effect in the chromatographic separation of isotopically labeled compounds in gas chromatography. These data can be used in the future both for the identification of compounds and the analysis of the biosynthesis pathways of secondary biologically active compounds and in the analysis of the production of isotopically labeled standards of compounds., Competing Interests: Conflicts of interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Spirulina maxima is a marine microalga that has been promoted worldwide as a super food. This study was conducted to evaluate its ability to improve memory in the older adults using Spirulina maxima 70% ethanol extract (SM70EE). This randomized, double-blind, placebo-controlled clinical trial comprised 80 volunteers recruited from Jeonbuk National University Hospital in Jeonju, Republic of Korea, who were randomly assigned to two groups. The participants received either 1 g/day of SM70EE or a placebo without otherwise changing their diet or physical activity. The participants were examined at baseline and after a 12-week interval to determine whether there were changes in their results for visual learning, visual working memory, and verbal learning tests from the Korean version of the Montreal Cognitive Assessment, brain-derived neurotrophic factor and beta-amyloid levels, and total antioxidant capacity. Compared to the placebo group, the treatment group showed a significant improvement in visual learning and visual working memory test results and enhanced vocabulary. SM70EE use was shown to improve memory, with no adverse effects. Its efficacy in alleviating Alzheimer's disease symptoms was verified for the first time through this clinical trial. SM70EE could play a role in the management of patients with dementia. This trial is registered with registration number of clinical research information service (CRIS: KCT0006161). [ABSTRACT FROM AUTHOR]

Background: As important producers using photosynthesis on Earth, cyanobacteria contribute to the oxygenation of atmosphere and the primary production of biosphere. However, due to the eutrophication of urban waterbodies and global warming, uncontrollable growth of cyanobacteria usually leads to the seasonal outbreak of cyanobacterial blooms. Cyanophages, a group of viruses that specifically infect and lyse cyanobacteria, are considered as potential environment-friendly agents to control the harmful blooms. Compared to the marine counterparts, only a few freshwater cyanophages have been isolated and genome sequenced to date, largely limiting their characterizations and applications. Results: Here, we isolated five freshwater cyanophages varying in tail morphology, termed Pam1~Pam5, all of which infect the cyanobacterium Pseudanabaena mucicola Chao 1806 that was isolated from the bloom-suffering Lake Chaohu in Anhui, China. The whole-genome sequencing showed that cyanophages Pam1~Pam5 all contain a dsDNA genome, varying in size from 36 to 142 Kb. Phylogenetic analyses suggested that Pam1~Pam5 possess different DNA packaging mechanisms and are evolutionarily distinct from each other. Notably, Pam1 and Pam5 have lysogeny-associated gene clusters, whereas Pam2 possesses 9 punctuated DNA segments identical to the CRISPR spacers in the host genome. Metagenomic data-based calculation of the relative abundance of Pam1~Pam5 at the Nanfei estuary towards the Lake Chaohu revealed that the short-tailed Pam1 and Pam5 account for the majority of the five cyanophages. Moreover, comparative analyses of the reference genomes of Pam1~Pam5 and previously reported cyanophages enabled us to identify three circular and seven linear contigs of virtual freshwater cyanophages from the metagenomic data of the Lake Chaohu. Conclusions: We propose a high-throughput strategy to systematically identify cyanophages based on the currently available metagenomic data and the very limited reference genomes of experimentally isolated cyanophages. This strategy could be applied to mine the complete or partial genomes of unculturable bacteriophages and viruses. Transformation of the synthesized whole genomes of these virtual phages/viruses to proper hosts will enable the rescue of bona fide viral particles and eventually enrich the library of microorganisms that exist on Earth. 4WYBiJEHr_CXoYqKn7ZoJM Video abstract [ABSTRACT FROM AUTHOR]

N2-fixing cyanobacteria are highly promising microorganisms for sustained and improved H2 production. Among various N2-fixing cyanobacteria that have ability to produce H2, Fischerella muscicola TISTR 8215 is a promising strain with high potential for H2 production. The production of H2 by the two microorganisms, i.e., cyanobacteria and microalgae was investigated to improve photobiological H2 production. The results showed that co-culturing the green microalga Chlorella sp. (initial biomass concentration = 0.025 g L−1, 5% algal culture) with dominant cyanobacterium F. muscicola TISTR 8215 (initial biomass concentration = 0.5 g L−1, 95% cyanobacterial culture) increased total accumulated H2 yield about 1.5-fold compared to the monoculture of F. muscicola TISTR 8215. However, the decrease of accumulated H2 yield was observed when increasing initial cell concentration of Chlorella sp. to initial biomass concentration = 0.125 g L−1 in co-cultivation system. Notably, the co-immobilization of F. muscicola TISTR 8215/Chlorella sp. in 0.8% (w/v) agar led to a 11-fold increase in maximum H2 yield of 13.2 mmol H2 L−1 compared to the co-culture with no immobilization. In addition, the co-immobilization of F. muscicola TISTR 8215 and Chlorella sp. in agar cubes was able to prolong biohydrogen production for 3 cycles up to 324 h. The overall results demonstrated the improvement of H2 production by co-cultivation of F. muscicola TISTR 8215 and Chlorella sp. under optimized conditions. [ABSTRACT FROM AUTHOR]

Cyanobacteria are microorganisms that are well-adapted to sudden changes in their environment, namely to light conditions. This has allowed them to develop mechanisms for photoprotection, which encompass alteration in pigment composition. Therefore, light modulation appears to be a suitable strategy to enhance the synthesis of specific pigments (e.g., phycocyanin) with commercial interest, in addition to conveying a more fundamental perspective on the mechanisms of acclimatization of cyanobacterium species. In this study, Synechocystis salina was accordingly cultivated in two light phase stages: (i) white LED, and (ii) shift to distinct light treatments, including white, green, and red LEDs. The type of LED lighting was combined with two intensities (50 and 150 µmolphotons·m−2·s−1). The effects on biomass production, photosynthetic efficiency, chlorophyll a (chl a) content, total carotenoids (and profile thereof), and phycobiliproteins (including phycocyanin, allophycocyanin, and phycoerythrin) were assessed. White light (under high intensity) led to higher biomass production, growth, and productivity; this is consistent with higher photosynthetic efficiency. However, chl a underwent a deeper impact under green light (high intensity); total carotenoids were influenced by white light (high intensity); whilst red treatment had a higher effect upon total and individual phycobiliproteins. Enhanced PC productivities were found under modulation with red light (low intensities), and could be achieved 7 days earlier than in white LED (over 22 days); this finding is quite interesting from a sustainability and economic point of view. Light modulation accordingly appears to be a useful tool for supplementary studies pertaining to optimization of pigment production with biotechnological interest. [ABSTRACT FROM AUTHOR]