Genera Of Cyanobacteria Research Articles

A systematic review on analytical methods of the neurotoxin β-N-methylamino-L-alanine (BMAA), and its causative microalgae and distribution in the environment

β-N-Methylamino-L-alanine (BMAA), a neurotoxin produced by various microalgal groups, is associated with neurodegenerative diseases and is considered a major environmental factor potentially linked to sporadic amyotrophic lateral sclerosis. This study systematically reviews the analytical methods used to study BMAA in publications from 2019 to the present. It also investigates the causative microalgae of BMAA and its geographical distributions in aquatic ecosystems based on studies conducted since 2003. A comprehensive search using the Web of Science database revealed that hydrolysis for extraction (67%), followed by quantification using LC-MS/MS (LC: 84%; MS/MS: 88%), is the most commonly employed method in BMAA analysis. Among analytical methods, RPLC-MS/MS had the highest percentage (88%) of BMAA-positive results and included a high number of quality control (QC) assessments. Various genera of cyanobacteria and diatoms have been reported to produce BMAA. The widespread geographical distribution of BMAA across diverse ecosystems highlights significant environmental and public health concerns. Notably, BMAA accumulation and biomagnification are likely more potent in marine or brackish water ecosystems than in freshwater ecosystems, potentially amplifying its ecological impacts. Future research should prioritize advanced, sensitive methods, particularly LC-MS/MS with as many QC assessments as possible, and should expand investigations to identify novel microalgal producers and previously uncharted geographical areas, with a special focus on marine or brackish water ecosystems. This effort will enhance our understanding of the environmental distribution and impacts of BMAA.

A first evaluation of biological soil crusts diversity in three distinctive rocky outcrops in Brazil

Biological soil crusts (biocrust hereafter) are communities structured by the interaction between bacteria, fungi, algae, cyanobacteria, lichens and bryophytes over the most superficial particles of the soil. These complex communities are mostly found in arid and semiarid regions, but they can also be conspicuous members of the vegetation in moist tropical ecosystems. This study presents the first taxonomic and ecological investigation of biocrusts in three prevalent Brazilian rocky outcrop types: ironstone, quartzite-sandstone, and limestone, while also assessing the distribution of these outcrop types across Brazil as potential biocrust habitats. We identified thirty-four bryophyte species (29 mosses, 5 liverworts), seven cyanobacteria genera, and one genus from each of the Charophyta and Chlorophyta algae groups. Twenty-four of the species (19 mosses and 5 liverworts) have never been previously reported in biocrusts associations in any ecosystem. Six microhabitats were characterized. Analysis of soil composition in the studied rocky outcrops highlighted pH, total acidity, phosphorus, organic matter, calcium, and iron concentrations as key distinguishing factors, emphasizing limestone as the most unique environment among the outcrops studied. Positive co-occurrence patterns were observed solely in ironstone and limestone outcrops, suggesting potential ecological interactions between mosses and cyanobacteria. The proportions of Brazilian rocky outcrops within Protected Areas (PAs) exhibited disparities, with ironstone and limestone outcrops being the most threatened, representing only 0.25 % and 5.11 % of PA sites, respectively. Our findings address crucial knowledge gaps within these unique ecosystems, offering valuable insights for biocrust research.

Antimicrobial Activity of Arthrospira (Former Spirulina) and Dunaliella Related to Recognized Antimicrobial Bioactive Compounds.

With the increasing rate of the antimicrobial resistance phenomenon, natural products gain our attention as potential drug candidates. Apart from being used as nutraceuticals and for biotechnological purposes, microalgae and phytoplankton have well-recognized antimicrobial compounds and proved anti-infectious potential. In this review, we comprehensively outline the antimicrobial activity of one genus of cyanobacteria (Arthrospira, formerly Spirulina) and of eukaryotic microalgae (Dunaliella). Both, especially Arthrospira, are mostly used as nutraceuticals and as a source of antioxidants for health supplements, cancer therapy and cosmetics. Their diverse bioactive compounds provide other bioactivities and potential for various medical applications. Their antibacterial and antifungal activity vary in a broad range and are strain specific. There are strains of Arthrospira platensis with very potent activity and minimum inhibitory concentrations (MICs) as low as 2-15 µg/mL against bacterial fish pathogens including Bacillus and Vibrio spp. Arthrospira sp. has demonstrated an inhibition zone (IZ) of 50 mm against Staphylococcus aureus. Remarkable is the substantial amount of in vivo studies of Arthrospira showing it to be very promising for preventing vibriosis in shrimp and Helicobacter pylori infection and for wound healing. The innovative laser irradiation of the chlorophyll it releases can cause photodynamic destruction of bacteria. Dunaliella salina has exhibited MIC values lower than 300 µg/mL and an IZ value of 25.4 mm on different bacteria, while Dunaliella tertiolecta has demonstrated MIC values of 25 and 50 μg/mL against some Staphylococcus spp. These values fulfill the criteria for significant antimicrobial activity and sometimes are comparable or exceed the activity of the control antibiotics. The bioactive compounds which are responsible for that action are fatty acids including PUFAs, polysaccharides, glycosides, peptides, neophytadiene, etc. Cyanobacteria, such as Arthrospira, also particularly have antimicrobial flavonoids, terpenes, alkaloids, saponins, quinones and some unique-to-them compounds, such as phycobiliproteins, polyhydroxybutyrate, the peptide microcystin, etc. These metabolites can be optimized by using stress factors in a two-step process of fermentation in closed photobioreactors (PBRs).

Sphaerothrix gracilis gen. et sp. nov. (Nodosilineales, Cyanobacteria): a novel filamentous cyanobacterium isolated from tropical coastal microplastics

SUMMARYCyanobacteria are ancient organisms that contribute significantly to primary production in aquatic ecosystems. Although they are a group of microbes present in a wide range of environments, their diversity on anthropogenic substrates, namely microplastics, is still largely unknown. In the present study, we describe a new genus and species of cyanobacteria from the Nodosilineaceae family. Strains were isolated from foam microplastic particles obtained from beach sediments facing the Singapore Strait. This species is morphologically similar to the polyphyletic, cosmopolitan Leptolyngbya spp.; however, it forms an independent clade with 16S rRNA phylogeny and has a unique 16S–23S internal transcribed spacer secondary structure. To date, no cyanobacteria have been isolated and cultured from the surfaces of microplastic particles. Using a polyphasic approach combining morphological, phylogenetic and ecological traits, we describe a new genus and species Sphaerothrix gracilis. The presence of certain cyanobacteria rafting on microplastic surfaces can potentially indicate a long‐distance transport into new ecosystems with implications on toxicity and biodiversity.

Physico-chemical characterisation of irrigation basin waters and inventory study of their algal communities.

To cope with the water shortage in Sous Massa region of Morocco, agricultural producers in the region have resorted to different types of water supply basins, known as "irrigation basins" but the phenomenon of eutrophication has hindered the continuity of agricultural productivity by altering the quality of the water used for irrigation on the one hand, and causing economic damage to agricultural producers due to the clogging of the water pumping network on the other. We began by characterising the physico-chemical quality of the water to determine the causes of its high nutrient content, then we determined the taxonomy of the algal species in the irrigation basins to which we had access. A qualitative study of the water in the irrigation basins in order to better explain the inventory obtained from the taxonomic identification of the algal biomass collected, which proved the existence of new species, not previously identified, characterising the freshwaters of the Moroccan region, is under the scope of this work. The species studied belong mainly to the following groups: green algae (11 genera of Chlorophyta and 7 genera of Charophyta), blue algae (7 genera of Cyanobacteria), brown algae (7 genera of Diatoms), and one genus of Euglenophyta.

Proteome changes in larval zebrafish (Danio rerio) and fathead minnow (Pimephales promelas) exposed to (±) anatoxin-a

Anatoxin-a and its analogues are potent neurotoxins produced by several genera of cyanobacteria. Due in part to its high toxicity and potential presence in drinking water, these toxins pose threats to public health, companion animals and the environment. It primarily exerts toxicity as a cholinergic agonist, with high affinity at neuromuscular junctions, but molecular mechanisms by which it elicits toxicological responses are not fully understood. To advance understanding of this cyanobacteria, proteomic characterization (DIA shotgun proteomics) of two common fish models (zebrafish and fathead minnow) was performed following (±) anatoxin-a exposure. Specifically, proteome changes were identified and quantified in larval fish exposed for 96 h (0.01–3 mg/L (±) anatoxin-a and caffeine (a methodological positive control) with environmentally relevant treatment levels examined based on environmental exposure distributions of surface water data. Proteomic concentration - response relationships revealed 48 and 29 proteins with concentration - response relationships curves for zebrafish and fathead minnow, respectively. In contrast, the highest number of differentially expressed proteins (DEPs) varied between zebrafish (n = 145) and fathead minnow (n = 300), with only fatheads displaying DEPs at all treatment levels. For both species, genes associated with reproduction were significantly downregulated, with pathways analysis that broadly clustered genes into groups associated with DNA repair mechanisms. Importantly, significant differences in proteome response between the species was also observed, consistent with prior observations of differences in response using both behavioral assays and gene expression, adding further support to model specific differences in organismal sensitivity and/or response. When DEPs were read across from humans to zebrafish, disease ontology enrichment identified diseases associated with cognition and muscle weakness consistent with the prior literature. Our observations highlight limited knowledge of how (±) anatoxin-a, a commonly used synthetic racemate surrogate, elicits responses at a molecular level and advances its toxicological understanding.

An Electrochemical Aptasensor for the Detection of Freshwater Cyanobacteria.

Aphanizomenon is a genus of cyanobacteria that is filamentous and nitrogen-fixing and inhabits aquatic environments. This genus is known as one of the major producers of cyanotoxins that can affect water quality after the bloom period. In this study, an electrochemical aptasensor is demonstrated using a specific aptamer to detect Aphanizomenon sp. ULC602 for the rapid and sensitive detection of this bacterium. The principal operation of the generated aptasensor is based on the conformational change in the aptamer attached to the electrode surface in the presence of the target bacterium, resulting in a decrease in the current peak, which is measured by square-wave voltammetry (SWV). This aptasensor has a limit of detection (LOD) of OD750~0.3, with an extension to OD750~1.2 and a sensitivity of 456.8 μA·OD750-1·cm-2 without interference from other cyanobacteria. This is the first aptasensor studied that provides rapid detection to monitor the spread of this bacterium quickly in a targeted manner.

Cellulose Synthase in Atacama Cyanobacteria and Bioethanol Production from Their Exopolysaccharides.

Cyanobacteria produce exopolysaccharides (EPSs) as an adaptative mechanism against ultraviolet radiation and desiccation. Cellulose is present in the extracellular polymeric substance in some cyanobacteria genera and it has been proposed as a raw material for biofuel production. The goal of this work was to evaluate the cellulose presence in EPS of Atacama cyanobacteria strains and its use as an alternative and innovative biological source to produce bioethanol. The presence of cellulose was evaluated using techniques of molecular biology, bioinformatics, and electronic microscopy. The conserved motif D,D,D,35QXXRW, characteristic of processive β-glycosyltransferase in all cellulose-producing organisms, was identified in the genome of the LLA-10 strain. This is evidence that cellulose synthase in the LLA-10 strain is a functional enzyme. EPS from Atacama cyanobacteria was hydrolyzed by β-glucosidases (cellobiase and cellulase) and the released glucose was yeast-fermented to ethanol. Ethanol production reached 172.69 ± 0.02 mg ethanol/g EPS after 48 h of incubation. These results are the first step in the evaluation of EPS produced by native cyanobacteria isolated from northern Chile for future biotechnological applications such as the production of bioethanol.

Understanding the Risks of Diffusion of Cyanobacteria Toxins in Rivers, Lakes, and Potable Water.

Blue-green algae, or cyanobacteria, may be prevalent in our rivers and tap water. These minuscule bacteria can grow swiftly and form blooms in warm, nutrient-rich water. Toxins produced by cyanobacteria can pollute rivers and streams and harm the liver and nervous system in humans. This review highlights the properties of 25 toxin types produced by 12 different cyanobacteria genera. The review also covered strategies for reducing and controlling cyanobacteria issues. These include using physical or chemical treatments, cutting back on fertilizer input, algal lawn scrubbers, and antagonistic microorganisms for biocontrol. Micro-, nano- and ultrafiltration techniques could be used for the removal of internal and extracellular cyanotoxins, in addition to powdered or granular activated carbon, ozonation, sedimentation, ultraviolet radiation, potassium permanganate, free chlorine, and pre-treatment oxidation techniques. The efficiency of treatment techniques for removing intracellular and extracellular cyanotoxins is also demonstrated. These approaches aim to lessen the risks of cyanobacterial blooms and associated toxins. Effective management of cyanobacteria in water systems depends on early detection and quick action. Cyanobacteria cells and their toxins can be detected using microscopy, molecular methods, chromatography, and spectroscopy. Understanding the causes of blooms and the many ways for their detection and elimination will help the management of this crucial environmental issue.

Astudy of organic solvents to obtain bio-products from two genus of cyanobacteria, Anabaena sp. 65, Nostoc sp. 69 and identification of toxins in these bio-products by Hplc/Ms technique

This study was conducted to determine the effect of the types of organic solvents (Ethanol, Methanol, Diethyl ether, Acetone and water) on the amount of bio-products derived from two genus of cyanobacteria (Anabaena sp. Tu 65 and Nostoc sp. Tu 69) who were isolated and growth on selective media ASM-1 under temperature at (26) °C and pH (7.6) under continuous lighting intensity (2500) Lux for 30 days. The growth were measured by optical density by spectrophotometer at wave length 436 nm. The daily growth of the genus Anabaena sp. Tu 65 showed higher than that of the genus Nostoc sp. Tu 69.Extractionby organic solvents shown that the Methanol is the best solvent for extraction of bio-products from the two genus followed by Ethanol, Diethyl ether, Acetone and water respectively.
 Identification the toxic compounds in the bio-products by HPLC_MS technique shown that the bio-products from the genus Anabaena sp. Tu 65, the presence of neurotoxin (anatoxin a (s)) as well as the presence of the compound ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid), one of the key parts for all types of Microcystins which considered as important of liver toxins produced by cyanobacteria, which, as the spectrum readings showed the presence of hepatic toxin [D-Asp3, Dha7] MCYST-LR is one of the types of Microcystins.
 While the bio-products from the genus Nostoc sp. Tu 69 shown the presence of the compound (MCYST-YM (O)) which also one of the types of liver toxin Microcystin, as well as the presence of another hepatic toxin [D-Asp3, Dha7] MCYST-LR, whichis another type of Microcystins too, as well as the presence of neurotoxin Anatoxin a( s),also the probability of the presence of another neurotoxin Anatoxin, which appeared in the spectrum readings.

Sources of off-flavor in high nutrient-load Nile tilapia (Oreochromis niloticus) ponds in north-central Bangladesh

Recently, toxins and off-flavor compounds produced by phytoplankton in freshwater ponds have become a concern as it affects consumer acceptability and food safety. The purpose of this research was to investigate the relationship between phytoplankton abundance and water-sediment physicochemical parameters in high-nutrient-load Nile tilapia (Oreochromis niloticus) ponds from three sub-districts (upazila) in north-central Bangladesh. Water and sediment samples were collected from 9 randomly selected ponds of Sadar, Trishal, and Muktagachha upazila, and temperature, transparency, pH, phytoplankton concentration for water and pH, organic C and organic matter for sediment samples were determined. Water temperature and transparency were more or less similar across all the ponds, while pH varied significantly (p<0.05). Soil pH also varied significantly (p<0.05). The abundance of Bacillariophyceae, Chlorophyceae, and Euglenophyceae in pond water was almost equal but Cyanophyceae differed among the ponds with the highest in Muktagachha (5.22±2.30×104 cells/L) and the lowest in Trishal (4.84±0.740×104 cells/L). Correspondingly, Algal Genus Pollution Index (AGPI) was employed to study the water quality of Nile tilapia ponds, and it revealed that ponds in Muktagaccha had ‘probable high organic pollution’ compared to ponds in the other two locations. Five cyanobacteria genera were identified viz., Anabaena, Aphanizominon, Gomphosphaeria, Mycrocystis and Osoillatoria where Anabaena showed a strong positive correlation with water temperature and pH. The significantly higher abundance of cyanobacteria in Muktagachha is possibly linked to the favorable water temperature and pH and indicates a higher risk of off-flavor creation in the Nile tilapia ponds from this upazila. It is, therefore suggested that the right management measures must be put in place to control the cyanobacteria to ensure the profitability of fish farming.

Possible involvement of extracellular polymeric substrates of Antarctic cyanobacterium Nostoc sp. strain SO-36 in adaptation to harsh environments.

Cyanobacteria are some of the primary producers in extremely cold biospheres such as the Arctic, Antarctic, and vast ice sheets. Many genera of cyanobacteria are identified from these harsh environments, but their specific mechanisms for cold adaptation are not fully understood. Nostoc sp. strain SO-36 is a cyanobacterium isolated in Antarctica more than 30years ago and regarded as a psychrotolelant species. To determine whether the strain is psychrotolelant or psychrophilic, it was first grown at 30°C and 10°C. The cells grew exponentially at 30°C, but their growth stopped at 10°C, indicating that the strain is only psychrotolerant. Microscopic analysis revealed that the morphology of the cells grown at 30°C was filamentous and differentiated heterocysts, which are specialized cells for gaseous nitrogen fixation under nitrogen-deprived conditions, indicating that the strain can grow diazotrophically. The cells grown at 10°C have a smaller size, shortened filament length and decreased chlorophyll content per cell. At 10°C, the cells are aggregated with extracellular polymeric substrates (EPSs), which is a common mechanism to protect cells from ultraviolet light. These results imply that segmentation into short filaments was induced by photodamage at low temperatures. To fully understand the adaptation mechanisms of Nostoc sp. strain SO-36 for low-temperature conditions, next-generation sequencing analyses were conducted. Complete genome sequence of the strain revealed that it has one main chromosome of approximately 6.8 Mbp with 4 plasmids, including 6855 coding sequences, 48 tRNA genes, 4 copies of rRNA operons, and 5 CRISPR regions. Putative genes for EPS biosynthesis were found to be conserved in Nostocaceae regardless of their habitat. These results provide basic information to understand the adaptation mechanisms at low temperatures, and the strain can be a model organism to analyze adaptation to extreme environments.

Assessment of microcystins in surface water and irrigated vegetables in Kwaru stream, Hayin Danmani, Kaduna-Nigeria.

Microcystins (MCs) are hepatotoxic secondary metabolites produced by several genera of cyanobacteria. Human exposure routes include drinking contaminated water and consuming contaminated fish, vegetables, crops, and even food supplements that contain cyanotoxin. This study investigated the presence of MCs in a stream with a long history of use as a source of water for irrigation farming. To establish the risk of a lack of monitoring programs, we studied MCs contamination of irrigated vegetables. Toxin levels in the water were generally <0.05 μg L-1 in all the investigated stations. Total microcystin concentrations in spinach (0.306 μg Kg-1 upstream and 0.217 μg Kg-1 downstream), lettuce (0.085 μg Kg-1 upstream and 0.462 μg Kg-1 downstream), carrot (0.050 μg Kg-1 downstream and 0.116 μg Kg-1 downstream), cabbage (0.014 μg Kg-1 upstream and 0.031 μg Kg-1 downstream), tomatoes (0.233 μg Kg-1 upstream), and bitter leaf (0.460 μg Kg-1 upstream and 0.050 μg Kg-1 downstream) collected in March were higher than the levels detected in samples of the same vegetables collected in April. These results highlight Nigeria's severe public health problem, especially in regions with long dry season spells. The level of MCs contamination of irrigated vegetables implies a potential for chronic exposure and associated health challenges.

Diversity assessment of photosynthesizers: comparative analysis of pre-cultivated and natural microbiome of sediments from Cerrado biome in Maranhão, Brazil

Photosynthetic microorganisms are important components of most ecosystems and have important roles regarding biogeochemical cycles and the basis of the trophic chain. However, they sometimes are present in low abundance compared to other heterotrophic organisms. The Chapada das Mesas National Park (PNCM) is a Conservation Unit in Brazilian Cerrado biome, which is considered a hotspot for biodiversity conservation and possesses important rivers, waterfalls, and springs with economical and touristic importance. The aim of this study was to perform a comparative analysis of enriched and total microbiome of sediments to understand the impact of pre-cultivation in discovery of underrepresented groups like photosynthesizers. All sediment samples were cultivated in BG-11 medium under illumination to enrich for photosynthetic microorganisms and both the raw samples and the enriched ones were submitted to DNA extraction and sequencing of the V3-V4 hypervariable region of the 16S rRNA gene on the Ion Torrent platform. The reads were analyzed using QIIME2 software and the Phyloseq package. The enrichment allowed detection and identification of many genera of cyanobacteria in the Chapada das Mesas National Park (PNCM), which would probably not be possible without the combination of approaches. A total of 58 groups of photosynthetic microorganisms were classified in the samples from the enrichments and their relative abundance based on amplified 16S rRNA sequences were estimated, highlighting the genus Synechocystis which represented 10.10% of the abundance of the phylum Cyanobacteria and the genus Dunaliella, which represented 45.66% of the abundance of algae as the most abundant groups at the PNCM. In the enrichments, microorganisms from the phyla Proteobacteria (45.2%), Bacteroidetes (18%), and Planctomycetes (3.3%) were also identified, since there are ecological associations between the photosynthetic community and other groups of heterotrophic microorganisms. As for the functional analysis, metabolic functions associated with methanotrophy and methylotrophy, hydrocarbon degradation, phototrophy, and nitrogen fixation were predicted. The results highlight a great diversity of photosynthetic microorganisms in Cerrado and the importance of using a combination of approaches when analyzing target groups which are usually underrepresented such as cyanobacteria and microalgae.

In vitro and in silico assessment of cytotoxicity and chromosome instability induced by saxitoxin in human derived neural cell line

In freshwater, saxitoxins (STX) are produced by different cyanobacteria genera, including Raphidiopsis. Data regarding cytogenotoxicity effects of STX on human cells are scarse, this merit further studies of its toxicology. This study assessed the cytotoxicity and the chromosome instability of STX on SHSY-5Y human cell line. The CBMN assay allows the detection of chromosome breaks and abnormal chromosomal segregation. Additionally, in silico systems biology approach, used to search for known and predicted interaction networks, was applied to study the interactions between STX and SHSY-5Y cellular components. The results of the CBMN assay demonstrated that STX concentrations of 2.5 - 10 µg/L induced cytostasis and chromosome instability in a dose-response relationship. Apoptosis was detected after exposure of SHSY-5Y cultured cells to STX concentration of 10 µg/L. The results of the systems biology analysis revealed the interaction of STX with proteins related with acetylcoline pathway, cell cycle regulation and apoptosis. Furthermore, combining the in vitro and in silico approachs, it was possible to suggest a mechanism of action of STX in SHSY-5Y cells. Overall, the data demonstrated the cytotoxicity and mutagenicity of environmentally relevant concentrations of STX. These results should be considered when setting up guidelines for monitoring STX in water supply.

Photosynthetic microorganisms and their bioactive molecules as new product to healing wounds.

Wounds are a public health problem due to long periods required to repair damaged skin, risk of infection, and amputations. Thus, there is a need to obtain new therapeutic agents with less side effects, more effective oxygen delivery, and increased epithelial cell migration. Photosynthetic microorganisms, such as microalgae and cyanobacteria, may be used as a source of biomolecules for the treatment of different injuries. The aim of this review article focuses on healing potential using phytoconstituents from photosynthetic microorganisms. Cyanophyte Spirulina and Chlorophyte Chlorella are more promising due to steroids, triterpenes, carbohydrates, phenols, and proteins such as lectins and phycocyanin. However, there are few reports about identification and specific function of these molecules on the skin. In other microalgae and cyanobacteria genus, high contents of pigments such as β-carotene, chlorophyll a, allophycocyanin, and hydroxypheophytin were detected, but their effects on phases of wound healing is absent yet. The development of new topical drugs from photosynthetic microorganisms could be a potential alternative to maximize healing. KEY POINTS: • Conventional treatment to skin injuries has limitations. • Proteins, terpenes, and phenols increase collagen deposition and re-epithelialization. • Microalgae and cyanobacteria may be used as a source of biomolecules to wound healing.

Multi-proxy approaches to investigate cyanobacteria invasion from a eutrophic lake into the circumjacent groundwater

To verify whether cyanobacteria can travel from eutrophic lakes into the surrounding groundwater, a large-scale field investigation, laboratorial incubations, and quartz column penetration tests were carried out in Lake Taihu (China). High-throughput sequencing of 16S rRNA gene amplicons indicated that cyanobacteria operational taxonomic units (OTUs) were present at fifteen out of forty total wells in four cardinal directions at varying distances from the shore of Lake Taihu, up to a maximum of forty-three kilometers. Six cyanobacteria genera were detected including Microcystis, Dolichospermum, Phormidium, Leptolyngbya, Pseudanabaena and Synechococcus. The proportions of Phormidium, Microcystis and Synechococcus OTUs in the total cyanobacterial community were 45.2%, 32.2% and 19.4%, respectively. The qRT-PCR results showed that cyanobacterial abundance decreased with increasing distance from the shore of Lake Taihu. Based on the microscopic analysis of cultures inoculated with groundwater, we found Microcystis, Dolichospermum and Phormidium. Five cyanobacterial genera were able to penetrate columns filled with quartz particles ranging from 100∼200 μm. Finer layers of quartz sands were found to be impenetrable. The rating of infiltration capabilities was Microcystis > Synechococcus > Nostoc > Phormidium > Cylindrospermopsis. Deficient concentrations of microcystins were found (< 1 µg L−1) in the groundwater samples. Based on the consideration of different factors (cyanobacterial composition in Lake Taihu, peripheral groundwater, and algal soil crusts), it was deduced that Microcystis likely originated from the lake. Still, Phormidium was probably originated from the soil infiltration. These results suggest that cyanobacteria and their toxins could travel in the groundwater, but this is a size-dependent mechanism.

Bioprospecting of cyanobacterium in Chilean coastal desert, Geitlerinema sp. molecular identification and pressurized liquid extraction of bioactive compounds

This study presents a new cyanobacterium of the genus Geitlerinema sp. isolated from the Chilean coastal desert as a rich source of bioactive compounds. Phylogenetic tree is shown along with a broad biochemical characterization using conventional and pressurized liquid extraction. Variables as extraction yield, phycobiliproteins, lipids and methyl palmitate (C16:0) were studied by means of two experimental designs based on a response surface methodology (RSM) employing two factorial design 32. Factors as temperature (20–200 °C) and percentage of solvents were selected resulting in Factorial Design A with 0–100% (v/v) of ethanol–water and Factorial Design B with 0–100 (v/v) of ethanol–limonene solvents. The main bioactive compounds were total proteins (∼52% wt), phycobiliproteins (especially C-phycocyanin) and methyl palmitate (C16:0). Data obtained showed that water and ethanol:water (1:1, v/v) improved the extraction yield and phycobiliproteins recovery. As for ethanol:limonene extracts, they were better for lipids and methyl palmitate extractions. In general, high temperatures only improved the extraction yield whereas low temperatures favor the extraction of phycobiliproteins. Therefore, results indicated that Geitlerinema sp. could be one of the several cyanobacteria genera that display functional properties for nutritional, pharmaceutical or industrial use as sustainable and cost-effective bioactive compounds in algal biorefinery model.

The detection of airborne anatoxin-a (ATX) on glass fiber filters during a harmful algal bloom

Sutherland JW, Turcotte RJ, Molden E, Moriarty V, Kelly M, Aubel M, Foss A. 2021. The detection of airborne anatoxin-a (ATX) on glass fiber filters during a harmful algal bloom. Lake Reserv Manage. 37:113–119. Anatoxin-a (ATX) is a neurotoxic alkaloid produced by certain cyanobacteria genera that can occur during harmful algal blooms (HABs). This study is the first to report airborne ATX collected outside an aquatic ecosystem. ATX was captured on glass fiber filters using a field-deployed air sampler during an active 2019 HAB at Capaum Pond on Nantucket Island, Massachusetts (USA). These findings indicate that emission of ATX molecules, or cyanobacteria containing ATX, during HABs presents a potential human health exposure not previously examined.

Neochroococcus gongqingensis gen. et sp. nov., a new member of coccoid cyanobacteria from a watercourse, Eastern China

The taxonomy of coccoid cyanobacteria has been largely revised in recent years. In this study, a novel coccoid cyanobacterial strain was isolated from a watercourse at the Poyang Lake Model Research Base, Jiangxi province, Eastern China. A polyphasic approach combining morphological and molecular testing was used to characterize this strain referred to as CHAB 4018. Regarding colonial form and cellular spatial arrangement, this strain was morphologically similar to strains of the genus Eucapsis. The maximum 16S rRNA gene sequence similarity of this strain to the currently described cyanobacteria genera was 93.40%, exceeding the cutoff for genus delimitation in bacteriology. Furthermore, a phylogenetic tree based on 16S rRNA gene sequences indicated that strain CHAB 4018 formed a unique clade in the family Chroococcaceae and was phylogenetically close to the recently established genus Cryptococcum but distant from the Chroococcus 'sensu stricto' clade and from Eucapsis. Thus, a novel coccoid cyanobacterial genus with a new species is here described as Neochroococcus gongqingensis. A large phylogenetic tree using more strains suggested phylogenetic intermixture of Chroococcus-like and Eucapsis-like cyanobacteria, suggesting the need for further studies on the phylogeny and taxonomy of coccoid cyanobacteria.