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The thermophilic microbial mat communities at hot springs in the Black Canyon of the Colorado River, thought to harbor the protistan human pathogen Naegleria fowleri, were surveyed using both culture-independent and -dependent methods to further understand the ecology of these hot spring microbiomes. Originating from Lake Mead source water, seven spring sites were sampled, varying in temperature from 25 to 55 °C. Amplicon-based high-throughput sequencing of twelve samples using 16S rRNA primers (hypervariable V4 region) revealed that most mats are dominated by cyanobacterial taxa, some but not all similar to those dominating the mats at other studied hot spring systems. 18S rRNA amplicon sequencing (V9 region) demonstrated a diverse community of protists and other eukaryotes including a highly abundant amoebal sequence related to Echinamoeba thermarum. Additional taxonomic and diversity metric analyses using near full-length 16S and 18S rRNA gene sequencing allowed a higher sequence-based resolution of the community. The mat sequence data suggest a major diversification of the cyanobacterial orders Leptolyngbyales, as well as microdiversity among several cyanobacterial taxa. Cyanobacterial isolates included some representatives of ecologically abundant taxa. A Spearman correlation analysis of short-read amplicon sequencing data supported the co-occurrences of populations of cyanobacteria, chloroflexi, and bacteroidetes providing evidence of common microbial co-occurrences across the Black Canyon hot springs.

La cianobacteria Leptolyngbya sp. se caracteriza por ser fuente de enzimas, toxinas, auxinas y pigmentos por lo que se requiere seguir realizando estudios debido a su potencial biotecnológico. El presente trabajo tuvo como objetivo caracterizar una cepa de la cianobacteria Leptolyngbya sp. mediante cultivos discontinuos alimentados y así como valorar la calidad bioquímica de la biomasa y analizar su posible toxicidad en el pez cebra. Para ello, se tomaron muestras en el embalse “Sixto Durán Ballén”, Manabí, Ecuador y para su aislamiento se utilizó una combinación de técnicas por estriación en placas de agar y diluciones seriadas en medio BG110. Posteriormente, se escalaron los cultivos desde 10 mL hasta 14 L. Los cultivos fueron mantenidos a diferentes intensidades luminosas de 2, 4 y 8 Klux con fotoperiodo de 24:0, a 20 ⁰C ± 2 y el medio BG110 enriquecido con 1 y 5 mL de NaNO3 (0,085 y 0,425 mM; respectivamente). Se monitorearon las variables de clorofila a, y ficocianina durante los experimentos. Se realizó un análisis proximal de la biomasa cosechada y de toxicidad aguda del sobrenadante del cultivo y de la fracción lipídica de la biomasa, utilizando como organismo de prueba a peces cebra (Danio rerio). Se obtuvieron 5,06±0,15 mL de biomasa/10 mL de cultivo, biomasa seca de 1,5 g/L, con un contenido de clorofila a de 9,04±0,76µg/L y de ficocianina de 0,013±0,003mg*L-1, así mismo, 29,59, 25,50 y 27,49 % de carbohidratos, proteínas y cenizas; respectivamente. Se reporta toxicidad en el sobrenadante y fracción liposoluble al 100, 50 y 25 %, y nula al 10 % y en controles. Esta cepa de Leptolyngbya presentó capacidad de crecimiento, en los cultivos discontinuos, alta producción de proteínas y ficocianina, a bajas concentraciones de NaNO3 en medio BG110 y además expresó toxicidad sobre el pez cebra. Se recomienda su monitoreo cuando se observe su presencia en cuerpos de agua lenticas.

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 co-culture of cyanobacteria and heterotrophic bacteria can utilize the advantages of both bacteria, effectively remove pollutants and relieve the feedback inhibition effect in algae culture; however, little information is available in heavy metal removal. In this study, a filamentous cyanobacterium, Leptolyngbya sp. XZ1, isolated from biological soil crusts and four heterotrophic bacterial strains, namely, Y3, Y4, S1 and T2, isolated from the phycosphere were co-inoculated into BG-11 media containing Cd. Amongst co-culture systems, Leptolyngbya + S1 showed the highest Cd removal efficiencies of 93.2%, 71.8%, 60.7%, 56.8% and 41.0% at initial Cd concentrations of 2, 5, 10, 20 and 50 mg L−1, respectively. In this co-culture system, Cd adsorbed on the cell wall was increased by 42.8%, 52.9%, 50.0% and 22.6%, and the intracellular Cd was decreased by 37.9%, 37.0%, 51.0% and 50.6% at initial Cd concentrations of 5, 10, 20 and 50 mg L−1, respectively, compared with the Leptolyngbya monoculture. Under Cd stress, the biomass, extracellular polymeric substances (EPS)-polysaccharides and photosystem II activity of Leptolyngbya sp. XZ1 were increased by co-culture with Bacillus sp. S1. In addition, the Cd stress on Leptolyngbya was alleviated by co-culture with S1 as proven by the superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, scanning electron microscopy (SEM) images, soluble protein content and SDS-PAGE analysis. Results indicated that the cyanobacteria-heterotrophic bacteria co-culture system can be used as an effective bioremediation method to remove heavy metals from aqueous solution. [ABSTRACT FROM AUTHOR]

Cyanobacteria that grow above seawater salinity at temperatures above 45°C have rarely been studied.The present study is an attempt to decipher these unknown facts where the unique properties of phosphatase enzymes in a thermo-halotolerant Iceland clone 2 Leptolyngbyahas been studied under some important environmental conditions that play a distinctive rolein the growth of these extremophiles in those adverse ecological niches. Leptolyngbyaused in this present study is a unique species having 2 extreme characteristics of tolerance to high salt concentrations and temperature, so it is of intrinsic and scientific interest to study the phosphate dynamics and its variability under different ecological factors.The results of these experiments clearly show that under very adverse conditions of low light or high temperature and very high salt concentrations (almost 3 times of salt present in seawater 90g/L) this extremophile has the capacity to maintain its growth and metabolism which is the key to its survival in these extreme habitats.Observations from growth experiments under different environmental conditions(Temperatures, pH, salt concentrations, different light intensities) under laboratory conditions were found to be like its diverse patterns and adaptive ability in the extreme environment this organism has been isolated from. Phosphatase activity as a wayof understanding how P is metabolized under extreme conditions revealed that the highest phosphatase activity was observed in high salt concentrations (3 times that of seawater) and high temperatures of 45°C and low light intensities that is a very significant observation and scientifically important.

Spirulina is consumed worldwide, in the form of food or dietary supplements, for its nutritional value and health potential. However, these products may contain cyanotoxins, including hepatotoxic microcystins (MCs), produced by cyanobacterial contaminants. The French spirulina market has the particularity of being supplied half-locally by approximately 180 small-scale spirulina production farms. Data about this particular production and possible contaminations with other cyanobacteria and MCs are scarce. Thus, we collected the results of MC analyses and total cyanobacteria counts, carried out between 2013 and 2021, from 95 French spirulina producers who agreed to share their data. These data consisted of MC concentrations determined with an enzyme-linked immunosorbent assay (ELISA) using 623 dry spirulina samples and 105 samples of spirulina cultures. In addition, potentially unsafe samples of dry spirulina were further investigated through mass spectrometry, as duplicate analysis. We confirmed that the situation of the French spirulina production stayed within the safe regulatory level in terms of MC levels. On the other hand, the inventory of cyanobacterial contaminants, based on 539 count results, included 14 taxa. We present their prevalence, interannual evolution and geographical distribution. We also suggested improvements in cultivation practices to limit their propagation. [ABSTRACT FROM AUTHOR]

The immense use of conventional plastic is becoming the major cause of environmental issues. To solve these problems, bioplastic is a promising alternative of conventional plastic. The polyhydroxybutyrate (PHB) is a common biodegradable bioplastic naturally synthesized in various microorganisms. The main limitation with bacterial fermentation-based PHB bioplastic is its high production cost. This study aimed to screen, optimize, and selection of cyanobacteria, the oxygenic photosynthetic prokaryotes, for PHB production. Ten cyanobacterial morphotypes isolated from Garhwal Himalaya. The highest PHB content 1.38% was noted in Leptolyngbya sp. and lowest 0.24% in Cylinderospermum sp. Similarly, in case of biomass yield, highest 6.16 (g/L) biomass observed in Leptolyngbya sp. and lowest 0.986 (g/L) biomass noted in Cylinderospermum sp. Based on the current findings, Leptolyngbya sp. might be the promising candidate for PHB production. [ABSTRACT FROM AUTHOR]

Leptolyngbya, a well-known genus of cyanobacteria, is found in various ecological habitats including marine, fresh water, swamps, and rice fields. Species of this genus are associated with many ecological phenomena such as nitrogen fixation, primary productivity through photosynthesis and algal blooms. As a result, there have been a number of investigations of the ecology, natural product chemistry, and biological characteristics of members of this genus. In general, the secondary metabolites of cyanobacteria are considered to be rich sources for drug discovery and development. In this review, the secondary metabolites reported in marine Leptolyngbya with their associated biological activities or interesting biosynthetic pathways are reviewed, and new insights and perspectives on their metabolic capacities are gained.

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.

Cyanobacteria that grow above seawater salinity at temperatures above 45°C have rarely been studied. The present study is an attempt to decipher these unknown facts where the unique properties of phosphatase enzymes in a thermo-halotolerant Iceland clone 2 Leptolyngbya has been studied under some important environmental conditions that play a distinctive role in the growth of these extremophiles in those adverse ecological niches. Leptolyngbya used in this present study is a unique species having 2 extreme characteristics of tolerance to high salt concentrations and temperature, so it is of intrinsic and scientific interest to study the phosphate dynamics and its variability under different ecological factors. The results of these experiments clearly show that under very adverse conditions of low light or high temperature and very high salt concentrations (almost 3 times of salt present in seawater 90g/L) this extremophile has the capacity to maintain its growth and metabolism which is the key to its survival in these extreme habitats. Observations from growth experiments under different environmental conditions (Temperatures, pH, salt concentrations, different light intensities) under laboratory conditions were found to be like its diverse patterns and adaptive ability in the extreme environment this organism has been isolated from. Phosphatase activity as a way of understanding how P is metabolized under extreme conditions revealed that the highest phosphatase activity was observed in high salt concentrations (3 times that of seawater) and high temperatures of 45°C and low light intensities that is a very significant observation and scientifically important. [ABSTRACT FROM AUTHOR]

Cyanobacteria, can be found in many different terrestrial or aquatic habitats that are sometimes unbearable for many other organisms. Biosynthesis of mycosporine-like amino acids (MAAs) enables growth in such environments due to their UV screening and antioxidant activity. MAAs are water-soluble bioactive molecules with vast biotechnological potentials due to their UV screening properties and antioxidant activities. In the present study, the occurrence of MAAs in the cyanobacterium Leptolyngbya sp. (Gomont) Anagnostidis and Komárek was assessed by HPLC–PDA ESI–MS analysis. The combination of UV and MS data values revealed the occurrence of nine different MAAs, including; palythine (1), palythenic acid (2), euhalothece-362 (3), palythene (4), usujirene (5), palythine serine (6), asterina-330 (7), palythinol (8), and palythine-threonine (9). As well, some different in vitro antioxidant assays such as ABTS, FRAP, and RP were applied to evaluate the antioxidant properties of the MAA-enriched extract. The results indicate a significant and dose-dependent antioxidant activity of the MAA-enriched extract (54% ABTS scavenging activity at the dose of 2 mg mL−1 extract) in this cyanobacterium which was comparable with those of ascorbic acid (81% antioxidation rate at 2 mg mL−1 of ascorbic acid). All these observations suggest that Leptolyngbya sp. may act as a new, promising source of MAA compounds. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPSs) produced by the filamentous cyanobacterium identified as Leptolyngbya sp. IkmLPT16 were isolated and characterized chemically, and their antioxidant, functional, and rheological properties were studied. The strain produces a significant amount of EPSs (2.15 g L−1) conjointly with a biomass production achieved at a maximum of 1.35 g L−1 after nine production days. Chemical analysis of EPSs revealed the presence of mannose (35%), arabinose (24%), glucose (15%), rhamnose (2%), and one uronic acid (8%). Fourier transformed infrared spectrum of EPSs further revealed the presence of νC-N groups indicating the presence of peptide moieties. Elemental analysis of EPSs showed the presence of sulfate groups (S = 0.59%) as inorganic substituents. Functional properties of Leptolyngbya EPSs were determined based on water holding capacity, oil holding capacity, foaming ability, and metal sorption ability. Experimental results showed high water holding capacity (119%), water solubility index (97.43%), and oil holding ability (87.52%), with a strong metal sorption ability and consequent foam stability (22%). The rheological properties of EPSs were comparable with commercial xanthan gum with higher resistance to Temperature. Leptolyngbya sp. EPSs displayed an effective antioxidant activity via directly scavenging free radicals particularly DDPH• (IC50 = 4 mg. mL−1 against 10 mg. mL−1 for l-ascorbic acid) and •OH (IC50 = 10 mg. mL−1 against 20 mg. mL−1 for l-ascorbic acid) and as an iron-chelating agent (IC50 = 40 mg. mL−1 against 60 mg.mL−1 for EDTA). The outcomes of this study demonstrate the potential use of Leptolyngbya sp. EPSs in several food and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Cyanobacteria are a promising source for the sustainable production of biodegradable bioplastics such as poly(3-hydroxybutyrate) (PHB). The auto-phototrophic biomass formation is based on light and CO2, which is an advantage compared to heterotrophic PHB-producing systems. So far, only a handful of cyanobacterial species suitable for the high-yield synthesis of PHB have been reported. In the present study, the PHB formation, biomass, and elemental composition of Leptolyngbya sp. NIVA-CYA 255 were investigated. Therefore, a three-stage cultivation process was applied, consisting of a growth stage; an N-, P-, and NP-depleted phototrophic stage; and a subsequent mixotrophic deficiency stage, initiated by sodium acetate supplementation. The extracted cyanobacterial PHB was confirmed by FTIR- and GC-MS analyses. Furthermore, the fluorescent dyes LipidGreen2 and Nile red were used for fluorescence-based monitoring and the visualization of PHB. LipidGreen2 was well suited for PHB quantification, while the application of Nile red was limited by fluorescence emission crosstalk with phycocyanin. The highest PHB yields were detected in NP- (325 mg g−1) and N-deficiency (213 mg g−1). The glycogen pool was reduced in all cultures during mixotrophy, while lipid composition was not affected. The highest glycogen yield was formed under N-deficiency (217 mg g−1). Due to the high carbon storage capacity and PHB formation, Leptolyngbya sp. NIVA-CYA 255 is a promising candidate for PHB production. Further work will focus on upscaling to a technical scale and monitoring the formation by LipidGreen2-based fluorometry. [ABSTRACT FROM AUTHOR]

Abstract Background Dietary omega-3 (n-3), long chain (LC-, ≥ 20 carbons), polyunsaturated fatty acids (PUFAs) derived largely from marine animal sources protect against inflammatory processes and enhance brain development and function. With the depletion of natural stocks of marine animal sources and an increasing demand for n-3 LC-PUFAs, alternative, sustainable supplies are urgently needed. As a result, n-3 18-carbon and LC-PUFAs are being generated from plant or algal sources, either by engineering new biosynthetic pathways or by augmenting existing systems. Results We utilized an engineered plasmid encoding two cyanobacterial acyl-lipid desaturases (DesB and DesD, encoding Δ15 and Δ6 desaturases, respectively) and “vesicle-inducing protein in plastids” (Vipp1) to induce production of stearidonic acid (SDA, 18:4 n-3) at high levels in three strains of cyanobacteria (10, 17 and 27% of total lipids in Anabaena sp. PCC7120, Synechococcus sp. PCC7002, and Leptolyngbya sp. strain BL0902, respectively). Lipidomic analysis revealed that in addition to SDA, the rare anti-inflammatory n-3 LC-PUFA eicosatetraenoic acid (ETA, 20:4 n-3) was synthesized in these engineered strains, and ~ 99% of SDA and ETA was complexed to bioavailable monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) species. Importantly, novel molecular species containing alpha-linolenic acid (ALA), SDA and/or ETA in both acyl positions of MGDG and DGDG were observed in the engineered Leptolyngbya and Synechococcus strains, suggesting that these could provide a rich source of anti-inflammatory molecules. Conclusions Overall, this technology utilizes solar energy, consumes carbon dioxide, and produces large amounts of nutritionally important n-3 PUFAs and LC-PUFAs. Importantly, it can generate previously undescribed, highly bioavailable, anti-inflammatory galactosyl lipids. This technology could therefore be transformative in protecting ocean fisheries and augmenting the nutritional quality of human and animal food products.

Bioassay-guided fractionation of two marine cyanobacterial extracts using the H-460 human lung cancer cell line and the OVC-5 human ovarian cancer cell line led to the isolation of three related α-methoxy-β, β'-dimethyl-γ-pyrones each containing a modified alkyl chain, one of which was identified as the previously reported kalkipyrone and designated kalkipyrone A. The second compound was an analog designated kalkipyrone B. The third was identified as the recently reported yoshinone A, also isolated from a marine cyanobacterium. Kalkipyrone A and B were obtained from a field-collection of the cyanobacterium Leptolyngbya sp. from Fagasa Bay, American Samoa, while yoshinone A was isolated from a field-collection of cyanobacteria (cf. Schizothrix sp.) from Panama. One-dimensional and two-dimensional NMR experiments were used to determine the overall structures and relative configurations of the kalkipyrones, and the absolute configuration of kalkipyrone B was determined by (1)H NMR analysis of diastereomeric Mosher's esters. Kalkipyrone A showed good cytotoxicity to H-460 human lung cancer cells (EC50=0.9μM), while kalkipyrone B and yoshinone A were less active (EC50=9.0μM and >10μM, respectively). Both kalkipyrone A and B showed moderate toxicity to Saccharomyces cerevisiae ABC16-Monster strain (IC50=14.6 and 13.4μM, respectively), whereas yoshinone A was of low toxicity to this yeast strain (IC50=63.8μM).

Aplysina cauliformis , the Caribbean purple rope sponge, is commonly affected by Aplysina Red Band Syndrome (ARBS). This transmissible disease manifests as circular lesions with red margins and results in bare spongin fibers. Leptolyngbya spp. appear to be responsible for the characteristic red coloration but transmission studies with a sponge-derived isolate failed to establish disease, leaving the etiology of ARBS unknown. To investigate the cause of ARBS, contact transmission experiments were performed between healthy and diseased sponges separated by filters with varying pore sizes. Transmission occurred when sponges were separated by filters with pore sizes ≥ 2.5 μm, suggesting a prokaryotic pathogen(s) but not completely eliminating eukaryotic pathogen(s). Using 16S rRNA gene sequencing methods, 38 prokaryotic taxa were significantly enriched in diseased sponges, including Leptolyngbya , whereas seven taxa were only found in some, but not all, of the ARBS-affected sponges. These results do not implicate a single taxon, but rather a suite of taxa that changed in relative abundance with disease, suggesting a polymicrobial etiology as well as dysbiosis. As a better understanding of dysbiosis is gained, changes in the composition of associated prokaryotic communities may have increasing importance for evaluating and maintaining the health of individuals and imperiled coral reef ecosystems. [ABSTRACT FROM AUTHOR]

Cyanobacteria morphotypes with simple morphology, mainly thin filamentous homocytous strains, comprise a taxonomically complex group and represent a challenge in systematic studies. However, the polyphasic approach applied nowadays to investigate the cyanobacterial diversity has emerged as a powerful tool to undercover cryptic taxa and to set up a more natural classification system. Yet, studies exploring the cultured diversity of cyanobacteria from extreme tropical environments have paved the way to the discovery of new cyanobacteria taxa, enabling the description of Pantanalinema, Alkalinema, and Cephalothrix as novel genera from saline–alkaline lakes in Pantanal wetlands (Brazil). The present study investigated a set of cyanobacterial strains resembling Leptolyngbya morphotypes by means of its morphology, 16S ribosomal RNA (16S rRNA) phylogeny, and ITS secondary structures. Based on the shape and structure of their trichomes, the low levels of 16S rRNA identity coupled with the distinct phylogenetic position with regard to well establish genera, and their divergent ecological feature, these strains must be accommodated into a novel genus, named as Monilinema gen. nov., described under the provisions of the International Code of Nomenclature for algae, fungi, and plants. Accordingly, based on the singularity of the D1–D1′ and V3 helixes, these strains should be considered as a single species, Monilinema alkalinum. [ABSTRACT FROM AUTHOR]

Background: Dietary omega-3 (n-3), long chain (LC-, ≥ 20 carbons), polyunsaturated fatty acids (PUFAs) derived largely from marine animal sources protect against inflammatory processes and enhance brain development and function. With the depletion of natural stocks of marine animal sources and an increasing demand for n-3 LC-PUFAs, alternative, sustainable supplies are urgently needed. As a result, n-3 18-carbon and LC-PUFAs are being generated from plant or algal sources, either by engineering new biosynthetic pathways or by augmenting existing systems. Results: We utilized an engineered plasmid encoding two cyanobacterial acyl-lipid desaturases (DesB and DesD, encoding Δ15 and Δ6 desaturases, respectively) and "vesicle-inducing protein in plastids" (Vipp1) to induce production of stearidonic acid (SDA, 18:4 n-3) at high levels in three strains of cyanobacteria (10, 17 and 27% of total lipids in Anabaena sp. PCC7120, Synechococcus sp. PCC7002, and Leptolyngbya sp. strain BL0902, respectively). Lipidomic analysis revealed that in addition to SDA, the rare anti-inflammatory n-3 LC-PUFA eicosatetraenoic acid (ETA, 20:4 n-3) was synthesized in these engineered strains, and ~ 99% of SDA and ETA was complexed to bioavailable monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) species. Importantly, novel molecular species containing alpha-linolenic acid (ALA), SDA and/or ETA in both acyl positions of MGDG and DGDG were observed in the engineered Leptolyngbya and Synechococcus strains, suggesting that these could provide a rich source of anti-inflammatory molecules. Conclusions: Overall, this technology utilizes solar energy, consumes carbon dioxide, and produces large amounts of nutritionally important n-3 PUFAs and LC-PUFAs. Importantly, it can generate previously undescribed, highly bioavailable, anti-inflammatory galactosyl lipids. This technology could therefore be transformative in protecting ocean fisheries and augmenting the nutritional quality of human and animal food products. [ABSTRACT FROM AUTHOR]

In this research work the biotreatment of traditional Greek Pudding Dessert production line's wastewater (PDW-Pudding Dessert Wastewater) of a confectionery industry was studied, combining an attached growth aerobic biological filter as pretreatment step and a cyanobacteria-based cultivation system, with the aim to develop a viable treatment process providing simultaneously high-value biomass production. Initially, experiments in attached growth pilot-scale bioreactor were performed using various initial concentrations of dissolved Chemical Oxygen Demand (of about 1000, 2500, 5500, 7500 and 10,500 mg d-COD L−1) and two recirculation rates (1.0 and 0.5 L min−1), achieving d-COD and sugars removal up to about 75–92 % and 99 %, respectively. Then, the biologically pretreated effluent was further treated (without sterilization) using a cyanobacteria-based system. Three different cyanobacteria species (Leptolyngbya sp., Arthrospira sp. and Geitlerinema sp.) were examined separately, achieving significant d-COD (up to 83 %), NO 3 −-N (up to 95.5 %) and PO 4 3− (up to 99.5 %) removal. Carbohydrates, proteins, chlorophyll-a and phycocyanin contents were also measured in Dry Weight (DW) (up to about 23.4 %, 40.7 %, 27.70 mg g−1 DW and 64.39 mg g−1 DW, respectively). The proposed hybrid system combines both efficiency and sustainability since can efficiently treat PDW (total d-COD, NO 3 −-N and PO 4 3− removal up to about 98.9 %, 99.5 % and 99.7 %, respectively), reducing simultaneously the operational costs via the recovery of high added value compounds. [Display omitted] • Confectionary wastewater (CW) was treated using two-stage hybrid biological systems. • Attached growth filter with indigenous microorganisms was used as pre-treatment step. • The pretreated effluent was further treated using three different cyanobacteria. • The hybrid system presented high removals (up to 99.7 %) of all tested pollutants. • Biomass presented significant carbohydrates, proteins and pigments contents. [ABSTRACT FROM AUTHOR]

Microsatellites (simple sequence repeats, SSRs) are ubiquitously distributed in almost all known genomes. Here, the first investigation was designed to examine the SSRs and compound microsatellites (CSSRs) in genomes of Leptolyngbya-like strains. The results disclosed diversified patterns of distribution, abundance, density, and diversity of SSRs and CSSRs in genomes, indicating that they may be subject to rapid evolutionary change. The numbers of SSRs and CSSRs were extremely unevenly distributed among genomes, ranging from 11,086 to 24,000 and from 580 to 1865, respectively. Dinucleotide SSRs were the most abundant category in 31 genomes, while the other 15 genomes followed the pattern: mono- > di- > trinucleotide SSRs. The patterns related to SSRs and CSSRs showed differences among phylogenetic groups. Both SSRs and CSSRs were overwhelmingly distributed in coding regions. The numbers of SSRs and CSSRs were significantly positively correlated with genome size (p < 0.01) and negatively correlated with GC content (p < 0.05). Moreover, the motif (A/C)n and (AG)n was predominant in mononucleotide and dinucleotide SSRs, and unique motifs of CSSRs were identified in 39 genomes. This study provides the first insight into SSRs and CSSRs in genomes of Leptolyngbya-like strains and will be useful to understanding their distribution, predicting their function, and tracking their evolution. Additionally, the identified SSRs may provide an evolutionary advantage of fast adaptation to environmental changes and may play an important role in the cosmopolitan distribution of Leptolyngbya strains to globally diverse niches.

The last decade was marked by efforts to define and identify the main cyanobacterial players in biological crusts around the world. However, not much is known about biocrusts in Brazil’s tropical savanna (cerrado), despite the existence of environments favorable to their development and ecological relevance. We examined the community composition of cyanobacteria in biocrusts from six sites distributed in the Southeast of the country using high throughput sequencing of 16S rRNA and phylogenetic placement in the wider context of biocrusts from deserts. Sequences ascribable to 22 genera of cyanobacteria were identified. Although a significant proportion of sequences did not match those of known cyanobacteria, several clades of Leptolyngbya and Porphyrosiphon were found to be the most abundant. We identified significant differences in dominance and overall composition among the cerrado sites, much larger than within-site variability. The composition of cerrado cyanobacterial communities was distinct from those known in biocrusts from North American deserts. Among several environmental drivers considered, the opposing trend of annual precipitation and mean annual temperature best explained the variability in community composition within Brazilian biocrusts. Their compositional uniqueness speaks of the need for dedicated efforts to study the ecophysiology of tropical savanna biocrust and their roles in ecosystem function for management and preservation.

The last decade was marked by efforts to define and identify the main cyanobacterial players in biological crusts around the world. However, not much is known about biocrusts in Brazil's tropical savanna (cerrado), despite the existence of environments favorable to their development and ecological relevance. We examined the community composition of cyanobacteria in biocrusts from six sites distributed in the Southeast of the country using high throughput sequencing of 16S rRNA and phylogenetic placement in the wider context of biocrusts from deserts. Sequences ascribable to 22 genera of cyanobacteria were identified. Although a significant proportion of sequences did not match those of known cyanobacteria, several clades of Leptolyngbya and Porphyrosiphon were found to be the most abundant. We identified significant differences in dominance and overall composition among the cerrado sites, much larger than within-site variability. The composition of cerrado cyanobacterial communities was distinct from those known in biocrusts from North American deserts. Among several environmental drivers considered, the opposing trend of annual precipitation and mean annual temperature best explained the variability in community composition within Brazilian biocrusts. Their compositional uniqueness speaks of the need for dedicated efforts to study the ecophysiology of tropical savanna biocrust and their roles in ecosystem function for management and preservation. [ABSTRACT FROM AUTHOR]

Cyanobacterial diversity associated with sponges remains underestimated, though it is of great scientific interest in order to understand the ecology and evolutionary history of the symbiotic relationships between the two groups. Of the filamentous cyanobacteria, the genus Leptolyngbya is the most frequently found in association with sponges as well as the largest and obviously polyphyletic group. In this study, five Leptolyngbya‐like sponge‐associated isolates were investigated using a combination of molecular, chemical, and morphological approach and revealed a novel marine genus herein designated Leptothoe gen. nov. In addition, three new species of Leptothoe, Le. sithoniana, Le. kymatousa, and Le. spongobia, are described based on a suite of distinct characters compared to other marine Leptolyngbyaceae species/strains. The three new species, hosted by four sponge species, showed different degrees of host specificity. Leptothoe sithoniana and Le. kymatousa hosted by the sponges Petrosia ficiformis and Chondrilla nucula, respectively, seem to be more specialized than Le. spongobia, which was hosted by the sponges Dysidea avara and Acanthella acuta. All three species contained nitrogen‐fixing genes and may contribute to the nitrogen budget of sponges. Leptothoe spongobia TAU‐MAC 1115 isolated from Acanthella acuta was shown to produce microcystin‐RR indicating that microcystin production among marine cyanobacteria could be more widespread than previously determined. [ABSTRACT FROM AUTHOR]

Leptolyngbya, a well-known genus of cyanobacteria, is found in various ecological habitats including marine, fresh water, swamps, and rice fields. Species of this genus are associated with many ecological phenomena such as nitrogen fixation, primary productivity through photosynthesis and algal blooms. As a result, there have been a number of investigations of the ecology, natural product chemistry, and biological characteristics of members of this genus. In general, the secondary metabolites of cyanobacteria are considered to be rich sources for drug discovery and development. In this review, the secondary metabolites reported in marine Leptolyngbya with their associated biological activities or interesting biosynthetic pathways are reviewed, and new insights and perspectives on their metabolic capacities are gained.

The observation of Leptolyngbya growth on temperature 35oC with initial pH variation had been done. The study was descriptive research. The study aimed to determine the best initial growth pH for Leptolyngbya HS (Hot Spring)-16 and HS-36. Leptolyngbya HS-16 was isolated from Pancar Mountain hotspring, while Leptolyngbya HS-36 was isolated from Maribaya hot spring. The acidity (pH) of Pancar mountain and Maribaya hot spring was 7. Each strain was grown in Blue Green medium number 11 (BG-11) with variation initial pH (6, 7, 8 and 9) and incubated on 35 oC. Parameters was wet biomass weight of Leptolyngbya in each strain. Observation were made on 15 days with 11 sampling. From the observation, the average of wet biomass weight of Leptolyngbya HS-16 was obtained at pH 6 (0,0295 g/L), pH 7 (0,0404 g/L), pH 8 (0,03825 g/L), and pH 9 (0,02735 g/L), meanwhile Leptolyngbya HS-36 was obtained at pH 6 (0,02905 g/L), pH 7 (0,01995 g/L), pH 8 (0,05345 g/L) and pH 9 (0,05995 g/L) on the 15th day. The results of 15 days observation showed that the best initial pH for growing Leptolyngbya HS-16 is 7, while Leptolyngbya HS-36 is 9. From this study it could be seen that Leptolyngbya HS-16 and HS-36 could be cultured with alkaline condition.

South Ural is a territory with a unique geographical position and heterogeneous natural conditions. Unexplored biodiversity of the terrestrial cyanobacteria of this territory is very high. We undertook a floristic study covering all botanical-geographical zones of the Bashkiria and Bredinskiy district of the Chelyabinsk region. In a total of 85 soil samples collected, 56 species of cyanobacteria were identified. The number of cyanobacteria was highest in the boreal-forest zone (39 species) and notably lower in the other zones (18, 29, and 24 species for broad-leaved forest, forest steppe and steppe regions, respectively). Leptolyngbya voronichiniana, Leptolyngbya foveolarum, cf. Trichocoleus hospitus, Pseudophormidium hollerbachianum, Nostoc cf. punctiforme, Microcoleus vaginatus, Phormidium breve, Phormidium dimorphum, Phormidium corium, and Leptolyngbya cf. tenuis were detected in all studied zones. Trichormus variabilis and Cylindrospermum majus were detected in the forest zone, Phormidium ambiguum was typical for forest-steppe and steppe zones, Pseudophormidium hollerbachianum and Nostoc cf. commune were most abundant in the steppe. Humidity and heterogeneity of the substrate were likely the most important factors influencing terrestrial cyanobacteria diversity. For full understanding of the biodiversity of cyanobacteria in the South Urals, future molecular-genetic research is necessary. [ABSTRACT FROM AUTHOR]

Utilizing novel approaches for the green synthesis of metal nanoparticles are of great importance. Therefore, we reported biogenic synthesis of silver nanoparticles (AgNPs) using extracts of Leptolyngbya strain JSC-1, and their significant applications against pathogenic bacteria and cancerous HeLa cell line. The biofabricated AgNPs were characterized by UV-visible spectroscopy, FTIR, SEM, TEM, DLS and zeta-potential. The as prepared AgNPs were assessed for inhibition of bacterial growth and induction of apoptosis in HeLa cells by different doses of AgNPs was evaluated. UV-visible spectroscopy and FTIR of AgNPs demonstrated the surface plasmon resonance at 413 nm and interaction among extract and nanoparticles, respectively. Electron microscopy revealed the morphology and DLS demonstrated size distribution of the particles (10-100 nm). Zeta potential values were between −47 and 0 mV, indicating stability of the particles. Proliferation of HeLa cells was significantly inhibited and severe cytotoxicity with higher intracellular uptake were observed after applying high concentration of AgNPs. Efficient inhibition zones (17 ± 2 and 21 ± 2 mm) were produced at maximum concentration (100 µl from 1 mg ml−1 stock of AgNPs) for Staphylococcus aureus and Escherichia coli, respectively. These findings reveal that the biofabricated AgNPs possess strong antibacterial activity and ability to induce apoptosis in cancer cell line (HeLa). [ABSTRACT FROM AUTHOR]

The genus Leptolyngbya comprises filamentous cyanobacteria that are important in rice fields. In the rhizosphere, cyanobacteria produce a variety of secondary metabolites such as auxins that are important in agriculture soil performance. To assess this, Leptolyngbya strain MMG-1, was isolated from the rhizosphere of rice plants and described. For this, the morphology of this strain was studied by light microscopy as well as by confocal laser scanning microscopy. Besides, the ability of this strain to synthesize an auxin-like bioactive compound was demonstrated under various culture conditions (different amounts of tryptophan; pH; different alternating light:dark periods; duration of the incubation). The auxin-like compound was extracted from the culture of Leptolyngbya strain MMG-1 and identified as indole-3-acetic acid (IAA) by thin layer chromatography (TLC) as well as by high performance liquid chromatography (HPLC). Our results showed that the strain required the precursor L-tryptophan for the synthesis of IAA. Leptolyngbya strain MMG-1 accumulated IAA intracellularly. The IAA secreted by Leptolyngbya strain MMG-1 was significantly correlated with the initial concentration of L-tryptophan in the medium, as well as with the duration of the incubation. The bioactivity of the secreted IAA was determined by its effect on the rooting pattern of Pisum sativum seedlings. The culture supernatant of Leptolyngbya strain MMG-1 stimulated the seedling lateral rooting, while it decreased root length. Hence, rhizospheric Leptolyngbya produced auxin under different conditions and affected the plants rooting pattern. Rev. Biol. Trop. 62 (3): 1251-1260. Epub 2014 September 01.

Colony pattern formations of bacteria with motility manifest complicated morphological self-organization phenomena. Leptolyngbya boryana is a filamentous cyanobacterium, which has been used as a genetic model organism for studying metabolism including photosynthesis and nitrogen fixation. A widely used type strain [wild type (WT) in this article] of this species has not been reported to show any motile activity. However, we isolated a spontaneous mutant strain that shows active motility (gliding activity) to give rise to complicated colony patterns, including comet-like wandering clusters and disk-like rotating vortices on solid media. Whole-genome resequencing identified multiple mutations in the genome of the mutant strain. We confirmed that inactivation of the candidate gene dgc2 ( LBDG&#95;02920 ) in the WT background was sufficient to give rise to motility and morphologically complex colony patterns. This gene encodes a protein containing the GGDEF motif which is conserved at the catalytic domain of diguanylate cyclase (DGC). Although DGC has been reported to be involved in biofilm formation, the dgc2 mutant significantly facilitated biofilm formation, suggesting a role for the dgc2 gene in suppressing both gliding motility and biofilm formation. Thus, Leptolyngbya is expected to be an excellent genetic model for studying dynamic colony pattern formation and to provide novel insights into the role of DGC family genes in biofilm formation. IMPORTANCE Self-propelled bacteria often exhibit complex collective behaviors, such as formation of dense-moving clusters, which are exemplified by wandering comet-like and rotating disk-like colonies; however, the molecular details of how these structures are formed are scant. We found that a strain of the filamentous cyanobacterium Leptolyngbya deficient in the GGDEF protein gene dgc2 elicits motility and complex and dynamic colony pattern formation, including comet-like and disk-like clusters. Although c-di-GMP has been reported to activate biofilm formation in some bacterial species, disruption of dgc2 unexpectedly enhanced it, suggesting a novel role for this GGDEF protein for inhibiting both colony pattern formation and biofilm formation.

The evolutionary relationships of 10 Antarctic cyanobacterial strains of the order Oscillatoriales isolated from King George and Deception Islands, South Shetland Islands were studied by a polyphasic approach (morphology, 16S rRNA and internal transcribed spacer sequences). The studied taxa are characteristic of coastal Antarctic biotopes, where they form distinct populations and ecologically delimited communities. They were isolated from terrestrial habitats: microbial mats in seepages; crusts on soil, rocks, bones and mosses; mud, sometimes close to bird colonies; and from guano. Based on major phenotypic features, the strains were divided into four distinct morphotypes: Leptolyngbya borchgrevinkii (A), Leptolyngbya frigida (B), Microcoleus sp. (C) and Wilmottia murrayi (D). This morphological identification was in agreement with the phylogenetic relationships. For the first time, the 16S rRNA gene sequence of a strain corresponding to the L. borchgrevinkii morphotype was determined. Morphotype B is most related to sequences assigned to L. frigida isolated from microbial mats of coastal lakes in East Antarctica. Morphotype C belongs to a cluster including strains with morphotypes corresponding to Microcoleus attenuatus, Microcoleus favosus and Microcoleus sp., which are from Antarctica and other continents. Morphotype D is grouped with sequences assigned to W. murrayi mostly isolated from Antarctica. [ABSTRACT FROM AUTHOR]

Bioassay-guided fractionation of two marine cyanobacterial extracts using the H-460 human lung cancer cell line and the OVC-5 human ovarian cancer cell line led to the isolation of three related α-methoxy- β , β ′-dimethyl-γ-pyrones each containing a modified alkyl chain, one of which was identified as the previously reported kalkipyrone and designated kalkipyrone A. The second compound was an analog designated kalkipyrone B. The third was identified as the recently reported yoshinone A, also isolated from a marine cyanobacterium. Kalkipyrone A and B were obtained from a field-collection of the cyanobacterium Leptolyngbya sp. from Fagasa Bay, American Samoa, while yoshinone A was isolated from a field-collection of cyanobacteria (cf. Schizothrix sp.) from Panama. One-dimensional and two-dimensional NMR experiments were used to determine the overall structures and relative configurations of the kalkipyrones, and the absolute configuration of kalkipyrone B was determined by 1 H NMR analysis of diastereomeric Mosher’s esters. Kalkipyrone A showed good cytotoxicity to H-460 human lung cancer cells (EC 50 = 0.9 μM), while kalkipyrone B and yoshinone A were less active (EC 50 = 9.0 μM and >10 μM, respectively). Both kalkipyrone A and B showed moderate toxicity to Saccharomyces cerevisiae ABC16-Monster strain (IC 50 = 14.6 and 13.4 μM, respectively), whereas yoshinone A was of low toxicity to this yeast strain (IC 50 = 63.8 μM). [ABSTRACT FROM AUTHOR]

In this paper, the use of lithium fluoride (LiF) as imaging radiation detector to analyse living cells by single-shot soft X-ray contact microscopy is presented. High resolved X-ray images on LiF of cyanobacterium Leptolyngbya VRUC135, two unicellular microalgae of the genus Chlamydomonas and mouse macrophage cells (line RAW 264.7) have been obtained utilizing X-ray radiation in the water window energy range from a laser plasma source. The used method is based on loading of the samples, the cell suspension, in a special holder where they are in close contact with a LiF crystal solid-state X-ray imaging detector. After exposure and sample removal, the images stored in LiF by the soft X-ray contact microscopy technique are read by an optical microscope in fluorescence mode. The clear image of the mucilaginous sheath the structure of the filamentous Leptolyngbya and the visible nucleolus in the macrophage cells image, are noteworthiness results. The peculiarities of the used X-ray radiation and of the LiF imaging detector allow obtaining images in absorption contrast revealing the internal structures of the investigated samples at high spatial resolution. Moreover, the wide dynamic range of the LiF imaging detector contributes to obtain high-quality images. In particular, we demonstrate that this peculiar characteristic of LiF detector allows enhancing the contrast and reveal details even when they were obscured by a nonuniform stray light. [ABSTRACT FROM AUTHOR]

The genus Leptolyngbya comprises filamentous cyanobacteria that are important in rice fields. In the rhizosphere, cyanobacteria produce a variety of secondary metabolites such as auxins that are important in agriculture soil performance. To assess this, Leptolyngbya strain MMG-1, was isolated from the rhizosphere of rice plants and described. For this, the morphology of this strain was studied by light microscopy as well as by confocal laser scanning microscopy. Besides, the ability of this strain to synthesize an auxin-like bioactive compound was demonstrated under various culture conditions (different amounts of tryptophan; pH; different alternating light:dark periods; duration of the incubation). The auxin-like compound was extracted from the culture of Leptolyngbya strain MMG-1 and identified as indole-3-acetic acid (IAA) by thin layer chromatography (TLC) as well as by high performance liquid chromatography (HPLC). Our results showed that the strain required the precursor L-tryptophan for the synthesis of IAA. Leptolyngbya strain MMG-1 accumulated IAA intracellularly. The IAA secreted by Leptolyngbya strain MMG-1 was significantly correlated with the initial concentration of L-tryptophan in the medium, as well as with the duration of the incubation. The bioactivity of the secreted IAA was determined by its effect on the rooting pattern of Pisum sativum seedlings. The culture supernatant of Leptolyngbya strain MMG-1 stimulated the seedling lateral rooting, while it decreased root length. Hence, rhizospheric Leptolyngbya produced auxin under different conditions and affected the plants rooting pattern. Rev. Biol. Trop. 62 (3): 1251-1260. Epub 2014 September 01. [ABSTRACT FROM AUTHOR]

This paper describes in detail the phenotypic traits of the newly discovered Leptolyngbya sieminskae sp. n. (Cyanobacteria). The species was found at two islands of the Svalbard archipelago (Spitsbergen and Nordaustlandet) in habitats which differed in humidity, water sources and altitude. The research was conducted at two fjords: on the southern side of Spitsbergen - Hornsund (77N, 015E) and the north-west side of Nord- austlandet - Murchisonfjord (80N, 018E). Although Leptolyngbya sieminskae was found in different latitudes no significant morphological differences were found between the specimens from both sites. The only visible difference is in the thickness of filaments and sheaths. [ABSTRACT FROM AUTHOR]

A locally isolated co-culture of two photosynthetic species [ Chlorella vulgaris ( Chlorophyta) and Leptolyngbya sp. ( Cyanobacteria)] displayed enhanced growth when compared to a Chlorella monoculture; however, the biological mechanisms driving such improvement are currently not well understood. To investigate these mechanisms, this study examined the differential gene expression in the Chlorella between the co-culture and the monoculture. Suppression subtractive hybridization was performed between m RNA from Chlorella in the co-culture and in a monoculture, and 105 genes were identified as being putatively differentially expressed. Nine of these genes, corresponding to the key functional categories of energy, metabolism, and protein synthesis, were further examined using quantitative real-time PCR and showed differential regulation of photosystem I and photosystem II and upregulation of stress-response genes and a gene encoding an oil-globule-associated gene in the co-culture Chlorella. This differential gene expression study of a Chlorella/cyanobacteria co-culture will aid in the development of culture strategies capable of taking advantage of these differences for the production of biomass and bioproducts of interest. Knowledge of the underlying genetic causes of the changes in growth and productivity of the species in co-culture provides insights on possible target genes for optimization of the culture. [ABSTRACT FROM AUTHOR]

ABSTRACT Microscopic, molecular, and biochemical investigations were conducted to describe a benthic mat-forming Leptolyngbya isolate collected from wastewater canal in Helwan area, Egypt. Microscopic examination revealed that the isolate was filamentous, nonheterocystous, with obvious granular surface ornamentation. Electron microscopy was used to reveal the isolate's ultrastructure. Cross walls were thick with uneven deposition. Thylakoids were convoluted and irregularly distributed. Granular content differed from one cell to the other probably due to their physiological stages/position within the filaments and/or their age. Nycridial cells were present. Highly refractile gas vesicle-like structures were detected and their identity as gas vesicles was confirmed by amplifying the gene coding for the gas vesicle protein GvpA. The presence of gas vesicles in benthic microorganisms is intriguing, and it is possible that those vesicles serve as a floating and dispersal mechanism as they increase in filaments that are about to break and release vacuolated hormogonia. To further confirm the isolate's identity, molecular analysis using 16S rRNA gene was performed. The sequence showed only 94% similarity to Leptolyngbya badia and less than 92% to other leptolyngbya. The phylogenetic analyses showed the coclustering of this strain with other Leptolyngbya strain. The fatty acid composition, used as a chemotaxonomic marker, revealed the presence of a considerable amount of polyunsaturated acids. Nevertheless, saturated fatty acids represented the highest proportion of the total fatty. Surprisingly, fatty acids of relatively limited occurrence within oscillatorian cyanobacteria such as saturated myristic fatty acid and polyunsaturated fatty acid C16:3 were found. Microsc. Res. Tech. 76:249-257, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The food web of the saline-alkaline Lake Nakuru is dominated by the cyanobacterium Arthrospira fusiformis as the primary producer and a huge population of Lesser Flamingos as direct consumers. However, the dense blooms of Arthrospira are not stable, and collapse irregularly and unpredictably. During such periods they are replaced by other algae or cyanobacteria. The wide fluctuation in the cyanobacterial and algal populations of Lake Nakuru has a great influence on food availability for Lesser Flamingos, and is therefore of high ecological importance. To support the descriptive work on these phenomena, we describe here a new cyanobacterial taxon from this soda lake: Haloleptolyngbya alcalis Dadheech, Mahmoud, Kotut et Krienitz gen. et sp. nov. The study was based on multilocus molecular analyses of 16S rRNA gene, 16S-23S internal transcribed spacer, partial sequences of beta and alpha subunits including intergenic spacer ( cpcBA-IGS) of phycocyanin operon, phenotypic features using light microscopy, scanning electron microscopy, transmission electron microscopy, and ecology. The new taxon established a separate lineage within the family of Peudanabaenaceae (Oscillatoriales). [ABSTRACT FROM AUTHOR]

We studied the interactions of the CO-concentrating mechanism and variable light in the filamentous cyanobacterium Leptolyngbya sp. CPCC 696 acclimated to low light (15 μmol m s PPFD) and low inorganic carbon (50 μM Ci). Mass spectrometric and polarographic analysis revealed that mediated CO uptake along with both active Na-independent and Na-dependent HCO transport, likely through Na/HCO symport, were employed to concentrate Ci internally. Combined transport of CO and HCO required about 30 kJ mol of energy from photosynthetic electron transport to support an intracellular Ci accumulation 550-fold greater than the external Ci. Initially, Leptolyngbya rapidly induced oxygen evolution and Ci transport to reach 40-50% of maximum values by 50 μmol m s PPFD. Thereafter, photosynthesis and Ci transport increased gradually to saturation around 1,800 μmol m s PPFD. Leptolyngbya showed a low intrinsic susceptibility to photoinhibition of oxygen evolution up to PPFD of 3,000 μmol m s. Intracellular Ci accumulation showed a lag under low light but then peaked at about 500 μmol photons m s and remained high thereafter. Ci influx was accompanied by a simultaneous, light-dependent, outward flux of CO and by internal CO/HCO cycling. The high-affinity and high-capacity CCM of Leptolyngbya responded dynamically to fluctuating PPFD and used excitation energy in excess of the needs of CO fixation by increasing Ci transport, accumulation and Ci cycling. This capacity may allow Leptolyngbya to tolerate periodic exposure to excess high light by consuming electron equivalents and keeping PSII open. [ABSTRACT FROM AUTHOR]