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Allelopathy plays a crucial role in shaping phytoplankton community dynamics and diversity. It influences competition between photoautotrophs for resources and affects species succession in aquatic ecosystems. This article evaluates the allelopathic activity of cyanobacteria isolated from Lake Tuzkol, Kazakhstan. The allelopathic effects, including growth inhibition or stimulation, were assessed by adding cell‐free filtrates of the cyanobacteria Oscillatoria sp. SS‐9, Nostoc sp. CZS 2205, Synechococcus sp. SS‐5, or Anabaena sp. SS‐8 to the tested microalgae. The most pronounced effect was observed with Nostoc sp. CZS 2205, which reduced the cell counts of Chlorella vulgaris SP BB‐2 and Chlamydomonas reinhardtii CC‐124 by 60% and 57%, respectively, and Scenedesmus quadricauda CC‐1 and Ankistrodesmus falcatus CB‐2 by 55% and 53%, respectively. Synechococcus sp. SS‐5, in contrast, stimulated the growth of Chlorella vulgaris SP BB‐2 and Scenedesmus quadricauda CC‐1 by 11% and 8.8%, respectively. Filtrates from Oscillatoria sp. SS‐9 and Anabaena sp. SS‐8 had no significant impact on microalgal growth. Considering the significant allelopathic activity of Nostoc sp. CZS 2205, an agar diffusion test using biomass extracts confirmed a significant inhibitory effect, with the biomass extracts showing stronger activity than cell‐free filtrates. A detailed analysis of the cell‐free filtrates revealed eight compounds, including methyl heptadecanoate, methyl eicosanoate, tricosane, methyl octadeca‐9,12‐dienoate, methyl 13,16‐octadecadienoate, and 2,2‐dimethoxybutane. Additionally, nostocyclamide, a cyclic peptide, was identified in the biomass extract. The detection of nostocyclamide emphasizes its ecological importance and potential evolutionary role. These results enhance our understanding of the role of cyanobacteria in aquatic ecosystems and lay the groundwork for future research into their ecological applications. [ABSTRACT FROM AUTHOR]

This investigation reports the polyphasic characterization of six cyanobacterial strains that were isolated from Basantgarh village of district Udhampur in the union territory of Jammu and Kashmir, India. Morphological examination of the isolated strains indicated that the strains are members of the genus Nostoc or its morphotypes. Phylogenetic analyses using the 16S rRNA gene showed that five strains clustered in the Nostoc sensu stricto clade, whereas one strain clustered in the Desmonostoc clade. Further, comparative studies with their phylogenetically related taxa, based on morphology, folded secondary structures, phylogeny of the ITS rRNA region, and the percent genetic homology of 16S rRNA gene and ITS rRNA region clearly established the strains as novel taxa belonging to the genera Nostoc and Desmonostoc. Also, two strains 21A‐PS and 2JNA‐PS emerged as conspecific to each other, representing the same species of Nostoc. Hence, in accordance with the International code of Nomenclature for algae, fungi, and plants, this study describes Nostoc jammuense, Nostoc globosum, Nostoc breve, and Nostoc coriaceum, as novel species of the genus Nostoc, while Desmonostoc raii is described as a novel species of the genus Desmonostoc. This study adds novel species of Nostoc from Indian habitats and reinforces the need to explore the Nostoc sensu stricto clade for more novel taxa. [ABSTRACT FROM AUTHOR]

The floating freshwater fern Azolla is the only plant that retains an endocyanobiont, Nostoc azollae (aka Anabaena azollae), during its sexual and asexual reproduction. The increased interest in Azolla as a potential source of food and its unique evolutionary history have raised questions about its cyanotoxin content and genome. Cyanotoxins are potent toxins synthesized by cyanobacteria which have an anti-herbivore effect but have also been linked to neurodegenerative disorders including Alzheimer's and Parkinson's diseases, liver and kidney failure, muscle paralysis, and other severe health issues. In this study, we investigated 48 accessions of Azolla–Nostoc symbiosis for the presence of genes coding microcystin, nodularin, cylindrospermopsin and saxitoxin, and BLAST analysis for anatoxin-a. We also investigated the presence of the neurotoxin β-N-methylamino-L-alanine (BMAA) in Azolla and N. azollae through LC-MS/MS. The PCR amplification of saxitoxin, cylindrospermospin, microcystin, and nodularin genes showed that Azolla and its cyanobiont N. azollae do not have the genes to synthesize these cyanotoxins. Additionally, the matching of the anatoxin-a gene to the sequenced N. azollae genome does not indicate the presence of the anatoxin-a gene. The LC-MS/MS analysis showed that BMAA and its isomers AEG and DAB are absent from Azolla and Nostoc azollae. Azolla therefore has the potential to safely feed millions of people due to its rapid growth while free-floating on shallow fresh water without the need for nitrogen fertilizers. [ABSTRACT FROM AUTHOR]

Abstract Cyanobacteria possess special defense mechanisms to protect themselves against ultraviolet (UV) radiation. This study combines experimental and computational methods to identify the role of protective strategies in Nostoc species against UV-C radiation. To achieve this goal, various species of the genus Nostoc from diverse natural habitats in Iran were exposed to artificial UV-C radiation. The results indicated that UV-C treatment significantly reduced the photosynthetic pigments while simultaneously increasing the activity of antioxidant enzymes. Notably, N. sphaericum ISB97 and Nostoc sp. ISB99, the brown Nostoc species isolated from habitats with high solar radiations, exhibited greater resistance compared to the green-colored species. Additionally, an increase in scytonemin content occurred with a high expression of key genes associated with its synthesis (scyF and scyD) during the later stages of UV-C exposure in these species. The molecular docking of scytonemin with lipopolysaccharides of the cyanobacteria that mainly cover the extracellular matrix revealed the top/side positioning of scytonemin on the glycans of these lipopolysaccharides to form a UV-protective shield. These findings pave the way for exploring the molecular effects of scytonemin in forming the UV protection shield in cyanobacteria, an aspect that has been ambiguous until now.

Considering the potential of biopolymers from underutilized Andean sources in Peru to improve the characteristics of edible films, this work aimed to evaluate the formation of a polymeric matrix composed of Nostoc and modified potato starch for the formulation of edible films for food coating. The effects of polymer matrix ratio and drying temperature on films obtained by thermoforming were studied, determining the water vapor permeability and mechanical properties using a multifactorial design. Additionally, thermal properties were characterized by TGA and DSC, and structural properties by FT-IR and scanning electron microscopy. The results showed that the films exhibited lower solubility, lighter hues, better water vapor resistance, higher tensile strength, and improved thermal stability with increasing modified starch content. The formulation with higher Nostoc content exhibited a more homogeneous surface according to microscopy images, and no new chemical bonds were formed by adding modified starch and Nostoc to the polymer matrix, according to FT-IR spectra. These findings are promising and suggest using Nostoc for elaborating edible films composed of native and modified starch from native Andean potatoes as bio-based materials with potential application in the food industry. [ABSTRACT FROM AUTHOR]

Nostoc sphaeroides Kützing is a freshwater edible cyanobacterium that is rich in active substances such as polysaccharides, proteins and lipids; it has a variety of pharmacological effects such as antioxidant, anti‐inflammatory, antitumor and cholesterol‐lowering effects; and is often used as a traditional Chinese medicine with many potential applications in food, cosmetics, medical diagnostics and disease treatment. However, to meet the needs of different fields, such as medicine, there is an urgent need for basic research and technological innovation in culture technology, extraction and preparation of active substances, and the pharmacological mechanism of N. sphaeroides. This paper reviews the pharmacological effects of N. sphaeroides active substances, discusses current culture techniques and methods for extracting active components, and outlines the challenges encountered in cultivating and industrializing N. sphaeroides while discussing future development trends. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Azolla is the only plant with a co-evolving nitrogen-fixing (diazotrophic) cyanobacterial symbiont (cyanobiont), Nostoc azollae, resulting from whole-genome duplication (WGD) 80 million years ago in Azolla's ancestor. Additional genes from the WGD resulted in genetic, biochemical, and morphological changes in the plant that enabled the transmission of the cyanobiont to successive generations via its megaspores. The resulting permanent symbiosis and co-evolution led to the loss, downregulation, or conversion of non-essential genes to pseudogenes in the cyanobiont, changing it from a free-living organism to an obligate symbiont. The upregulation of other genes in the cyanobiont increased its atmospheric dinitrogen fixation and the provision of nitrogen-based products to the plant. As a result, Azolla can double its biomass in less than two days free-floating on fresh water and sequester large amounts of atmospheric CO2, giving it the potential to mitigate anthropogenic climate change through carbon capture and storage. Azolla's biomass can also provide local, low-cost food, biofertiliser, feed, and biofuel that are urgently needed as our population increases by a billion every twelve years. This paper integrates data from biology, genetics, geology, and palaeontology to identify the location, timing and mechanism for the acquisition of a co-evolving diazotrophic cyanobiont by Azolla's ancestor in the Late Cretaceous (Campanian) of North America. [ABSTRACT FROM AUTHOR]

This study examines the effect of phycoerythrin (PE) from a cyanobacterial Nostoc strain encapsulated with alginate as a potential prebiotic to produce synbiotic ice cream products with Lactobacillus casei. It was found that the addition of the encapsulated PE affected, mostly favourably, the physicochemical properties, antioxidant activity, probiotic survival, volatile compound contents, and sensory acceptability of the synbiotic ice cream samples before and after aging at the freezing periods of one day to eight weeks. Thus, it confirms the prebiotic potential of PE for synbiotic ice creams with L. casei. [ABSTRACT FROM AUTHOR]

Geosiphon pyriformis, a representative of the fungal sub‐phylum Glomeromycotina, is unique in its endosymbiosis with cyanobacteria within a fungal cell. This symbiotic relationship occurs in bladders containing nuclei of G. pyriformis, Mollicutes‐like bacterial endosymbionts (MRE), and photosynthetically active and dividing cells of Nostoc punctiforme. Recent genome analyses have shed light on the biology of G. pyriformis, but the genome content and biology of its endosymbionts remain unexplored. To fill this gap, we gathered and examined metagenomic data from the bladders of G. pyriformis, where N. punctiforme and MRE are located. This ensures that our analyses are focused on the organs directly involved in the symbiosis. By comparing this data with the genetic information of related cyanobacteria and MREs from other species of Arbuscular Mycorrhizal Fungi, we aimed to reveal the genetic content of these organisms and understand how they interact at a genetic level to establish a symbiotic relationship. Our analyses uncovered significant gene expansions in the Nostoc endosymbiont, particularly in mobile elements and genes potentially involved in xenobiotic degradation. We also confirmed that the MRE of Glomeromycotina are monophyletic and possess a highly streamlined genome. These genomes show dramatic differences in both structure and content, including the presence of enzymes involved in environmental sensing and stress response. [ABSTRACT FROM AUTHOR]

The biocontrol potential of three native soil cyanobacteria from biological soil crusts (Nostoc commune, Scytonema hyalinum, and Tolypothrix distorta) was tested by means of in vitro mycelial growth inhibition assays for eighteen cyanobacteria-based products against three phytopathogenic soilborne fungi (Phytophthora capsici, Pythium aphanidermatum, and Fusarium oxysporum f. sp. radicis-cucumerinum). Three cyanobacteria-based production factors were considered: (i) cyanobacterium strain, (ii) cyanobacterial culture growth phase, and (iii) different post-harvest treatments: raw cultures, cyanobacterial filtrates, and cyanobacterial extracts. Results showed that any of the factors considered are key points for successfully inhibiting fungal growth. N. commune showed the highest growth inhibition rates for the three phytopathogens; stationary phase treatments produced higher inhibition percentages than logarithmic ones; and all the post-harvest treatments of N. commune at the stationary phase inhibited the growth of P. capsici, up to 77.7%. Thus, N. commune products were tested in planta against P. capsici, but none of the products showed efficacy in delaying the onset nor reducing the damage due to P. capsici, demonstrating the complexity of the in planta assay's success and encouraging further research to design an appropriate scaling up methodology. [ABSTRACT FROM AUTHOR]

Cushuro (Nostoc sphaericum) polysaccharide was used to co-microencapsulate sacha inchi oil, natural antioxidant extracts from the oleoresin of charapita chili peppers (Capsicum frutescens L.) and grape orujo (Vitis vinifera L.). Encapsulation efficiency, moisture, particle size, morphology, oxidative stability, shelf-life, solubility, essential fatty acid profile, sterol content and antioxidant capacity were evaluated. The formulations with grape orujo extract showed higher oxidative stability (4908 ± 184 h), antioxidant capacity (4835.33 ± 40.02 µg Trolox/g ms), higher phenolic contents (960.11 ± 53.59 µg AGE/g ms) and a smaller particle size (7.55 µm) than the other formulations, as well as good solubility and a low moisture content. Therefore, grape orujo extracts can be used as natural antioxidants. The fatty acid composition (ω-3) remained quite stable in all the formulations carried out, which also occurred for sterols and tocopherols. In combination with gum arabic, grape orujo extract offered oxidative protection to sacha inchi oil during the first week of storage. [ABSTRACT FROM AUTHOR]

Cyanobacteria require liquid water for photosynthesis, whereas green algae can photosynthesise with water vapour alone. We discovered that several Lobaria spp. which normally have cyanobacteria as the sole photobiont, in some regions of the trans-Himalayas also harboured green algae. We tested whether green algal acquisition was: limited to high elevations; obtained from neighbouring chloro- Lobaria species; enabled photosynthesis at low humidity. Lobaria spp. were collected from 2000 to 4000 m elevation. Spectrophotometry quantified green algal abundance by measuring chlorophyll b (absent in cyanobacteria). Thalli cross-sections visually confirmed green algal presence. We sequenced gene regions: Lobaria (ITS-EF-1α-RPB2), green algae (18S-RBC-L) and Nostoc (16S). Phylogenetic analysis determined myco-photobiont associations. We used a custom closed-circuit gas exchange system with an infrared gas analyser to measure CO2 exchange rates for desiccated specimens at 33%, 76%, 86% and 98% humidity. Cross-sections revealed that the photobiont layers in putative cyano -Lobaria contained both cyanobacteria and green algae, indicating that they should be considered chloro-cyanolichens. Chloro- Lobaria had no visible cephalodia nor cyanobacteria in the photobiont layer. Chloro- Lobaria and chloro-cyano- Lobaria had comparable levels of chlorophyll b. Chloro- Lobaria usually contained Symbiochloris. Chloro-cyano- Lobaria mainly associated with Parachloroidium and Nostoc ; infrequently with Symbiochloris , Apatococcus, Chloroidium , Pseudochlorella, Trebouxia. Sequences from two green algal genera were obtained from within some thalli. Desiccated specimens of every Lobaria species could attain net photosynthesis with light exposure and 33% humidity. CO2 exchange dynamics over a five-day period differed between species. At all elevations, chloro-cyano- Lobaria spp. had abundant green algae in the photobiont layer, but green algal strains mostly differed to those of chloro- Lobaria spp. Both chloro- Lobaria and chloro-cyano- Lobaria were capable of conducting photosynthesis without liquid water. The data strongly suggest that they attained positive net photosynthesis. [ABSTRACT FROM AUTHOR]

Flow pulses mobilize particulate organic matter (POM) in streams from the surrounding landscape and streambed. This POM serves as a source of energy and nutrients, as well as a means for organismal dispersal, to downstream communities. In the barren terrestrial landscape of the McMurdo Dry Valleys (MDV) of Antarctica, benthic microbial mats occupying different in-stream habitat types are the dominant POM source in the many glacier-fed streams. Many of these streams experience daily flow peaks that mobilize POM, and diatoms recovered from underlying stream sediments suggest that mat-derived diatoms in the POM are retained there through hyporheic exchange. Yet, 'how much' and 'when' different in-stream habitat types contribute to POM diatom assemblages is unknown. To quantify the contribution of different in-stream habitat types to POM diatom assemblages, we collected time-integrated POM samples over four diel experiments, which spanned a gradient of flow conditions over three summers. Diatoms from POM samples were identified, quantified, and compared with dominant habitat types (i.e., benthic 'orange' mats, marginal 'black' mats, and bare sediments). Like bulk POM, diatom cell concentrations followed a clockwise hysteresis pattern with stream discharge over the daily flow cycles, indicating supply limitation. Diatom community analyses showed that different habitat types harbor distinct diatom communities, and mixing models revealed that a substantial proportion of POM diatoms originated from bare sediments during baseflow conditions. Meanwhile, orange and black mats contribute diatoms to POM primarily during daily flow peaks when both cell concentrations and discharge are highest, making mats the most important contributors to POM diatom assemblages at high flows. These observations may help explain the presence of mat-derived diatoms in hyporheic sediments. Our results thus indicate a varying importance of different in-stream habitats to POM generation and export on daily to seasonal timescales, with implications for biogeochemical cycling and the local diatom metacommunity. [ABSTRACT FROM AUTHOR]

Simple Summary: The study focused on cultivating the cyanobacterial strain Nostoc sp. 136 under controlled laboratory conditions. Various factors such as nutrient media, initial biomass concentration, nutrient supplementation, and light conditions were investigated to optimize growth and productivity. Results showed that the strain adapted well to the laboratory conditions, with the highest growth rates observed at lower initial biomass concentrations and with mBG11 medium. Nutrient supplementation, particularly nitrogen, showed potential for enhancing growth, while different light wavelengths had varied effects on growth and productivity. Biochemical analysis revealed promising levels of proteins and phycobiliproteins, with potential applications in biotechnology. The study highlighted the suitability of Nostoc sp. 136 for laboratory cultivation and suggested avenues for further research, particularly in exploring biomass composition and bioactivities. Cyanobacteria, photoautotrophic Gram-negative bacteria, play a crucial role in aquatic and terrestrial environments, contributing significantly to fundamental ecological processes and displaying potential for various biotechnological applications. It is, therefore, critical to identify viable strains for aquaculture and establish accurate culture parameters to ensure an extensive biomass supply for biotechnology purposes. This study aims to establish optimal laboratory batch culture conditions for Nostoc 136, sourced from Alga2O, Coimbra, Portugal. Preliminary investigations were conducted to identify the optimal culture parameters and to perform biomass analysis, including protein and pigment content. The highest growth was achieved with an initial inoculum concentration of 1 g.L−1, using modified BG11 supplemented with nitrogen, resulting in a Specific Growth Rate (SGR) of 0.232 ± 0.017 μ.day−1. When exposed to white, red, and blue LED light, the most favourable growth occurred under a combination of white and red LED light exhibiting an SGR of 0.142 ± 0.020 μ.day−1. The protein content was determined to be 10.80 ± 2.09%. Regarding the pigments, phycocyanin reached a concentration of 200.29 ± 30.07 µg.mL−1, phycoerythrin 148.29 ± 26.74 µg.mL−1, and allophycocyanin 10.69 ± 6.07 µg.mL−1. This study underscores the influence of light and nutrient supplementation on the growth of the Nostoc biomass. [ABSTRACT FROM AUTHOR]

Pyruvate, the end product of glycolysis, is an important metabolite for the tricarboxylic acid (TCA) cycle and lipid metabolism. Pyruvate is converted to acetyl-CoA, which enters the TCA cycle for citrate formation. Citrate is the precursor for isocitrate that undergoes oxidative decarboxylation reaction forming α-ketoglutarate (α-KG) coupled with NADP+ reduction catalyzed by the enzyme isocitrate dehydrogenase (IDH). In cyanobacteria, α-KG donates its carbon skeleton to the glutamine synthetase-glutamine oxoglutarate aminotransferase (GS-GOGAT) pathway, thereby linking carbon and nitrogen metabolisms. In this study, the effect of pyruvate on IDH activity, its protein content, and its mRNA expression level were analyzed. Amongst the concentrations studied (100 µM, 250 µM, and 500 µM), in 250 µM externally supplied pyruvate, IDH registered the highest activity as well as maximum protein and mRNA contents when compared to the control. At this concentration, all biochemical parameters of nitrogen and carbon metabolisms- heterocyst frequency, nitrogenase, and glutamine synthetase activities, photosynthetic pigments, OEC (oxygen evolving complex) activity, carbohydrate content, proteins, and total biomass were also found to be highest. However, at an exposure to 500 µM pyruvate, there was a reduction in all the above-mentioned parameters indicating that although pyruvate is a key metabolite in the cellular metabolism, it tends to become toxic beyond this concentration. The compromised state of the cells was also evident from the micrographs developed from SEM (Scanning electron microscope) and TEM (Transmission electron microscope) studies under 500 µM pyruvate exposure. [ABSTRACT FROM AUTHOR]

Euryhaline cyanobacteria are autotrophic microbes that can be suitable for use in the development of nutraceutical formulation because of their high metabolic activity, resistance to euryhaline environments, ability to multiply quickly, and capacity to accumulate the economically important bioactive chemicals. The objective of this study was to characterize Nostoc BGLR1 for the production of nutraceutical compounds like carbohydrates, proteins, lipids, carotenoids, flavonoids, phenols, astaxanthin, and phycocyanin, as well as to standardize physio-chemical parameters such as pH (7.5–11.5), temperature (20–40 °C), light intensity (4000–8000 lux), growth period (20–40 days), and inoculum concentration (1–10%). Following optimization, the contents of Nostoc BGLR1 viz. biomass, chlorophyll a, chlorophyll b, total chlorophyll, carbohydrate, protein, and lipid augmented by 28,708.03%, 651.9%, 410.34%, 283.98%, 656.25%, 164.6%, and 860%, respectively. Twelve therapeutic compounds, including 2 acetoxyisobutyryl chloride, cyclohexasiloxane, dodecamethyl, caryophyllene, and cycloheptasiloxane tetradecamethyl, were found in the study by gas chromatography-mass spectrometry. BGLR1 also contained 6 ethyl 3-octyl butyl ester, 9,12-octadecadienoic acid, 9-octadecenoic acid (Z), methyl ester, 1-monolinoleoylglycerol trimethylsilyl ether, phytol, and methyl stearate. With the use of 16S rRNA gene sequencing, it was determined that BGLR1 belongs to the genus Nostoc (GenBank accession number OQ600797.1). Nostoc BGLR1 cyanobacteria is a potentially useful source for nutraceutical formulation. [ABSTRACT FROM AUTHOR]

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

Heterocyst-forming cyanobacteria that colonize the drylands contribute to carbon and nitrogen supplies in nutrient-poor soils. As one of the representative cyanobacteria, Nostoc flagelliforme adapts well to the arid environment in the form of filamentous colonies (or filaments). To date, the adaptive changes, either genetic or micromorphological, that occur within single colonies of dryland cyanobacteria remain largely unclear. In this study, unusual long chains or trichomes of vegetative cells (not containing heterocysts) were observed within N. flagelliforme filaments. And the overall heterocyst frequency in the trichomes was counted to be 1.3–2.7%, different from the usually observed 5–10% heterocyst frequency in model Nostoc strains when grown in nitrogen-deprived medium. Thus, these phenomena seem contradictory to our usual recognition of Nostoc strains. Related transcriptional and heterocyst frequency analyses suggested no genetically significant alteration in heterocyst formation and nitrogen fixation in this strain. Also, the amounts of nitrogen sources in the extracellular polysaccharide (EPS) matrix released by N. flagelliforme cells that may cause the low heterocyst frequency were assessed to be equivalent to 0.28–1.10 mM NaNO3. When combining these findings with the habitat characters, it can be envisaged that the released nitrogen sources from cells are confined, accumulated, and re-utilized in the EPS matrix, thereby leading to the formation of reduced heterocyst frequency and long-chained vegetative cells. This study will contribute to our understanding of the distinctive adaptation properties of colonial cyanobacteria in dryland areas. [ABSTRACT FROM AUTHOR]

There is a growing emphasis on seeking stabilizing agents with minimal transformation, prioritizing environmentally friendly alternatives, and actively contributing to the principles of the circular economy. This research aimed to assess the stability of a novel spray-dried hydrocolloid from high Andean algae when introduced into an aqueous solution. Nostoc sphaericum freshwater algae were subject to atomization, resulting in the production of spray-dried hydrocolloid (SDH). Subsequently, suspension solutions of SDH were meticulously prepared at varying pH levels and gelling temperatures. These solutions were then stored for 20 days to facilitate a comprehensive evaluation of their stability in suspension. The assessment involved a multifaceted approach, encompassing rheological analysis, scrutiny of turbidity, sedimentation assessment, ζ-potential, and measurement of particle size. The findings from these observations revealed that SDH exhibits a dilatant behavior when in solution, signifying an increase in with higher shear rate. Furthermore, it demonstrates commendable stability when stored under ambient conditions. SDH is emerging as a potential alternative stabilizer for use in aqueous solutions due to its easy extraction and application. [ABSTRACT FROM AUTHOR]

This study aimed to maximize the biomass productivity of cyanobacterium Nostoc sp. AARL C008 by high-throughput bioprocess optimization, and to utilize the Nostoc biomass for application in multiproduct biorefinery towards holistic zero-waste technology. Through bioprocess optimization, maximum biomass productivity was obtained as 37.59 mg/L/day under modified BG-11 medium (0.190 g/L K2HPO4·3H2O, 0.0018 g/L citric acid and 2.53 mL/L trace metal solution) and continuous light feeding at 40 µmol/m2/s. The zero-waste biorefining process was successfully used for Nostoc biomass to sequentially recover polysaccharides, phytochemicals, and lipids. Nostoc polysaccharides exhibited the bio-stimulant potential having the ability to improve soil properties such as moisture content, organic matter, microbiological activity, and cation exchange capacity by increases measured as 1.30, 1.55, 1.53, and 1.47-fold, respectively, compared to the control in which polysaccharides were absent. With 120 mg/L polysaccharides, the short length of melon was significantly enhanced 1.29-fold, higher than the control. After polysaccharide extraction, the cyanobacterial biomass residue (CBR) was used to extract the phytochemicals. Nostoc phytochemicals showed high antioxidant activity, giving ABTS activity of 26.10 mg TE/g-extract, DPPH activity of 5.71 mg GAE/g-extract, and PFRAP activity of 7.79 mg GAE/g-extract, as well as offering high-efficiency inhibitive effects on cancer cells with the IC50 recorded at 0.50 mg/mL. The CBR after phytochemical extraction can potentially be used to extract lipids prior to biodiesel production. The extracted lipid contained long-chain fatty acids with satisfactory fuel properties. The overall results evidenced that the multiproduct biorefining approach will make a significant contribution to the zero-waste industrialization of cyanobacterial-based bioproducts. [ABSTRACT FROM AUTHOR]

Flow pulses mobilize particulate organic matter (POM) in streams from the surrounding landscape and streambed. This POM serves as a source of energy and nutrients, as well as a means for organismal dispersal, to downstream communities. In the barren terrestrial landscape of the McMurdo Dry Valleys (MDV) of Antarctica, benthic microbial mats occupying different in-stream habitat types are the dominant POM source in the many glacier-fed streams. Many of these streams experience daily flow peaks that mobilize POM, and diatoms recovered from underlying stream sediments suggest that mat-derived diatoms in the POM are retained there through hyporheic exchange. Yet, ‘how much’ and ‘when’ different in-stream habitat types contribute to POM diatom assemblages is unknown. To quantify the contribution of different in-stream habitat types to POM diatom assemblages, we collected time-integrated POM samples over four diel experiments, which spanned a gradient of flow conditions over three summers. Diatoms from POM samples were identified, quantified, and compared with dominant habitat types (i.e., benthic ‘orange’ mats, marginal ‘black’ mats, and bare sediments). Like bulk POM, diatom cell concentrations followed a clockwise hysteresis pattern with stream discharge over the daily flow cycles, indicating supply limitation. Diatom community analyses showed that different habitat types harbor distinct diatom communities, and mixing models revealed that a substantial proportion of POM diatoms originated from bare sediments during baseflow conditions. Meanwhile, orange and black mats contribute diatoms to POM primarily during daily flow peaks when both cell concentrations and discharge are highest, making mats the most important contributors to POM diatom assemblages at high flows. These observations may help explain the presence of mat-derived diatoms in hyporheic sediments. Our results thus indicate a varying importance of different in-stream habitats to POM generation and export on daily to seasonal timescales, with implications for biogeochemical cycling and the local diatom metacommunity.

Interactions between Sphagnum (peat moss) and cyanobacteria play critical roles in terrestrial carbon and nitrogen cycling processes. Knowledge of the metabolites exchanged, the physiological processes involved, and the environmental conditions allowing the formation of symbiosis is important for a better understanding of the mechanisms underlying these interactions. In this study, we used a cross-feeding approach with spatially resolved metabolite profiling and metatranscriptomics to characterize the symbiosis between Sphagnum and Nostoc cyanobacteria. A pH gradient study revealed that the Sphagnum-Nostoc symbiosis was driven by pH, with mutualism occurring only at low pH. Metabolic cross-feeding studies along with spatially resolved matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) identified trehalose as the main carbohydrate source released by Sphagnum, which were depleted by Nostoc along with sulfur-containing choline-O-sulfate, taurine and sulfoacetate. In exchange, Nostoc increased exudation of purines and amino acids. Metatranscriptome analysis indicated that Sphagnum host defense was downregulated when in direct contact with the Nostoc symbiont, but not as a result of chemical contact alone. The observations in this study elucidated environmental, metabolic, and physiological underpinnings of the widespread plant-cyanobacterial symbioses with important implications for predicting carbon and nitrogen cycling in peatland ecosystems as well as the basis of general host-microbe interactions.

The floating freshwater fern Azolla is the only plant that retains an endocyanobiont, Nostoc azollae (aka Anabaena azollae), during its sexual and asexual reproduction. The increased interest in Azolla as a potential source of food and its unique evolutionary history have raised questions about its cyanotoxin content and genome. Cyanotoxins are potent toxins synthesized by cyanobacteria which have an anti-herbivore effect but have also been linked to neurodegenerative disorders including Alzheimer’s and Parkinson’s diseases, liver and kidney failure, muscle paralysis, and other severe health issues. In this study, we investigated 48 accessions of Azolla–Nostoc symbiosis for the presence of genes coding microcystin, nodularin, cylindrospermopsin and saxitoxin, and BLAST analysis for anatoxin-a. We also investigated the presence of the neurotoxin β-N-methylamino-L-alanine (BMAA) in Azolla and N. azollae through LC-MS/MS. The PCR amplification of saxitoxin, cylindrospermospin, microcystin, and nodularin genes showed that Azolla and its cyanobiont N. azollae do not have the genes to synthesize these cyanotoxins. Additionally, the matching of the anatoxin-a gene to the sequenced N. azollae genome does not indicate the presence of the anatoxin-a gene. The LC-MS/MS analysis showed that BMAA and its isomers AEG and DAB are absent from Azolla and Nostoc azollae. Azolla therefore has the potential to safely feed millions of people due to its rapid growth while free-floating on shallow fresh water without the need for nitrogen fertilizers.

The biocontrol potential of three native soil cyanobacteria from biological soil crusts (Nostoc commune, Scytonema hyalinum, and Tolypothrix distorta) was tested by means of in vitro mycelial growth inhibition assays for eighteen cyanobacteria-based products against three phytopathogenic soilborne fungi (Phytophthora capsici, Pythium aphanidermatum, and Fusarium oxysporum f. sp. radicis-cucumerinum). Three cyanobacteria-based production factors were considered: (i) cyanobacterium strain, (ii) cyanobacterial culture growth phase, and (iii) different post-harvest treatments: raw cultures, cyanobacterial filtrates, and cyanobacterial extracts. Results showed that any of the factors considered are key points for successfully inhibiting fungal growth. N. commune showed the highest growth inhibition rates for the three phytopathogens; stationary phase treatments produced higher inhibition percentages than logarithmic ones; and all the post-harvest treatments of N. commune at the stationary phase inhibited the growth of P. capsici, up to 77.7%. Thus, N. commune products were tested in planta against P. capsici, but none of the products showed efficacy in delaying the onset nor reducing the damage due to P. capsici, demonstrating the complexity of the in planta assay’s success and encouraging further research to design an appropriate scaling up methodology.

Fully understanding the environmental implications of engineered nanomaterials is crucial for their safe and sustainable use. Cyanobacteria, as the pioneers of the planet earth, play important roles in global carbon and nitrogen cycling. Here, we evaluated the biological effects of molybdenum disulfide (MoS2) nanosheets on a N2-fixation cyanobacteria (Nostoc sphaeroides) by monitoring growth and metabolome changes. MoS2 nanosheets did not exert overt toxicity to Nostoc at the tested doses (0.1 and 1 mg/L). On the contrary, the intrinsic enzyme-like activities and semiconducting properties of MoS2 nanosheets promoted the metabolic processes of Nostoc, including enhancing CO2-fixation-related Calvin cycle metabolic pathway. Meanwhile, MoS2 boosted the production of a range of biochemicals, including sugars, fatty acids, amino acids, and other valuable end products. The altered carbon metabolism subsequently drove proportional changes in nitrogen metabolism in Nostoc. These intracellular metabolic changes could potentially alter global C and N cycles. The findings of this study shed light on the nature and underlying mechanisms of bio-nanoparticle interactions, and offer the prospect of utilization bio-nanomaterials for efficient CO2 sequestration and sustainable biochemical production.

The present study describes two new Nostoc species, N. montejanii and N. tlalocii, based on a polyphasic approach that combines morphological, ecological, and genetic characteristics. The five investigated populations, including those from newly collected material from central Mexico, were observed to possess morphological features characteristic of the Nostoc genus. Results showed that both new species are strictly associated with running water, and they show clear differences in their habitat preferences. The 16S rRNA gene sequences of the five strains displayed between 98% and 99% similarity to the genus Nostoc sensu stricto. The 16S rRNA gene phylogenetic analyses inferred using Bayesian inference, maximum likelihood, and parsimony methods, placed these five strains in two separate clades distinct from other Nostoc species. The secondary structures of the 16S–23S internal transcribed spacer rRNA region in the two new species showed >10.5% dissimilarities in the operons when compared with other Nostoc species. In addition, clear morphological differences were observed between the two Mexican species, including the color of the colonies (black in N. montejanii and green in N. tlalocii), the size of the cells (greater in N. montejanii), and the number of polyphosphate granules present in the cells (one in N. montejanii and up to four in N. tlalocii). [ABSTRACT FROM AUTHOR]

Background: In recent years, the incidence of alcoholic liver disease (ALD) has gradually increased, the development of ALD is attached great attentions. Nostoc commune Vauch. polysaccharide (NCVP) is beneficial to maintain the gut health, but the protective effect of NCVP on the liver has not been reported yet. Purpose: To study the protective effect and the underlying mechanisms of NCVP on ALD, a mouse model of acute ALD was established. Study design and methods: We built an acute ALD mouse model and explored the protective effect of NCVP through the detection of cytokines, histological examination, determination of short chain fatty acids, and 16S rRNA analysis of gut microbiota. Results: NCVP had hepatoprotective effects on acute alcohol‐induced mice by improving antioxidant capacity, reducing oxidative stress and the serum cytokine levels (IL‐1β, IL‐6, and TNF‐α). Simultaneously, histopathological changes in liver indicated that NCVP could inhibit local hepatocyte necrosis, cytoplasmic vacuolation and inflammatory cell infiltration induced by alcohol. NCVP also increased the level of total short‐chain fatty acids of acute ALD mice. In addition, NCVP could significantly decrease the Firmicutes/Bacteroidetes ratio and the abundance of Patescibacteria, Helicobacter, and Actinomycetes and increase the abundance of Lachospiraceae, Prevotellaceae‐UCG‐003, Lactobacillaceae, and Desulfovibrio. Conclusion: Our study proved that NCVP had in vivo hepatoprotective effect on acute ALD mice and provided scientific evidences that NCVP might be a promising drug candidate for the prevention and treatment of ALD. [ABSTRACT FROM AUTHOR]

Nitrogen fixation can be a substantial flux of new biologically available nitrogen (N) into some aquatic ecosystems. The most commonly used method for measuring N2-fixation is the acetylene reduction method, which measures nitrogenase activity. This method requires the assumption of a theoretical ratio of ethylene produced to N2-fixed unless the estimates are calibrated using 15N2 as a tracer. We measured N2-fixation using both the acetylene reduction method and 15N2 uptake methods to examine the ratio of ethylene produced to N2-fixed (C2H4:N2), estimate controls on variation in this ratio, and quantify the immediate release of N2-fixed as dissolved N. We estimated N2-fixation for benthic biofilms and separated Nostoc in four streams in Wyoming, Little Laramie River, Ditch Creek, Spread Creek, and Polecat Creek. Estimates of the C2H4:N2 ratio for any one stream and date ranged from 1.6 to 7.1 with a group-level mean of 3.8. Immediate release of N2-fixed as dissolved organic and inorganic N was < 1% of N2-fixation. Ethylene production increased 1.8 times faster than N2-fixation as temperature increased showing strong control of temperature in the C2H4:N2 ratio. Temperature contributed substantially to the variability in ratios of ethylene produced to N2-fixed. Slight differences in the C2H4:N2 ratio can considerably alter N2-fixation estimates particularly in N2-fixation dominated stream biofilms, thus when calibrating using a range of temperatures may be essential. [ABSTRACT FROM AUTHOR]

Nitrogen (N) fixation is a fundamental mechanism by which N enters streams. Yet, because of modern N saturation, it is difficult to study the importance of N-fixation to stream nutrient budgets. Here, we utilized relatively simple and pristine McMurdo Dry Valley streams to investigate the role of N-fixing Nostoc abundance, streamwater dissolved inorganic N (DIN) concentration, and distance from the source glacier in regulating the elemental and isotopic composition of three microbial mat types (black, orange, and green) at the landscape scale. We found Nostoc-based black mats were the most enriched in δ15N, and δ15N signatures of mats increased where Nostoc was abundant, but did not surpass the atmospheric standard (δ15N ≈ 0‰). Furthermore, green and orange mat δ15N signatures became more depleted with increasing DIN, indicating that mats utilize glacial meltwater-sourced N when available. The distance from the source glacier explained limited variability in mat δ15N across sites, indicating the influence of individual stream characteristics on N spiraling. To further explore longitudinal N spiraling processes generating observed δ15Ν patterns, we developed a simple steady-state mathematical model. Analysis of plausible scenarios with this model confirmed that streams both have the capacity to remove allochthonous DIN over the plausible range of inputs, and that internal N sources are required to account for δ15N signatures and observed DIN concentrations at stream outlets. Collectively, these data and modeling results demonstrate that N-fixation exerts substantial influence within and across these streams, and is presumably dependent upon interconnected organic matter reserves, mineralization rates, and geomorphology. [ABSTRACT FROM AUTHOR]

Background: Marine cyanobacteria have been known to contain several unique bioactive compounds which have different therapeutic potentials. The current research focuses to identify the efficacy of Nostoc calcicola to counteract the harmful effects of free radicals and testing its anticancer activity against colorectal adenocarcinoma cells (HT-29). Results: Methanol is used as a solvent for the extraction of bioactive metabolites from Nostoc calcicola followed by phytochemical screening representing the presence of flavonoids, phenols, tannins, saponins, and steroids to find out bioactive metabolites. Furthermore, evaluation of the extract efficacy revealed the profound ability of Nostoc calcicola to scavenge free radicals by neutralizing different reactive oxygen species. At 100 µg/mL concentration, it inhibited DPPH radicals (73.4%), enhanced phosphomolybdenum reduction (53.5%), displayed ferric-reducing power (55.1%), and finally the extract revealed remarkable hydroxyl radicals scavenging capacity (94.8%), compared to the standards. These compelling results emphasize the robust antioxidant potential of the Nostoc calcicola extract. In vitro, studies demonstrated the selective cytotoxic effects of methanol extracts of Nostoc calcicola on the HT-29 human colorectal cancer cell line, as indicated by IC50 values of 25 µg/mL for the extracts. Treatment with me Nostoc calcicola decreased the cell viability of HT-29 cells followed by consistent morphological changes leading to cytotoxicity. Nuclear condensation and DNA fragmentation were observed using AO/EtBr and DAPI staining. Flow cytometry analysis further confirmed the incidence of apoptosis during the S phase of the cell cycle. Furthermore, western blotting analysis confirmed the activation of caspase 9, a pivotal enzyme in the intrinsic apoptosis pathway, suggesting the ability of Nostoc calcicola to induce apoptosis in HT-29 colorectal cancer cells. Conclusion: These findings underscore the potential of Nostoc calcicola as a valuable source of bioactive compounds with antioxidant and anticancer properties, warranting further investigation for their potential therapeutic applications in colorectal cancer. [ABSTRACT FROM AUTHOR]

Cyanobacteria are photosynthetic prokaryotes and are reservoir of bioactive compounds having substantial antimicrobial and antioxidant activity. They serve as a rich source of structurally novel and biologically active metabolites, holding great potential for various pharmaceutical applications. The aim of this study is to investigate in vitro antimicrobial and antioxidant activities of the extracts of Nostoc punctiforme, a filamentous heterocystous cyanobacterium predominant in the rice fields of Lakhanpur (Bargarh District), Odisha. The heterocystous cyanobacteria was collected from rice field and identified by means of morphological and molecular approach (Nostoc punctiforme Jbr02). Subsequently, in vitro antimicrobial and antioxidant activity was assayed using acetone, methanol, and benzene extract. The cyanobacterial extracts established important antimicrobial actions against bacterial and fungal pathogens with significant MIC values from 62.5 to 500 µg/ml. The methanolic extract displayed better inhibitory activities against both V. Cholerae and P. verrucosun with the MIC value 62.5µg/ml while no such activity was recorded in benzene extract against B. subtilis, A. niger and F. oxysporum pathogens. The antioxidant study, depicted that the methanolic extract showed relatively higher antiradical activity of IC50 542±0.012 µg/ml among the three solvents. The Ferric reducing assay result was also maximum in methanolic extract (0.478±0.78) as compared to benzene and acetone extract. These findings infer that Nostoc punctiforme has potential antimicrobial and antioxidant activity, unveiling its potential as a valuable source of bioactive compounds. Thus, N. punctiforme in specific and cyanobacteria in general are one of the most promising candidates for commercial applications. [ABSTRACT FROM AUTHOR]

The filamentous cyanobacterium Anabaena sp. PCC 7120 is able to form heterocysts for nitrogen fixation. Heterocyst differentiation is initiated by combined‐nitrogen deprivation, followed by the commitment step during which the developmental process becomes irreversible. Mature heterocysts are terminally differentiated cells unable to divide, and cell division is required for heterocyst differentiation. Previously, we have shown that the HetF protease regulates cell division and heterocyst differentiation by cleaving PatU3, which is an inhibitor for both events. When hetF is required during the developmental program remains unknown. Here, by controlling the timing of hetF expression during heterocyst differentiation, we provide evidence that hetF is required just before the beginning of heterocyst morphogenesis. Consistent with this finding, transcriptome data show that most of the genes known to be involved in the early step (such as hetR and ntcA) or the commitment step (such as hetP and hetZ) of heterocyst development could be expressed in the ΔhetF mutant. In contrast, most of the genes involved in heterocyst morphogenesis and nitrogen fixation remain repressed in the mutant. These results indicated that in the absence of hetF, heterocyst differentiation is able to be initiated and proceeds to the stage just before heterocyst envelope formation. [ABSTRACT FROM AUTHOR]

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Nostoc sphaeroides is an edible Cyanobacterium which has high nutritional value and is widely used in dietary supplements and therapeutic products. N. sphaeroides contains protein, fatty acid, minerals and vitamins. Its polysaccharides, phycobilin, phycobiliproteins and some lipids are highly bioactive. Thus, N. sphaeroides possesses anti-oxidation, anti-inflammation and cholesterol reducing functions. This paper reviews and evaluates the literature on nutritionally and functionally important compounds of N. sphaeroides. It also reviews and evaluates the processing of technologies used to process N. sphaeroides from fresh harvest to dry particulates including pretreatment, sterilization and drying, including their impact on sensorial and nutritional values. This review shows that a suitable combination of ultrasound, radio frequency and pulse spouted microwave with traditional sterilization and drying technologies greatly improves the sensorial and nutritive quality of processed N. sphaeroides and improves their shelf life; however, further research is needed to evaluate these hybrid technologies. Once suitably processed, N. sphaeroides can be used in food, cosmetics and pharmaceutical drugs as an ingredient. [ABSTRACT FROM AUTHOR]

Nitrogen-fixing cyanobacteria from the order Nostocales are able to establish symbiotic relationships with diverse plant species. They are promiscuous symbionts, as the same strain of cyanobacterium is able to form symbiotic biological nitrogen-fixing relationships with different plants species. This review will focus on the different types of cyanobacterial–plant associations, both endophytic and epiphytic, and provide insights from a structural viewpoint, as well as our current understanding of the mechanisms involved in the symbiotic crosstalk. In all these symbioses, the benefit for the plant is clear; it obtains from the cyanobacterium fixed nitrogen and other bioactive compounds, such as phytohormones, polysaccharides, siderophores, or vitamins, leading to enhanced plant growth and productivity. Additionally, there is increasing use of different cyanobacterial species as bio-inoculants for biological nitrogen fixation to improve soil fertility and crop production, thus providing an eco-friendly, alternative, and sustainable approach to reduce the over-reliance on synthetic chemical fertilizers. [ABSTRACT FROM AUTHOR]

Nowadays, various industrial and urban activities result in discharging enormous quantities of various pollutants and their accumulation in the environment. Considering that heavy metals in wastewater are a serious threat to the environment and human health and that conventional methods for their removal are not highly efficient, the current study mainly focuses on estimating cyanobacterial capability to accumulate different heavy metals from water and comparing bioaccumulation and biosorption processes. Cyanobacteria Nostoc sp. was used, and five heavy metals were selected for this experiment (Cd2+, Cu2+, Pb2+, Ni2+, Zn2+). Examined concentrations of HMs were 20 mg/dm³, 80 mg/dm ³, and 200 mg/dm³ for the bioaccumulation study, while 20 mg/dm³ and 80 mg/dm³ of each HMs were used for biosorption experiments. Living cells of Nostoc sp. have the highest affinity for Pb2+ (98.15%) and Cu2+ (95.14%) removal from the solution by bioaccumulation. During the biosorption process, dried biomass of Nostoc sp., besides Pb2+ (92.27%) and Cu2+ (96.00%), shows a high affinity for Cd2+ (91.00%) removal. Living cyanobacterial cells of Nostoc sp. could accumulate 82% of Zn, while dried biomass adsorbs 87% of Zn2+. Although the highest bioaccumulation of Ni2+ was only 38% while using the biosorption process, it was significantly higher (63.80%). These results could provide a preliminary study for further investigation in the direction of the development of immobilized biosorbents which could be used for industrial effluent treatment. [ABSTRACT FROM AUTHOR]

The trend in protein consumption is towards plant-based foods, for this reason a powdered beverage with a balanced profile of essential amino acids was developed, combining two different sources of protein, cushuro (Nostoc commune) and quinoa (Chenopodium quinoa). The cushuro is an ancient Andean cyanobacteria that grows over 3000 and 4000 m above sea level, and quinoa is an important Andean seed, and they are part of the basic diet of the Andean Peruvian population. The cushuro obtained from the region of Ancash-Peru was dried (60 °C, 18 h) and the flour was dissolved in 0.1 N HCl at 90 °C for 20 min to obtain a protein concentrate with 6.79% moisture, 0.16% fat, 71.03% protein, and good balance of essential amino acids. Quinoa flour presented 8.52% moisture, 4.84% fat, 12.90% protein, and essential amino acids such as phenylalanine, and lysine. Quinoa flour (65.45%), cushuro concentrated protein (4.76%), cocoa (17.85%), panela (11.90%), and stevia (0.05%), were mixed to obtain the powdered beverage. The results showed that powdered beverage presented an adequate balance of amino acids according to FAO/WHO, with 14.36% proteins, 72.53% carbohydrate, 5.19% fat, 716.6 mg/kg potassium, 319.8 mg/kg phosphorus, 139.2 mg/kg magnesium, 82.69 mg/100 g vitamin C, 1.49 µg/100 g vitamin B12, heavy metals below the detection evel (<0.050 mg/kg). The powdered beverage complied with the Peruvian legislation of the Healthy Law No. 30021 and with the microbiological requirements. [ABSTRACT FROM AUTHOR]

Cyanobacteriochromes (CBCRs) are cyanobacterial photoreceptors that exhibit photochromism between two states: a thermally stable dark-adapted state and a metastable light-adapted state with bound linear tetrapyrrole (bilin) chromophores possessing 15Z and 15E configurations, respectively. The photodynamics of canonical red/green CBCRs have been extensively studied; however, the time scales of their excited-state lifetimes and subsequent ground-state evolution rates widely differ and, at present, remain difficult to predict. Here, we compare the photodynamics of two closely related red/green CBCRs that have substantial sequence identity (∼68%) and similar chromophore environments: AnPixJg2 from Anabaena sp. PCC 7120 and NpR6012g4 from Nostoc punctiforme. Using broadband transient absorption spectroscopy on the primary (125 fs to 7 ns) and secondary (7 ns to 10 ms) time scales together with global analysis modeling, our studies revealed that AnPixJg2 and NpR6012g4 have comparable quantum yields for initiating the forward (15ZPr → 15EPg) and reverse (15EPg → 15ZPr) reactions, which proceed through monotonic and nonmonotonic mechanisms, respectively. In addition to small discrepancies in the kinetics, the secondary reverse dynamics resolved unique features for each domain: intermediate shunts in NpR6012g4 and a Meta-Gf intermediate red-shifted from the 15ZPr photoproduct in AnPixJg2. Overall, this study supports the conclusion that sequence similarity is a useful criterion for predicting pathways of the light-induced evolution and quantum yield of generating primary intermediate Φp within subfamilies of CBCRs, but more studies are still needed to develop a comprehensive molecular level understanding of these processes.

The transformation of modern industries towards enhanced sustainability is facilitated by green technologies that rely extensively on rare earth elements (REEs) such as cerium (Ce), neodymium (Nd), terbium (Tb), and lanthanum (La). The occurrence of productive mining sites, e.g., is limited, and production is often costly and environmentally harmful. As a consequence of increased utilization, REEs enter our ecosystem as industrial process water or wastewater and become highly diluted. Once diluted, they can hardly be recovered by conventional techniques, but using cyanobacterial biomass in a biosorption-based process is a promising eco-friendly approach. Cyanobacteria can produce extracellular polymeric substances (EPS) that show high affinity to metal cations. However, the adsorption of REEs by EPS has not been part of extensive research. Thus, we evaluated the role of EPS in the biosorption of Ce, Nd, Tb, and La for three terrestrial, heterocystous cyanobacterial strains. We cultivated them under N-limited and non-limited conditions and extracted their EPS for compositional analyses. Subsequently, we investigated the metal uptake of a) the extracted EPS, b) the biomass extracted from EPS, and c) the intact biomass with EPS by comparing the amount of sorbed REEs. Maximum adsorption capacities for the tested REEs of extracted EPS were 123.9–138.2 mg g−1 for Komarekiella sp. 89.12, 133.1–137.4 mg g−1 for Desmonostoc muscorum 90.03, and 103.5–129.3 mg g−1 for Nostoc sp. 20.02. A comparison of extracted biomass with intact biomass showed that 16% (Komarekiella sp. 89.12), 28% (Desmonostoc muscorum 90.03), and 41% (Nostoc sp. 20.02) of REE adsorption was due to the biosorption of the extracellular EPS. The glucose- rich EPS (15%–43% relative concentration) of all three strains grown under nitrogen-limited conditions showed significantly higher biosorption rates for all REEs. We also found a significantly higher maximum adsorption capacity of all REEs for the extracted EPS compared to cells without EPS and untreated biomass, highlighting the important role of the EPS as a binding site for REEs in the biosorption process. EPS from cyanobacteria could thus be used as efficient biosorbents in future applications for REE recycling, e.g., industrial process water and wastewater streams.

Microalgae produce many secondary metabolites that are biologically active, including compounds that inhibit microbial growth. These could potentially function as biofungicides. The first selection criteria for potential strains suitable in the phytosanitary market is good in vitro inhibition of growth against specific phytopathogenic fungi and oomycetes and higher biomass productivity rates. In the present study, water extracts were prepared from 280 strains comprising of 33 Cyanophyceae strains (13 genera), 157 Chlorophyceae strains (29 genera), 80 Trebouxiophyceae strains (19 genera), 5 Klebsormidiophyceae strains (1 genus) and 1 Zygnematophyceae strain. These were tested in vitro against 6 phytopathogenic fungi and 3 phytopathogenic oomycetes. In total, 45% of the species had mycelial growth inhibitory activity against at least one pathogen. Cyanobacteria had the highest "hit-rate" (64%), followed by the Chlorophyceae (49%) and Trebouxiophyceae (30%). Water extracts of 19 strains had fungicidal and/or oomyceticidal activity – these were predominantly Cyanobacteria. The Cyanobacteria displayed a wider spectrum of inhibition with five strains being active against three or more phytopathogenic strains. Trichormis variabilis MACC-304 and Tolypothrix tenuis MACC-205 had inhibitory activity against 6 phytopathogens and Nostoc linckia MACC-612 inhibited 4 phytopathogenic strains. Each Chlorophyta strain was only active against 1-2 strains. However, the daily productivity rates of Cyanobacteria were significantly lower than Chlorophyta strains. Further investigation of 15 Nostocales species (Nostocaceae, Tolypothrichaceae and Calotrichaceae) showed the Nostoc species generally had significantly lower biomass generation compared to other Nostocacaeae strains. The most promising strain was Tolypothrix tenuis MACC-205 which had the most potent, broad spectrum fungal and oomyceticidal inhibitory activity as well as significantly higher daily biomass productivity rates. Thus, Cyanobacteria can potentially be developed as an effective agricultural tool for environmentally-friendly disease management. [ABSTRACT FROM AUTHOR]

Stereocaulon alpinum is a lichenized fungus commonly found in the Antarctic, circumarctic, alpine, and in mountainous areas of temperate regions. It forms a tripartite lichen symbiosis together with trebouxioid green microalgae, as its primary photobiont, and cyanobacteria of the genus Nostoc inside delimited cephalodia. Previous DNA-based analyses revealed two lineages for this fungus. This research discusses the morphological and chemical circumscription of S. alpinum and its geographic distribution and, to this end, we included new DNA data from the mycobiont and its photosynthetic partners. Phylogenetic reconstructions rejected infraspecific categories and revealed that specimens from the southern hemisphere (maritime Antarctica and South America) formed a well-supported "bipolar clade" with specimens from Finland, Greenland, and Canada. In addition, S. alpinum also formed a "northern clade" with sequences from Europe and North Atlantic islands. In specimens from the southern hemisphere, the identified lineages of phyco- and cyanobionts were already known to be associated with other lichenized fungi. The phycobiont was identified as Asterochloris pseudoirregularis and the cyanobiont as a member of the genus Nostoc. The phenotypic differences among the southern hemisphere specimens examined in this study pointed towards a broad morphological circumscription of S. alpinum. Simultaneously, the available descriptions of S. alpinum collected in the northern hemisphere, including the type specimen, do not provide characters distinguishing them from the southern specimens. These two clades likely represent cryptic species, one new and potentially only recognized using genetic data. Additional integrative studies, including a comprehensive analysis of specimens from the northern hemisphere, are necessary to know the diversity contained in the lichens identified as Stereocaulon alpinum worldwide. [ABSTRACT FROM AUTHOR]

FurC (PerR, Peroxide Response Regulator) from Anabaena sp. PCC 7120 (also known as Nostoc sp. PCC 7120) is a master regulator engaged in the modulation of relevant processes including the response to oxidative stress, photosynthesis and nitrogen fixation. Previous differential gene expression analysis of a furC-overexpressing strain (EB2770FurC) allowed the inference of a putative FurC DNA-binding consensus sequence. In the present work, more data concerning the regulon of the FurC protein were obtained through the searching of the putative FurC-box in the whole Anabaena sp. PCC 7120 genome. The total amount of novel FurC-DNA binding sites found in the promoter regions of genes with known function was validated by electrophoretic mobility shift assays (EMSA) identifying 22 new FurC targets. Some of these identified targets display relevant roles in nitrogen fixation (hetR and hgdC) and carbon assimilation processes (cmpR, glgP1 and opcA), suggesting that FurC could be an additional player for the harmonization of carbon and nitrogen metabolisms. Moreover, differential gene expression of a selection of newly identified FurC targets was measured by Real Time RT-PCR in the furC-overexpressing strain (EB2770FurC) comparing to Anabaena sp. PCC 7120 revealing that in most of these cases FurC could act as a transcriptional activator. [ABSTRACT FROM AUTHOR]

The ecological success of lichens is related to both myco- and photobionts which condition the physiological limits of the lichen symbioses and thus affect their ecological niches and geographic ranges. A particular type of lichen, called cephalolichen, is characterized by housing both green algal and cyanobacterial symbionts—the latter is restricted to special structures called cephalodia. In this type of lichen, questions related to specialization within species or within individuals are still unsolved as different patterns have previously been observed. In order to study the variability at the intrathalline, intraspecific, and interspecific level, cyanobionts from different cephalodia within the same thalli and from different thalli were genetically analysed in three cephalolichen species at two different forests (18 thalli, 90 cephalodia). The results showed variability in the cephalodial Nostoc OTUs in all the studied species, both at the intrathalline and intraspecific levels. The variability of Nostoc OTUs found in different cephalodia of the same thallus suggests low specialization in this relationship. Additionally, differences in OTU diversity in the three studied species and in the two forests were found. The variability observed may confer an increased ecological plasticity and an advantage to colonize or persist under additional or novel habitats or conditions. [ABSTRACT FROM AUTHOR]

In this study, we used microscopic, spectroscopic, and molecular analysis to characterize endolithic colonization in gypsum (selenites and white crystalline gypsum) from several sites in Sicily. Our results showed that the dominant microorganisms in these environments are cyanobacteria, including: Chroococcidiopsis sp., Gloeocapsopsis pleurocapsoides, Gloeocapsa compacta, and Nostoc sp., as well as orange pigmented green microalgae from the Stephanospherinia clade. Single cell and filament sequencing coupled with 16S rRNA amplicon metagenomic profiling provided new insights into the phylogenetic and taxonomic diversity of the endolithic cyanobacteria. These organisms form differently pigmented zones within the gypsum. Our metagenomic profiling also showed differences in the taxonomic composition of endoliths in different gypsum varieties. Raman spectroscopy revealed that carotenoids were the most common pigments present in the samples. Other pigments such as gloeocapsin and scytonemin were also detected in the near-surface areas, suggesting that they play a significant role in the biology of endoliths in this environment. These pigments can be used as biomarkers for basic taxonomic identification, especially in case of cyanobacteria. The findings of this study provide new insights into the diversity and distribution of phototrophic microorganisms and their pigments in gypsum in Southern Sicily. Furthemore, this study highlights the complex nature of endolithic ecosystems and the effects of gypsum varieties on these communities, providing additional information on the general bioreceptivity of these environments. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a method for assessing the growth of photoautotrophs on plaster coatings, which will be used to reliably assess the resistance of these materials to photoautotrophic growth in the simulation of long-term exposure. In the course of the study, mineral and silicone plaster substrates were inoculated with a mixture of Stichococcus bacillaris, Nostoc commune, Pseudochlorella signiensis, and Coenochloris signiensis, and incubated for 28 days in model conditions. At 14 and 28 days after inoculation, the degree of photoautotrophic growth was determined using hemocytometer cell counting, a HY-LiTE 2 ATP measuring system, chlorophyll a concentration quantification, CIE L*a*b spectrophotometric color change evaluation, and visual assessment. The acquired results allowed us to select visual assessment and spectrophotometric color change evaluation as quick-to-perform and reliable techniques for further laboratory studies. The impact of minor changes introduced in the inoculation and incubation procedures on the rate of biofilm formation and severity of microbial fouling was studied. Differences in inoculation and incubation procedures strongly affected the results of the performed tests. Both methods have shown high potential and should be further expanded upon in environmental studies. [ABSTRACT FROM AUTHOR]