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Platinum nanoparticles (PtNPs) are one of the widely used NPs, which contribute to potential risks to the aquatic ecosystem. However, PtNPs toxicity in phytoplankton remains inadequately understood, with significant gaps in knowledge regarding their biochemical bases and species-specific responses. Herein, we investigated the impact of PtNPs on two cyanobacterial species (Anabaena laxa and Nostoc muscorum) to explore the harmful pathways triggered by PtNPs in cyanobacteria, which may help in selecting appropriate biomarkers for PtNPs pollution in aquatic environments. We studied the effect of PtNPs on growth, oxidative stress markers, and antioxidant defense systems of the two species. The obtained results showed that PtNPs reduced the level of chlorophyll. Furthermore, they induced dose-dependent oxidative stress to the two species, expressed by significant increases in H 2 O 2 , malondialdehyde (MDA), and protein oxidation (p < 0.05). Stress-induced oxidative damages were more pronounced in N. muscorum , yet the two cyanobacterial species showed higher levels (p < 0.05) of antioxidant metabolites and antioxidant enzymes to combat oxidative stress. Compared to N. muscorum , A. laxa invested more in the induction of antioxidant metabolites including FRAP, polyphenols, flavonoids, and glutathione (GSH), as well as in antioxidant enzymes such as POX, CAT, GR, and GPX. Overall, A. laxa species could be exploited as efficient biomarkers for monitoring PtNPs-induced ecotoxicology. Further investigation of bio-absorption and uptake of PtNPs by microalgae is recommended for developing algae-based bioremediation technologies. [Display omitted] • Impact of PtNPs on two cyanobacterial species was investigated. • PtNPs reduced the levels of chlorophylls in cyanobacterial species. • PtNPs induced dose-dependent oxidative stress to the two cyanobacterial species. • Stress-induced oxidative damages were more pronounced in N. muscorum. • A. laxa can be used as a biomarker for monitoring PtNPs-induced toxicology. [ABSTRACT FROM AUTHOR]

Elevated geosmin concentrations in drinking water reservoirs can lead to customer complaints and increased treatment costs for utilities. Use of molecular approaches, like qPCR and targeted amplicon sequencing, can help with prediction and preventive measures, but many of the primers targeting the geosmin synthase gene suffer from limited coverage of taxa or poor specificity. Here, a set of primers (CGeo1F/R) were developed that had high specificity for geosmin synthase in cyanobacteria without the use of probes. When tested on samples from three drinking water reservoirs with elevated geosmin levels, these primers amplified the geosmin synthase gene in seven cyanobacterial genera, including Dolichospermum, Aphanizomenon, Cylindrospermum, Planktothrix, Nostoc, Coelosphaerium, and Tychonema. These primers exhibited acceptable amplification efficiency (∼ 90 %) and a linear amplification range of 6 × 101–6 × 105 copies per ml in lake water. Within the limited set of samples used to evaluate these primers, a good correlation was observed (r = 0.8) between abundance of geosmin synthase and geosmin concentration. When compared to some existing, well-utilized primers in the literature, these new primers had better specificity and amplification properties, and thus may prove valuable to other researchers. • Primers (Cgeo1) targeting geosmin synthase in cyanobacteria were developed. • Cgeo1 primers were specific to cyanobacteria and included seven genera in samples. • Cgeo1 primers outperformed two existing primers in efficiency and dynamic range. • Strong correlation observed (r = 0.8) between geosmin level and gene copy number. [ABSTRACT FROM AUTHOR]

We studied the genotype diversity of cyanobacterial symbionts in the predominately terricolous cyanolichen genus Peltigera (Peltigerales, Lecanoromycetes) in Estonia. Our sampling comprised 252 lichen specimens collected in grasslands and forests from different parts of the country, which represented all common Peltigera taxa in the region. The cyanobacteria were grouped according to their tRNALeu (UAA) intron sequences, and mycobiont identities were confirmed using fungal ITS sequences. The studied Peltigera species associated with 34 different " Peltigera -type" Nostoc trnL genotypes. Some Peltigera species associated with one or a few trnL genotypes while others associated with a much wider range of genotypes. Mycobiont identity was the primary factor that determined the presence of the specific Nostoc genotype within the studied Peltigera thalli. However, the species-specific patterns of cyanobiont selectivity did not always reflect phylogenetic relationships among the studied fungal species but correlated instead with habitat preferences. Several taxa from different sections of the genus Peltigera were associated with the same Nostoc genotype or with genotypes in the same habitat, indicating the presence of functional guild structure in the photobiont community. Some Nostoc trnL genotypes were only found in the Peltigera species of moist and mesic forest environments, while another set of Nostoc genotypes was typically found in the Peltigera species of xeric habitats. Some Nostoc trnL genotypes were only found in the Peltigera taxa that are common on alvars and may have specialized to living in this unusual and threatened habitat type. [ABSTRACT FROM AUTHOR]

Abstract The present study is pursuing our previous research, focused on some aspects of Nostoc entophytum ISC32 cell response to the stress caused by exposure to cadmium at the cellular and molecular levels. Variations in the antioxidant system (catalase and ascorbate peroxidase activity) of N. entophytum ISC32 exposed to varying concentrations of Cd (2, and 5 mg/L) resulted in a significant increase in the activity of both catalase and peroxidase. Activity of these enzymes was, however, not significantly changed in the presence of Cd concentrations of 10 and 20 mg/L. Levels of lipid peroxidation, as measured by malondialdehyde (MDA) assay, were observed in response to exposure to Cd (20 mg/L). There was, however, a sharp drop in both antioxidant and lipid peroxidation activities of Cd treated cells after 5 days exposure, likely in consequence of cellular damage. The content of chlorophyll a and phycobiliproteins of living cells were altered under Cd-induced conditions. TEM images of cyanobacterial cells treated with Cd showed cell surface alteration and modification along with altered cellular microcompartments. Cyanobacterial cells treated with Cd at concentrations below the minimum inhibitory concentration (MIC) remained with no apparent structural changes. However, at a higher concentration of Cd (30 mg/L), a clear detachment effect was observed between the mucilage external layer and cell membrane which may be attributed to cell plasmolysis due to toxic effects of Cd. Subsequently, the thickness of the ring-shaped mucilage external layer increased likely as a result of the cell defense mechanisms against toxic concentrations of Cd. Characterization of cells treated with Cd (30 and 150 mg/L) by scanning electron microscopy (SEM) indicated cell shrinkage with varying degrees of distortion and surface wrinkling. Energy-dispersive X-ray spectrometry (EDS) analysis suggested that Cd was not present as nanoparticles within the cell, but in the form of salt or other molecular structures. The up-regulation of chaperons was confirmed for GroEL and HtpG using real-time PCR and northern blot analyses. Interestingly, the expression of GroEL was markedly increased at lower Cd concentration (5 mg/L). However, the ISC32 strain accrued higher levels of HtpG transcript in response to an elevated concentration of Cd (15 mg/L). This pattern seems to be related to the fast and early induction of GroEL, which may be necessary for induction of other factors and heat shock proteins such as HtpG in Cd-treated Nostoc cells. The result of this study paves the way for a more detailed exploration of Cd effects on the defense mechanisms of cyanobacteria. Our research also shed some light on how cyanobacterial cells have evolved to respond to the heavy metal toxicity at the cellular, molecular and ultrastructural levels. Highlights • Nostoc entophytum ISC32 response to Cd stress at the cellular and molecular levels. • Chlorophyll a and phycobiliproteins contents of the cells altered by Cd treatment. • The activity of catalase and peroxidase was affected in ISC32 strain by Cd treatment. • TEM analysis showed detachment of mucilage layer and cell membrane by Cd treatment. • EDS analysis suggested that Cd was not present as nanoparticles in the cell. • Real-time PCR showed the up-regulation of GroEL & HtpG in cells exposed to Cd. [ABSTRACT FROM AUTHOR]

Abstract Natural sources have always been the primary sources of bioactive principles. Cyanobacteria with its wide spectrum of metabolites represents a favourable source of compounds having medicinal properties like antioxidant, anti-proliferative etc. In this study we tested different organic extracts [Diethyl ether (DE), Dichloromethane (DM), Ethyl acetate (EA) and Heptane (HE) extracts] of cyanobacterium Nostoc muscorum NCCU-442 for the same. Antioxidant activity was evaluated through DPPH and FRAP assay. Phenolic content was estimated using FCR reagent as phenolic compounds are the well-established antioxidants. MTT assay was used to estimate anti-proliferative activity against cervical cancer cell line, SiHa. DE extract was found to have the highest Phenolic content, i.e. 96.71 ± 2.41 mgGAE/g as well as most antioxidant effect in DPPH assay (IC 50 =118 ± 0.34 µg/ml) and FRAP assay (EC 1 =380.7 ± 2.43 µg/ml). The order of phenolic content of different extracts is: DE > EA> DM > HE. The order of antioxidant potential was same as the phenolic content. HE extract had the least antioxidant effect in the two assays (IC 50 =686 ± 3.3 µg/ml and EC 1 >10 mg/ml for DPPH and FRAP respectively). All the extracts showed anti-proliferative activity against the cancer cell line in the order: DE (IC 50 = 70 ± 0.22 µg/ml) > HE (116.5 ± 0.53 µg/ml) > EA (205 ± 0.77 µg/ml) > DM (190 ± 0.45 µg/ml). During Gas Chromatography-Mass Spectrometry (GC-MS), bioactives like Benzofuranone derivatives, Myristoleic acid, Resorcinol, Citronellyl butyrates, hydroquinone, hexadecanoic acid, farnesol were identified in the organic extracts. Thus, our study indicated that Nostoc muscorum NCCU-442 has an inherent capacity as a potential source of therapeutic compounds. [ABSTRACT FROM AUTHOR]

Abstract Industrial wastewater containing heavy metals is a major environmental problem that needs to be treated. This study reported the ability of two fresh water algae cyanobacteria (Nostoc muscorum and Anabaena variabilis) to remove lead from aqueous solutions of four different initial concentrations (0–50 mg/L−1) for 21 days under controlled laboratory conditions. Results obtained in this study showed a maximum removal of Pb(II) (97.8%) by N. muscorum at 15 mg/L−1 initial metal concentration however the maximum removal by A. variabilis at the same concentration was 71.4% after 16 day of incubation. These N. muscorum appeared to be more efficient than A. variabilis for removing Pb(II). Algal growth, pigments in the algae cells were measured during incubation period. Lower concentrations of lead increased biomass, OD, chlorophyll a and carotenoids in both algae. On the other hand, higher concentrations of lead were inhibitory for growth. Highlights • N. muscorum and A. variabilis were tested to remove lead from water for 21 days. • After 16 days of incubation, algae were reached to the saturation level. • There were increased in growth rate in both algae in lower concentrations of lead. • N. muscorum was more effective than A. variabilis for bioremovel of lead. [ABSTRACT FROM AUTHOR]

This comprehensive phylogenetic revision of sections Peltigera and Retifoveatae of the cyanolichen genus Peltigera is based on DNA sequences from more than 500 specimens from five continents. We amplified five loci (nrITS, ß-tubulin and three intergenic spacers part of colinear orthologous regions [COR]) for the mycobiont, and the rbcLX locus for the cyanobacterial partner Nostoc. Phylogenetic inferences (RAxML, BEAST) and species delimitation methods (bGMYC, bPTP, bPP) suggest the presence of 88 species in section Peltigera, including 50 species new to science, hence uncovering a surprisingly high proportion of previously unnoticed biodiversity. The hypervariable region in ITS1 (ITS1-HR) is a powerful marker to identify species within sections Peltigera and Retifoveatae. Most newly delimited species are restricted to a single biogeographic region, however, up to ten species have a nearly cosmopolitan distribution. The specificity of mycobionts in their association with Nostoc cyanobionts ranges from strict specialists (associate with only one Nostoc phylogroup) to broad generalists (up to eight Nostoc phylogroups uncovered), with widespread species recruiting a broader selection of Nostoc phylogroups than species with limited distributions. In contrast, species from the P. didactyla clade characterized by small thalli and asexual vegetative propagules (soredia) associate with fewer Nostoc phylogroups (i.e., are more specialized) despite their broad distributions, and show significantly higher rates of nucleotide substitutions. [ABSTRACT FROM AUTHOR]

The present study deals with impact of varied doses of arsenite (As III ; 50, 100 and 150 µM) and arsenate (As V ; 50, 100 and 150 mM) on growth, photosynthetic pigments, photochemistry of photosystem II, oxidative biomarkers, (O 2 • ¯, H 2 O 2 and MDA equivalents contents) and activity of antioxidant enzymes in diazotrophic cyanobacterium Nostoc muscorum after 48 and 96 h of the treatments. The reduction in growth, pigment contents (Chl a , Phy and Car) and PS II photochemistry was found to increase with enhanced accumulation of test metal in cells, and the damaging effect on photosynthetic pigments showed the order (Phy > chl a > Car). The negative effect on PS II photochemistry was due to significant decrease in the value of JIP kinetics ϕP 0 , F V /F 0 , ϕE 0 ,Ψ 0 and PI ABS except F 0 /F V and significant rise in values of energy flux parameters such as ABS/RC, TR 0 /RC, ET 0 /RC and DI 0 /RC. Both the species of arsenic caused significant rise in oxidative biomarkers as evident by in vitro and in vivo analysis of (O 2 • ¯, H 2 O 2 and MDA equivalents contents) despite of appreciable rise in the activity antioxidative enzymes such as SOD, POD, CAT and GST. The study concludes that in among both forms of arsenic, arsenite effect was more dominant on growth, photosynthetic pigments; oxidative stress biomarkers as evident by weak induction of anti-oxidative defense system to overcome the stress as compared to arsenate. [ABSTRACT FROM AUTHOR]

The current study was undertaken to elucidate the impact of the herbicide pretilachlor (3 µg ml −1 and 6 µg ml −1 ) on cyanobacteria, Nostoc muscorum ATCC 27893 and Anabaena sp. PCC 7120 under three levels of photoacclimatization (suboptimum, 25 µmol photon m −2 s −1 ; optimum, 75 µmol photon m −2 s −1 ; and supra-optimum, 225 µmol photon m −2 s −1 ) by analyzing certain physiological (biomass accumulation, photosynthesis, Chl a fluorescence and respiration) and biochemical parameters (photosynthetic pigments‒ chlorophyll a , carotenoids and phycocyanin; reactive oxygen species‒ O 2 • ¯, H 2 O 2 , lipid peroxidation; antioxidant system‒ superoxide dismutase, peroxidise, catalase and glutathione- S -transferase). The light conditioning played the most prominent role in deciding the extent of herbicide toxicity on both the tested cyanobacteria as the maximum toxicity was observed in suboptimum light acclimatized cyanobacterial cells corroborated by the least growth in the same cells. The impact of pretilachlor treatment on photosystem II photochemistry viz. φP 0 , Ѱ 0 , φE 0 , PI ABS , ABS/RC, TR 0 /RC, ET 0 /RC and DI 0 /RC was also altered by light acclimatization. The percent rise in oxidative stress markers (SOR and H 2 O 2 ) and consequent lipid peroxidation (MDA equivalents) were also highest in suboptimum light acclimatized cells exposed to pretilachlor which could not be prospered with compatible antioxidant performance. Conversely, supra-optimum light acclimatized cells of both the cyanobacteria was found to accelerate the activities of all the studied enzymes and thus able to counterbalance the pretilachlor toxicity and supported the healthier growth. [ABSTRACT FROM AUTHOR]

Phycobiliproteins are colored water-soluble proteins found in cyanobacteria with potential applications in food and pharmaceuticals. Phycobiliproteins extracted from the Thai karstic cave cyanobacterium Nostoc sp. strain SW02 were purified, and their biological properties were characterized. Scale-up cultivation for 12 days revealed that maximum biomass and phycobiliproteins producing yield were 1.53 g/L and 31.92%, respectively. After purification, phycoerythrin was obtained as the principal component of phycobiliproteins, with a purity index up to 2.62, sufficient to be considered food and cosmetic grade. Native and SDS-PAGE analysis displayed that purified phycoerythrin and phycocyanin contained the αβ-subunits in hexamer form. Purified phycobiliproteins had a more stable structure and functionality in pH range 5.0–7.0, were resistant to strong oxidizers, and could withstand temperatures up to 60 °C. They also exhibited DPPH scavenging capabilities comparable to standard ascorbic acid. Pathogenic bacterial inhibition (MIC 250 μg/mL) and anticancer activity against the human HeLa cancer cell line (IC 50 140 μg/mL) were also observed. With these prospective characteristics, phycobiliproteins obtained from Nosto c sp. SW02 have biotechnological value for biomedical research and also as a natural colorant for food and cosmetic applications. [Display omitted] • High biomass and PBPs yield were obtained from Nostoc sp. strain SW02. • Phycoerythrin (PE) was a major component of PBPs after purification. • Purified PBPs quality was sufficient to be considered food and cosmetic grade. • Purified PBPs were thermally stable and resistant to oxidative stress. • Purified PBPs showed potential for use as biological substances in many applications. [ABSTRACT FROM AUTHOR]

Nostocacean cyanobacteria are one of the important components of paddy fields due to their ability to fix atmospheric nitrogen and supply phytohormones for crop growth. In this study, 13 Nostoc strains isolated from paddy soils in Vietnam were classified using a polyphasic approach. The results showed a high diversity of the isolated strains that represented seven morphotypes corresponding to five genotypes, with 16S rRNA gene sequence similarity values ranging between 94.97–99.78% compared to the available sequences from GenBank. Bioassay assessment revealed that 11 out of 13 strains possessed antibacterial activities, three of which exhibited cytotoxic activities on MCF7 and HCT116 cells with an IC 50 ranging from 47.8 μg mL −1 to 232.0 μg mL −1 . Interestingly, strains with identical 16S rRNA gene sequences displayed different antibacterial and cytotoxic activity profiles. [ABSTRACT FROM AUTHOR]

Nostoc sp. PCC 7120 ( Nostoc ), a typical filamentous cyanobacterium ubiquitous in aquatic system, is recognized as a model organism to study prokaryotic cell differentiation and nitrogen fixation. In this study, Nostoc cells incubated with arsenite (As(III)) for two weeks were extracted with dichloromethane/methanol (DCM/MeOH) and the extract was partitioned between water and DCM. Arsenic species in aqueous and DCM layers were determined using high performance liquid chromatography - inductively coupled plasma mass spectrometer/electrospray tandem mass spectrometry (HPLC-ICPMS/ESIMSMS). In addition to inorganic arsenic (iAs), the aqueous layer also contained monomethylarsonate (MAs(V)), dimethylarsinate (DMAs(V)), and the two arsenosugars, namely a glycerol arsenosugar (Oxo-Gly) and a phosphate arsenosugar (Oxo-PO4). Two major arsenosugar phospholipids (AsSugPL982 and AsSugPL984) were detected in DCM fraction. Arsenic in the growth medium was also investigated by HPLC/ICPMS and shown to be present mainly as the inorganic forms As(III) and As(V) accounting for 29%–38% and 29%–57% of the total arsenic respectively. The total arsenic of methylated arsenic, arsenosugars, and arsenosugar phospholipids in Nostoc cells with increasing As(III) exposure were not markedly different, indicating that the transformation to organoarsenic in Nostoc was not dependent on As(III) concentration in the medium. Our results provide new insights into the role of cyanobacteria in the biogeochemical cycling of arsenic. [ABSTRACT FROM AUTHOR]

In this study the proteome response of the two diazotrophic organism’s viz . Nostoc muscorum and Bradyrhizobium japonicum exposed to salt (NaCl) and osmotic (sucrose) stresses was compared. Out of the total over expressed proteins; we have selected only three over expressed proteins viz . GroEL chaperonin, nitrogenase Mo-Fe protein and argininosuccinate synthase for further analysis, and then we analyzed the amino acid frequencies of all the three over expressed proteins. That led to the conclusion that amino acids e.g. alanine, glycine and valine that were energetically cheaper to produce were showing higher frequencies. This study would help in tracing the phylogenetic relationship between protein families. [ABSTRACT FROM AUTHOR]

Lichenized Nostoc cells isolated from the lichen Peltigera canina develop chemotaxis towards a lectin purified from the lichen thallus. Similar movements in unicellular eukaryotes require actin and myosin to generate contraction and relaxation along the chemotactic axis. We provide evidences for prokaryotic actin-like and myosin-like proteins in the cyanobiont Nostoc sp using cross-reacting antibodies against α- and β-actin and non-muscle myosin II light and heavy chains, and two-dimensional gel electrophoresis to determine the isoelectric point (IP) of the actin-like protein. Actin antibodies bound to a single reactive Nostoc polypeptide of an approximate molecular mass of 50 kD with IP values between 4 and 7 pH, similar to eukaryotic actin. The myosin light chain antibody reacted with a Nostoc protein with an apparent molecular weight of 20 kDa and another of 48 kDa. Immunoprecipitation of cell free extracts using anti-heavy chain myosin separately yielded only one signal corresponding to a protein of a molecular weight around 200 kDa. A bioinformatics analysis indicated that (cyano)bacterial actins are rare but do exist. Our results are consistent with the possible existence of protein homologues of actins and myosins in cyanobionts of P. canina , suggesting the existence of an actin-like apparatus that supports chemotactic swimming. [ABSTRACT FROM AUTHOR]

Nostoc flagelliforme has been reported from deserts of all continents and more recently from semiarid environments in south-east Spain and Australia. Its cylindrical thalli are very conspicuous on soils after rains and can be easily differentiated from other taxa and it is considered endangered in some countries, e. g. China. It was firstly described as variety flagelliforme of Nostoc commune but later was considered a separate species. The morphology, fine structure and ecology of populations of both taxa from Australia and different regions of Spain were studied and 16S rRNA and trn L Leu (UAA) genes were sequenced to identify their intraspecific genetic variation. The morphological study revealed the presence of several intermediate morphs, from spheres and sheets to ribbons followed by the cylindrical thalli and the overlapping of cell dimensions, permitting the differentiation of cylindrical morphs from the others. The molecular data did not allow for a distinction between N. commune and N. flagelliforme which is clearly polyphyletic and both show a high genetic diversity. The presence of cylindrical thalli seems to be related to extreme conditions of aridity, usually on soils but occasionally on rock walls. The ecotype that N. flagelliforme represents deserves to be protected for itself and for the evolutionary process it represents opening up the possibility of implementation of recovery measures and even opportunities to explore its biotechnological production from a different point of view. [ABSTRACT FROM AUTHOR]

High investment costs have switched the perspective of cyanobacterial biorefinery concepts from biofuels towards approaches with multiple high-value products including residual biomass utilization. For the purpose of residual biomass utilization, this study investigated the biomass of several Nostoc strains. The saccharide profiles of the highly complex heteroglycans in seven Nostoc strains was elucidated. Besides neutral sugars, uronic acids, amino sugars, other substituted sugars as well as different methylated sugars and their methylation patterns were identified. Also, the biocomposition of the exemplary strains Nostoc sp. De1, Nostoc sp. Cc3, and Nostoc muscorum I was investigated totaling 77.4%, 91.8%, and 71.4% biomass, respectively. Ash and moisture made up 11–15%, lipids 2–2.7%, starch 1.4–8.4%, structural saccharides 12.6–16.8%, and protein 37.7–49.3%. While overall the detected masses were 28.6%–8.2% short to full recovery, many identified sugars could not be quantified. Further, different industry enzymes were tested on these three Nostoc strains for saccharification and solubilization. The highest saccharification results for all three strains were 36 mg g−1, 73 mg g−1, and 75 mg g−1 for Nostoc sp. De1, Nostoc sp. Cc3 and N. muscorum I, respectively. The obtained results demonstrate the extremely complex heteroglycans in Nostoc biomass as well as the difficulty for industrial utilization of these saccharides. Yet, the achieved biomass solubilization of 57%, 49%, and 56% for Nostoc sp. De1, Nostoc sp. Cc3, N. muscorum I, respectively could still allow for efficient biomass utilization. • Saccharide profiles of seven Nostoc cyanobacteria strains were elucidated. • Uncommon saccharide monomer building blocks could be identified. • Methylated hexoses could be identified based on MS2 fragmentation pattern. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) is an environmentally friendly algaecide with good prospects for cyanobacterial bloom control. In this study, 0.2–1.5 mg L−1 of H 2 O 2 was applied to an aquatic microcosm containing cyanobacteria, bacteria, and eukaryotic phytoplankton at the early cyanobacterial growth stage·H 2 O 2 generated hormesis in cyanobacteria at 0.2 mg L−1; significantly (p < 0.05) inhibited cyanobacterial growth, cyanobacterial photosynthesis, and microcystin production at 0.5–1.5 mg L−1; and effectively prevented the formation of cyanobacterial bloom without generating adverse effects on eukaryotic phytoplankton at 1.0 and 1.5 mg L−1. Application of 0.5–1.5 mg L−1 H 2 O 2 directly inhibited the abundance of five typical bloom-forming cyanobacterial genera (Microcystis , Anabeana , Synechococcus , Nostoc , and Oscillatoria), which were negatively correlated with four bacterial genera (Actinotalea , Flavobacterium , Fluviicola , and Exiguobacterium) and five eukaryotic phytoplankton genera (Cyclotella , Desmodesmus , Dinobryon , Fragilaria , and Mychonastes) and positively correlated with six proteobacterial genera (Brevundimonas , Devosia , Limnohabitans , Porphyrobacter , Pseudomonas , and Rhodobacter). After application of 1.0 and 1.5 mg L−1 H 2 O 2 for 15 days, H 2 O 2 -treated groups showed significantly (p < 0.05) different prokaryotic community structures from that of the control group at the bloom stage (15th day), while eukaryotic community structures in H 2 O 2 -treated groups remained stable and showed high similarity with that of the control group at a non-bloom stage (5th day). Application of low-dose H 2 O 2 during the early cyanobacterial growth stage could effectively prevent the formation of cyanobacterial blooms without disrupting non-target organisms. [Display omitted] • Low-dose H 2 O 2 prevents cyanobacterial bloom without affecting eukaryotic algae. • H 2 O 2 reduces the dominance of Microcystis and Anabeana in cyanobacterial community. • H 2 O 2 regulates prokaryotic and eukaryotic community towards a healthy direction. • H 2 O 2 treatment reduces intracellular and extracellular microcystin concentrations. • H 2 O 2 stress induces interactions among bacteria, cyanobacteria and eukaryotic algae. [ABSTRACT FROM AUTHOR]

Abstract: To understand how carbon and nitrogen metabolism are regulated in diazotrophically and non-diazotrophically grown cultures of the cyanobacterium Nostoc muscorum, we investigated the role of bicarbonate (HCO3 −) in regulating diazotrophy and autotrophy. Results showed that HCO3 − concentration up to 12molm−3 enhanced growth, specific growth rate, photosynthetic pigments, photosynthetic O2 evolution and nitrogenase activity under diazotrophic growth conditions. The co-existence of different nitrogen sources in the growth medium further accelerate the examined parameters in the order of NO3 −2 −4 +++ -dependent ATPase activity and cytochrome c oxidase activity in the presence of graded concentration of HCO3 − under diazotrophically grown and non-diazotrophically grown cultures. The activity of these enzymes was higher in the cells grown under elevated HCO3 − concentration. The Ca++-dependent ATPase activity was higher than that of cytochrome c oxidase, when NAPH was supplied as the electron donor. This finding suggested that photosynthetic generation of ATP utilized NADPH as an electron donor and cytochrome c oxidase activity is independent of NADPH. [Copyright &y& Elsevier]

Abstract: Nostoc ellipsosporum is a highly potent cyanobacterium for production of pharmaceutically important chemicals. In this study, an effort has been made to determine the effect of glucose and phytohaemagglutinin (PHA) rich Phaseolus vulgaris extract on N. ellipsosporum growth and protein production. Maximum growth was observed in Fog’s medium supplemented with glucose. SEM analysis showed that the regular and well developed heterocysts were observed in Fog’s media supplemented with glucose. Significant medium components were evaluated by Plackett–Burman (PB) design and PHA extract was found to be the most significant in growth medium. Results of this study showed that both glucose and PHA rich P. vulgaris extract have positive effects and enhance the growth and protein synthesis. [Copyright &y& Elsevier]

Abstract: The challenging task of bringing high efficiency transformed plants attracts lot of attention in recent times. In search for this, there have been many attempts made using, different techniques like tissue culture and plant breeding methods. Here we report a suitable alternative facile route, where cyanobacterial extracellular products are utilized as growth regulators and its performance validated on Gossypium hirsutum L. MS medium is tested with cyanobacterial extracellular products of Nostoc ellipsosporum, Dolichospermum flos-aquae and Oscillatoria acuminata .Our best results show that the addition of O. acuminata extracellular product with plant growth hormones gives the excellent induction and elongation in cotton. In addition to this, the multiple shoot was obtained on MS medium fortified with 1.0mg L−1 BA with 8% O. acuminata and 1.5mgL−1 TDZ with 12% O. acuminata. High frequency of shoot elongation supplemented with MS medium, iP 2.5mgL−1 and 16% O. acuminata and root production MS medium fortified with 12% O. acuminata best responsible for regeneration in cotton plants. The rooted plants were hardened and transferred to soil with 90% survival rate. [Copyright &y& Elsevier]

Abstract: Approximately, 20 years ago, a haemoglobin gene was identified within the genome of the cyanobacterium Nostoc commune. Haemoglobins have now been confirmed in multiple species of photosynthetic microbes beyond N. commune, and the diversity of these proteins has recently come under increased scrutiny. This chapter summarizes the state of knowledge concerning the phylogeny, physiology and chemistry of globins in cyanobacteria and green algae. Sequence information is by far the best developed and the most rapidly expanding aspect of the field. Structural and ligand-binding properties have been described for just a few proteins. Physiological data are available for even fewer. Although activities such as nitric oxide dioxygenation and oxygen scavenging are strong candidates for cellular function, dedicated studies will be required to complete the story on this intriguing and ancient group of proteins. [Copyright &y& Elsevier]

Abstract: Objective: To test Candonocypris novaezelandiae (Baird) (C. novaezelandiae), sub-class Ostracoda, obtained from the Nile, Egypt for its predatory activity on snail, Biomphalaria alexandrina (B. alexandrina), intermediate host of Schistosoma mansoni (S. mansoni) and on the free-living larval stages of this parasite (miracidia and cercariae). Methods: The predatory activity of C. novaezelandiae was determined on B. alexandrina snail (several densities of eggs, newly hatched and juveniles). This activity was also determined on S. mansoni miracidia and cercariae using different volumes of water and different numbers of larvae. C. novaezelandiae was also tested for its effect on infection of snails and on the cercarial production. Results: C. novaezelandiae was found to feed on the eggs, newly hatched and juvenile snails, but with significant reduction in the consumption in the presence of other diet like the blue green algae (Nostoc muscorum). This ostracod also showed considerable predatory activity on the free-living larval stages of S. mansoni which was affected by certain environmental factors such as volume of water, density of C. novaezelandiae and number of larvae of the parasite. Conclusions: The presence of this ostracod in the aquatic habitat led to significant reduction of snail population, infection rate of snails with schistosme miracidia as well as of cercarial production from the infected snails. This may suggest that introducing C. novaezelandiae into the habitat at schistosome risky sites could suppress the transmission of the disease. [Copyright &y& Elsevier]

Abstract: This study deals with the comparative responses of the two cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against single and combined doses of low (UV-BL, 0.1μmolm−2 s−1) and high (UV-BH, 1.0μmolm−2 s−1) fluence rates of ultraviolet-B radiation with low (CPL, 1μgml−1) and high (CPH, 2μgml−1) doses of the insecticide chlorpyrifos by measuring changes in growth, ascorbate-glutathione cycle enzymes and related metabolites. CPL and UV-BL both caused lesser increase in ROS but significantly stimulated AsA-GSH cycle enzymes. On the other hand, CPH and UV-BH posed inhibitory effects by enhancing ROS and inhibiting AsA-GSH cycle enzymes. Inhibitions in CPH or UV-BH treated samples were significantly prevented when they were supplemented with UV-BL and CPL (after 72h), respectively by lowering down ROS and enhancing AsA-GSH enzymes and related metabolites which manifested in terms of improved biomass accumulation. [Copyright &y& Elsevier]

In the present study, degree of tolerance and tolerance strategies of two paddy field cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against oxyfluorfen (10 and 20μgml−1) and UV-B (7.2kJm−2 d−1) stress were investigated. Oxyfluorfen and UV-B decreased growth, photosynthesis, nutrient uptake, nitrate reductase, acid and alkaline phosphatase activities, which accompanied with the increase in the level of oxidative stress. However, growth was more affected in N. muscorum than P. foveolarum. Antioxidants exhibited differential responses against oxyfluorfen and UV-B stress. Ascorbate and proline levels were higher in P. foveolarum. A protein of 66kDa was expressed in N. muscorum, however, it was absent in P. foveolarum than those of N. muscorum. Besides this, a protein of 29kDa appeared in P. foveolarum under all the treatments, but it was present only in control cells of N. muscorum cells. Overall results indicated resistant nature of P. foveolarum against oxyfluorfen and UV-B stress in comparison to N. muscorum. [Copyright &y& Elsevier]

In this study, we found that UV-B radiation decreased photosynthetic activity and boosted lipid peroxidation of desert Nostoc sp., and exogenous chemicals (ascorbate acid (ASC), N-acetylcysteine (NAC), and sodium nitroprusside (SNP)) had obvious protective effects on photosynthesis and membranes under UV-B radiation. High-concentration SNP boosted the activities of antioxidant enzymes, but low-concentration SNP reduced the activities of antioxidant enzymes. Both NAC and ASC treatments of cells decreased activities of antioxidant enzymes. The results suggested that those chemicals possibly had different mechanisms of protection of algae cells against UV-B radiation. SNP might play double roles as a signal molecule in the formation of algae cell protection of Photosystem II under UV-B radiation and as a (reactive oxygen species) scavenger, while NAC and ASC might function as antioxidant reagents or precursors of other antioxidant molecules, which could protect cells directly against ROS initiated by UV-B radiation. [Copyright &y& Elsevier]

The article presents a study which examines the ratio of functionally different groups of carbohydrates in cells of the most common terrestrial algae. It reveals the peculiarities of carbohydrate composition of representatives of various taxonomic groups. It adds that in cells of aquatic blue-green algae the ratio of carbohydrate groups is the same as those of terrestrial algae.

Results of the study of the influence of the cationie surfactant (catamine) on the growth, reproduction, motion, and energy potential of the test-culture of Chlamydomonas reinhardtii (Dan.) (Chlorophayta), and also on the same characteristics of" representatives of the genera Nostoc, Synechocystis. and Anabaena (Cyanophyta), are presented. The vital activity of the algae was assessed by the microscopie and fluorescent methods, and also by the method of laser-Doppler spectrometry used for evaluating the rate and energy potential of their motion. It has been found that in the presence of surfactants morphological, functional, and metabolic characteristics of the algae belonging to various taxonomic groups changed. [ABSTRACT FROM AUTHOR]

Discusses the variability of life cycles of the genus Nostoc Vauch. Conditions of cultivation in which the peculiarities of onthomorphogenesis in Nostocaceae depend on; Description of the shape of the cells; Characters of akinete that are useful for identification of strains.

Presents a study that aimed to elucidate conditions stimulating the production of exogenic carbohydrates of Nostoc linckia by the influence of different sources of nitrogen. Effect of ammonium nitrogen on the growth process; Function of exoglycanes; Content of carbohydrates in the biomass of algae with mucous sheaths.

This study investigated the influences of three frequently detected antibiotics in surface waters, ciprofloxacin, tetracycline and sulfamethoxazole, on the growth, photosynthetic activity, nitrogen-fixing capacity and proteomic expression profiles of Nostoc sp. PCC 7120, through a 15-day exposure test at environmentally relevant exposure doses of 50–200 ng/L. Cyanobacterial growth was stimulated by 100 ng/L and 200 ng/L of ciprofloxacin and sulfamethoxazole as well as 50–200 ng/L of tetracycline. The nitrogenase synthesis ability in each cyanobacterial cell was stimulated by 50–200 ng/L of ciprofloxacin while inhibited by 100 ng/L and 200 ng/L of tetracycline and sulfamethoxazole. At the exposure dose of 100 ng/L for each antibiotic, the variation of total nitrogen in the culture medium indicated that the nitrogen-fixing capacity of Nostoc sp. was determined by total nitrogenase concentration calculated by cell density × nitrogenase synthesis ability. Therefore, ciprofloxacin enhanced nitrogen fixation through the stimulation of both cyanobacterial growth and nitrogenase synthesis, while tetracycline and sulfamethoxazole enhanced nitrogen fixation merely through growth stimulation. At the exposure dose of 100 ng/L, only two downregulated proteins, a phosphonate ABC transporter and a methionine aminopeptidase, as well as one upregulated protein, the phenylalanine-tRNA ligase alpha subunit, were commonly shared by three antibiotic-treated groups. Ciprofloxacin upregulated proteins related to nitrogen fixation, carbon catabolism and biosynthesis, but downregulated photosynthesis-related proteins. In contrast, tetracycline and sulfamethoxazole increased the photosynthetic activity of Nostoc sp. through upregulating photosynthesis-related proteins, but downregulated proteins related to nitrogen fixation, carbon catabolism and biosynthesis. The resistance of Nostoc sp. PCC 7120 to three target antibiotics were related with the responses of RNA synthesis regulatory proteins. Stimulation of cyanobacterial nitrogen fixation by antibiotic contaminants could aggravate eutrophication in aquatic environments. [Display omitted] • Influences of antibiotics on nitrogen-fixing capacity of Nostoc sp. were studied. • Ciprofloxacin stimulated both growth and nitrogenase synthesis ability in Nostoc sp. • Sulfamethoxazole and tetracycline enhanced nitrogen fixation via growth stimulation. • Nitrogen fixation positively correlated with carbon catabolism and biosynthesis. • Nitrogen fixation negatively correlated with photosynthesis at the proteomic level. [ABSTRACT FROM AUTHOR]

The culture of microalgae and cyanobacteria in open systems has been improved through the novel approach of thin-layer raceway ponds. The importance of studying mass cultivation of the cyanobacterium Nostoc calcicola (further as Nostoc) lies in its biotechnological potential as a source of bioactive compounds for food and non-food applications. These compounds include polysaccharides, mycosporine-like amino acids and phycocyanin. Nostoc was cultured outdoors in a thin-layer raceway pond where the biomass production, physiological status, photosynthetic activity, and biochemical composition were monitored through the experimental period of 5 days. The biomass, as did the maximal quantum yield of PSII, maximal electron transport rate (ETR max) and photosynthetic efficiency (α ETR) increased throughout the experimental period showing the optimal operation of the thin-layer raceway ponds, due to the light penetrates deeper into the thin culture layer and thus more light is available to the cells. Oxygen levels in the culture increased over time, but no photoinhibition was evident indicating optimal action of non-photochemical mechanisms. Nostoc increased the total internal carbon content over the experimental period. Chlorophyll increased, whereas the N compounds such as the biliprotein phycocyanin decreased. Among the UV-absorbing compounds, polyphenols, mycosporine-like amino acids, such as shinorine and other unknown UV-A absorbing compounds were detected. There components showed a positive correlation to antioxidant activity. Thus, the optimal accumulation of biomass and the accumulation of bio-active compounds having antioxidant capacity show the possible biotechnological applications of Nostoc. • A novel approach of thin-layer raceway ponds for cyanobacteria culture. • Cultivation of the cyanobacterium; Nostoc calcicola with biotechnological potential for to obtain bioactive compounds. • Increased the maximal electron transport rate showed the optimal operation of the thin-layer raceway pond. [ABSTRACT FROM AUTHOR]

In this present study, hydro-deoxygenation (HDO) process was performed to upgrade the liquefied bio-oil of Nostoc punctriforme biomass. The engine performance and emission properties of the enriched bio-oil and blends (with diesel) were evaluated. The HTL resulted in highest bio-oil yield of 47.5 wt% at a temperature of 300 °C at 60 min with calorific value of 32.5 MJ/kg. At 60 min and temperature of 300 °C with 1 wt% of heterogeneous catalyst the upgraded HDO-bio-oil yield reached 38.4 wt% with deoxygenation percentage of 70%. The properties of upgraded bio-oil are HHV of 44.74 MJ/kg, Kinematic viscosity of 6.23 mm2/s and density 923 kg/m3 respectively. The response surface methodology (RSM) was used for modeling and optimizing the upgraded bio-oil yield. The optimized RSM conditions for upgraded bio-oil yield (44.5 wt%) are temperature of 280 °C, catalyst load of 0.6 wt%, and time of 120 min. The physiochemical properties of upgraded bio-oil are in agreement with ASTM standards. Equal proportion of bio-oil to diesel (D50: B50) reduced the brake thermal efficiency to 6.66% with reduced NO x emission and slight increase in CO emission. This study highlights that microalga fuels are better renewable energy resource with reduced greenhouse gas emission. [Display omitted] • Hydrothermal liquefaction of N. punctiforme produced 47.5 wt% of bio-oil. • Hydro-deoxygenation resulted in 38.4 wt% of upgraded bio-oil with HHV 44.74 MJ/kg. • Upgraded fuel physiochemical properties are within ASTM standards. • Engine performance and emissions tests of bio-oil were comparable to diesel fuel. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study was to predict the anticancer drug from the members of the cyanobacteria. In silico molecular docking was carried out between the cyanobacterial drug, cryptophycin-F and different types of cancer target proteins. Molecular docking also helped to compare the commercial drug, cabazitaxel with cyanobacterial drug, cryptophycin-F. The energy values produced by the cryptophycin-F with various cancer receptor molecules were ranging from −259.14 to −330.01 while, cabazitaxel showed −228.18 to −385.32. From the above results, it is concluded that cabazitaxel and cryptophycin-F produced more or less similar docking energy with cancer receptor molecules. Therefore, cryptophycin-F, a cyanobacterial drug can be employed as an alternative drug for treating various cancers without any side effects. [Copyright &y& Elsevier]

The Nostoc genus is a well-known heterocytous, filamentous cyanobacterium which can be found all over the world. The size of terrestrial and/or freshwater colonies can be microscopic and macroscopic as well. In addition, Nostoc species are one of the most common photosynthetic cyanobacterial partners in symbiotic interactions. Terrestrial cyanobacterial colonies were collected and isolated in this study from various alkali grassland habitats (Great Hungarian Plain). Altogether 133 colonies were isolated from the 65 collected samples. The peptide patterns of the Nostoc -like strains were examined using HPLC-ESI-MS/MS and 41 peptides were identified from 45 isolated Nostoc -like strains; these compounds belonged to 4 different peptide classes. Twelve nostoginin/microginin, 16 anabaenopeptin, 12 banyaside/suomilide variants were identified. 37% of our isolated Nostoc -like strains produced some of the peptide metabolites we tested. These strains showed distinct chemotypes according to their peptide patterns, and can be divided into 4 groups based on their metabolisms. Strains either contained: (1) nostoginins/microginins, (2) anabaenopeptins, (3) anabaenopeptins and banyasides or (4) banyasides as major compounds. Banyasides were present in many of our strains and showed very high intensity in some cases. A number of previously unknown banyaside variants have been identified. • Nostoc -like strains appeared in alkali grassland habitats were investigated. • Peptide metabolite pattern of Nostoc -like strains was examined with HPLC-MS/MS. • Anabaenopeptin, nostoginin/microginin and banyaside/suomilide variants were found. • Chemotype groups were compared with heat map clustering visualization. • High peptide variability with frequent banyaside occurrences was detected. [ABSTRACT FROM AUTHOR]

An environment friendly approach towards heavy metal remediation from water is the need of the hour. A novel approach to heavy metal bioremediation from water was attempted using axenic cultures of the photoautotrophic cyanobacterium, Nostoc muscorum immobilised on to glass surface through the formation of biofilms. Being a biofilm, it exhibited much higher cellular integrity than cell suspension cultures when exposed to high concentrations of cadmium, and could also withstand the harsh conditions prevalent in industrial effluents. Being a photosynthetic organism, culturing of N. muscorum as a biofilm was achieved with minimal requirements, such as water with minerals, light and stationary conditions, which also enabled ease of scalability. The strong adherence of the N. muscorum biofilm to the glass surface was beneficial as (i) no diffusion of cell mass on to the media was observed even with the use of top-end stirrer, (ii) no expensive separation techniques were required for separation of biomass from the treated solution, and (iii) direct contact of the solution containing metals to the active components on biofilm surface allowed better interaction. The N. muscorum biofilm exhibited the capability to sequester Cd(II) in the pH range 5–9, concentration range <0.05 ppm to 100 ppm and from different waste waters. Sequestration of Cd(II) resulted in cell surface changes, the mode of sequestration being chemisorption through the >C=O and >C=N functional groups, and followed the Langmuir's adsorption isotherm. It is proposed to use the N. muscorum biofilm as a potential green technology for waste water treatment in future. • A novel approach to wastewater management: use of axenic Nostoc muscorum biofilms • Environment friendly, low cost and low waste approach: a step towards development of green technology • Tolerance to heavy metals and inherent toxicity of industrial effluents, ease of generation and scale up of Nm biofilms • Wide concentration (ppb-ppm) & pH range (5–9) and chemisorption of Cd(II) by Nm biofilm • Gives thrust to the area of wider usage of algal systems in wastewater management [ABSTRACT FROM AUTHOR]

In order to create synthetic lichens, extracellular polysaccharide (EPS)-secreting cyanobacterium Nostoc PCC 7413 was cultured together with fungal Aspergillus nidulans and Aspergillus niger species without extraneous organic carbon. Cyanobacterial supernatants and harvested EPS both supported fungal growth, while fungal supernatants slightly enhanced Nostoc growth. Furthermore, when Nostoc and A. nidulans were co-cultured together, total biomass was approximately 3-fold higher than the axenic Nostoc cultures in pH 6 buffered BG-11 media. The spectrum of fatty acids generated in co-culture differed from those of the individual cyanobacterial and fungal species. The fatty acid fractions of C18:0 and C18:1 were reduced or intermediate in co-cultures compared to mono-cultures while fractions of C16:1 and C18:3 fatty acids increased in co-culture, suggesting a shift in the fatty acid biosynthesis following co-cultivation. Our study establishes a low-cost mutualistic co-culture platform composed of cyanobacteria and filamentous fungi for producing biomass and biofuel precursors with potential commercial applications. • We established a two-partner co-culture system composed of cyanobacteria and fungi. • Cyanobacterial supernatants supported fungal growth. • Fungal supernatants enhanced cyanobacterial growth. • Levels of major fatty acids in co-culture were intermediate between two partners. • Some fatty acids decreased accompanied by increase of others in co-cultures. [ABSTRACT FROM AUTHOR]

Some filamentous cyanobacteria are phototrophic bacteria with a true multicellular life style. They show patterned cell differentiation with the distribution of metabolic tasks between different cell types. This life style requires a system of cell-cell communication and metabolite exchange along the filament. During our study of the cell wall of species Nostoc punctiforme and Anabaena sp. PCC 7120 we discovered regular perforations in the septum between neighboring cells, which we called nanopore array. AmiC-like amidases are drilling the nanopores with a diameter of 20 nm, and are essential for communication and cell differentiation. NlpD-like regulators of AmiC activity and septum localized proteins SepJ, FraC and FraD are also involved in correct nanopore formation. By focused ion beam (FIB) milling and electron cryotomography we could visualize the septal junctions, which connect adjacent cells and pass thru the nanopores. They consist of cytoplasmic caps, which are missing in the fraD mutant, a plug inside the cytoplasmic membrane and a tube like conduit. A destroyed membrane potential and other stress factors lead to a conformational change in the cap structure and loss of cell-cell communication. These gated septal junctions of cyanobacteria are ancient structures that represent an example of convergent evolution, predating metazoan gap junctions. [ABSTRACT FROM AUTHOR]

Cyanobacteria are oxygenic phoautotrophs that can utilize inorganic nitrogen salts, atmospheric nitrogen and some amino acids such as arginine as nitrogen source. Under unbalanced growth in the presence of sufficient nitrogen, many cyanobacteria accumulate cyanophycin, a co-polymer of aspartate and arginine that serves as a nitrogen reservoir. Cyanophycin metabolism enzymes include cyanophycin synthetases, cyanophycinase and isoaspartyl dipeptidase. The latter splits β‑aspartyl arginine released from cyanophycin by cyanophycinase into aspartate and arginine. The arginine catabolic pathway of cyanobacteria has been recently elucidated and consists of two bifunctional enzymes, arginine-guanidine removing enzyme (AgrE) and proline oxidase (PutA). This pathway makes available to metabolism the four nitrogen atoms of arginine, three as ammonia and one as glutamate. A variant of the pathway cycles ornithine (an intermediate in the AgrE-catalyzed reactions) back to arginine incorporating aspartate and, hence, recovering its nitrogen atom for metabolism. Many cyanobacteria also make use of this pathway to utilize arginine taken up from the outer medium through a high-affinity ABC transporter. An analysis of co-occurrence in cyanobacteria of genes encoding cyanophycin metabolism and arginine catabolism enzymes and arginine and aspartate transporters indicates a strong correlation between the presence of cyanophycin and the AgrE/PutA pathway. • Cyanobacteria accumulate cyanophycin (a poly-aspartate-arginine material) under unbalanced growth with sufficient nitrogen. • Cyanophycin serves as a transient storage of nitrogen that is very relevant in the fixation of atmospheric nitrogen. • Cyanophycin is synthesized non-ribosomally and degraded stepwise producing free aspartate and arginine. • The arginine catabolic pathway consists of two bifunctional enzymes (AgrE and PutA) that provide nitrogen to metabolism. [ABSTRACT FROM AUTHOR]