Nostoc Ellipsosporum Research Articles

Growth enhancement, metabolic profile improvement, and DXR and TPS2 gene expression changes in Thymus vulgaris L. by cyanobacterial inoculation.

In recent decades cyanobacterial species have attracted research attention as potential sources of new biostimulants. In this study, the biostimulant effects of five cyanobacterial suspensions on the growth and essential oil composition of Thymus vulgaris L. were evaluated. The expression of key genes involved in the biosynthesis of thymol and carvacrol, such as DXR and TPS2, were investigated. A pot culture experiment revealed that cyanobacterial application significantly improved T. vulgaris L. growth indices, including plant height, dry and fresh weight, leaf and flower number, leaf area, and photosynthetic pigment content. Total phenol and flavonoid content in inoculated plants also showed a significant increase compared with the control. Anabaena torulosa ISB213 inoculation significantly increased root and shoot biomass by about 65.38% and 92.98% compared with the control, respectively. Nostoc calcicola ISB215 inoculation resulted in the highest amount of essential oil accumulation (18.08 ± 0.62) in T. vulgaris leaves, by about 72.19% compared with the control (10.5 ± 0.50%). Interestingly, the amount of limonene in the Nostoc ellipsosporum ISB217 treatment (1.67%) increased significantly compared with the control and other treatments. The highest expression rates of DXR and TPS2 genes were observed in the treatment of N. ellipsosporum ISB217, with 5.92-fold and 5.22-fold increases over the control, respectively. This research revealed the potential of the cyanobacteria that were studied as promising biostimulants to increase the production of biomass and secondary metabolites of T. vulgaris L., which could be a suitable alternative to chemical fertilizers. © 2024 Society of Chemical Industry.

Toxicity evaluation of iron oxide nanoparticles to freshwater cyanobacteria Nostoc ellipsosporum.

The extensive usage of iron oxide nanoparticles (FeO NPs) in commercial and biomedical applications raises the risk of releasing their remains into the aquatic ecosystems and this could possibly cause cytotoxic effects on aquatic organisms. Thus, the toxicity assessment of FeO NPs on cyanobacteria, which are primary producers at the bottom of food chain in aquatic ecosystems, is essential to gain information about the potential ecotoxicological threat on aquatic biota. The present study investigated the cytotoxic effects of FeO NPs on Nostoc ellipsosporum using different concentrations (0, 10, 25, 50 and 100mg L-1) to track the time-dependent and dose-dependent effects and compared with its bulk equivalent. In addition, the impacts of FeO NPs and bulk counterpart on cyanobacterial cells were assessed under nitrogen as well as nitrogen-deficient conditions, because of ecological role of cyanobacteria in nitrogen fixation. The study revealed that the highest protein content was observed in the control in both types of BG-11 media compared to treatments of nano and bulk particles of Fe2O3. A 23% reduction in protein in nanoparticle treatment and a 14% reduction in bulk treatment at 100mg L-1 was observed in BG-11 medium. At same concentration, in BG-110 media, this decline was even more intense with 54% reduction in nanoparticle and a 26% reduction in bulk. Catalytic activity of catalase and superoxide dismutase was found to be linearly correlated with the dose concentration for nano and bulk form in BG-11 as well as BG-110 media. The increased levels of lactate dehydrogenase act as biomarker of the cytotoxicity brought on by nanoparticles. Optical, scanning electron, and transmission electron microscopy all demonstrated the cell entrapment, nanoparticle deposition on the cell surface, cell wall collapse and membrane degradation. A cause for concern is that nanoform was found to be more hazardous than bulk form.

Engineering recombinantly expressed lectin-based antiviral agents.

Cyanovirin-N (CV-N), a lectin from Nostoc ellipsosporum was found an infusion inhibitory protein for human immunodeficiency virus (HIV)-1. A tandem-repeat of the engineered domain-swapped dimer bound specific sites at hemagglutinin (HA), Ebola and HIV spike glycoproteins as well as dimannosylated HA peptide, N-acetyl-D-glucosamine and high-mannose containing oligosaccharides. Among these, CV-N bound the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein at a dissociation constant (KD) of 18.6 µM (and KD=260 µM to RBD), which was low-affinity carbohydrate-binding as compared with the recognition of the other viral spikes. Binding of dimannosylated peptide to homo-dimeric CVN2 and variants of CVN2 that were pairing Glu-Arg residues sterically located close to its high-affinity carbohydrate binding sites, was measured using surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). Binding affinity increased with polar interactions, when the mutated residues were used to substitute a single, or two disulfide bonds, in CVN2. Site-specific N-linked glycans on spikes were mediating the infection with influenza virus by broadly neutralizing antibodies to HA and lectin binding to HA was further investigated via modes of saturation transfer difference (STD)-NMR. Our findings showed that stoichiometry and the lectin’s binding affinity were revealed by an interaction of CVN2 with dimannose units and either the high- or low-affinity binding site. To understand how these binding mechanisms add to viral membrane fusion we compare our tested HA-derived peptides in affinity with SARS-CoV-2 glycoprotein and review lectins and their mechanisms of binding to enveloped viruses for a potential use to simulate neutralization ability.

ANN based process optimization for the growth kinetic study of Nostoc ellipsosporum NCIM 2786

ANN based process optimization for the growth kinetic study of Nostoc ellipsosporum NCIM 2786

Genome description of Nostoc ellipsosporum strain NOK (Nostocales, Cyanobacteria) isolated from an arsenic contaminated paddy field of the Bengal Delta Plains

A diazotrophic cyanobacterium, Nostoc ellipsosporum strain NOK, was isolated from an arsenic contaminated paddy field of the Bengal Delta Plains (BDP). Located across India and Bangladesh, BDP, is one of the worst arsenic (As)-affected regions of the world. Previous studies have shown this isolate to be tolerant to high concentration of arsenic (≦400 μM). The genome of this isolate was sequenced to identify the genes involved in various metabolic pathways including arsenic resistance and biofilm formation. Whole genome analyses showed Nostoc ellipsosporum strain NOK to be closely related to N. punctiforme strain PCC73102. The genome is about 10.9 Mbp which assembled into 694 contigs. Genome annotation identified 10120 genes out of which 10000 were CDSs. There are a total of 9927 protein coding genes in addition to 120 RNA coding genes. The genome codes three 5S rRNA, four 16S rRNA and three 23S rRNA genes along with 103 tRNAs, 7 ncRNAs and 73 pseudo-genes. The G + C% of the genome is 54.28. The genome codes for crucial genes involved in biofilm formation in response to stress conditions including arsenic stress. The arsBHC operon is present within the genome which makes this tolerant to high concentration of arsenic which might lead to biofilm formation. A number of ABC transporters including cysUW and sbp (sulfate/thiosulfate), nrtABC (nitrate/nitrite/cyanate), cmpABCD (bicarbonate), ssuABC (alkane sulfonate), modABCF (molybdate; 2 copies), afuAC (iron), pstA (phosphate; 2 copies), pstBC, pstS (4 copies), cbiOQ (cobalt and nickel) and opuBC, opuBB and opuBA (osmoprotectants) were identified.

Enhancement in Bell Pepper (Capsicum annuum L.) Plants with Application of Roholtiella sp. (Nostocales) under Soilless Cultivation

Cyanobacteria are found to be renewable and sustainable additives for growth improvement in crops. Extracts and biomass of three nitrogen-fixing cyanobacteria namely, Roholtiella sp. (QUCCCM97), Nostoc ellipsosporum (QUCCCM99), and Desmonostoc danxiaense (QUCCCM112) isolated from Qatar desert environment were tested for their ability to enhance the growth of bell pepper (Capsicum annuum L.) seedlings. Soilless cultivation experiments were carried out by applying the biomass and the aqueous extract of the three cyanobacteria separately. Seedlings were transplanted to Hoagland’s solution under regulated conditions. In total, 2, 4, and 6 mL L−1 of the three microalgae extract as well as 1 and 2 mg L−1 of the three microalgae biomasses (as biofertilizer) were added to the Hoagland solution. An assessment of seedling growth parameters such as shoot length, root length, fresh weight, dry weight, spad index, number of leaves per plant, and growth rate was performed. However, among the different doses and concentrations of investigated QUCCCM97, 99, and 112, our findings revealed that shoot length (cm), root length (cm), fresh weight (g), the number of leaves per plant, and growth rate were positively affected and significantly increased at maximum dose/concentration compared to control plants. With QUCCCM97, shoot length, root length, fresh weight, the number of leaves, and the growth rate increased by 17.5%, 40.3%, 26.0%, 21.6%, and 22.8%, respectively, compared to the control. Additionally, with QUCCCM99, the same parameters increased by 12.3%, 25.3%, 15.1%, 9.3%, 51.8%, respectively. While in presence of QUCCCM112, they increased by 8.7%, 30.1%, 15.6%, 5.4%, 48.6%, respectively. Our results demonstrated that extracts and biomass of cyanobacteria strains investigated here, and particularly Roholtiella sp. (Nostocales), have an enhancement potential of the seedling growth and could be used in modern agriculture to enhance productivity under the soilless system and ensure sustainability.

Photo‐catalytic reforming of aqueous phase derived from hydrothermal liquefaction of Nostoc ellipsosporum for bio‐hydrogen production

In this study, green fuel (hydrogen energy) was produced from the aqueous phase obtained from the hydrothermally liquefied Nostoc ellipsosporum biomass via photo-catalytic reforming. Initially, algae were cultivated in municipal wastewater and fog medium (80:20) in photo bio-reactor for biomass production. Later the algae biomass was liquefied under varying temperature of 220°C to 320°C at 5Mpa for 60 min. From the results, it was seen that the maximum bio-oil yield was 31 wt% for biomass to solvent ratio of 0.05 g/mL at 300°C. Gas Chromatography-Mass Spectroscopy (GC-MS) analysis of bio-oil showed the presence of hydrocarbons like octadecane, heptadecane, etc. Aqueous phase comprised of hydrogen generating low molecular weight compounds. Photo-catalytic reforming process with 0.1 g of TiO2 catalyst at time of 2 h resulted in hydrogen yield of 27 wt%. Catalyst reusability study resulted in cumulative hydrogen yield of 76 wt% from five consecutive cycles.

Genomic screening and molecular dynamics simulations of cyanovirin-N homologs from cyanobacteria phylum.

The phylum cyanobacteria are one of the most ancient groups of organisms on the planet and are well recognized due to its wide distribution, ecological role, and biotechnological potential. Cyanobacterial lectins are being extensively explored due to their antiviral activity, mainly because of their capacity of inhibiting HIV strains from infecting human cells by gp120 and gp41 binding. Cianovirin-N from Nostoc ellipsosporum was the first lectin isolated with this property. Since then, various homologs have been discovered and characterized. In this article, we present results of a genomic screening to find cyanovirin-N homologs (CVNH) in all cyanobacteria genomes available in the GenBank, resulting in 155 CVNH proteins with 63 presenting significant identity differences of cyanovirin-N. Homology modeling and molecular dynamics were employed to characterize 18 unexplored models and their functional capacity of binding to Manα(1-2)Man. Results presented here support the hypothesis of multiple ligand recognition for the CVNH family and may help to understand the function of these lectins for the producer cyanobacteria. Additionally, the theoretical results observed here justify carrying out experimental investigations that can expand the therapeutic potential of cyanobacterial lectins.

Hydrothermal liquefaction of Nostoc ellipsosporum biomass grown in municipal wastewater under optimized conditions for bio-oil production

Microalgae offer numerous potential applications, however the industrial scale-up of algal technology still remains a challenge due to high production cost. Optimization of growth conditions and integration with waste streams can improve the economic viability of microalgal production systems. This study investigated on the optimal growth conditions of microalgae Nostoc ellipsosporum cultivated in municipal wastewater with the objective of achieving maximum biomass production, nutrient removal efficiency and bio-oil yield. The effect of light intensity, photoperiod, wavelength, aeration and growth media composition were studied. Different formulations of municipal wastewater blended with Fog's nutrient were used as growth medium. Optimization of growth conditions and acclimatization to wastewater enhanced the biomass yield of Nostoc ellipsosporum from 1.42 to 2.9 g L−1, achieving 87.59% of nitrogen removal and 88.31% of phosphate removal from wastewater. Furthermore, hydrothermal liquefaction of biomass produced bio-oil yield of 24.62% at 300 °C.

Effect of arsenic on exopolysaccharide production in a diazotrophic cyanobacterium

The Bengal Delta Plain (BDP), located across India and Bangladesh, is one of the worst arsenic (As)-affected regions, including contaminated agricultural lands. The effect of As on the growth and exopolysaccharide (EPS) production was investigated in Nostoc ellipsosporum, a diazotrophic cyanobacterium isolated from a paddy field located in BDP. The cells were exposed to 0 (control), 50, 200, and 400 μM concentrations of sodium arsenite salt and monitored for 21 days. For 50 and 200 μM arsenite treatments, cellular growth was found to be stimulated, whereas, at 400 μM treatment, a characteristic growth behavior was observed compared with growth in control culture. There was an inhibition phase for the first 9 days, followed by a steady increase of growth. During the initial 9 days, the released EPS production (normalized to cell density) in 400 μM As-treated culture was very high compared with that of the lower As treatments. Based on microscopy, it was observed that there was an aggregation of cell filaments in 400 μM treatment culture. In case of capsular EPS, no difference was observed in 50 μM treatment. However, in 200 and 400 μM treatments, capsules were disintegrated after 12 and 15 days of incubation, respectively. Energy-dispersive X-ray spectroscopy (EDS) study showed the binding potential of released and capsular EPS toward As. The adaptive capabilities of N. ellipsosporum, including behavior of multicellularity and protective role of EPS from As stress, can be useful for incorporating in cost-effective bioremediation strategies to remove As from agricultural fields.

Morphological analysis of Spirulina sp. NCIM 5143 and Nostoc ellipsosporum NCIM 2786 and comparative characterization of associated enzymes through in silico approach

Cyanobacteria are the only prokaryotes that can utilize energy sources from sunlight, electrons from water, carbon from the air, and have the capability of fixing nitrogen. The characterization of various cyanobacteria reveals the performance as well as growth differences when compared among different genus of cyanobacteria, which emphasizes the value of characterization in the cellular grounds. In this paper, we have performed a comparative study on the morphology, growth pattern, physiochemical properties as well as structural features of Spirulina sp. NCIM 5143 and Nostoc ellipsosporum NCIM 2786. The comparison is performed through microscopic images, FESEM and statistical study of cell growth by ANOVA. In silico approach was also carried out on the two enzymes present in both the cyanobacteria, Cyanophycin synthestase (EC: 6.3.2.29) and Nitrate reductase (EC: 1.7.1.1) by studying the physicochemical properties, sequential features and structural modeling. A descriptive profile study was completed on these microorganisms and their proteins that may help to interpret the molecular mechanism of the enzymatic reaction of 1, 3-Propanediol (PDO) production in the future.

Modeling the effects of light wavelength on the growth of Nostoc ellipsosporum

Mathematical models provide information about population dynamics under different conditions. In the study, four models were evaluated and employed to describe the growth kinetics of Nostoc ellipsosporum with different light wavelengths: Baranyi-Roberts, Modified Gompertz, Modified Logistic, and Richards. N. ellipsosporum was grown in BG-11 liquid medium for 9 days, using 12 hours of photoperiod and the following treatments: white light (400-800 nm), red light (650-800 nm), yellow light (550-580 nm) and blue light (460-480 nm). Each experiment was performed in triplicate. The optical density (OD) was measured on days 1, 3, 5, 7 and 9, using a spectrophotometer at 650 nm. The maximum cell growth was obtained under white light (OD650 : 0.090 ± 0.008), followed by the yellow light (OD650 :0.057 ± 0.004). Conversely, blue light showed a marked inhibitory effect on the growth of N. ellipsosporum (OD650 : 0.009 ± 0.001). The results revealed that the Baranyi-Roberts model had a better fit with the experimental data from N. ellipsosporum growth in all four treatments. The findings from this modeling study could be used in several biotechnological applications that require the productionof N. ellipsosporum and its bioproducts.

Occurrence of Nostoc Vaucher ex Bornet And Flahault in Water Bodies of Maldah District, West Bengal

Present investigation deals with systematic enumeration, importance and uses of Genus Nostoc Vaucher ex Bornet and Flahault collected from different water bodies of Maldah District, West Bengal. Six species and one variety of Genus Nostoc Vaucher ex Bornet and Flahault (Nostoc calcicola Bréb. ex Bornet and Flahault, Nostoc carneum C.Agardh ex Bornet and Flahault, Nostoc comminutum Kütz., Nostoc ellipsosporum Rabenh. ex Bornet and Flahault, Nostoc linckia Bornet ex Bornet and Flahault, Nostoc oryzae (F.E.Fritsch) Komárek and Anagn. and Nostoc ellipsosporum var. violaceum C.B.Rao) were recorded from water bodies of out of fifteen, four blocks - Harishchandrapur-I, Harishchandrapur-II, Ratua II and Gazol of Maldah District, West Bengal. Nostoc ellipsosporum var. violaceum C.B.Rao has been reported for the first time from barabilla bil of block Ratua II of Maldah District, West Bengal. Some of the species of Nostoc Vaucher ex Bornet and Flahault are very important and useful in different ways which has been described in this paper.

Antioxidative responses of Nostoc ellipsosporum and Nostoc piscinale to salt stress

The responses of the cyanobacteria Nostoc ellipsosporum and Nostoc piscinale to salt stress during various growth stages were studied. Nostoc ellipsosporum was more NaCl tolerant and attained more biomass under salinity than N. piscinale. Accumulation of proline was detected in N. ellipsosporum under salinity stress. Malondialdehyde content decreased in both species on day 9 (mid log phase) under salt stress. A similar trend was detected in hydrogen peroxide (H2O2) content in N. ellipsosporum. Strong induction in catalase (CAT) activity was observed in N. ellipsosporum on day 9 in the presence of salt. The increase in CAT activity of N. piscinale was observed only at higher concentrations of NaCl. In contrast to N. ellipsosporum, induction in peroxidase and polyphenol oxidase (PPO) activities on day 9 was stronger in N. piscinale. Salinity enhanced superoxide dismutase (SOD) and PPO activity in N. ellipsosporum at all growth stages. Moreover, different isoforms of CAT and SOD were detected in these cyanobacteria. Apparently, selection pressure in these cyanobacteria has led to the evolution of SODs and CATs as the main antioxidant enzymes against reactive oxygen species. Phycobiliprotein content in N. ellipsosporum under all conditions was significantly higher than that in N. piscinale. NaCl at moderate concentrations significantly increased phycobiliprotein content in the middle of the log phase in both species. Moreover, contrary to N. piscinale, the size of phycobilisomes [phycoerythrin + phycocyanin / allophycocyanin] in N. ellipsosporum increased significantly under salt stress at the mid of log phase and later. The increase in size of phycobilisomes in N. ellipsosporum could help this species to withstand salt stress by enhancing energy transfer capacity. These results suggest that N. ellipsosporum cells could be better protected against salinity-induced oxidative damage by maintaining higher levels of antioxidative enzymes, proline, and phycobiliproteins than the cells of N. piscinale.

New technologies from the bioworld: selection of biopolymer-producing microalgae

Abstract Microalgae are studied because of their biotechnological potential. The growth of microalgae aims at obtaining natural compounds. Due to the large amount of accumulated polymer waste, one of the solutions is the use of biodegradable polymers. The objective of this work was to select biopolymer-producing microalgae and to study the cell growth phase in which maximum production occurs. Microalgae Cyanobium sp., Nostoc ellipsosporum, Spirulina sp. LEB 18 and Synechococcus nidulans were studied. The growth was carried out in closed 2 L photobioreactors kept in a chamber thermostated at 30 °C with an illuminance of 41.6 μmolphotons.m-2.s-1 and a 12 h light/dark photoperiod. The biopolymers were extracted at times of 5, 10, 15, 20 and 25 d. The microalgae that had the highest yields were Nostoc ellipsosporum and Spirulina sp. LEB 18 with crude biopolymer efficiency of 19.27 and 20.62% in 10 and 15 d, respectively, at the maximum cell growth phase.

Bioremediation of salt affected soils using cyanobacteria in terms of physical structure, nutrient status and microbial activity

In present investigation, consortia of two indigenous heterocystous cyanobacteria, Nostoc ellipsosporum HH-205 and Nostoc punctiforme HH-206 isolated from a salt affected area of Hisar, Haryana (India) were used as biofertilizer in bioremediation of salt affected soils having high electrical conductivity (13.5 dS/m) and pH (8) with poor organic carbon (0.3%) as well as nitrogen content (0.008%). The experiments were conducted in a pot house for the period of 240 days. There was a significant (P < 0.05) increase in carbon, phosphate, nitrogen, potassium, magnesium, cation exchange capacity, mean weight diameter and hydraulic conductivity of soil with biofertilizer treatment whereas sodium ion and electrical conductivity were found to be decreased. Improvement in soil aggregation and stability due to increased soil microbial activities (dehydrogenase, invertase and phosphomonoesterase) were also observed. Significant increase in growth and yield of pearl millet–wheat crop was observed in amended pots even under low water regime. Thus, the indigenous cyanobacterial species show promise in effective exploitation for phytoremediation and improved productivity of saline soils under semi-arid condition.

Gold (III) bioreduction by cyanobacteria with special reference to in vitro biosafety assay of gold nanoparticles

Bioreduction of Au3+ to Au0 and subsequent synthesis of gold nanoparticles using three cyanobacterial strains Leptolyngbya tenuis, Coleofasciculus chthonoplastes, and Nostoc ellipsosporum was investigated. The optimized condition for maximum gold nanoparticle synthesis was determined as 20 mg cyanobacterial biomass per 100 mL of 15 mg L−1 Au3+ solution as inoculum size at pH 5. At the onset of nanoparticle synthesis (up to 3 h) increased activity of catalase, ascorbate peroxidase, super oxide dismutase, and malondialdehyde content along with rapid loss of pigments and protein content (1–72 h) indicated gold toxicity at cellular level. Associated changes in thallus morphology were also significant. Nostoc biomass produced spherical- to irregular-shaped nanoparticles with diverse sizes and small number of nanorods. On the other hand, Coleofasciculus showed nanoparticle synthesis at extracellular medium which was either absent in Nostoc or very low in Leptolyngbya. Biosafety analysis by MTT assay using peripheral blood mononuclear cells (PBMC), two cancer cell lines viz. T cell acute (T-ALL) and human acute lymphoblastic leukemia (MOLT-4) and antibacterial effect against Pseudomonas aeruginosa and Staphylococcus aureus showed no toxic effect of synthesized gold nanoparticles.

Optimization of Critical Medium Components for Protein Production by Nostoc ellipsosporum Using Response Surface Methodology

Nostoc ellipsosporum is a pharmaceutically important cyanobacteria known for the production of anti-HIV drug called cyanovirin. A five-level four factor central composite design of response surface methodology (RSM) was performed to identify the optimal level for maximum protein production. Four medium variables, PHA extract, glucose, Fe-EDTA and micronutrients, were chosen for RSM optimization study. Experimental data were analyzed by regression, and model equation was constructed. Maximum protein production was expected at the predicted optimal level of PHA extract, 2.50 % (v/v), glucose, 0.05 % (w/v), Fe-EDTA, 0.125 % (v/v) and micronutrients, 0.125 % (v/v). Validation experiment results were in good agreement with the results predicted by RSM. Results of this study showed that optimization by RSM approach improves the protein production, and also PHA extract was found to be a significant medium component for enhancing the protein synthesis.

Expression, purification and analysis of the anti-HIV Cyanovirin-N produced in transgenic soybeans seeds

Background Human immunodeficiency virus (HIV) is infecting over 34.0 million people worldwide, being responsible for one of the major current pandemics [1]. The most severely affected region is the Sub-Saharan Africa where nearly 1 in 20 adults is infected with HIV, accounting for 69% of infections worldwide [1]. Several strategies to halt HIV spread are currently being pursued, including the use of ectopic microbiocides. This approach is particularly important for women, among which the infection rate can be almost three more times than men. CyanovirinN (CVN) is a lectin-like protein isolated from blue algae Nostoc ellipsosporum. CVN is highly thermo stable and is capable of binding to HIV GP120 protein blocking viral infection [2,3]. In this report we describe the use of transgenic soybean plants as a potential platform to achieve large scale, cost-effective production of CVN.

Sex hormonal disruption by cyanobacterial bioactive compounds

This study investigated the effect of some cyanobacterial exudates on the level of sex hormones in a mammalian model and to identify the molecules that could act as endocrine disruptor. In this study, the cytotoxicity of purified exudates of some axenic cyanobacterial cultures (Nostoc ellipsosporum, Nostoc muscorum, Anabaena oryzae & Anabaena. sp.) was evaluated against normal melanocyte cell line (HFB4). The intraperitoneal injection of the cyanobacterial exudates demonstrated a marked disturbance in the serum level of testosterone, progesterone, follicular stimulating hormone (FSH) and luteinizing hormone (LH) of male mice. GC-MS and LC-MS/MS analysis showed the presence of some sterol-like compounds in the cyanobacterial filtrates. This work demonstrated that the nontoxic cyanobacterial species have the ability to produce some bioactive compounds into their surroundings that can disrupt the mammalian reproductive hormones. The cyanobacterial extracellular bioactive molecules can affect on the production of the sex hormones via positive and negative feedback and may be a risk to human beings.