Nostoc Linckia Research Articles

A preliminary survey of the diversity of soil algae and cyanoprokaryotes on mafic and ultramafic substrates in South Africa

Despite a large body of work on the serpentine-substrate effect on vascular plants, little work has been undertaken to describe algal communities found on serpentine soils derived from peridotite and other ultramafic rocks. We report a preliminary study describing the occurrence of algae and cyanoprokaryotes on mafic and ultramafic substrates from South Africa. Results suggest that slope and aspect play a key role in species diversity and community composition and, although low pH, nutrients and metal content do not reduce species richness, these edaphic features also influence species composition. Further, typical soil genera such as Leptolyngbya, Microcoleus, Phormidium, Chlamydomonas, Chlorococcum and Hantzschia were found at most sites. Chroococcus sp., Scytonema ocellatum, Nostoc linckia, Chlorotetraedron sp., Hormotilopsis gelatinosa, Klebsormidium flaccidium, Pleurococcus sp. and Tetracystis elliptica were unique to one serpentine site. The preliminary survey provides directions for future research on the serpentine-substrate effect on algal and cyanoprokaryote diversity in South Africa.

Screening metal-dye-tolerant photoautotrophic microbes from textile wastewaters for biohydrogen production

In the present study, tolerance of ten microalgal strains isolated from wastewaters of different textile mills in relation to two metals and dyes was studied based on cell growth estimated spectrophotometrically. Three cyanobacterial strains that were found to tolerate both Cr(VI) and Co(II) along with the dyes reactive red 198 (RR 198) and crystal violet (CV) were investigated further for the concen- tration of various photosynthetic pigments and exopolymer production in the presence of the dyes and metals. All three tolerant species—Nostoc linckia HA-46, Myxosarcina spectabilis HP-43 and Gloeocapsa calcarea HP-45—showed a significantly higher concentration (P 0.05). Production of hydrogen by these photoautotrophic microbes was moderate (19-28 nmol h �1 mg �1 dry wt). The best performing strain, N. linckia, when examined further for its hydrogen production potential in the presence of the two dyes and metals, showed significantly higher rates of hydrogen production in the presence of Cr, Co and RR 198. Its hydrog- enase activity also followed the same trend. Immobilization of the microbe into alginate beads almost doubled the hydrogen production by the organism in the control as well as in the presence of suitable concentrations of the two metals (10 mg L �1 ) and dyes (50 mg L �1 ).

Nostoc Linckia as Biosorbent of Chromium and Nickel from Electroplating Industry Wastewaters

The present study relates to the use of cyanobacterium Nostoc linkia for removal of chromium and nickel from wastewater of galvanic industry. To determine concentrations of Cr and Ni in wastewater samples atomic absorption spectrometry was used. The samples of dried nostoc biomass after exposure to wastewater were subject to nondestructive instrumental neutron activation analysis. During 30 min of the contact of biomass with wastewater 84% of chromium was removed from the wastewaters. Beside chromium after 30 min nostoc biomass accumulates the amount of iron and zinc that exceeds their concentrations in the control biomass samples by a factor of 6 and 8, respectively. Nickel content in biomass after interaction with Cr-containing wastewater increases sixty fold and copper-sixteen fold. During the same time of biomass-Ni-containing wastewater interaction, 50% of nickel were accumulated. The method of Fourier transform infrared spectroscopy was applied to identify functional groups responsible for metal binding.

Limnology and cyanobacterial diversity of high altitude lakes of Lahaul-Spiti in Himachal Pradesh, India.

Limnological data of four high altitude lakes from the cold desert region of Himachal Pradesh, India, has been correlated with cyanobacterial diversity. Physico-chemical characteristics and nutrient contents of the studied lakes revealed that Sissu Lake is mesotrophic while Chandra Tal, Suraj Tal and Deepak Tal are ultra-oligotrophic. Based on morphology and 16S rRNA gene sequence, a total of 20 cyanobacterial species belonging to 11 genera were identified. Canonical correspondence analysis distinguished three groups of species with respect to their occurrence and nutrient/physical environment demand. The first group, which included Nostoc linckia, N. punctiforme, Nodularia sphaerocarpa, Geitlerinema acutissimum, Limnothrix redekii, Planktothrix agardhii and Plank. clathrata, was characteristic of water with high nutrient content and high temperature. The second group, including Gloeocapsopsis pleurocapsoides, Leptolyngbya antarctica, L. frigida, Pseudanabaena frigida and N. spongiaeforme, occurred in oligotrophic water with high pH and low temperature. The distribution of third group of Cyanobium parvum, Synechocystis pevalekii, L. benthonica, L. foveolarum, L. lurida, L. valderiana, Phormidium autumnale and P. chalybeum could not be associated with a particular environmental condition because of their presence in all sampling sites.

Moving bed biofilm reactor technology as batch system in wastewater treatment

Biofilm slime layer is one of the advanced biological treatment technologies for industrial and municipal wastewater treatment with the capacity to reuse of treated water for agricultural purposes. Bacterial, fungal and algal biofilm slime layer were grown on the interior surfaces of polyethylene pellet (carrier) and suspended in municipal wastewater for organic pollutants removal. Bacterial species (Pseudomonas aeruginosa, Bacillus megaterium, Sphingobacterium thalpophilum), fungal species (Penicillium citrinum, Aspergillus niger, Trichoderma harzianum) and algal species (Nostoc linckia, Scendesmus dimorphus) were used separately for biofilm slime layer growth under controlled laboratory conditions (pH, temperature, and aeration). Bacterial biofilm layer thickness was measured and recorded 9, 6 and 5 mm respectively as compared with 3mm for control group through the retention time of 16 day. Bacterial P. aeruginosa biofilm slime layer showed an efficiency for COD, TOC, NO3 and PO4 removal after 24 hour of 75%, 65%, 69% and56% respectively while the removal rates of the same factors using the fungal biofilm layer of P. citrinum was 83%, 78%, 53% and 60% after 48 hour respectively. The algal biofilm reactor with S. dimorphus showed the highest percentage removal rate of total nitrogen 93% as compared to control group 87% after 72 hours of treatment due to the biofilm slime thickness of S. dimorphus 7.5mm as compared to the thickness of the N. linckia slime layer 5.3mm. Mixture of microbial species biofilm layer was used for wastewater treatment through 18 and 24 hours, using aerobic and anoxia. The mixture of microbial species biofilm layer showed removal rates for TOC, COD, and TN of 90%, 83%, and 59% respectively in an aerobic condition, while the removal rates were 66%, 52%, and 84% in an anoxic condition. From the above results, one concludes that controlling the biofilm slim layer is a promising technology for municipal wastewater treatment, as long as it is used under the suitable conditions.

Prolonged hydrogen production by Nostoc in photobioreactor and multi-stage use of the biological waste for column biosorption of some dyes and metals

Hydrogen production by Nostoc linckia was studied using both free and alginate immobilized biomass of the cyanobacterium in separate lab-scale photobioreactors (PBRs). Hydrogen production rates improved significantly when immobilized cyanobacterial biomass was used in PBR and the production continued up to 25 days by maintaining required anoxic conditions and carbohydrate supplement. Average hydrogen production rate over 25 days was 132 μmolH2/h/mg Chl a. The biological waste from the PBRs was utilized for sequestration of two toxic heavy metals (chromium and cobalt) and carcinogenic dyes (Reactive Red 198 and Crystal Violet) from aqueous solutions in packed-bed column. From the PBR containing free N. linckia cells, the spent biomass was collected after 7 d, dried and immobilized in alginate matrix, and used as a biosorbent for optimizing bed height and flow rate of the column. Breakthrough capacity of the packed-bed column was determined and breakthrough curves were analyzed using BDST model. Three PBRs containing immobilized cyanobacterial biomass were run for 5, 15 and 25 days, and the biological waste collected at the end of the operation was used for biosorption studies under optimized conditions (bed height, 25 cm; flow rate, 3 mL/min). Biosorption efficiency of the waste biomass was found to be influenced by the operation time of the hydrogen photobioreactor.

ADVANTAGES OF APPLICATION OF ALGORIZOBACTERIAL CONSORTIA IN CULTIVATION OF LEGUME CROPS

Possibility of creation of effective algobacterial consortia with high nodulе ability of rhizobial cells is experimentally proven. Pre-sowing bakterization treatment of chickpea seeds provided the increase of the productivity of plants such polyfunctional cyanorhizobial complex by 43,4% in the conditions of the field experiment. It may serve as a base for biological technology of growing chickpea for obtaining of ecologically safe production. We brought under cultivation 12 strains associated with a strain of cyanobacteria Nostoc linckia 144, identified by their morphological, cultural, physiological, and biochemical properties. We revealed that on nitrogen-free substrate some 62 and 77% of strains satellite cyanobacteria and algae itself positively affect tuberization of soybeans and chickpeas and increase the dry weight of aboveground plant up to 28,6-35,7%; under condition of Southern black soils the bacterization of strains of Microbacterium laevaniformans KAGK and Mesorhizobium siceri raised the ground dry weight of plants per 0.82 g / plant (21.1%) compared with mono-farmery. We created the effective algological bacterial consortium of high activity of Mesorhizobium siceri cells, whose number was 9.7 h105 BUOD / mL, which exceed by two orders of magnitude higher the monoculture rhizobia. We proved experimentally the efficiency of usage of cyanobacteria combined with nodule bacteria in agrobiotechnology and suggested the high efficiency of prebacteryzation of seed by cyan-rhyzo-consortium of chickpeas which ensuring the increase of plant productivity by 43.4%.

Bioactivity of natural compounds isolated from cyanobacteria and green algae against human pathogenic bacteria and yeast

Analysis of bioactive natural compounds of algae such as cyanobacteria (Spirulina platensis; Nostoc linckia; Phormidium autumnale; Tolypothrix distorta and Microcystis aeruginosa) and green algae (Chlorella vulgaris and Dunaliella salina), and their activity against human pathogenic bacteria and yeast such as Salmonella suis ATCC 13076;Pseudomonas aeruginosa ATCC 27583; Escherichia coli ATCC 25922; Staphyllococcus aureus ATCC 25923; Bacillus subtilis ATCC 6633; Shigella sonnei ATCC 11060 andCandida albicans ATCC 10231 have been studied in Saudi Arabia. Extraction of algal metabolites was performed by using the mixture of three organic reagents, methanol:acetone:diethyl ether as 5:2:1 v/v, respectively. All metabolites of algae isolates had shown weak to strong antimicrobial activity toward one or more human pathogenic microorganisms. Almost all the algal extract showed strong activity against S. sonnei in agar well diffusion technique. Crude extract of cyanobacteria, T. distorta showed moderate to strong activity against S. aureus, B. subtilis and S. sonnei. Further, crude extract of all the algal metabolites have been analyzed using gas chromatography-mass spectrometry (GC-MS). Results indicated that the main component in the crude extracts of P. autumnaleis 1-Hexyl-2-Nitrocyclohexane (91.7%); C. vulgaris is 2-Butanol, 3-methyl-, (S)- (90.8%); S. platensis is Nitrocyclohexane-2-Hexyl-1 (92.1%); N. nostoc is Octadecanal (aldehyde) (86.8%); D. salina is 3-Methyl-2-(2-Oxopropyl) Furan (90.%); T. distorta is Boronic acid, Ethyl-, Dimethyl ester (83.9%) and lastly M. aeruginosa is (S)-(+)-1-Cyclohexylethylamine representing 91.9%, respectively. Further, in this study, the extracts of all the algal species especially T. distorta, P. automonate, C. vulgaris and D. salina have been found potential for the production of several compounds including biomedically important organic metabolites such as ethane,1,1-diethoxy-; butanal; heptanal and octanal. Further study for the purification of the potent compound will explain their usefulness in the pharmaceutical and biotechnological industry. Key words: Cyanobacteria, green algae, algal extract, gas chromatography-mass spectrometry (GC-MS), antimicrobial activity, human pathogenic bacteria, biomedical properties.

Antibacterial activities of the extracts of cyanobacteria and green algae isolated from desert soil in Riyadh, Kingdom of Saudi Arabia

In compliance to the recent surveys on algal species and their potentials to produce biologically active compounds, seven algal species belonging to cyanobacteria such as Spirulina platensis, Nostoc linckia, Phormidium autumnale, Tolypothrix distorta and Microcystis aeruginosa and green algae such as Chlorella vulgaris, and Dunaliella salina, were isolated from soil in Riyadh, Saudi Arabia. All algal species were morphologically identified using scanning electron microscopy, in addition to light microscopic analysis. Liquid media BG11 was used for cultivation of algal isolates for four weeks; chlorophylls were estimated in the exponential growth phase after two weeks growth in liquid BG11 medium; in liquid medium after four weeks incubation, maximum growth was recorded for Dunaliella salina and N. linckia using cell mass weight. Extraction of algal species were tested for antibacterial activity using agar well diffusion method against a variety of human pathogenic bacteria such as Salmonella suis ATCC 13076; Pseudomonas aeruginosa ATCC 27583; Escherichia coli ATCC 25922; Staphylococcus aureus ATCC 25923; Bacillus subtilis ATCC 6633; Shigella sonnei ATCC 11060 and one yeast Candida albicans ATCC 10231. The bioactive metabolites from algal species were extracted using three different solvent system as methanol: acetone: diethyl ether (5:2:1), acetone and ethanol. The methanol : acetone : diethyl ether solvent system was the most effective solvent system among the three and showed strong activity against S. sonnei, S. aureus, and B. subtilis. Ethanol extract of P. autumnale showed activity against only C. albicans. Key words : Algae isolation, scanning electron microscope, cyanobacteria, green algae, algal extract, antimicrobial activity, human pathogenic bacteria and yeast.

The species composition cyanobacteria in the cultivated soils of Dak Lak and Dak Nong provinces

A total of 129 species and subspecies of cyanobacteria were found in the cultivating soils (rice, cotton and coffee) of Dak Lak and Dak Nong provinces. They belonged to 20 genera, 10 families, 4 orders. The Ocillatoriales order was the most diverse with 71 species and subspecies (55.03% total found species); the Nostocales order with 44 species and subspecies (55.03%); Chroococcales order: 7 species (5.43%); and Stigonematales order: 7 species (5.43%). They are morphologically diverse: fibrifrom with 122 species (94.57%); unicellular with 7 species (5.43%). Among them there are 5 genera, 11 species and subspecies exicting in 3 types of cultivated soils the genera are: Lyngbya, Microcoleus, Phormidium, Nostoc and Hapalosiphon; the species are Gloeocapsa montana, Lyngbya aerugineo-coerulea, Oscillatoria brevis, Phormidium corium, Phormidium tenue, Cylindrospermum licheniforme, Nostoc carneum, Nostoc linckia, Calothrix elenkinii, Hapalosiphon welwitschi, Hapalosiphon sp. Among them 1 genus (Westiellopsis Janet), 38 species and subspecies were firstly recorded in Vietnam. Of the cultivated soils of Daklak and Daknong provinces, the rice soil was determined to possess the most species of cyanobacteria (101 species and subspecies, 18 genera, 9 families, 4 orders), it was folowed by the cotton-paddy soil (55 species and subspecies, 14 genera, 8 families, 4 orders) and the coffee-planted soil showed the least (26 species and subspecies, 11 genus, 8 families, 4 orders).

Biological control of fusarium wilt of tomato by antagonist fungi and cyanobacteria

Biological control of Fusarium oxysporum f. sp . lycopersici (FOL) causing wilt disease of tomato was studied in vitro as well as under pot conditions. Dual culture technique showed that Aspergillus niger, Penicillium citrinum, Penicillium sp. and Trichoderma harzianum inhibited the radial colony growth of the test pathogen. Methanol extract of Nostoc linckia and Phormidium autumnale showed moderate and minor zone of inhibition. Maximum seed germination was observed in seeds treated with N. linckia (93%), whereas, T. harzianum, P. autumnale, P. citrinum showed 80% seed germination, while A. niger treated seeds showed 50% germination. Under pot conditions, the plant heights, fresh and dry weight of plants were found to be increased significantly (p ≤ 0.05) in all treatments except in P. autumnale amended soil. Similar results were observed in chlorophyll (a+b) content of treated plants. Maximum control of wilt disease was observed with T. harzianum (44.4%) treated plants as compared to FOL inoculated plants. Whereas, effectiveness of the other antagonists were recorded in the following order: A. niger (35.6%), N. linckia (33.3%), P. citrinum (24.4%), and P. autumnale (0.9 %). Key words : Biological control, fusarium wilt, tomato, antagonist fungi, cyanobacteria

Biodegradation of Phenolic and Polycyclic Aromatic Compounds by Some Algae and Cyanobacteria

In this work, the oxidation of phenolic compounds was accompanied by shift in the wavelength and change in the colour such as the oxidation of phenol to catechol by Volvox aureus, Nostoc Linckia and Oscillatoria rubescens . The oxidation of β-naphthol by Volvox aureus, Lyngbya lagerlerimi and Nostoc linckia , and the oxidation of catechol by Chlorella vulgaris and V. aureus were suggested. The degradation of polycyclic aromatic hydrocarbons by different algae seems to be related to the molecular structures of the compound and physiological metabolism of the algae. The highest percentage of degradation of naphthalene by N. linckia after 7 days was 47.71%, while the highest percentage of degradation of anthracene by E. viridis after 7 days was 92.28%. The highest percentage of degradation of 2-methythie 3-phenyl quinazlin-4- 3H (one) by V. aureus after 7 days was 83.39%, and the highest percentage of degradation of 2- phenyl 3,1benzexazin-4 one by E. viridis after 7 days was 79.74%. The obtained results suggest that microbial biodegradation of pollutants can be used to clean up contaminated environments. Biotreatment of wastes using living organisms is an environmentally friendly, relatively simple and cost-effective alternative to physico-chemical processes.

Biosorption of reactive dye by waste biomass of Nostoc linckia

Potential of spent biomass of a cyanobacterium, Nostoc linckia HA 46, from a hydrogen bioreactor was studied for biosorption of a textile dye, reactive red 198. The waste biomass was immobilized in calcium alginate and used for biosorption of the dye from aqueous solution using response surface methodology (RSM). Kinetics of the dye in aqueous solution was studied in batch mode. Interactive effects of initial dye concentration (100–500 mg/L), pH (2–6) and temperature (25–45 °C) on dye removal were examined using Box-Behnken design. Maximum adsorption capacity of the immobilized biomass was 93.5 mg/g at pH 2.0, initial concentration of 100 mg/L and 35 °C temperature, when 94% of the dye was removed. Fourier transform infrared (FT-IR) studies revealed that biosorption was mainly mediated by functional groups like hydroxyl, amide, carboxylate, methyl and methylene groups present on the cell surface.

Biosorption of chromium(VI) by spent cyanobacterial biomass from a hydrogen fermentor using Box-Behnken model

The study explores utilization of waste cyanobacterial biomass of Nostoc linckia from a lab-scale hydrogen fermentor for the biosorption of Cr(VI) from aqueous solution. The biomass immobilized in alginate beads was used for removal of the metal in batch mode optimizing the process conditions adopting response surface methodology (RSM). Kinetic studies were done to get useful information on the rate of chromium adsorption onto the cyanobacterial biomass, which was found to follow pseudo second-order model. Four important process parameters including initial metal concentration (10–100 mg/L), pH (2–6), temperature (25–45 °C) and cyanobacterial dose (0.1–2.0 g) were optimized to obtain the best response of Cr(VI) removal using the statistical Box-Behnken design. The response surface data indicated maximum Cr(VI) biosorption at pH 2–4 with different initial concentrations of the metal in the aqueous solution. The biosorbent could remove 80–90% chromium from solutions with initial metal concentration of 10–55 mg/L. Involvement of the surface characteristics of the biomass was studied through its scanning electron micrographs and Fourier transform infrared (FTIR) analysis.

Sequestration of Co(II) from aqueous solution using immobilized biomass of Nostoc linckia waste from a hydrogen bioreactor

The study was conducted to explore the potential of spent biomass of a hydrogen producing cyanobacterium, Nostoc linckia for removal of Co(II) from aqueous solution. The biomass waste generated from a lab-scale hydrogen bioreactor was immobilized in calcium alginate and used as a biosorbent. Kinetic studies indicated that biosorption of Co(II) on the cyanobacterial biomass followed pseudo second order model with an equilibrium time of 125min.Response surface methodology (RSM) was used to design experiments for optimization of pH (1.0–6.0), temperature (25–45°C) and initial metal concentration (10–100mg/L) for achieving maximum removal of Co(II) by the biosorbent. The data was fitted to a second-order polynomial equation and highly significant regression coefficients confirmed that the model could be applied for obtaining the desired response within the design range using the present biosorbent. The response surface data showed a maximum of 97% metal removal at pH 3.5 and 25°C temperature at initial metal concentrations of 10mg/L.

Waste biomass of Nostoc linckia as adsorbent of crystal violet dye: Optimization based on statistical model

The potential of spent biomass of a hydrogen producing cyanobacterial strain Nostoc linckia from a hydrogen fermentor was studied for decolorization of a tri-phenylmethane dye, crystal violet. The waste cyanobacterial biomass immobilized in calcium alginate was used as a biosorbent and the process variables were optimized for maximum dye removal using the statistical response surface methodology (RSM). Batch mode experiments were performed to determine the kinetic behavior of the dye in aqueous solution allowing the computation of kinetic parameters. Influence of interacting parameters like temperature (25–35 °C), pH (4–8), initial dye concentration (100–200 mg/L) and cyanobacterial dose (0.2–0.4 g) on dye removal were examined using central composite design (CCD) which included two additional levels for each parameter. Second-order polynomial regression model, was applied which was statistically validated using analysis of variance. Ability of the immobilized biomass to decolorize the dye was maximum (72%) at pH 8.0, temperature 35 °C, 200 mg/L initial dye concentration and 0.2 g cyanobacterial dose. Adsorption of the dye on cell surface was further confirmed by scanning electron micrographs of the biomass before and after dye loading. FT-IR studies revealed that decolorization was due to biosorption mediated mainly by functional groups like hydroxyl, amide, carboxylate, methyl and methylene groups present on the cell surface.

Post-storage potential of Nostoc linckia (Cyanobacteria) immobilized in Ca-alginate (synthetic seed) as biofertilizer inocula

Post-storage potential of Nostoc linckia (Cyanobacteria) immobilized in Ca-alginate (synthetic seed) as biofertilizer inocula

Anti-Fusarium activity of cyanobacteria and actinomycetes in soil and rhizosphere

The effect of cyanobacteria (Nostoc linckia, N. commune, and Microchaeta tenera) and streptomycetes on the pathogenic micromycete Fusarium was studied in laboratory simulation experiments. Interpopulational relationships in the rhizosphere of spring wheat (Triticum aestivum L.) and in soddy-podzolic soil were investigated.

Hydrogen production and metal-dye bioremoval by a Nostoc linckia strain isolated from textile mill oxidation pond

Biohydrogen production by Nostoc linckia HA-46, isolated from a textile-industry oxidation-pond was studied by varying light/dark period, pH, temperature and ratio of carbon-dioxide and argon in the gas-mixture. Hydrogen production rates were maximum under 18 h of light and 6 h of darkness, pH 8.0, 31°C, a CO(2):Ar ratio 2:10. Hydrogen production of the strain acclimatized to 20 mg/L of chromium/cobalt and 100 mg/L of Reactive red 198/crystal violet dye studied in N-supplemented/deficient medium was 6-10% higher in the presence of 1.5 g/L of NaNO(3). Rates of hydrogen production in the presence of dyes/metals by the strain (93-105 μmol/h/mg Chlorophyll) were significantly higher than in medium without metals/dyes serving as control (91.3 μmol/h/mg Chlorophyll). About 58-60% of the two metals and 35-73% of dyes were removed by cyanobacterium. Optimal conditions of temperature, pH and metals/dyes concentration for achieving high hydrogen production and wastewater treatment were found practically applicable as similar conditions are found in the effluent of regional textile-mills.

Screening for acetylcholinesterase inhibitory activity in cyanobacteria of the genus Nostoc

Fifty-four cyanobacterial strains of the genus Nostoc from different habitats were screened for acetylcholinesterase inhibitory activity. Water-methanolic extracts from freeze-dried biomasses were tested for inhibitory activity using Ellman's spectrophotometric method. Acetylcholinesterase inhibitory activity higher than 90% was found in the crude extracts of Nostoc sp. str. Lukešová 27/97 and Nostoc ellipsosporum Rabenh. str. Lukešová 51/91. Extracts from Nostoc ellipsosporum str. Lukešová 52/91 and Nostoc linckia f. muscorum (Ag.) Elenk. str. Gromov, 1988, CALU-980 inhibited AChE activity by 84.9% and 65.3% respectively. Moderate AChE inhibitory activity (29.1–37.5%) was found in extracts of Nostoc linckia Roth. str. Gromov, 1962/10, CALU-129, Nostoc muscorum Ag. str. Lukešová 127/97, Nostoc sp. str. Lhotsky, CALU-327 and Nostoc sp. str. Gromov, CALU-998. Extracts from another seven strains showed weak anti-AChE activities.The active component responsible for acetylcholinesterase inhibition was identified in a crude extract of Nostoc sp. str. Lukešová 27/97 using HPLC and found to occur in one single peak.