Promising microbial consortia for producing biofertilizers for rice fields

Two cyanobacterial cultures from rice paddies of Kyzylorda Provence, Kazakhstan were isolated and characterized: Anabaena variabilis and Nostoc calsicola. Based on these cultures, new consortia of cyanobacteria, microalgae and Azotobacter were developed: ZOB-1 (Anabaena variabilis, Chlorella vulgaris, and Azotobacter sp.) and ZOB-2 (Nostoc calsicola, Chlorella vulgaris, and Azotobacter sp.). High growth rate and photosynthetic activity of microalgae were observed in these consortia. The active consortium ZOB-1 was selected, which improved germination and growth of rice plants. ZOB-1 was recommended as a biostimulator and biofertilizer for crops.     

Hepatosplenomegaly and phytotoxicity of a planktonic cyanobacterium Nostoc sp. BHU001 isolated from agricultural pond

Nostoc sp. BHU001, a planktonic cyanobacterium isolated from an agricultural pond in India, was examined for its toxicity. Mice, administered intraperitoneally with Nostoc sp. BHU001 crude extract (50 mg kg^?1 body weight) died at 4.5 h. Examination of liver and spleen showed microcystin (MC)-like symptoms. Serum enzyme aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities increased by 1.6–1.8 and 2.6–3.0-folds, respectively at 50 and 100 mg crude extract kg^?1 body weight. Thin layer chromatography of the crude extract produced five bands (N-1 to N-5). UV absorption maxima of band N-4 corresponded to that of standard microcystin-LR. Further analysis of the band N-4 by high-performance liquid chromatography gave a retention time (R _t ) of 4.61 min similar to that of standard microcystin–LR (LR stands for lysine and arginine). Total MC content was quantified by enzyme-linked immunosorbent assay, and was 189.9 μg g^?1 of crude extract, 9.8 μg l^?1 of spent medium and 5.5 μg l^?1 of pond water. Exposure of rice (Oryza sativa var. Sonam) seeds to the crude extract did not affect their germination, but inhibited the root and shoot growth of seedlings by 27.3 and 42.89 folds at 3 mg ml^?1 crude extract, respectively.     

Influence of Manganese and Zinc on Biochemical Profiles of Selected Algal Species: A Laboratory Study

The present study focused on the responses of six freshwater algal species (Anabaena ambigua, Anabaena subcylindrica, Nostoc commune, Nostoc muscorum, Spirogyra sp., and Spirulina sp.) to manganese and zinc. Laboratory experiments were conducted for the assessment of biochemical responses to manganese and zinc at various concentrations (0.1, 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 mg/L) for 15 days of exposure. After the incubation period, 10 ml of sample was centrifuged at 6000 rpm for 15 min and the pellets were used for measurement of the various experimental parameters. The toxicological study of manganese on algae showed that Anabaena ambigua was most sensitive algae. Regarding effects of manganese concentrations, chlorophyll, protein, carbohydrate, starch, and amino acid were inhibited 50% (IC₅₀) at 3 mg/L, whereas the toxicological study of zinc on algae Anabaena subcylindrica showed most adverse effects. Regarding effects of zinc concentrations, chlorophyll, protein, carbohydrate, starch, and amino acid were inhibited 50% (IC₅₀) at 1 mg/L. The inhibitory and stimulatory effects of either of the used heavy metals depend on concentration. Different organisms, however, have different sensitivities to the same metal, and the same organism may be more or less damaged by different metals.     

Phylogenetic comparison among the heterocystous cyanobacteria based on a polyphasic approach

Phylogenetic comparison has been done among the selected heterocystous cyanobacteria belonging to the sections IV and V. The hierarchical cluster analysis based on antibiotics sensitivity showed a distant relationship between the members of Nostocales and Stigonematales. Thus, multiple antibiotic resistance pattern used as marker provide easy, fast, and reliable method for strain discrimination and genetic variability. However, morphological, physiological (both based on principal component analysis) and biochemical analysis grouped true branching cyanobacteria along with the members of section IV. Molecular analysis based on 16S rRNA gene sequences revealed that Hapalosiphon welwitschii and Westiellopsis sp. were grouped in cluster I whereas Scytonema bohnerii, a false branching genera showed a close proximity with Calothrix brevissima in cluster II. Cluster III of clade 2 included Nostoc calcicola and Anabaena oryzae which proved the heterogeneity at the generic level. Cluster IV the largest group of clade 2 based on 16S rRNA gene sequences includes six strains of the genera Nostoc, Anabaena, and Cylindrospermum showing ambiguous evolutionary relationship. In cluster IV, Anabaena sp. and Anabaena doliolum were phylogenetically linked by sharing 99% sequence similarity. Probably, they were of the same genetic makeup but appear differently under the diverse physiological conditions. Section IV showed polyphyletic origin whereas section V showed monophyletic origin. Results suggested that either morphological or physiological or biochemical or molecular attribute is not sufficient to provide true diversity and phylogeny of the cyanobacteria at the generic level and thus, a polyphasic approach would be more appropriate and reliable.     

转基因鱼腥藻中hTNF-α基因表达与光合作用间的相关性研究

分析了培养光强对转基因鱼腥藻生长和hTNF-α基因表达的影响,以及转基因鱼腥藻IB02的光合放氧活性、光系统Ⅰ及光系统Ⅱ活性。发现光强对转基因鱼腥藻IB02的生长和hTNF-α基因表达都有促进;hTNF-α基因在鱼腥藻中的表达率与真正光合、光系统Ⅰ和光系统Ⅱ活性存在一定的联系。hTNF-α基因表达同时对宿主的光合放氧特性也产生了显著的影响,与正对照相比转基因藻光呼吸速率增强68%,饱和点降低66%,说明转基因鱼腥藻的代谢负荷增加,并在低光强下生长比野生型快。     

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. Luke?ová 27/97 and Nostoc ellipsosporum Rabenh. str. Luke?ová 51/91. Extracts from Nostoc ellipsosporum str. Luke?ová 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. Luke?ová 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. Luke?ová 27/97 using HPLC and found to occur in one single peak.     

Evaluation of Nostoc Strain ATCC 53789 as a Potential Source of Natural Pesticides

The cyanobacterium Nostoc strain ATCC 53789, a known cryptophycin producer, was tested for its potential as a source of natural pesticides. The antibacterial, antifungal, insecticidal, nematocidal, and cytotoxic activities of methanolic extracts of the cyanobacterium were evaluated. Among the target organisms, nine fungi (Armillaria sp., Fusarium oxysporum f. sp. melonis, Penicillium expansum, Phytophthora cambivora, P. cinnamomi, Rhizoctonia solani, Rosellinia, sp., Sclerotinia sclerotiorum, and Verticillium albo-atrum) were growth inhibited and one insect (Helicoverpa armigera) was killed by the extract, as well as the two model organisms for nematocidal (Caenorhabditis elegans) and cytotoxic (Artemia salina) activity. No antibacterial activity was detected. The antifungal activity against S. sclerotiorum was further studied with both extracts and biomass of the cyanobacterium in a system involving tomato as a host plant. Finally, the herbicidal activity of Nostoc strain ATCC 53789 was evaluated against a grass mixture. To fully exploit the potential of this cyanobacterium in agriculture as a source of pesticides, suitable application methods to overcome its toxicity toward plants and nontarget organisms must be developed.     

Molecular Characterization of a Fungicidal Endoglucanase from the Cyanobacterium Calothrix elenkinii

A gene responsible for fungicidal activity was identified in the cyanobacterial strain Calothrix elenkinii RPC1, which had shown promise as a biocontrol agent. Functional screening of the genomic library revealed fungicidal (against Pythium aphanidermatum) and endoglucanase activities in two clones. Sequencing revealed an open reading frame of 1,044 bp, encoding 348 amino acid residues with a predicted molecular weight of 38 kDa. Analysis of the deduced amino acid sequence of the putative gene (cael1) showed 99% similarity with the β-1,4-endoglucanase from Anabaena laxa RPAN8 and 97% with the glucanase belonging to the peptidase M20 family of Anabaena variabilis and Nostoc sp. PCC7120, respectively. The putative promoters, ribosomal binding sites and a signal peptide of 22 amino acid residues were identified, revealing the secretory nature of the protein. The phylogenetic tree indicated a close relationship of the gene with Bacillus sp. This study is the first to report on the characterization of an endoglucanase in Calothrix sp.     

Effects of temperature pre-treatment,desiccation and aging on the viability of spores of halophilic blue-green algae

The effects of temperature, desiccation and aging on the viability of spores of Sambhar salt lake blue-green algae, Anabaena fertilissima and Anabaenopsis arnoldii, were studied. Spores of A. arnoldii were found to be more susceptible to temperature variation, desiccation and storage than spores of A. fertilissima. Pre-treatment of spores with higher temperatures, 37° and 47°C, stimulated germination in A. fertilissima. In a sporulated filament, spores which developed first were generally bigger and more resistant to adverse environmental conditions than spores formed later. The differential loss of viability in spores of a filament may be due to certain intrinsic differences in the physiological/ biochemical properties of the spores.     

Comparative growth and metabolism of gelatinous colonies of three cyanobacteria,Nostoc commune,Nostoc pruniforme and Nostoc zetterstedtii,at different temperatures

相似文献   

Oxidation of c-Type Cytochromes by the Membrane-Bound Cytochrome Oxidase (Cytochrome aa(3)) of Blue-Green Algae

Respiratory particles containing an aa₃-type cytochrome oxidase were prepared from Anacystis nidulans, Synechocystis 6714, Synechococcus lividus, Anabaena variabilis, Nostoc sp. strain MAC, Nostoc muscorum, and Mastigocladus laminosus. Oxidation of c-type cytochromes by membrane preparations of the different blue-green algae was observed using purified cytochromes from horse heart, Candida krusei, tuna, Saccharomyces oviformis, Rhodospirillum rubrum, Rhodospirillum molischianum, Rhodopseudomonas palustris, Rhodocyclus purpureus, Paracoccus denitrificans, Anacystis nidulans, Anabaena variabilis, Euglena gracilis, and Scenedesmus obliquus. Rapid oxidations were consistently observed with the mitochondrial c-type cytochromes (horse heart cytochrome c reacts most rapidly) and with cytochromes c₂ from Rhodopseudomonas palustris and Rhodocyclus purpureus; in contrast, the cytochrome c₂ from Rhodospirillum rubrum and the plastidic cytochromes from E. gracilis and Scendesmus obliquus were inactive with all membrane preparations. All reactions were inhibited by low concentrations of KCN, NaN₃, and CO, and they were activated by Tween 80, thus indicating participation of the terminal oxidase. The results are discussed in view of the spectral similarities between the terminal oxidase of blue-green algae and the mitochondrial aa₃-type cytochrome oxidase of plants and other eukaryotes.     

Algae as Bio-fertilizers: Between current situation and future prospective

Bio-fertilization is a sustainable agricultural practice that includes using bio-fertilizers to increase soil nutrient content resulting in higher productivity. Soil micro-flora has been exposed to improve soil fertility and increase biomass productivity and identified as a correct environmentally friendly bio-based fertilizer for pollution-free agricultural applies. The majority of cyanobacteria can fix nitrogen from the atmosphere and several species including Anabaena sp., Nostoc sp., and Oscillatoria angustissima is known to be effective cyanobacterial based bio fertilizers. Acutodesmus dimorphus, Spirulina platensis Chlorella vulgaris, Scenedesmus dimorphus, Anabaena azolla, and Nostoc sp. are some of the green microalgae and cyanobacteria species that have been successfully used as bio fertilizers to boost crop growth. Also, Chlorella vulgaris is one of the most commonly used microalgae in bio fertilizer studies. The addition of seaweed species that are Sargassum sp. and Gracilaria verrucosa leads to chemical changes as a soil fertility indicator on clay and sandy soils, and the addition of seaweed conditioner to soil can improve its organic content, return pH to normal, and reduce C/N ratio in both sandy and clay soil. This review provides an effective approach to increase soil fertility via environmentally friendly bio-based fertilizer using micro and macro algae. Instead of the usage of inorganic and organic fertilizers that have polluted impacts to soil as aggregation of heavy metals, in addition to there their human carcinogenic effects.     

Endophytic <Emphasis Type="Italic">Alcaligenes</Emphasis> Isolated from Horticultural and Medicinal Crops Promotes Growth in Okra (<Emphasis Type="Italic">Abelmoschus</Emphasis><Emphasis Type="Italic">esculentus</Emphasis>)

The potential of endophytic bacteria to act as biofertilizers and bioprotectants has been demonstrated, and considerable progress has been made in explaining their role in plant protection. In the present study, three endophytic bacterial strains (BHU 12, BHU 16 isolated from the leaves of Abelmoschus esculentus, and BHU M7 isolated from the leaves of Andrographis paniculata) were used which displayed high sequence similarity to Alcaligenes faecalis. The biofilm formation ability of these endophytic strains in the presence of okra root exudates confirms their chemotactic ability, an initial step for successful endophytic colonization. Further, reinoculation of spontaneous rifampicin-tagged mutants into okra seedlings revealed a CFU count above 10⁵ cells g^?1 of all three endophytic strains in root samples during the first 15 days of plant growth. The CFU count increased up to 10¹³ by 30 days of plant growth, followed by a gradual decline to approximately 10¹⁰ cells g^?1 at 45 days of plant growth. Systemic endophytic colonization was further supported by 2, 3, 5-triphenyl tetrazolium chloride staining and fluorescence imaging of ds-RED expressing conjugants of the endophytic strains. The strains were further assessed for their plausible in vivo and in vitro plant growth-promoting and antagonistic abilities. Our results demonstrated that the endophytic strains BHU 12, BHU 16, and BHU M7 augmented plant biomass by greater than 40 %. Root and shoot lengths of okra plants when primed by BHU 12, BHU 16, and BHU M7 increased up to 34 and 14.5 %, respectively. The endophytic isolates also exhibited significant in vitro antagonistic potential against the collar rot pathogen Sclerotium rolfsii. In summary, our results demonstrate excellent potential of the three endophytic bacterial strains as biofertilizers and biocontrol agents, indicating the possibility for use in sustainable agriculture.     

Nezha, a novel active miniature inverted-repeat transposable element in cyanobacteria

Miniature inverted-repeat transposable elements (MITEs) were first identified in plants and exerted extensive proliferations throughout eukaryotic and archaeal genomes. But very few MITEs have been characterized in bacteria. We identified a novel MITE, called Nezha, in cyanobacteria Anabaena variabilis ATCC 29413 and Nostoc sp. PCC 7120. Nezha, like most previously known MITEs in other organisms, is small in size, non-coding, carrying TIR and DR signals, and of potential to form a stable RNA secondary structure, and it tends to insert into A+T-rich regions. Recent transpositions of Nezha were observed in A. variabilis ATCC 29413 and Nostoc sp. PCC 7120, respectively. Nezha might have proliferated recently with aid from the transposase encoded by ISNpu3-like elements. A possible horizontal transfer event of Nezha from cyanobacteria to Polaromonas JS666 is also observed.     

An angiotensin-converting enzyme-inhibitory metabolite with partial structure of microginin in a cyanobacterium <Emphasis Type="Italic">Anabaena fertilissima</Emphasis> CCC597, producing fibrinolytic protease

Whole cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of Anabaena fertilissima CCC597 revealed the presence of a microginin (M _r?=?565 Da), which was purified using ODS C18 solid-phase extraction followed by quaternary methyl ammonium (QMA)-ion exchange and reverse-phase liquid chromatography. Its partial structure was deduced upon LC-MS/MS as β-amino-α-hydroxy-decanoic acid-Ala-MeLeu-Tyr. Microginin-565 inhibited rabbit angiotensin-converting enzyme activity at an apparent IC₅₀?=?9.8 μM.     

Effect of pH,irradiance and population size on the toxicity of Furadan to two species of Anabaena

In two selected nitrogen-fixing cyanobacterial speciesAnabaena fertilissima andAnabaena variabilis pH, irradiance and different inocula sizes considerably modified the toxic effect of 50 % effective concentration (EC 50) dose of the pesticideFuradan (carbofuran 75 DB). Maximum growth and chlorophyll (Chl)a content ofA. fertilissima was observed in the pH range of 8 - 9 and that ofA. variabilis at pH 7-8, while at acidic pH (5 - 6) and at pH above 9 these parameters were considerably retarded. Toxicity of the EC 50 dose ofFuradan was increased further at pH 5-6, whereas reduction in the toxicity to the test cyanobacteria was observed at pH 7.8 - 9.0. The experimental organisms grew comparatively better and synthesized higher amount of Chl a at an irradiance of 12.5 than at 7.5 or 2.5 W m^-2. The toxicity of EC 50 dose of the pesticide gradually decreased with the increasing irradiance. The toxic effect ofFuradan was larger when the initial cyanobacterial population concentration was low andvice versa.     

EFFECT OF TEMPERATURE ON THE SENSITIVITY OF NITROGENASE TO OXYGEN IN TWO HETEROCYSTOUS CYANOBACTERIA1

The effect of temperature and oxygen on nitrogenase activity in two heterocystous cyanobacteria, Anabaena variabilis Kütz. ATCC29413 and Nostoc sp. PCC7120, was investigated. The cyanobacteria were grown under a 12:12 light:dark (L:D) cycle at 27°C and were subsequently exposed to different temperatures (27, 36, 39, and 42°C) at different steady‐state O₂ concentrations (20, 10, 5, 0%). Light response curves of nitrogenase activity were recorded under each of these conditions using an online acetylene reduction assay combined with a sensitive laser photoacoustic ethylene detection method. The light response curves were fitted with the rectangular hyperbola model from which the model parameters N_m, N_d, and α were derived. In both strains, nitrogenase activity (N_tot = N_m + N_d) was the highest at 39°C–42°C and at 0% O₂. The ratio N_tot/N_d was 4.1 and 3.1 for Anabaena and Nostoc, respectively, indicating that respectively 25% and 33% of nitrogenase activity was supported by respiration (N_d). N_tot/N_d increased with decreasing O₂ concentration and with increasing temperature. Hence, each of these factors caused a relative increase in the light‐driven nitrogenase activity (N_m). These results demonstrate that photosynthesis and respiration both contribute to nitrogenase activity in Anabaena and Nostoc and that their individual contributions depend on both O₂ concentration and temperature as the latter may dynamically alter the flux of O₂ into the heterocyst.