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1.
Two diazotrophic cyanobacteria, Westiellopsis prolifica and Anabaena variabilis were evaluated for elucidating the possible mechanism of mineral phosphate solubilization. Phosphate starved cyanobacteria evaluated for the presence of organic acids, extracellular compounds or enzymes that might have been produced and promoted the mineral phosphate solubilization with Mussorie Rock Phosphate and Tricalcium Phosphate as substrates. Both the cultures did not reveal production of organic acids throughout the incubation period when checked for decrease in pH of the media and thin layer chromatography Thin layer chromatography of culture filtrates showed the presence of hydrocarbon like compound. Further analysis of the culture filtrates with gas liquid chromatography, a single peak near to the retention time of 7.6 was observed in all extracts of culture filtrates irrespective of phosphate source. UV-visible spectra of culture filtrates revealed the absorption maxima of 276 nm. Gas Chromatographic-Mass Spectrometric analysis of culture filtrates showed most intense peak in the electron impact (EI) ionization was at m/z 149 and molecular ion peaks at m/z 207 and 167, inferring the presence of phthalic acid. Among the mechanisms in mineral phosphate solubilization, it was evident that these cyanobacteria used phthalic acid as possible mode of P solubilization. 相似文献
2.
Mahesh S. Yandigeri Arvind K. Yadav Kamlesh Kumar Meena Sunil Pabbi 《Antonie van Leeuwenhoek》2010,97(3):297-306
The nitrogen fixing cyanobacterial strains namely Anabaena variabilis (Nostocales, Nostocaceae) and Westiellopsis prolifica (Nostocales, Hapalosiphonaceae) were evaluated for their nitrogen fixation and growth potential in response to different
concentrations (10, 20 and 30 mg P) of the alternate insoluble P-sources Mussorie Rock Phosphate and Tricalcium Phosphate.
Distinct and significant intergeneric differences were observed with respect to nitrogen fixation measured as Acetylene Reduction
Activity (ARA) and growth potential as soluble proteins, total carbohydrate content, dry weight and total chlorophyll content
in response to different concentrations of Mussorie Rock Phosphate and Tricalcium Phosphate. Both the strains showed higher
soluble protein content at 20 mg P (Mussorie Rock Phosphate) that increased with time of incubation in A. variabilis. Both cyanobacteria recorded maximum Acetylene Reduction Activity at 20 mg P (Tricalcium Phosphate) followed by activity
in presence of soluble phosphate (K2HPO4). The mean activity at all concentrations of insoluble phosphate (Mussorie Rock Phosphate and Tricalcium Phosphate) was more
than in the presence of soluble phosphate. 相似文献
3.
A psychrotolerant phosphate solubilizing fungus has been isolated from the rock soil of a cold desert site in Indian Himalaya.
The fungus grows from 4 to 35°C (optimum 21°C), and from 2 to 13.5 pH (optimum 9) under laboratory conditions. Based on phenotypic
characters and 26S rDNA analysis, the fungus is identified as Paecilomyces hepiali. In quantitative estimation that was carried out at 9, 14, and 21°C, the fungus solubilized maximum phosphate at 14°C. In
view of the slow growth and persistence of the desired activity at low temperature, the estimation was carried out for a longer
period, i.e., up to 6 weeks. The suboptimal conditions for growth and biomass production were found to be optimal for phosphate
solubilization by the fungus. At 14 and 9°C, the solubilization touched its maximum on day 42. Decline in pH was found to
be significantly correlated with the phosphate solubilization at all the temperatures, under consideration. The acid phosphatase
activity was found to be more prominent than alkaline phosphatase in culture filtrate. High performance thin layer chromatography
(HPTLC) analysis showed production of six organic acids, gluconic and α-keto glutaric acid being in maximum amount in the
culture filtrate. The study has ecological significance in view of the nutrient cycling under low temperature environment,
prevalent in Himalayan region. 相似文献
4.
Forty-six Rhizobium isolates from legume root and stem nodules were examined for their phosphate-solubilizing ability on Pikovskaya’s agar medium.
Rhizobium isolates from root nodules of Cassia absus, Vigna trilobata and three strains from Sesbania sesban showed zone of tricalcium phosphate (TCP) solubilization. The isolate from C. absus showed maximum solubilization (620 μg/ml) after 12 d of incubation, while the Rhizobium sp. strain 26 (from S. sesban) showed the least amount (150 μg/ml) of phosphate solubilization. Among the carbon sources tested for their ability to solubilize
TCP, maximum solubilization (620 μg/ml) was observed in glucose by Rhizobium isolate from C. absus. Phosphate solubilization increased with increase in glucose concentration steeply up to 2% and slowly
above this concentration in four isolates. Among the nitrogen sources tested, maximum solubilization (620 μg/ml) was observed
in ammonium sulphate by Rhizobium isolate from C. absus. 相似文献
5.
Samantha?Caixeta?de?Oliveira Gilberto?de?Oliveira Mendes Ubiana?Cássia?da?Silva Ivo?Ribeiro?da?Silva José?Ivo?Ribeiro?Júnior Maurício?Dutra?Costa
Microbial solubilization of rock phosphate (RP) is mainly achieved by the production of organic acids and medium acidification through H+ release. During RP solubilization, mineral nutrient availability is likely to be critical for determining how much carbon is channeled either for metabolite synthesis or for microbial growth, influencing organic acid release by microorganisms. Thus, the objective of this work was to study the relationships between the concentration of mineral nutrients in the growth medium and the efficiency of RP solubilization by Aspergillus niger FS1. For this, the fungus was grown in Czapek medium containing 0, 1, 2, 10, 50, and 100 % of its original concentration of mineral nutrients. Decreasing mineral availability in the growth medium led to decreases in fungal biomass and solubilized P, and increases in titratable acidity and solubilization efficiency as expressed by mg solubilized P per g fungal biomass (YP/B), indicating a shift in fungal metabolism from biomass production to organic acid release. The transfer of pre-grown biomass to media with or without added minerals confirmed that lower mineral availability increases YP/B and led to the solubilization of 76 % of P present in Patos RP. These observations open new perspectives on improving RP solubilization systems by manipulating mineral nutrient availability in the medium, with consequent gains in cost reduction. 相似文献
6.
Shockey J Chapital D Gidda S Mason C Davis G Klasson KT Cao H Mullen R Dyer J 《Applied microbiology and biotechnology》2011,92(6):1207-1217
Saccharomyces cerevisiae is frequently used as a bioreactor for conversion of exogenously acquired metabolites into value-added products, but has
not been utilized for bioconversion of low-cost lipids such as triacylglycerols (TAGs) because the cells are typically unable
to acquire these lipid substrates from the growth media. To help circumvent this limitation, the Yarrowia lipolytica lipase 2 (LIP2) gene was cloned into S. cerevisiae expression vectors and used to generate S. cerevisiae strains that secrete active Lip2 lipase (Lip2p) enzyme into the growth media. Specifically, LIP2 expression was driven by the S. cerevisiae PEX11 promoter, which maintains basal transgene expression levels in the presence of sugars in the culture medium but is rapidly
upregulated by fatty acids. Northern blotting, lipase enzyme activity assays, and gas chromatographic measurements of cellular
fatty acid composition after lipid feeding all confirmed that cells transformed with the PEX11 promoter–LIP2 construct were responsive to lipids in the media, i.e., cells expressing LIP2 responded rapidly to either free fatty acids or TAGs and accumulated high levels of the corresponding fatty acids in intracellular
lipids. These data provided evidence of the creation of a self-regulating positive control feedback loop that allows the cells
to upregulate Lip2p production only when lipids are present in the media. Regulated, autonomous production of extracellular
lipase activity is a necessary step towards the generation of yeast strains that can serve as biocatalysts for conversion
of low-value lipids to value-added TAGs and other novel lipid products. 相似文献
7.
Allelopathic effects of the submerged macrophyte Potamogeton malaianus on Scenedesmus obliquus were assessed using a two-phase approach under controlled laboratory conditions. In the co-culture experiment (phase І),
the growth of S. obliquus at two different initial cell densities was significantly inhibited by P. malaianus. Moreover, the growth inhibition was dependent on the biomass density of P. malaianus. Antioxidant enzymes (SOD, CAT and POD), MDA, APA, total soluble protein, protein electrophoretic pattern and morphology
of S. obliquus were determined after the co-culture experiment was terminated. The activities of SOD, CAT, POD and APA at the low initial
cell density were stimulated, the contents of MDA and total soluble protein were increased, and some special protein bands
disappeared in P. malaianus treatments. The macrophyte had no effect on the activities of SOD and APA at the high initial cell density, but significantly
influenced other physiological parameters of S. obliquus with the increase of biomass density. The morphology of S. obliquus showed no difference in the macrophyte treatments and the controls, and the cultures were dominated by 4-celled coenobia.
The results indicated P. malaianus had significant allelopathic effects on the growth and physiological processes of S. obliquus. Moreover, the allelopathic effects depended on initial algal cell density, biomass density of the macrophyte, and their
interaction. In the experiment of P. malaianus culture filtrates (phase II), filtrates from combined culture of plant and S. obliquus at the low initial cell density exhibited no apparent growth inhibitory effect on S. obliquus. The result showed that initial addition of growth-inhibiting plant filtrates had no allelopathic effect on S. obliquus. We concluded that the allelopathic effects on S. obliquus were found in the presence of P. malaianus, but not in P. malaianus filtrates. However, the absence of allelopathic effect on S. obliquus might be due to the very low concentrations of allelochemicals in the filtrates.
Handling editor: S. M. Thomas 相似文献
8.
Hai-Nan Su Bin-Bin Xie Xiu-Lan Chen Jin-Xia Wang Xi-Ying Zhang Bai-Cheng Zhou Yu-Zhong Zhang 《Journal of applied phycology》2010,22(1):65-70
Allophycocyanin (APC) is a minor component of phycobiliproteins in cyanobacteria and red algae. This paper describes a simple
and inexpensive extracting method for isolating APC from Spirulina (Arthrospira) platensis with high efficiency. The crude phycobiliprotein extract was pretreated by ammonium sulfate fractionation. Then, by adding
hydroxylapatite into crude phycobiliprotein extract dissolved in 20 mM phosphate buffer (pH 7.0), APC was selectively adsorbed
by hydroxylapatite but C-phycocyanin (C-PC) was not. The hydroxylapatite was collected and APC was extracted from the crude
phycobiliprotein extract. Then, the enriched APC was washed off from the hydroxylapatite using 100 mM phosphate buffer (pH 7.0).
In this simple extracting method it was easy to remove C-PC and isolate APC in large amounts. The absorbance ratio A
650/A
280 of extracted APC reached 2.0. The recovery yield was 70%, representing 4.61 mg · g−1 wet weight. The extracted APC could be further purified by a simple anion-exchange chromatography with a pH gradient from
5.6 to 4.0. The absorbance ratio A
650/A
280 of the purified APC reached 5.0, and the overall recovery yield was 43%, representing 2.83 mg · g−1 wet weight. Its purity was confirmed by native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE. 相似文献
9.
Balasubramanian Radhakrishnan Radha Prasanna Pranita Jaiswal Saswati Nayak Prem Dureja 《Biologia》2009,64(5):881-889
An investigation was undertaken to evaluate a set of cyanobacterial strains in terms of production of biocidal compounds exhibiting
allelochemical and fungicidal properties. Two cyanobacterial strains — Anabaena sp. and Calothrix sp. were selected for further investigation, on the basis of their larger inhibition zones on the lawn of Synechocystis and Synechococcus sp. and two phytopathogenic fungi — Rhizoctonia bataticola and Pythium debaryanum. The diameter of the inhibition zone was largest when extracellular filtrates of the two cultures incubated at high light
intensity (90–100 μmol photons m−2 s−1) and temperature (40 ± 2 °C) or grown in medium containing two-folds higher P (1.4 mg/L, as compared to 0.7 mg/L in BG 11
medium) were taken. A pH of 8 was the most optimal for both strains, in terms of growth and biocidal activity. Partial purification
of ethyl acetate extract using TLC, followed by GLC revealed a single peak. This study highlights the importance of environmental
factors in aggravating or reducing the toxic effects of these harmful cyanobacteria and their potential as a biocontrol agent. 相似文献
10.
Ting Liu Li Wang Yu-Xi Duan Xue Wang 《World journal of microbiology & biotechnology》2008,24(1):113-118
Culture filtrates of Beauveria bassiana at different concentrations were evaluated for nematicidal activity against the northern root knot nematode (Meloidogyne hapla); bioassays included egg hatching, mortality and infectivity on tomato plants in pots under glasshouse conditions. The percentage
mortality and inhibition of hatching of root-knot nematode were directly proportional to the concentration of culture filtrates
of B. bassiana. Soil drenching with culture filtrate of B. bassiana significantly reduced nematode population densities in soil and in the roots and subsequent gall formation and egg-mass production
by M. hapla under glasshouse conditions. 相似文献
11.
Yeong-Tae Kim Jonghee Oh Kyung-Hwan Kim Jae-Youl Uhm Byoung-Moo Lee 《Molecular biology reports》2010,37(2):717-727
Elicitins, extracellular proteins from Phytophthora fungi, elicit a hypersensitivity response (HR), including systemic acquired resistance, in some plants. The elicitin capsicein
(~10 kDa) was purified by FPLC from culture filtrates of P. capsici. Purified native and recombinant capsicein induced a hypersensitive response in leaves of the non-host plants Nicotiana glutinosa and Brassica rapa subsp. pekinensis. To search for candidate capsicein-interacting proteins from N. glutinosa, a yeast two-hybrid assay was used. We identified a protein interactor that is homologous to a serine/threonine kinase of
the plant receptor-like kinase (RLK) group and designated it NgRLK1. The ORF of NgRLK1 encodes a polypeptide of 832 amino acids (93,490 Da). A conserved domain analysis revealed that NgRLK1 has structural features
typical of a plant RLK. NgRLK1 was autophosphorylated, with higher activity in the presence of Mn2+ than Mg2+. 相似文献
12.
X. Zhou Z. Wang K. Jiang Y. Wei J. Lin X. Sun K. Tang 《Applied Biochemistry and Microbiology》2007,43(4):439-443
A total of 38 endophytic fungus strains were isolated from Taxus chinensis var. mairei by the aseptic technique. Genomic DNA was extracted from isolated endophytic fungi and subjected to polymerase chain reaction
(PCR) analysis for the presence of the Taxus taxadiene synthase (TS) gene, a rate-limiting enzyme gene in the taxol biosynthetic pathway. Twelve out of 38 isolated endophytic fungus strains
showed PCR positive for the ts gene. Subsequently, taxol and its related compounds were extracted from culture filtrates and mycelia of the PCR positive
strains, separated by column chromatography, and analyzed by High Performance Liquid Chromatography and Mass Spectrum. The
analysis result showed that 3 strains could produce taxol and its related compounds at the detectible level. This study indicates
that molecular detection of the ts gene is an efficient method for primary screening of taxol or its related compound-producing endophytic fungi, which can
improve prominently screening efficiency.
Published in Russian in Prikladnaya Biokhimiya i Mikrobiologiya, 2007, Vol. 43, No. 4, pp. 490–494.
The text was submitted by the authors in English. 相似文献
13.
Cultural filtrates obtained by a solid-state cultivation of wood-decaying white rot basidiomycetes Bjerkandera adusta BIMF-260 and Pleurotus ostreatus BIMF-247 demonstrate a prooxidant activity expressed via their ability to initiate the peroxidation of polyunsaturated fatty
acids, particularly linoleic acid. This prooxidant activity depends on the presence of ligninolytic enzymes, especially ligninolytic
peroxidases. 相似文献
14.
Adrian D. Allen Winston A. Anderson Folahan O. Ayorinde Broderick E. Eribo 《Journal of industrial microbiology & biotechnology》2010,37(8):849-856
Polyhydroxyalkanoates (PHAs) are naturally occurring biodegradable polymers with promising application in the formulation
of plastic materials. PHAs are produced by numerous bacteria as energy/carbon storage materials from various substrates, including
sugars and plant oils. Since these substrates compete as food sources, their use as raw material for industrial-scale production
of PHA is limited. Therefore, efforts have been focused on seeking alternative sources for bacterial production of PHA. One
substrate that seems to have great potential is the seed oil of Jatropha curcas plant. Among other favorable properties, J. curcas seed oil is non-edible, widely available, and can be cheaply produced. In this study, Pseudomonas oleovorans (ATCC 29347) was grown in a mineral salt medium supplemented with saponified J. curcas seed oil as the only carbon source under batch fermentation. Optimum PHA yield of 26.06% cell dry weight was achieved after
72 h. The PHA had a melting point (T
m) between 150 and 160°C. Results of polymer analyses by gas chromatography/mass spectrometry (GC/MS) identified only the methyl
3-hydroxybutanoate monomeric unit. However, electrospray ionization–time of flight mass spectroscopy (ESI–TOF MS) confirmed
that the PHA was a copolymer with the characteristic HB/HV peaks at m/z 1155.49 (HB) and 1,169, 1,184–1,194 (HV). The data were further supported by1H and 13C NMR analysis. Polymer analysis by gel permeation chromatography (GPC) indicated a peak molecular weight (MP) of 179,797,
molecular weight (M
W) of 166,838, weight number average mass (M
n) of 131,847, and polydispersity (M
w/M
n) of 1.3. The data from this study indicate that J. curcas seed oil can be used as a substrate to produce the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3HB-co-3HV). 相似文献
15.
This study was undertaken to explore the role of Trichoderma sp. in phosphate (P) solubilization and antagonism against fungal phytopathogens. All fungal isolates (SE6, KT6, KT28, and BRT11) and a standard culture of T. harzianum (Th-std) were able to antagonize two fungal phytopathogens (Sclerotium rolfsii and Rhizoctonia solani) of chickpea (Cicer arietinum L.) wilt complex. Transmission electron microscopic studies (TEM) further confirmed ultra-cytological changes in the sclerotia
of S. rolfsii parasitized by Trichoderma sp. All fungal cultures exhibited production of NH3 and siderophore, but only BRT11, SE6, and Th-std could produce HCN. Among all the cultures tested, isolate KT6 was found to be most effective for solubilization of ferric phosphate releasing 398.4 μg ml−1 phosphate while isolates BRT11 and SE6 showed more potential for tricalcium phosphate (TCP) solubilization releasing 449.05 and 412.64 μg ml−1 phosphate, respectively, in their culture filtrates. Part of this study focused on the influence of abiotic stress conditions
such as pH, temperature, and heavy metal (cadmium) on phosphate (TCP) solubilizing efficiency. Two selected cultures KT6 and T. harzianum retained their P solubilizing potential at varying concentrations of cadmium (0–1000 μg ml−1). Isolate KT6 and standard culture of T. harzianum released 278.4 and 287.6 μg ml−1 phosphate, respectively, at 1000 μg ml−1cadmium. Maximum solubilization of TCP was obtained at alkaline pH and at 28°C temperature. Isolate BRT11 was found most alkalo-tolerant releasing 448.0 μg ml−1 phosphate at pH 9. 相似文献
16.
Lubov P. Ryazanova Natalia E. Suzina Tatiana V. Kulakovskaya Igor S. Kulaev 《Archives of microbiology》2009,191(5):467-471
The cells of Acetobacter xylinum decreased phosphate concentration in the medium from 5 to 2.5 or 0.3 mM during incubation in the presence of Mg2+ and glucose, or Mg2+ and casamino acids, respectively. The prevalence of orthophosphate or polyphosphate in the biomass of A. xylinum depends on the medium composition. Under phosphate uptake in the presence of glucose, the content of orthophosphate in the
biomass changed little, while that of polyphosphate increased fourfold. At incubation with casamino acids, the content of
orthophosphate increased 15 times, while that of polyphosphate increased only 2.5 times. Some part of orthophosphate in this
case seems to be bound with the cell surface. The polyphosphate chain length in the cells of A. xylinim increases under phosphate uptake. This increase is more noticeable in the presence of glucose. Casamino acids can be replaced
by α-ketoglutaric acid in combination with (NH4)2SO4, or arginine, or glutamine, the catabolism of which results in formation of NH4
+ and α-ketoglutarate. 相似文献
17.
18.
Cytochrome c
6
, (cyt c
6) a soluble monoheme electron transport protein, was isolated and characterized from the chlorophyll d-containing cyanobacterium Acaryochoris marina, the type strain MBIC11017. The protein was purified using ammonium sulfate precipitation, ion exchange and gel filtration
column chromatography, and fast performance liquid chromatography. Its molecular mass and pI have been determined to be 8.87 kDa
and less than 4.2, respectively, by mass spectrometry and isoelectrofocusing (IEF). The protein has an alpha helical structure
as indicated by CD (circular dichroism) spectroscopy and a reduction midpoint potential (E
m) of +327 mV versus the normal hydrogen electrode (NHE) as determined by redox potentiometry. Its potential role in electron
transfer processes is discussed. 相似文献
19.
Kawaguchi H Sasaki M Vertès AA Inui M Yukawa H 《Applied microbiology and biotechnology》2008,77(5):1053-1062
Corynebacterium glutamicum was metabolically engineered to broaden its substrate utilization range to include the pentose sugar l-arabinose, a product of the degradation of lignocellulosic biomass. The resultant CRA1 recombinant strain expressed the Escherichia coli genes araA, araB, and araD encoding l-arabinose isomerase, l-ribulokinase, and l-ribulose-5-phosphate 4-epimerase, respectively, under the control of a constitutive promoter. Unlike the wild-type strain,
CRA1 was able to grow on mineral salts medium containing l-arabinose as the sole carbon and energy source. The three cloned genes were expressed to the same levels whether cells were
cultured in the presence of d-glucose or l-arabinose. Under oxygen deprivation and with l-arabinose as the sole carbon and energy source, strain CRA1 carbon flow was redirected to produce up to 40, 37, and 11%,
respectively, of the theoretical yields of succinic, lactic, and acetic acids. Using a sugar mixture containing 5% d-glucose and 1% l-arabinose under oxygen deprivation, CRA1 cells metabolized l-arabinose at a constant rate, resulting in combined organic acids yield based on the amount of sugar mixture consumed after
d-glucose depletion (83%) that was comparable to that before d-glucose depletion (89%). Strain CRA1 is, therefore, able to utilize l-arabinose as a substrate for organic acid production even in the presence of d-glucose. 相似文献
20.
A soil microorganism identified as Bacillum megaterium was found to produce several antibiotics substances after growth for 20 h at 37°C in a mineral culture medium. Analysis both
by electron spray ionization (ESI) and matrix-assisted laser desorption ionization—time of flight (MALDI-TOF) mass spectrometry
(MS) identified these substances as lipopeptides. Predominant peaks at m/z 1,041 and m/z 1,065 revealed ions which are compatible with surfactins and lichenysins, respectively. Two other ions m/z 1,057 and m/z 1,464 were further studied by collision-induced dissociation (CID) unveiling an iturin A at the first and fengycins A and
B at the second m/z peaks. The CID spectrum of the m/z 1,464 ion also suggests the existence of fengycins A and B variants in which Ile was changed to Val in the position 10 of
the peptide moiety. Raw mixtures of all these compounds were also assayed for antibiotic features. The data enlighten the
unusual diversity of the lipopeptide mixture produced by a sole Bacillus species. 相似文献