共查询到20条相似文献,搜索用时 15 毫秒
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Oksana Y. Shtark Alexey Y. Borisov Vladimir A. Zhukov Igor A. Tikhonovich 《Symbiosis (Philadelphia, Pa.)》2012,58(1-3):51-62
Legumes develop different mutually beneficial symbioses with soil microbes, such as arbuscular mycorrhizal (AM) fungi, nodule bacteria and plant growth promoting bacteria. Symbioses supply the plants with nutrients (predominantly with nitrogen and phosphorus), protect them from pathogens and abiotic stresses and improve soil microbial biodiversity and fertility. The synergistic activity of beneficial soil microbes (BSM) on the plants has great importance for the use of multi-component symbiotic systems in low-input sustainable environmentally-friendly agrotechnologies. However, the complex nature of the AM symbiosis when in a multi-component symbiosis (plant-fungus-bacteria) creates complications for the fungus to produce AM fungal propagules and poses questions (a) about the effectiveness of the fungus per se in interactions with the plants, without associates, and (b) about the necessity of using sterile/axenic conditions for the production of the AM fungi based inoculants because of any mixing and competition by microbes from the inoculants with the local soil microbial consortia. The legume genes controlling interactions with BSM (including genes responsible for effectiveness of such interactions) should be considered as a united genetic system. The plant genome is more stable than that of microbes and therefore crop plants should select beneficial microbes and control the effectiveness of the whole plant-microbe system in the field for the benefit of the crop and therefore of human beings. There is clearly a need to breed legume crops with improved performance under sustainable conditions involving interactions with BSM and optimising the use of agrochemicals. 相似文献
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Valizadeh Sara Enayatizamir Naeimeh Ghomsheh Habibolah Nadian Motamedi Hossein Moghadam Bijan Khalili 《International microbiology》2023,26(3):529-542
International Microbiology - Biosurfactants are amphiphilic compounds with extensive applications in oily contaminated environments to remove hydrocarbons. Moreover, enzymes such as laccase and... 相似文献
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Biosurfactants could potentially outperform traditional surfactants in many applications whilst being more sustainable to
source, manufacture, use and dispose of. However, currently available fermentation production methods are too inefficient
to manufacture biosurfactants for these high volume markets. Foaming in an inherent issue with biosurfactant production and
adds significantly to the cost of production using traditional unit operations. This review illustrates how the application
of process engineering has enabled nuisance foaming to be transformed into a cost saving feature of the production system.
The scope of biosurfactants and their application is discussed and the fundamentals of foam generation and control are reviewed.
The range of specific phenomena associated with the interaction of foams with bioproducts is assessed. Finally, recent work
which has aimed at taking advantage of some of these phenomena in order to intensify the biosurfactant production process
is discussed in detail. 相似文献
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Enhancing soil carbon storage for carbon remediation: potential contributions and constraints by microbes 总被引:1,自引:0,他引:1
King GM 《Trends in microbiology》2011,19(2):75-84
Terrestrial carbon sequestration represents an important option for partially mitigating anthropogenic CO(2) emissions. Evidence suggests that terrestrial ecosystems can be managed for carbon sequestration, but it is not certain to what extent the microbes within them can be manipulated. Challenges include identifying which specific microbes and mechanisms contribute to sequestered carbon; understanding how microbial communities respond over large spatial and long temporal scales to crucial environmental variables; and developing management strategies suitable for large spatial and long temporal scales. The growing recognition that microbes produce proteins that limit organic matter degradation suggests targets for basic research. Directly manipulating microbes to sequester CO(2) through other processes such as mineral formation offers intriguing alternatives that merit further attention, but at present the prospects for practical implementation appear remote. 相似文献
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Aims: To screen and identify biosurfactant producers from petroleum‐contaminated soil; to use response surface methodology (RSM) for medium optimization to enhance biosurfactant production; and to study the properties of the newly obtained biosurfactant towards pH, temperature and salinity. Methods and Results: We successfully isolated three biosurfactant producers from petroleum‐contaminated soil and identified them through 16S rRNA sequence analysis, which exhibit the highest similarities to Acinetobacter beijerinckii (100%), Kocuria marina (99%) and Kineococcus marinus (99%), respectively. A quadratic response model was constructed through RSM designs, leading to a 57·5% increase of the growth‐associated biosurfactant production by Acinetobacter sp. YC‐X 2 with an optimized medium: beef extract 3·12 g l?1; peptone 20·87 g l?1; NaCl 1·04 g l?1; and n‐hexadecane 1·86 g l?1. Biosurfactant produced by Acinetobacter sp. YC‐X 2 retained its properties during exposure to a wide range of pH values (5–11), high temperatures (up to 121°C) and high salinities [up to 18% (w/v) Na+ and Ca2+], which was more sensitive to Ca2+ than Na+. Conclusions: Two novel biosurfactant producers were isolated from petroleum‐contaminated soil. Biosurfactant from Acinetobacter sp. YC‐X 2 has good properties to a wide range of pH, high temperature and high salinity, and its production was optimized successfully through RSM. Significance and Impact of the Study: The fact, an increasing demand of high‐quality surfactants and the lack of cost‐competitive bioprocesses of biosurfactants for commercial utilization, motivates researchers to develop cost‐effective strategies for biosurfactant production through isolating new biosurfactant producers with special surface‐active properties and optimizing their cultural conditions. Two novel biosurfactant producers in this study will widen our knowledge about this kind of micro‐organism. This work is the first application of RSM designs for cultural optimization of biosurfactant produced by Acinetobacter genus and the first report that biosurfactant may be more sensitive to Ca2+ than Na+. 相似文献
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To analyse the frequency of natural gene transfer from genetically modified maize to phytopathogenic bacterium Erwinia stewartii 1082, a marker rescue system based on the restoration of ampicillin resistance gene was used in in vitro and in planta transformation
experiments. A set of three vectors containing defined deletions of the blaTEM116 ampicillin resistance gene in pBR322 was constructed. Recombinant strains of Erw. stewartii 1082 harboring these mutant plasmids were used for infection of transgenic maize plants. Restoration of ampicillin resistance
was observed only in transformed electro-competent Erw. stewartii 1082 cells. Frequency of the resistance restoration was found to be dependent on the size of the transforming DNA. In addition,
highly active non-specific endodeoxyribonuclease was detected in cell-free lysates of Erw. stewartii 1082, rapidly degrading linear DNA fragments. No ampicillin resistant Erw. stewartii 1082 transformants were observed during in planta experiments indicating that this pathogenic bacterium is not naturally
transformable under the conditions tested in this study. 相似文献
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The dimorphic basidiomycete Ustilago maydis produces large amounts of surface-active compounds under conditions of nitrogen starvation. These biosurfactants consist of derivatives of two classes of amphipathic glycolipids. Ustilagic acids are cellobiose lipids in which the disaccharide is O-glycosidically linked to 15,16-dihydroxyhexadecanoic acid. Ustilipids are mannosylerythritol lipids derived from acylated beta-d-mannopyranosyl-d-erythritol. Whereas the chemical structure of these biosurfactants has been determined, the genetic basis for their biosynthesis and regulation is largely unknown. Here we report the first identification of two genes, emt1 and cyp1, that are essential for the production of fungal extracellular glycolipids. emt1 is required for mannosylerythritol lipid production and codes for a protein with similarity to prokaryotic glycosyltransferases involved in the biosynthesis of macrolide antibiotics. We suggest that Emt1 catalyzes the synthesis of mannosyl-d-erythritol by transfer of GDP-mannose. Deletion of the gene cyp1 resulted in complete loss of ustilagic acid production. Cyp1 encodes a cytochrome P450 monooxygenase which is highly related to a family of plant fatty acid hydroxylases. Therefore we assume that Cyp1 is directly involved in the biosynthesis of the unusual 15,16-dihydroxyhexadecanoic acid. We could show that mannosylerythritol lipid production is responsible for hemolytic activity on blood agar, whereas ustilagic acid secretion is required for long-range pheromone recognition. The mutants described here allow for the first time a genetic analysis of glycolipid production in fungi. 相似文献
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Soil microbes and the availability of soil nutrients 总被引:2,自引:0,他引:2
M. Miransari 《Acta Physiologiae Plantarum》2013,35(11):3075-3084
It is likely to provide plants with their necessary nutrients using chemical and biological fertilization. Although chemical fertilization is a quick method, it is not recommendable economically and environmentally, especially if overused. Biological fertilization is the use of soil microbes including arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria to inoculate plants. It has been proved that biological fertilization is an efficient method to supply plants with their necessary nutrients. It is economically and environmentally recommendable, because it results in sustainability. In this article, some of the most important details including the mechanisms and processes regarding the effects of soil microbes on the availability and hence uptake of nutrients by plant are reviewed. Such details can be important for the selection and hence production of microbial inoculums, which are appropriate for biological fertilization. 相似文献
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Simultaneous hydrocarbon biodegradation and biosurfactant production by oilfield-selected bacteria 总被引:1,自引:0,他引:1
Aims: To study the bacterial diversity associated with hydrocarbon biodegradation potentiality and biosurfactant production of Tunisian oilfields bacteria. Methods and Results: Eight Tunisian hydrocarbonoclastic oilfields bacteria have been isolated and selected for further characterization studies. Phylogenetic analysis revealed that three thermophilic strains belonged to the genera Geobacillus, Bacillus and Brevibacillus, and that five mesophilic strains belonged to the genera Pseudomonas, Lysinibacillus, Achromobacter and Halomonas. The bacterial strains were cultivated on crude oil as sole carbon and energy sources, in the presence of different NaCl concentrations (1, 5 and 10%, w/v), and at 37 or 55°C. The hydrocarbon biodegradation potential of each strain was quantified by GC–MS. Strain C450R, phylogenetically related to the species Pseudomonas aeruginosa, showed the maximum crude oil degradation potentiality. During the growth of strain C450R on crude oil (2%, v/v), the emulsifying activity (E24) and glycoside content increased and reached values of 77 and 1·33 g l?1, respectively. In addition, the surface tension (ST) decreased from 68 to 35·1 mN m?1, suggesting the production of a rhamnolipid biosurfactant. Crude biosurfactant had been partially purified and characterized. It showed interest stability against temperature and salinity increasing and important emulsifying activity against oils and hydrocarbons. Conclusions: The results of this study showed the presence of diverse aerobic bacteria in Tunisian oilfields including mesophilic, thermophilic and halotolerant strains with interesting aliphatic hydrocarbon degradation potentiality, mainly for the most biosurfactant produced strains. Significance and Impact of the Study: It may be suggested that the bacterial isolates are suitable candidates for practical field application for effective in situ bioremediation of hydrocarbon‐contaminated sites. 相似文献
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Appaiah KA Parvathy A Mathew M Karanth NG 《Journal of microbiology and biotechnology》2011,21(8):858-860
Production of biosurfactant can be substantially increased by the addition of precursors like vegetable oils, petroleum products, and other water-insoluble substances. Pseudomonas Ptm+ strain produces biosurfactant in the presence of hexachlorocyclohexane (HCH), which specifically emulsifies HCH, a recalcitrant organochlorine pesticide. Addition of previously produced crude biosurfactant by the same organism as a precursor instead of HCH increased production of biosurfactants with a decrease in the total fermentation time from 32 to 24 h. The main objective of this paper was to find alternatives for HCH as an inducer. 相似文献
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H E Reiling U Thanei-Wyss L H Guerra-Santos R Hirt O K?ppeli A Fiechter 《Applied and environmental microbiology》1986,51(5):985-989
Rhamnolipid biosurfactants were continuously produced with Pseudomonas aeruginosa on the pilot plant scale. Production and downstream processing elaborated on the laboratory scale were adapted to the larger scale. Differences in performance resulting from the scale-up are discussed. A biosurfactant concentration of approximately 2.25 g liter-1 was achieved. The biosurfactant yield on glucose was 77 mg g-1 h-1, and the productivity was 147 mg liter-1 h-1, corresponding to a daily production of 80 g of biosurfactant. The first enrichment step consisted of an adsorption chromatography which was followed by an anion-exchange chromatography. The resulting product was 90% pure, and the overall recovery of active material was above 60% with the downstream processing used. 相似文献
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土壤微生物RAPD分析体系的优化研究 总被引:12,自引:0,他引:12
采用正交实验设计,对影响土壤微生物RAPD扩增体系的Mg2+、dNTP浓度及引物浓度进行了研究,同时对退火温度、延伸时间及循环次数进行摸索。结果表明,适宜土壤微生物PCR扩增反应在25μl体积中进行,包括7ng土壤微生物DNA样品、20pm随机引物l、.5uTaq酶、3.0mmol.L-1Mg-CL2和0.2mmol.L-1dNTP。PCR扩增反应进程如下:94℃3min,使土壤DNA变性;然后再进行39个循环,每个循环包括94℃1min,37℃40s,72℃90s,结束后72℃延伸7min。 相似文献
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H. G. van Faassen 《Plant and Soil》1973,38(2):485-487
Summary Even low concentrations of mercury compounds in agar media strongly decreased the number of soil microbes that could be isolated on these media.Mercury compounds added to the soil in very high concentrations inhibited CO2-evolution, dehydrogenase activity, and nitrification. In contrast, the number of microbes increased somewhat in a clay soil treated with HgCl2. Phenylmercury acetate had a stronger inhibiting effect than HgCl2. In sandy soil the microbial processes were inhibited more strongly than in clay soil.Mercury compounds present in the soil or added in low concentrations are not expected to seriously disturb organic-matter breakdown, nitrogen mineralization, or the soil-microbe numbers. 相似文献