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121.
U. WELANDER 《Soil & Sediment Contamination》2005,14(3):281-291
Cold-adapted microorganisms are potentially interesting for use in environmental biotechnology applications since a large part of the biosphere has low temperatures during at least parts of the year. Many studies have shown that both oil-contaminated and uncontaminated soils in the Arctic, the Antarctic and the Alps contain microbes that can degrade different hydrocarbons deriving from oils. A few studies have also been conducted on degradation of herbicides in soils at low temperatures. Furthermore, phenols and some polychlorinated biphenyl (PCB) congeners have proved to be degradable at low temperatures, using microorganisms isolated from sediments or soils. Additions of nitrogen and phosphorous to polluted soils have been shown to enhance the degradation of hydrocarbons in many cases. Bioaugmentation with hydrocarbon degrading cold-adapted microorganisms has given varying results. The inoculated microorganisms have probably been out-competed by the indigenous microorganisms in some cases. Different ways to increase the efficiency of microbial degradation of organic pollutants in soil in a cold climate is discussed. 相似文献
122.
Nitroaromatic compounds constitute a major class of widely distributed environmental contaminants. Compounds like nitrobenzene, nitrotoluenes, nitrophenols, nitrobenzoates and nitrate esters are of considerable industrial importance. They are frequently used as pesticides, explosives, dyes, and in the manufacture of polymers and pharmaceuticals. Many nitroaromatic compounds and their conversion products have been shown to have toxic or mutagenic properties. Most of them are biodegradable in nature by various microorganisms. However, most contaminated environments have combinations of nitroaromatic compounds present, which complicates the bioremediation efforts. During the last 10 years, research on the biodegradation of nitroaromatic compounds has yielded a wealth of information on the microbiological, biochemical and genetic aspects of the process. New metabolic pathways have been discovered and genes and enzymes responsible for key transformation reactions have been identified and characterized. Knowledge and advances in pathway engineering have helped further understanding of the nature of nitroaromatic biodegradation and the development of bioremediation solutions. In this paper, an overview of recent developments on the biodegradation of nitrogen-containing xenobiotics is presented. 相似文献
123.
植物根系分泌物的生态效应 总被引:35,自引:0,他引:35
根系分泌物是在一定的生长条件下 ,活的且未被扰动的根系释放到根际环境中的有机物质的总称 ,在植物主动适应和抵御不良环境中具有重要作用 :(1)通过化感作用影响根际微生物和周围其它植物的生长 ,并进一步改善植物的生态环境 (生物因素 ) ;(2 )通过对土壤中矿质元素的溶解、螯合作用、迁移和活化等作用 ,不仅在营养缺乏的情况下提高矿质营养元素的有效性 ,而且在面临重金属胁迫时能降低根际中金属污染物的活性 ,减少植物对金属的吸收。根系分泌物在植物与环境的相互作用中起着传递信息的作用 相似文献
124.
海洋石油污染物的微生物降解与生物修复 总被引:28,自引:0,他引:28
石油是海洋环境的主要污染物 ,已经对海洋及近岸环境造成了严重的危害。微生物降解是海洋石油污染去除的主要途径。海洋石油污染物的微生物降解受石油组分与理化性质、环境条件以及微生物群落组成等多方面因素的制约 ,N和P营养的缺乏是海洋石油污染物生物降解的主要限制因子。在生物降解研究基础上发展起来的生物修复技术在海洋石油污染治理中发展潜力巨大 ,并且取得了一系列成果。介绍了海洋中石油污染物的来源、转化过程、降解机理、影响生物降解因素及生物修复技术等方面内容 ,强调了生物修复技术在治理海洋石油污染环境中的优势和重要性 ,指出目前生物修复技术存在的问题。 相似文献
125.
防烟叶霉变菌株对烟叶霉变的影响 总被引:2,自引:0,他引:2
为有效防止烟叶霉变,采用平板对峙培养的方法,就3个防烟叶霉变菌株对霉变菌的抑制作用进行了研究.结果表明,JMBl42、B112、B329对供试霉变菌皆表现出一定的抑制作用,对不同霉变菌的平均抑制率分别为51.6%、52.9%、53.7%.3个防烟叶霉变菌株分别以每mL 10^7、10^8、10^9 cfu(colony当当forming unit)13个浓度单独处理和每mL10。cfu浓度混合处理烟叶,结果表明,JMBl42菌株每mL10,cfu处理浓度效果最好,与对照差异极显著,其次为B112菌株每mL10^8cfu处理浓度,但它与对照差异不显著,B329菌株处理效果最差,混合施用结果与对照差异不显著.由此确定JMBl42菌株每mL10^9cfu处理浓度为仓储烟叶防霉变最佳处理参数、 相似文献
126.
A study of the horizontal and vertical distribution of heterotrophic bacteria in brackish Lake Shira in summer periods showed that mesophilic bacteria dominated in all areas of the lake, whereas psychrotolerant bacteria dominated in the metalimnion and hypolimnion of its central part. Nonhalophilic bacteria were mostly mesophilic and dominated in coastal waters. Most psychrotolerant bacteria were able to grow in the presence of 5–10% NaCl. Heterotrophic bacteria isolated in different regions of the lake were identified to a generic level. The isolates were classified into autochthonous and allochthonous microorganisms on the bases of their distribution pattern in the lake water, halotolerance, and ability to grow at low temperatures. 相似文献
127.
128.
Identification of a novel 4-hydroxyphenylpyruvate dioxygenase from the soil metagenome 总被引:1,自引:0,他引:1
Lee CM Yeo YS Lee JH Kim SJ Kim JB Han NS Koo BS Yoon SH 《Biochemical and biophysical research communications》2008,370(2):322-326
4-Hydroxyphenylpyruvate dioxygenase (HPPD) is a Fe(II)-dependent, non-heme oxygenase that converts 4-hydroxyphenylpyruvate to homogentisate. Essential cofactors, such as plastoquinone and tocopherol, are produced by HPPD-dependent anabolic pathways in plants. To isolate a novel hppd using culture-independent method, a cosmid metagenomic library was constructed from soil in Korea. Screening of Escherichia coli metagenomic libraries led to the identification of a positive clone, YS103B, producing dark brown pigment in Luria-Bertani medium supplemented with l-tyrosine. In vitro transposon mutagenesis of YS103B showed that the 1.3 kb insert was sufficient to produce the hemolytic brown pigment. Sequence analysis of YS103B disclosed one open reading frame encoding a 41.4 kDa protein with the well-conserved prokaryotic oxygenase motif of the HPPD family of enzymes. The HPPD-specific β-triketone herbicide, sulcotrione, inhibited YS103B pigmentation. The recombinant protein expressed in E. coli generated homogentisic acid. Thus, we present the successful heterologous expression of a previously uncharacterized hppd gene from an uncultured soil bacterium. 相似文献
129.
130.
Popova L. Yu. Maksimova E. E. Lobova T. I. Kargatova T. V. Boyandin A. N. Krylova T. Yu. Pechurkin N. S. 《Microbiology》2001,70(6):685-691
The copy number of R plasmids weakly depends on the selective pressure of the respective antibiotic but does depend on the physiology of the host species and the type of plasmids and cloned genes, whose expression leads to a further load on the biosynthetic apparatus of cells. The last factor is critical in the maintenance of recombinant plasmids in transgenic microorganisms. 相似文献