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对一株从食草动物的粪便中分离出来的放线菌菌株(XW5),以秸杆粉和麸皮为底物,进行固态发酵,并提取纤维素酶粗酶。采用DNS法,进行酶活测定,研究发现该菌株的固态发酵酶活为4-7u/mg。并对酶活的影响因子、pH、温度以及金属离子等的影响进行了探讨,同时发现该酶为碱性纤维素酶。 相似文献
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一株放线菌代谢产物除草活性的初步研究 总被引:2,自引:0,他引:2
从土壤中分离筛选出1株编号为Z40的链霉菌菌株,其代谢产物具有明显的除草活性。室内生物测定结果表明,Z40菌株发酵液干物质的除草活性主要表现为抑制生长作用。对反枝苋的主根和主茎生长抑制中浓度(EC50)分别为276.76 mg/L和1 609.37 mg/L,对狗尾草的主根和主茎生长抑制中浓度分别为501.81mg/L和629.01 mg/L。浓度为10 000 mg/L对油菜的萌发抑制率和主茎生长抑制率均为100.00%,而对小麦的生长发育没有明显影响。田间试验结果表明,Z40菌株代谢产物对稗、狗尾草、铁苋菜的防治效果均在80%以上,抑制率分别为80.30%,81.59%和88.71%。 相似文献
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传统中药影响黏性放线菌对唾液获得性膜黏附的研究 总被引:3,自引:0,他引:3
目的:研究不同传统中药提取物对黏性放线菌在唾液获得性膜黏附的影响,进一步探讨中药防龋的可能机制。方法:采用唾液包被羟磷灰石(S-HA)形成实验性获得性膜的体外模式,以黏性放线菌作为实验菌株,用不同的药物提取物分别处理S-HA和菌细胞,观察细菌对SHA的黏附情况。结果:两组实验中三七均能抑制菌细胞对SHA的黏附,且随药物浓度的升高而逐渐增强。结论:三七等传统中药能有效抑制黏性放线菌对唾液获得性膜的早期黏附。 相似文献
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Summary The alder has a perennial nodule cluster. The nodule amount on the roots increases with tree age. The N2-fixing activity of nodules decreases with nodule age. Purple coloured soils with various soil pHs and CaCO3 contents are, in the main, the ones which influence nodulation and N2-fixing. Higher N2-fixing capacity existed in the neutral and low calcium soils. High calcium soils and acid soils can restrain nodulation and
the N2-fixing rate significantly. On the slope, where calcarous light loams are found, the annual nitrogen fixation capacity of
alder and cypress mixed plantations, less than 10 years old, is 16 or 17 kg/ha yr, but in the valley, a pure alder plantation
can reach 40 kg/ha yr. 相似文献
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Summary The protein sequences of seven 3-aminoglycoside phosphotransferases falling into the six identified types and three 6-aminoglycoside phosphotransferases were analyzed to give a rooted phylogenetic tree. This tree supports the origin of these groups of enzymes in an ancestor closely related to the actinomycetes, and that horizontal transfer of the resistance genes occurred, possibly via transposons. The implications for genetic engineering of a novel antibiotic are discussed. 相似文献
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M.H. De Jong J.S. Van der Hoeven C.W.A. Van den Kieboom P.J.M. Camp 《FEMS microbiology letters》1988,53(1):45-51
Abstract Actinomyces viscosus is a predominant microorganism in dental plaque. It is, just as the oral Streptococcus spp., a saccharolytic and aero-tolerant organism. We have investigated the effects of oxygen on the growth and metabolism of A. viscosus . To this end A. viscosus Ut 2 was grown in a glucose limited chemostat culture on a chemically defined medium ( D = 0.2 h−1 ) with exposure to variable amounts of oxygen. The Yglucose increased from 62.5 g · mol−1 under anaerobic conditions to 149 g · mol−1 under aerobic conditions, while, concomitantly, the carbon recovery from acidic fermentation products decreased from 75% to 7%. Addition of [14 C]glucose to the chemostat showed that the glucose, which was not converted to acidic fermentation products, was instead converted to carbon dioxide or used for the production of biomass. Under aerobic and anaerobic conditions identical cytochrome spectra, containing only two cytochrome b -type absorption bands, were found. It was concluded that electron transport phosphorylation probably occurs both under aerobic and anaerobic conditions. Anaerobically, fumarate served as the electron acceptor, while the high growth yields observed under aerobic conditions are likely to be explained by citric acid cycle activity coupled to electron transport phosphorylation. 相似文献
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