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91.
Formaldehyde Fixation Contributes to Detoxification for Growth of a Nonmethylotroph, Burkholderia cepacia TM1, on Vanillic Acid 总被引:2,自引:0,他引:2
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Ryoji Mitsui Yoko Kusano Hiroya Yurimoto Yasuyoshi Sakai Nobuo Kato Mitsuo Tanaka 《Applied microbiology》2003,69(10):6128-6132
During bacterial degradation of methoxylated lignin monomers, such as vanillin and vanillic acid, formaldehyde is released through the reaction catalyzed by vanillic acid demethylase. When Burkholderia cepacia TM1 was grown on vanillin or vanillic acid as the sole carbon source, the enzymes 3-hexulose-6-phosphate synthase (HPS) and 6-phospho-3-hexuloisomerase (PHI) were induced. These enzymes were also expressed during growth on Luria-Bertani medium containing formaldehyde. To understand the roles of these enzymes, the hps and phi genes from a methylotrophic bacterium, Methylomonas aminofaciens 77a, were introduced into B. cepacia TM1. The transformant strain constitutively expressed the genes for HPS and PHI, and these activities were two- or threefold higher than the activities in the wild strain. Incorporation of [14C]formaldehyde into the cell constituents was increased by overexpression of the genes. Furthermore, the degradation of vanillic acid and the growth yield were significantly improved at a high concentration of vanillic acid (60 mM) in the transformant strain. These results suggest that HPS and PHI play significant roles in the detoxification and assimilation of formaldehyde. This is the first report that enhancement of the HPS/PHI pathway could improve the degradation of vanillic acid in nonmethylotrophic bacteria. 相似文献
92.
Phylogeny and distribution of extra-slow-growing Bradyrhizobium japonicum harboring high copy numbers of RSα, RSβ and IS1631 总被引:1,自引:0,他引:1
93.
X-ray diffraction studies were carried out on the outer membranes of various strains of Salmonella typhimurium. Ten distinct diffraction peaks which seem to be caused by protein assemblies were observed for most strains. Three small-angle reflections were used to determine an average structure of the protein assembly in the outer membrane of mutant HN202. An electron density distribution of the averaged assembly was obtained by means of the Fourier-Bessel transform. It has a diameter of about 100A, in agreement with the results of electron microscope observations (Smit, Kamio, and Nikaido (1975) J. Bacteriol. 124, 942--958), and exhibits a low electron density region at its center, suggesting the presence of a pore, as predicted on the basis of transmembrane transport experiments (Nakae (1976) J. Biol. Chem. 251, 2176--2178). 相似文献
94.
Synchronously growing cells of nitrogen-fixing Synechococcus sp. Miami BG 043511 were harvested periodically and the capability for hydrogen photoproduction in closed vessels was measured under hydrogen production conditions. The capability for hydrogen photoproduction in cells was correlated with that of cellular carbohydrate content. Cells with a high carbohydrate content exhibited a high capacity for hydrogen production and those with low carbohydrate content exhibited low capacity for hydrogen production. Nitrogenase activity at the onset of incubation did not coincide with a capability for the cells to produce hydrogen during the subsequent incubation period. Interestingly, when cells with a high capacity for hydrogen photoaccumulation were incubated, alternate periods of hydrogen and oxygen accumulation were observed at 12 hour intervals. About 0.5 ml of hydrogen per ml of cell suspension was accumulated in flasks during the initial 12-h incubation period. These observations indicate that the use of synchronous culture can be one of the ways of provide materials suitable not only for basic studies but also for applied aspects of hydrogen photoproduction. 相似文献
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The phase transition of the purple membrane observed by differential scanning calorimetry (Jackson, M.B. and Sturtevant, J.M. (1978) Biochemistry 17, 911–915) has been investigated by X-ray diffraction, circular dichroism and absorption spectrum, in comparison with the phase transition in the brown holo-membrane. The two-dimensional crystal of bacteriorhodopsin transformed into two-dimensional liquid around 74–78°C in the purple membrane and around 50–60°C in the brown holo-membrane. The X-ray diffraction patterns obtained at 78°C for the purple membrane and at 60°C for the brown holo-membrane exhibit several broad peaks. Analysis of the pattern suggests that bacteriorhodopsin molecules aggregate in trimers even above the phase transition temperature. The negative circular dichroism band in the visible region is still present at 80°C in the purple membrane and at 60°C in the brown holo-membrane, but becomes negligibly small at 70°C in the brown holo-membrane. The 560 nm absorption peak due to bacteriorhodopsin changes its position and height drastically around 80°C in the brown holo-membrane as in the purple membrane. X-ray diffraction studies have been made on membranes of total lipids extracted from the purple membrane. No indication of the phase transition has been found between ?81°C and 77°C. 相似文献
100.
Advances in soil microbial ecology and the biodiversity 总被引:3,自引:0,他引:3
Tsutomu Hattori Hisayuki Mitsui Hideki Haga Norio Wakao Shuichi Shikano Krystyna Gorlach Yasuhiro Kasahara Adel El-Beltagy Reiko Hattori 《Antonie van Leeuwenhoek》1997,72(1):21-28
Recent studies on the colony formation of soil bacteria opened the way to categorize soil bacteria into colony forming curve (CFC) groups of different growth rates. A bacterial culture collection comprising organisms from every CFC group is called an ecocollection. Outlines of ECs of paddy soil 1992 and grassland soil 1987 and 1992 were described. Phylogenetic studies by 16S rDNA sequencing showed a great diversity of culture strains of the ecocollections (EC). A set of alternative concepts was proposed; the active and the quiescent forms of bacterial cells in soil. The former is able to be cultivated and thus counted by the plate method, while the latter is not unless it transforms into the former. Based on the results several points required for extensive cataloguing of soil bacteria were noted. 相似文献