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31.
Extracts of denitrifying bacteria grown anaerobically with phenol and nitrate catalyzed an isotope exchange between 14CO2 and the carboxyl group of 4-hydroxybenzoate. This exchange reaction is ascribed to a novel enzyme, phenol carboxylase, initiating the anaerobic degradation of phenol by para-carboxylation to 4-hydroxybenzoate. Some properties of this enzyme were determined by studying the isotope exchange reaction. Phenol carboxylase was rapidly inactivated by oxygen; strictly anoxic conditions were essential for preserving enzyme activity. The exchange reaction specifically was catalyzed with 4-hydroxybenzoate but not with other aromatic acids. Only the carboxyl group was exchanged; [U-14C]phenol was not exchanged with the aromatic ring of 4-hydroxybenzoate. Exchange activity depended on Mn2+ and inorganic phosphate and was not inhibited by avidin. Ortho-phosphate could not be substituted by organic phosphates nor by inorganic anions; arsenate had no effect. The pH optimum was between pH 6.5–7.0. The specific activity was 100 nmol 14CO2 exchange · min-1 · mg-1 protein. Phenol grown cells contained 4-hydroxybenzoyl CoA synthetase activity (40 nmol · min-1 · mg-1 protein). The possible role of phenol carboxylase and 4-hydroxybenzoyl CoA synthetase in anaerobic phenol metabolism is discussed. 相似文献
32.
A new strictly anaerobic bacterium was isolated from an enrichment culture with glutarate as sole substrate and freshwater
sediment as inoculum, however, glutarate was not metabolized by the pure culture. The isolate was a mesophilic, spore-forming,
Gram-negative, motile curved rod. It fermented various organic acids, alcohols, fructose, acetoin, and H2/CO2 to acetate, usually as the only product. Other acids were fermented to acetate and propionate or acetate and butyrate. Succinate
and malonate were decarboxylated to propionate or acetate, respectively, and served as sole sources of carbon and energy for
growth. No inorganic electron acceptors except CO2 were reduced. Yeast extract (0.05% w/v) was required for growth. Small amounts of cytochrome b were detected in membrane
fractions. The guanine-plus-cytosine content of the DNA was 44.1±2 mol%. The isolate is described as a new species of the
genus Sporomusa, S. malonica. 相似文献
33.
34.
Growth of Propionibacterium freudenreichii was studied with glycerol, lactate, and propionate as energy sources and a three-electrode poised-potential amperometric electrode system with hexacyanoferrate (III) as mediator. In batch culture experiments with glycerol and lactate as substrates, hexacyanoferrate (III) was completely reduced. Growth yields increased and the fermentation patterns were shifted towards higher acetate formation with increasing hexacyanoferrate (III) concentrations (0.25–8.0 mM). In experiments with regulated electrodes, glycerol, lactate, and propionate were oxidized to acetate and CO2, and the electrons were quantitatively transferred to the working electrode. Growth yields of 29.0, 13.4 and 14.2 g cell material per mol were calculated, respectively. The high cell yield obtained during propionate oxidation cannot be explained solely by substrate level phosphorylation indicating that additional energy was conserved via electron transport phosphorylation. Furthermore, this result indicated complete reversibility of the methyl-malonyl-CoA pathway in propionic acid bacteria. 相似文献
35.
4-aminobutyrate is not available to bacteroids of cowpea Rhizobium MNF2030 in snake bean nodules 总被引:1,自引:0,他引:1
Laboratory cultures of cowpea Rhizobium MNF2030 grew on 4-aminobutyrate (GABA) as sole source of carbon and nitrogen. GABA transport was active since it was inhibited by carbonyl cyanide mchlorophenyl hydrazone and 2,4-dinitrophenol and cells developed a 400-fold concentration gradient across the cell membrane. Arsenite treatment of GABA-grown cells revealed stoichiometric conversion of GABA to pyruvate, indicating that 2-oxoglutarate is not an intermediate in GABA catabolism. GABA catabolism by cells of strain MNF2030 grown on GABA appreared to involve GABA transaminase, succinic semialdehyde dehydrogenase and malic enzyme; the first two enzymes were specifically induced by growth on GABA. The deamination process and removal of NH3 in cells catabolizing GABA involved GABA: 2-oxoglutarate transaminase; glutamate: oxaloacetate aminotransferase; asparate: pyruvate aminotransferase and alanine dehydrogenase.Isolated snakebean bacteroids of strain MNF2030 transported only small amounts of GABA and had uninduced levels of GABA catabolic enzymes, even though the nodules contained significant levels of GABA. The data suggest that GABA is not available to snakebean nodule bacteroids, presumably because of a control imposed by the peribacteroid membrane.Abbreviations
CCCP
Carbonyl cyanide m-chlorophenyl hydrazone
-
HEPES
N-hydroxyethylpiperazine-N-2-ethanesulphonic acid
-
DTT
dithiothreitol
-
SSAD
succinic semialdehyde dehydrogenase
-
GABAT
4-aminobutyrate transaminase
-
GABA
4-aminobutyrate 相似文献
36.
Donald A. Bryant Robert de Lorimier Gerard Guglielmi S. Edward Stevens Jr 《Archives of microbiology》1990,153(6):550-560
The phycobilisomes and phycobiliproteins of Synechococcus sp. PCC 7002 wild-type strain PR6000 have been isolated and characterized. The hemidiscoidal phycobilisomes of strain PR6000 are composed of eleven different polypeptides: phycocyanin and subunits; allophycocyanin and subunits; subunit of allophycocyanin B; the allophycocyanin -subunit-like polypeptide of Mr 18 000; the linker phycobiliprotein of Mr 99 000; and non-chromophore-carrying linker polypeptides of Mr 33 000, 29 000, 9000, and 8000. Several of these polypeptides were purified to homogeneity and their amino acid compositions and amino-terminal amino acid sequences were determined. Analyses of the phycobiliproteins of Synechococcus sp. PCC 7002 were greatly facilitated by comparative studies performed with a mutant strain, PR6008, constructed to be devoid of the phycocyanin and subunits by recombinant DNA techniques and transformation of strain PR6000. The absence of phycocyanin did not greatly affect the allophycocyanin content of the mutant strain but caused the doubling time to increase 2–7-fold depending upon the light intensity at which the cells were grown. Although intact phycobilisome cores could not be isolated from this mutant, it is probable that functionally intact cores do exist in vivo.Abbreviations used SDS-PAGE
polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate
- 2D-PAGE
two-dimensional gel electrophoresis in which the first dimension consisted of isoelectric focusing in the presence of 8.0 M urea in the pH range 4–6 and the second dimension consisted of electrophoresis in the presence of sodium dodecylsulfate. The nomenclature employed for the phycobiliprotein subunits and linker polypeptides is that defined by Glazer (1985) 相似文献
37.
38.
云南省厉螨科一新属新种(蜱螨亚纲:革螨股) 总被引:4,自引:0,他引:4
在云南陇川县的蟋蟀Gryllus sp.体上采得一种革螨,系厉螨科Ltelapidae Berlese中未曾描述过的种类,并为之建立新属,订名为滇厉螨属Dianolaelaps gen.nov.,属模标本为蟋蟀滇厉螨Dianolaelaps gryllus sp.nov.。新属的主要鉴别特征是:雌螨螯钳动趾端部分三叉;颚角内侧有沟漕并具齿突;口下片末端,在颚角与下咽间有长圆形结构,其内缘并具透明的尖齿列;涎针有膜状结构包绕;足Ⅰ—Ⅲ基节各具一棘,各基节远端侧具细小毛列。 相似文献
39.
Ilari Suominen Jarmo Käpylä Carola Tilgmann Virpi Glumoff Pekka Mäntsälä 《FEMS microbiology letters》1988,55(1):3-8
Abstract In a previous study, we have described unusual cross-reactions among monoclonal antibodies (Mabs) to bacteria and in particular to the Inaba and Ogawa serotypes of Vibrio cholerae . In this study, the extent to which the binding sites of both antibodies and antigens overlap has been investigated by competitive binding and idiotypic analysis. The competitive binding data indicate that the cross-reactive binding of the Inaba Mabs to the Ogawa vibrios can be abolished by incubation with higher affinity Ogawa Mabs. However, rabbit antiserum raised against the Inaba series does not react with the Ogawa series, indicating that anti-Inaba Mabs do not share idiotypic determinants with anti-Ogawa Mabs. The results therefore suggest that the two sets of antibodies recognise different determinants which are closely related in spatial terms, and which consequently do not permit simultaneous binding of the two types of monoclonal antibody. 相似文献
40.
Meloidogyne mayaguensis n. sp. is described and illustrated from specimens obtained from galled roots of eggplant, Solanum melongena L., from Puerto Rico. The perineal pattern of females is round to ovoid with fine, widely spaced striae. It has occasional breaks of striation laterally and a circular tail tip area lacking striae. The stylet, 15.8 μm long, has reniform knobs that merge gradually with the stylet shaft. Males have a high, rectangular, smooth head region, not set off from the body contour. The labial disc is continuous with the medial lips which do not slope posteriorly. The styler, 22.9 μm long, has large rounded backward sloping knobs; the shaft is of uneven diameter. Mean body length of second-stage juveniles is 453.6 μm. The truncate head region is not annulated, and the rounded, slightly raised labial disc and the crescentic medial lips form dumbbell-shaped lip structures. The stylet, 11.6 μm long, has rounded, posteriorly sloping knobs. The slender tail, 54.4 μm long, gradually tapers to a bluntly pointed tip. Tomato, tobacco, pepper, and watermelon are good hosts; cotton and peanut are not hosts. M. mayaguensis n. sp. reproduces by mitotic parthenogenesis and has a somatic chromosome number of 2n = 44-45. The enzyme patterns are unique among Meloidogyne species. 相似文献