摘要:

The adsorption–desorption characteristics of glucose oxidase holoenzyme (EC 1.1.3.4; β-D-glucose: oxygen-1-oxidoreductase), glucose oxidase apoenzyme, and the coenzyme flavine adenine dinucleotide (FAD) todays were studied. The fixation of apoenzyme, at a solution pH of 4.5, was rapid and almost complete within 1 h of incubation, since less than 5% of adsorbed apoenzyme was desorbed on changing the pH to 6.5. On the other hand, the fixation of the holoenzyme was much slower, since after I and 24 h of incubation at pH 4.5, raising the pH to 6.5 resulted in the desorption of 45 and 35% of initially adsorbed protein respectively. Flavine adenine dinucleotide was adsorbed to clay at pH 4.5, but only minimal adsorption occurred at pH 6.5.Experiments were performed to determine the release of flavenoid(s) into supernates when the holoenzyme was fixed to clay at pH 4.5. Determinations of the increases in fluorescence of supernates indicated that up to 80% of the original FAD in reacted enzyme was released into supernates. These supernates contained two compounds which possessed differentRfvalues than the reference compounds, flavine mononucleotide, riboflavine, lumichrome, and lumiflavine. The addition of apoenzyme to supernates obtained from holoenzyme–clay complex to reconstitute enzyme activity indicated that less than 3% of the original FAD could be detected in supernates.When the enzyme–clay complex structured at pH 4.5 was adjusted to pH 6.5, data on desorption of both protein and FAD allowed the conclusion that the coenzyme was desorbed as an integral part of the enzyme.

ISSN:0008-4166    

DOI:10.1139/m77-166

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Four strains ofRhizobium japonicum, two of which produce slimy and non-slimy colony types and two others which produce large and small colony types, were isolated and cloned. All were infective and nodulated Lee soybean host plants. Each colony type was characterized as to its salt sensitivity to Na+and K+ions, relative level of symbiotic nitrogen fixation, and relative level of free-living nitrogen fixation. Growth studies performed in the presence of salts demonstrated that the non-slimy or small colony types were sensitive to salt with significantly depressed growth rates and cell yields. Growth rates and cell yields of slimy, large, colony types were relatively unaffected by salt. Both symbiotic and free-living (non-associative) nitrogen fixation analyses (by acetylene reduction) revealed that the non-slimy, small colonies were significantly more effective than slimy, large colonies.

ISSN:0008-4166    

DOI:10.1139/m77-167

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The taxonomic position of some telluric non-fermenting Gram-negative bacteria collected into a phenon representing about a quarter of the soil isolates by an earlier numerical analysis is specified. The Shapiro–Chargaff coefficient determined by thermal-transition curves of the DNA and their hybridization by nitrocellulose filters method show a close affinity withPseudomonas maltophilia.

ISSN:0008-4166    

DOI:10.1139/m77-168

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

AnArthrobactersp. metabolizesL-tyrosine by a pathway involving 3,4-dihydroxyphenyl-acetate as a key intermediate.p-Hydroxyphenylpyruvate is formed from tyrosine by an aminotransferase specifically requiring α-ketoglutarate for activity, and is then converted top-hydroxyphenylacetate by an oxidative decarboxylation.p-Hydroxyphenylacetaldehyde is not an intermediate in the formation ofp-hydroxyphenylacetate. Extracts of the bacterium oxidize 3,4-dihydroxyphenylacetate to δ-carboxymethyl-α-hydroxymuconic acid which, when supplemented with 2 mol of diphosphopyridine dinucleotide, results in the production of stoichiometric amounts of succinate and pyruvate.

ISSN:0008-4166    

DOI:10.1139/m77-169

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Aspergillus fumigatusATCC 28282 converted phenylacetic acid into a new dihydroxylated compound (2,6-dihydroxyphenylacetic acid) which was identified as 2,6-dimethoxyphenylacetic acid methyl ester. Two other new metabolites have been isolated also and identified asortho- hydroxyphenylacetic acid andmeta-hydroxyphenylacetic acid.

ISSN:0008-4166    

DOI:10.1139/m77-170

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Cells ofStaphylococcus aureus, strain S-6, can grow in the presence of 100 μg of cerulenin/ml if the basal medium is supplemented with certain saturated or unsaturated fatty acids. The production of enterotoxin B (SEB) is markedly influenced by both the ratio of saturated to unsaturated fatty acid and by the melting point of the unsaturated fatty acid supplement. The results presented suggest that a certain degree of membrane fluidity promotes maximum SEB production and that greater or lesser degrees of membrane fluidity prohibit substantial SEB formation but fail to affect final growth density.

ISSN:0008-4166    

DOI:10.1139/m77-171

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Ten different bacteriophages were isolated from untreated city sewage water. These phages were stable at 57 °C for 40 min. A modified agar layer technique was used to obtain high titre phages. Ninety-four of a stock of 101 cultures ofEscherichia coli, which were isolated from inflamed portions of intestines of chickens, were lysed by one or more of these phages.TheE.coliof a known serological grouping were phage typed.

ISSN:0008-4166    

DOI:10.1139/m77-172

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The mitogenic effects ofNeisseria gonorrhoeaeendotoxin, fractionated envelope components, and intact cells were examined on unsensitized mouse splenic lymphocytes in vitro. The stimulatory effect of these substances was measured by increased [3H]thymidine incorporation in spleen cell cultures. Intact cells, purified lipopolysaccharide (LPS), and cell envelope preparations were highly stimulatory and the stimulation index was dose dependent. Fractionated components of the envelope demonstrated variable stimulation when tested at identical LPS concentrations, reflecting the mitogenic activity of the protein moieties. The stimulatory dose responses for purifiedN.gonorrhoeaeandEscherichia coliLPS were compared and mitogenicity was higher with gonococcal LPS at all concentrations tested. Alkaline detoxification or succinylation ofN.gonorrhoeaeLPS results in loss of ability to induce blast transformation. The mitogenicity of cell-surface components ofN.gonorrhoeaeis discussed in terms of LPS and protein content.

ISSN:0008-4166    

DOI:10.1139/m77-173

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

This paper reports two different enterotoxigenic classes of the genusAeromonasisolated from fishes. Strains ofA.sobriawere isolated from healthy fishes only whereas strains ofA.hydrophilawere isolated from both healthy and moribund fishes.Aeromonas sobriaandhydrophilastrains produced a cytotoxic factor and were highly proteolytic. Seventy-five percent (75%) of theA.sobriastrains produced only one type of hemolysis on 5% blood agar, but 92% of theA.hydrophilaproduced two types of hemolysis. Enterotoxigenicity of all strains was tested by the rabbit gut loop technique and the suckling mouse test. Most of these Aeromonads were enterotoxigenic. Enterotoxigenic strains appeared to produce two different enterotoxins which were antigenically related, but they seemed to have different mechanisms of action. Enterotoxins ofAeromonaswere shown to be antigenically different from those ofE.coli.

ISSN:0008-4166    

DOI:10.1139/m77-174

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The applicability of flow-microfluorometry (FMF) to the study of bacterial samples was investigated on cultures ofRhizobium meliloti,Rhizobium japonicum, andEscherichia coliusing fluorescent and light-scattering signals. This technique which analyzes individual bacterial cells in a population was used to monitor the relative change in nucleic acid content and cell size during the growth cycle of the three microorganisms which were known to have different growth rates.Early log-phaseE.colicells contained at least eightfold more nucleic acid and were significantly larger than the stationary-phase cells. Cultures of early log-phaseR.meliloticells contained three to four-fold more nucleic acid and were slightly larger than cells in the stationary phase.Rhizobium japonicumhad very little change in either parameter. In general, the amount of change in both cell size and nucleic acid content upon initiation of log-phase growth was related to the overall growth rate of the organisms, withE.coliexperiencing the greatest change andR.japonicumthe least. Results obtained by FMF analyses, therefore, were consistent with observations reported by earlier workers. Cultures ofR.melilotialso were used to demonstrate that the intensity of the fluorescent signals was sensitive to digestion by DNase and RNase and to prolonged storage and fixation. The potential use of FMF in the study of microorganisms is discussed.

ISSN:0008-4166    

DOI:10.1139/m77-175

出版商:NRC Research Press    

年代:1977

数据来源: NRC