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B A Bryan

Publications and source records attributed to B A Bryan.

7 recordsLinked to original sources
PubMed1986

Variation in composition and yield of exopolysaccharides produced by Klebsiella sp. strain K32 and Acinetobacter calcoaceticus BD4.

The exopolysaccharides produced by Klebsiella sp. strain K32 and Acinetobacter calcoaceticus BD4 under different growth conditions have been analyzed for sugar composition. The first use of ion chromatography for the quantitative determination of microbial exopolysaccharide composition is reported. Klebsiella sp. strain K32 produced a polymer composed of rhamnose, galactose, and mannose early in its fermentation. The composition of the polymer varied markedly depending on the growth stage of the organism. Klebsiella sp. strain K32 grown in a fermentor produced a polymer which was rich in mannose during early exponential growth in a complex medium, but in the late stationary phase it did not contain detectable levels of mannose. The rhamnose present in the polymer increased from 12 to 55% over the course of growth, whereas galactose decreased from 63 to 45%. A. calcoaceticus BD4 produced a polymer containing rhamnose, glucose, mannose throughout its growth and stationary phase. Klebsiella sp. strain K32 and A. calcoaceticus BD4 were grown on various carbon sources in shake flasks. The polymer yield and composition from both organisms were found to vary with the carbon source. The exopolysaccharide with the highest mannose composition was obtained by using rhamnose as a carbon source for both organisms. These and other data suggest that regulatory changes caused by growth on different substrates result in either the production of a different distribution of polymers or a change in exopolysaccharide structure.

Acinetobacter↗
PubMed1985

Inability of Pseudomonas stutzeri denitrification mutants with the phenotype of Pseudomonas aeruginosa to grow in nitrous oxide.

Pseudomonas aeruginosa PAO1 reduced nitrous oxide to dinitrogen but did not grow anaerobically in nitrous oxide. Two transposon insertion Nos- mutants of Pseudomonas stutzeri exhibited the P. aeruginosa phenotype. Growth yield studies demonstrated that nitrous oxide produced in vivo was productively respired, but nitrous oxide supplied exogenously was not. The defect may be in electron transport or in nitrous oxide uptake.

Kinetics↗
PubMed1983

Variable expression of the nitrogen isotope effect associated with denitrification of nitrite.

The overall isotopic fractionation factor observed for denitrification of NO-2 by resting cultures and cell-free extracts of Pseudomonas stutzeri varied widely with the concentration of NO-2 and reductant. The observed isotope effect (beta obs) increased linearly with velocity when the concentration of nitrite was varied and decreased with velocity when reductant concentration was varied. At any given ratio of velocity to maximum velocity, beta obs was approximately the same in intact cells and cell free extracts. These results indicate the following: (a) neither uptake (whole cells) nor enzyme-substrate association (cell-free extracts) is the sole cause of saturation of the overall rate as [NO-2] is increased; (b) a reductive step lies beyond the initial step and at or before the first unidirectional step; and (c) in intact cells, uptake of NO-2 by the cell and egress of NO-2 from it are very rapid compared to reduction at all concentrations of NO-2. A corollary of the last conclusion is that variation of beta obs in intact cells is due entirely to variation in the relative rates of intracellular steps of the denitrification process. The linear relation between beta obs and velocity imposes constraints on any proposed mechanism of denitrification.

Isotope Labeling↗
PubMed1976

Denitrification.

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Air Pollution↗