Browsing by Author "Chapatwala, Kirit D."

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Degradation of acetonitrile by pseudomonas aeruginosa
(1989-05) Nawaz, M. S.; Richardson, Andrew D.; Chapatwala, Kirit D.; Wolfram, James H.
Degradation of Acetonitrile by Pseudomonas putida
(1989-09) Nawaz, M. S.; Chapatwala, Kirit D.; Wolfram, James H.
A bacterium capable of utilizing high concentrations of acetonitrile as the sole source of carbon and nitrogen was isolated from soil and identified as Pseudomonas putida. This bacterium could also utilize butyronitrile, glutaronitrile, isobutyronitrile, methacrylonitrile, propionitrile, succinonitrile, valeronitrile, and some of their corresponding amides, such as acetamide, butyramide, isobutyramide, methacrylamide, propionamide, and succinamide as growth substrates. Acetonitrile-grown cells oxidized acetonitrile with a K(m) of 40.61 mM. Mass balance studies with [C]acetonitrile indicated that nearly 66% of carbon of acetonitrile was released as CO(2) and 14% was associated with the biomass. Metabolites of acetonitrile in the culture medium were acetic acid and ammonia. The acetate formed in the early stages of growth completely disappeared in the later stages. Cell extracts of acetonitrile-grown cells contained activities corresponding to nitrile hydratase and amidase, which mediate the breakdown of actonitrile into acetic acid and ammonia. Both enzymes were intracellular and inducible and hydrolyzed a wide range of substrates. The specific activity of amidase was at least 150-fold higher than the activity of the enzyme nitrile hydratase.
Degradation of organic cyanides by pseudomonas aeruginosa
(1991-03) Nawaz, M. S.; Davis, John W.; Wolfram, James H.; Chapatwala, Kirit D.
A bacterium capable of utilizing acetonitrile (methyl cyanide) as the sole source of carbon and nitrogen was isolated from soil and identified asPseudomonas aeruginosa. This bacterium could also utilize and oxidize numerous lower-mol-wt nitrile compounds and their corresponding amides as growth substrates. A metabolite of acetonitrile in the culture medium was determined to be ammonia. The accumulation of ammonia in the culture medium was proportional to the concentration of the substrate and the inoculum. Cell extracts of the bacterium contained activities corresponding to nitrile aminohydrolase (E C 3.5.5.1) and amidase (E C 3.5.1.4), which regulate the degradation of acetonitrile. Both enzymes were inducible and hydrolyzed a wide range of substrates, and it was determined that the specific activity of amidase was far greater than the activity of nitrile aminohydrolase.
Screening of encapsulated microbial cells for the degradation of inorganic cyanides
(1993-02) Chapatwala, Kirit D.; Babu, G. R. V.; Wolfram, James H.
Different encapsulation matrices were screened to encapsulate cells ofPseudomonas putida for degradation of inorganic cyanides. Degradation of NaCN by free cells and cells immobilized in agar, alginate or carrageenan matrices was studied. The rate of NaCN degradation was monitored for 120 h by measuring pH, bacterial growth, dissolved and gaseous NH3 and gaseous CO2. Alginate-immobilized cells degraded NaCN more efficiently than free cells or agar- or carrageenan-immobilized cells.