Keizo Furuhashi

Asymmetric hydrolysis of α-aminonitriles to optically active amino acids by a nitrilase of Rhodococcus rhodochrous PA-34

SummaryRhodococcus rhodochrous PA-34 isolated from soil as a propionitrile-utilizing microorganism, hydrolysed several α-aminonitriles to optically active amino acids. The hydrolysis of α-aminonitriles was found to be catalysed by a nitrilase. The characteristics of the purified enzyme revealed that this is a new nitrilase as it has a molecular mass of 45 kDa and acts as a monomer. The optimum pH and temperature for the activity of the purified enzyme were 7.5 and 35° C, respectively. Thiol-specific reagents caused inhibition whereas chelators did not significantly alter the activity of this enzyme. The amino acids produced were of L-form, except for alanine. In the case of leucine production from α-aminoisocapronitrile, the enantiomeric ratio of L-leucine to D-leucine was about 60.

Effects of solvents on the production of epoxides by Nocardia corallina B-276

SummaryGlucose-grown cells of Nocardia corallina B-276 produced epoxides from C2 to C18 1-alkenes and styrene. Production of epoxides from C6-C10 1-alkenes and styrene was enhanced by the addition of n-hexadecane as a solvent to the reaction system, while addition of n-hexadecane lecreased the rate of epoxidation of longer chain length 1-alkenes. n-Hexadecane was found to reduce substrate inhibition by styrene and product nhibition by styreneoxide and 1,2-epoxyalkanes. a-Alkanes, 1-alkenes, alkylbenzenes, halogenated akanes and a diester of a dibasic acid could be sed as solvents.

Production of 1,2-epoxyalkanes from 1-alkenes by Nocardia corallina B-276

SummaryA gaseous hydrocarbon-assimilating microorganism, Nocardia corallina, grew on 1-alkenes (C3, C4 and C13 to C18) and produced corresponding 1,2-epoxyalkanes. One of the products, 1,2-epoxytetradecane, had a positive rotation [α]D20=+8.6°. The concentration of propyleneoxide reached 0.6 g/l after 5 days of cultivation. Accumulation of 1,2-epoxytetradecane continued till the end of cultivation when the pH was not controlled, though production stopped in a 24 h cultivation when the pH was controlled at an optimum pH for growth. Propylene-grown cells produced 1,2-epoxytetradecane from 1-tetradecene and degraded tetradecane. In the presence of chloramphenicol, propylene-grown cells did not degraded tetradecane though 1,2-epoxytetradecane was produced from 1-tetradecene. A spontaneous mutant, which neither grew on propylene nor produced propyleneoxide, was isolated. This strain grew on tetradecane and 1-tetradecene but produced only a trace amount of 1,2-epoxytetradecane from 1-tetradecene.

Optimization of a medium for the production of 1,2-epoxytetradecane by Nocardia corallina B-276

SummaryA medium for the production of 1,2-epoxytetradecane from 1-tetradecene by Nocardia corallina B-276 was optimized. The activity of cells producing 1,2-epoxytetradecane increased when cell growth was suppressed by limiting nitrogen or potassium ion in the medium. Mg2+ was found to be essential for the production of 1,2-epoxide. Cell mass was increased, without reducing production of 1,2-epoxide, by increasing the concentration of yeast extract and limiting the concentration of potassium ion. The concentration of 1,2-epoxytetradecane reached 80 g/l in 6 days after optimization and the yield of 1,2-epoxytetradecane was 65 mol% based on consumed 1-tetradecene. Long chain 1,2-epoxyalkanes containing 13–17 carbon atoms also were produced under these conditions.