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A moderate thermophilic bacterium that converts dl-5-(2-methylthioethyl)hydantoin stereospecifically to L-methionine was isolated from soil and designated NS1122A. The bacterial strain NS1122A was identified as Bacillus stearothermophilus. The optimal temperature and pH of the reaction with the resting cells were 60°–70°C and around 8, respectively. The addition of Co2 + or Mn2 + stimulated the production of L-methionine, while Cu2+ and Zn2 + strongly inhibited it. Under adequate conditions, 7.6mg/ml of L-methionine was produced from 10 mg/ml of DL-5-(2-methylthioethyl)hydantoin with a molar yield of 89%. The enzymes responsible for the conversion were purified from the cells of B. stearothermophilus NS1122A. The purified hydantoinase was homogeneous by the criterion of SDS-polyacrylamide gel electrophoresis. The molecular mass of the native enzyme was approximately 200 kDa by gel filtration. The hydantoinase was capable of hydrolyzing L- and D-5-substituted hydantoins, and the D-form of 5-substituted hyd...

A bacterial strain, NS671, which converts DL-5-(2-methylthioethyl)hydantoin stereospecifically to L-methionine, was isolated from soil and was classified into the genus Pseudomonas. With growing cells of Pseudomonas sp. strain NS671, DL-5-(2-methylthioethyl)hydantoin was effectively converted to L-methionine. Under adequate conditions, 34g of L-methionine per liter was produced with a molar yield of 93% from DL-5-(2-methylthioethyl)hydantoin added successively. In addition to L-methionine, other amino acids such as L-valine, L-leucine, L-isoleucine, and L-phenylalanine were also produced from the corresponding 5- substituted hydantoins, but these L-amino acids produced were partially consumed by strain NS671. The hydantoinase, by which 5-substituted hydantoin rings are opened, was ATP-dependent. The N-carbamylamino acid amidohydrolase was found to be strictly L-specific, and its activity was inhibited by high concentration of ATP.

More than 100 isolates were plaque-purified to examine the genetic variations in four wild stocks of Spodoptera litura. Nuclear polyhedrosis virus (NPV) collected in Japan. These isolates were characterized by their in vitro host range in three established insect cell lines, growth characteristics, polyhedral protein, DNA restriction endonuclease pattern and DNA hybridization. The isolates were separated into four distinct groups: (I) isolates corresponding to Autographa californica NPV, (II and IV) two different groups of isolates of S. littoralis NPV which had been previously characterized and (III) isolates with no correspondence to any reported virus group. Of the S. litura NPV wild stocks, two were mixtures of more than two different groups of NPVs. We have discussed the advantage of having a mixture of different NPV groups in the same wild virus stocks.