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Lactic acid bacteria exhibiting activity against the gram-positive bacterium Bacillus subtilis were isolated from rice bran. One of the isolates, identified as Enterococcus faecalis RJ-11, exhibited a wide spectrum of growth inhibition with various gram-positive bacteria. A bacteriocin purified from culture fluid, designated enterocin RJ-11, was heat stable and was not sensitive to acid and alkaline conditions, but it was sensitive to several proteolytic enzymes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that enterocin RJ-11 had a molecular weight of 5,000 in its monomeric form. The amino acid sequence determined for purified enterocin RJ-11 exhibited high levels of similarity to the sequences of enterocins produced by Enterococcus faecium.

A bacterial strain capable of utilizing chitosan as a sole carbon source was isolated from soil and was identified as a member of the genus Acinetobacter. This strain, designated CHB101, produced extracellular chitosan-degrading enzymes in the absence of chitosan. The chitosan-degrading activity in the culture fluid increased when cultures reached the early stationary phase, although the level of activity was low in the exponential growth phase. Two chitosanases, chitosanases I and II, which had molecular weights of 37,000 and 30,000, respectively, were purified from the culture fluid. Chitosanase I exhibited substrate specificity for chitosan that had a low degree of acetylation (10 to 30%), while chitosanase II degraded colloidal chitin and glycol chitin, as well as chitosan that had a degree of acetylation of 30%. Rapid decreases in the viscosities of chitosan solutions suggested that both chitosanases catalyzed an endo type of cleavage reaction; however, chitosan oligomers (molecules smaller than pentamers) were not produced after a prolonged reaction.

The closely linked structural genes of phosphofructokinase (pfkA) and triosephosphate isomerase (tpi) of Escherichia coli were separately cloned onto plasmid pBR322. By gene dosage effects, transformed cells of E. coli C600 with these pBR322 hybrid plasmids showed 7- and 16-fold increases in the specific activities of phosphofructokinase and triosephosphate isomerase, respectively, over the specific activities in C600. Dried preparations of E. coli cells dosed with these genes showed appreciably high ATP-regenerating activity.

A gene for glucokinase (Glk) in Escherichia coli B was cloned onto vector plasmid pBR322, and the hybrid plasmid obtained was designated pGK100. The gene for Glk was located in the central MluI fragment (0.82 megadalton) of the 6.0-megadalton chromosomal DNA inserted in the HindIII site of the vector. The introduction of pGK100 into E. coli 112L having a decreased level of Glk activity resulted in the about 15-fold increase in this enzyme activity. The poor growth rate of 112L cells on glucose or mannose was also improved by the introduction of pGK100. However, removal of some portion near the glk gene prevented the growth of 112L cells, although Glk activity was high enough to support growth. Therefore, some function of Glk may be regulated by a gene(s) near the glk gene.

A purine-sensitive phenotype results from a previously described mutation in the structural gene (pyrE) for orotate phosphoribosyltransferase (OPT) in Escherichia coli K-12. OPT from both the mutant and the wild-type was partially inhibited by adenine and adenosine, although other purine derivatives were not effective for this inhibition. The Km values of the mutant OPT were 580 and 760 microM for orotate and 5'-phosphoribosyl-1'-pyrophosphate (PRib-PP), respectively, whereas the corresponding values for the wild-type OPT were 40 and 60 microM. The intracellular level of PRib-PP was decreased to less than 15% of the normal level when purine derivatives were added to exponentially growing cultures of both the parent and mutant strains. However, this decrease of the PRib-PP level was not found in strains derived from the mutant, in which the purine-sensitive phenotype was suppressed by a secondary mutation. The purine-sensitive phenotype was caused by retardation of the pyrimidine de novo pathway, when the intracellular level of PRib-PP was diminished by exogenously supplied purine derivatives.