Toshikazu Oki

Bacteriophages of l-Glutamic Acid-Producing Bacteria: Part XI. Selection of Inhibitors for Phage Infection and Suppression of Phage Adsorption by Phytic AcidPart XII. Inhibition of Brevibacterium Phages by Non-Ionic Surface-Active Agents

Antiphage properties of many kinds of chemicals such as antibiotics, surface-active agents and chelating agents were examined on Brevibacterium lactofermentum No. 2256—phage P465 system using double-layer agar method, as a part of the basic study, for preventing phage infection in the industrial fermentation.A great majority of inhibitors which were selected were usually nonspecific and inhibited also bacterial growth. Among about 200 chemicals tested, 5 antibiotics such as chloramphenicol and tetracycline, 6 chelating agents such as phytic acid and 19 surface- active agents such as PEG monoester and POE alkyl ether showed the selective inhibitions for phage infection at the concentrations which did not affect bacterial growth, or at the subbactericidal concentrations that suppressed bacterial growth slightly.Of the above chemicals which showed selective inhibitions for phage infection, a possible mechanism of chelating agents chiefly of phytic acid was investigated. When 0.1 to 0.2% of phytic acid was pr...

Bacteriophages of l-Glutamic Acid-Producing Bacteria: Part VIII. Growth Characteristics of Brevibacterium Phages

The growth characteristics of phages were investigated with the four phages, active on Brevibacterium lactofermentum, which were selected from the respective serological groups, namely, P465 (group I), P468II (group II), Ap85III (group III) and P4 (group IV).The adsorption rate of the phages, P465 and P468II, on the host bacteria was low, whereas that of the phages, Ap85III and P4, was higher. The adsorption rate constants for the four phages were respectively calculated at 2.02 × 10−10, 1.87 × 10−10, 4.32 × 10−10 and 3.15 × 10−10 cm3 per minute, at 30°C in G5B2 medium. With reference to the ionic environment for adsorption, the phages, P465 and Ap85III, specifically required either for Ca++ or Mg++; the phage P468II, for both; and the phage P4, for neither.The growth characteristics of these phages were examined by the one-step growth experiment. The latent periods of the phages were 50, 53, 57 and 47 minutes, respectively; and the corresponding average burst sizes were about 98, 31, 145 and 126. The gro...

Bacteriophages of l-Glutamic Acid-Producing Bacteria: Part VI. Serological Characteristics of the Twenty-one Brevibacterium Phages

Several new phages were obtained from the abnormally fermented broths and from the air in l-glutamic acid fermentation factory using Br. lactofermentum. These twenty-one phages were classified into five serological groups on the basis of cross-neutralization tests with homologous and heterologous antisera. Group I contained ten phages, i.e., P61, P114, P401, P465, P468I, P508, P650, P204, Ap615 and L2. Group II contained five phages, i.e., P468II, Ap85II, Ap62, Ap72 and SI. Group III contained P468III, Ap85III, Ap93 and Ap518, and groups IV and V one phage each, P4 and L1, respectively.In view of serological similarities and of differences in the host specificity, the phages of group I are considered as host range mutants derived from a plaque type mutant, P114, of original phage P61.