Bacteriophages Attacking anl-Glutamic Acid-Producing Strain ofMicrobacterium ammoniaphilum

Abstract

Recei ved J ul y 7, 1967 As a counterwork for preventing phage growth in industrial L-glutamic acid fermentation, the screening of effective chemical agents was carried out. Of the sixty chemicals such as surface-active agents, antibiotics, organic acids, dyestuffs and others, citrate, oxalate and tri-or tetrapolyphosphate showed the selective inhibition for phage growth. The concentrations of these chemicals required to inhibit phage growth were 5 X 10-2 M for citra te or oxalate, and 0.196 for tri-or tetrapol yphospha te, respecti vel y.Application of these selected chemicals to L-glutamic acid fermentation resulted in the complete inhibition of phage growth without affecting on L-glutamic acid production. These results show that the addition of citrate, oxalate, sodium tri-or tetrapolyphosphate to the medium is a promising mean for preventing phage infection in the plant.In a previous paper," the authors have demonstrated that, although a resistant strain to one type of P-phages attacking Microbacterium ammoniaphiium produced as much L-glutamic acid as the phage-susceptible parent strain, a second type of P-phages existed to which resistent strain could be obtained only with difficulty. Therefore, the authors tried to obtain a resistant strain to all types of P-phages, but unfortunately failed to isolate such a strain.From these difficulties, the authors have directed attention to find out inhibitors which are able to inhibit the phage growth selectively without affecting bacterial growth and L-glutamic acid production. But the requirements for inhibitors limited the number of I) S. Seto, T. Osawa and S. Yamamoto, Nippon Nogeikagaku Kaishi, 39, 41 (1965).2) J. E. Lewis, J. Soc. Dairy Technol., 9, 123 (1956 45, 432, 486 (1962). available compounds, since most of them inhibited the growth of both phages and bacteria.In cheese-making employing lactic streptococci,z-61 in streptomycin production employing Streptomyces species,71 and in nisin production employing streptococci,S I some available compounds which are able to inhibit only the phage growth have been reported. Recently, chloramphenicol has been successfully used in acetone-butanol fermentation. 91 Oki et ai. lo.1l1 also showed in L-glutamic acid fermentation em ploying Breviacterium species that chloramphenicol and tetracycline were effective. The present paper describes the finding that citrate, oxalate and certain polyphosphates are most 7) D. Perlman, A. F. Langlynke and H. D. Rotherg, J. Bacteriol., 61, 135 (1951). 8) T. E. Galesloot, Proc. 15th Inter. Dairy Congr. (London), 3, 547 (1959). 9) M. Hongo and A. Murata, Agr. Biol. Chern., 31, 64 (1967). 10) T. Oki, K. Akahoshi, T. Matsui and R. Harada, Nippon Nogeikagaku Kaishi, 39, 22 (1965). 11) S. Oki, T. Matsui, K. Akahoshi and R. Harada, Amino Acid. Nucleic Acid, 10, 18 (1964). 262Susumu SETO, Takeyoshi OSAWA and Sotoo YAMAMOTO suitable compounds for inhibiting P-phages growth in L-glutamic acid fermentation. MATERIALS AND METHODSPhages and bacterial strain. P-phages!1 (phage P-I, P-2, P-...