Abstract
In medium containing D- and L- alanine (or DL-alanine) the growth curve of Leuconostoc mesenteroides exhibits an unusual phenomenon in the presence of the vitamin B6 antagonist, 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMPm). Increasing the concentration of the inhibitor, it increasingly inhibits growth up to a certain level, after which growth of the organisms resumes and increases until the amount of inhibitor is approximately doubled; with further increase of the amount of the inhibitor above this level, growth of the bacteria is again restricted.
The same characteristic curve was obtained with other antagonists of pyridoxal, 2-methyl-4-methylamino-5-hydroxymethylpyrimidine and isonicotinic acid hydrazide.
The appearance of the characteristic phenomenon was not related to the presence of vitamin B6. It occurred when the vitamin was supplied as pyridoxal, pyridoxal phosphate, pyridoxamine or pyridoxine, as well as when it was omitted completely from the medium.
This phenomenon was not observed in cultures of Streptococcus faecalis R.
