Production of Tyramine by Enterobacteria (III)

Abstract

In the previous reports, many studies on tyramine production by intestinal bacteria have reported. In this study, tyramine production from tyrosine was examined for anaerobic bacteria and eumycetes isolated from faeces of men and rats. Furthermore, tyramine production under some conditions of digestive canal (effect of starvation and antibiotics etc, ) was examined. Tyrosine consumption was also examined for some aerobic bacteria.
Many strains of clostridium, veillonella, peptostreptococcus and some strains of bifidus produced tyramine from tyrosine. Although bacteriodes in anaerobic condition was recognized as chief constant intestinal bacteria in normal subjects, tyramine production of these strains was not remarkable.
Some strains of eumycetes (Penicillium, Aspergillus) also produced tyramine from tyrosine.
Effect of Kanamycin and Neomycin against tyrosine decarboxylase (aceton powder) was investigated. Tyrosine decarboxylase was slightly inhibited by these antibiotics. Kanamycin and Neomycin has given for one month by mouth to rats, and after this research, amount of St. faecalis isolated from faeces of these experimental animals decreased and tyrosine decarboxylase activity in some strains of these microorganisms also reduced.
Effect of tyramine production by fasting was examined for St. faecalis isolated from faeces of rats. Amount of intestinal bacteria decreased by abstinence from food, but tyramine production of each strain was unchanged.
Tyrosine decomposition was examind for some aerobic bacteria. Tyrosine consumption in culture filtrate was not always in parallel with tyrosine decarboxylase activity.
It was demonstrated that tyramine production in digestive canal was effected by not only types, characters, and amount of chief constant intestinal microorganisms but also various conditions of digestive canal.