Growth Stimulating Activity for Microorganisms in Naturally Occurring Substances and Partial Characterization of the Substance for the Activity as Pyrroloquinoline Quinone

In various naturally occurring substances used for culture media, the universal occurrence of a growth stimulating substance for microorganisms was indicated, which markedly reduced the lag phase in microbial growth, whereas no appreciable increase was observed in the subsequent growth rate at the exponential phase or in the final cell yield at the stationary phase.Anextensive survey of the naturally occurring substances by means of chromatographic fractionation showed that the growth stimulating activity appeared in a restricted area of the gel filtration profiles, indicating the molecular similarity of these naturally occurring substances.The biological activity was specific not only for acetic acid bacteria but also for many other kinds of microbes.The possibility that the substances were identical with PQQwas indicated by several lines of analytical evidence.One reason for the faster cell growth on the use of these natural substances could be the functioning of PQQas the growth stimulating substance.