ABSTRACT
This chapter describes the growth stimulating effects of Pyrroloquinoline quinone (PQQ) and PQQ-adducts on microorganisms. When authentic PQQ is fed at the level of picograms to micrograms per ml of a synthetic medium for microorganisms, in which any naturally occurring substance is excluded, growth stimulation or rapid growth of inoculated microorganism is observed, while the control shows no appreciable growth. It has been observed, however, that the effect of the growth-stimulating substance can be seen at any inoculum size. A very poor coenzyme activity for the enzyme, estimated to be more than 100 times less active than authentic PQQ, was found with both peaks of PQQ-serine when compared with each other on the basis of an equimolar amount of authentic PQQ. The growth-stimulating effect of these PQQ-adducts has been shown to be more effective than that of authentic PQQ.
