抄録
The effect of amino acids on colistin production was investigated with Bacillus polymyxa var. KY-7584. Aspartic acid, the precursor of α, γ-diaminobutyric acid (one of the structural components of colistin), showed a remarkable difference of colistin production between Morido's fermentation medium and the modified medium containing the appropriate concentrations of phosphate ion (PO43-) and ammonium-nitrogen (NH4-N). Further studies revealed that a main factor which controlled the stimulatory effect of aspartic acid on colistin production was PO43-.The optimum concentrations of aspartic acid, PO43- and NH4-N in the medium for colistin production were above 0.2%, below 0.01% and 0.17%, respectively. The maximum titer of colistin (51, 900u/ml) by the addition of 0.25% aspartic acid showed the increment of about 30% as compared with that in the reference medium. However, the increase of cell concentration was slight.This study also showed that PO43- was an effector to inhibit the metabolic pathway from aspartic acid to α, γ-diaminobutyric acid.
