Abstract
Recently, we isolated and reported the antagonism of Paenibacillus polymyxa JB05-01-1 (P. polymyxa JB05-01-1) against Gram-negative bacteria. Here, we provide more insights and attribute the abovementioned antagonism to the production of colistins A and B, which were purified by Amberlite column exchange, C18 column hydrophobicity, superdex 75 16/60 gel filtration chromatography connected to fast protein liquid chromatography and identified by MALDI TOF/TOF, and manual nanospray analysis. The amount of colistin A and colistin B recovered from 500 ml of culture supernatant was about 0.05 mg. The specific activity and the average recovery of the eluted substances were 5,120 AU/mg and 1.1%, respectively. The minimal inhibitory concentrations of the purified colistins against Escherichia coli O157:H7 and Pseudomonas fluorescens LRC R73 were 0.13 and 0.62 mu g/ml, respectively.