Flocculation Properties of -PGA by B. pumilus C2 in Extreme Conditions

Abstract

The optimization of fermentation conditions and flocculation characteristics of -PGA produced by Bacillus pumilus C2 were studied in this paper. The strain C2 with high flocculating activity in extreme conditions was screened from the sediment of a saltern pool in Dalian. The strain C2 was named Bacillus pumilus C2 after the identification of morphological characteristics, physiology biochemistry experiment and 16S rDNA. The flocculation active substance was identified as -PGA by 1H-Nuclear magnetic resonance. The optimal fermentation conditions of B. pumilus C2 were 25 g/L sucrose, 25 g/L sodium glutamate, 10 g/L sodium citrate, 10 g/L (NH4)2SO4, 5 g/L NaCl with the initial pH of 7. The highest production of -PGA was 69 g/L under the optimal fermentation in fed-batch fermentation. The study of flocculation property of -PGA showed that it has high activity in the conditions of high temperature, pH and NaCl concentration.