Isolation and Characterization of n-Butanol Tolerant Microorganisms

n-butanol is produced traditionally by acetone butanol ethanol (ABE) fermentation with relatively low productivity. To improve n-butanol synthesis level, microbes naturally with high tolerance to n-butanol are required for metabolic engineering. In this study, a total of 30 n-butanol tolerant microorganisms were isolated from various environmental samples by screening the enriched cultures. Ten of them were able to tolerate more than 2 % (v/v) n-butanol, and strain YY-23 even thrived in the presence of 3 % (v/v) n-butanol. In addition, n-butanol tolerance mechanisms were investigated by quantitatively analyzing degradation ability of the isolates. The results showed that strains YY-13, YY-14, YY-15, and YY-18 didn’t metabolize n-butanol in LB medium, suggesting that they didn’t have n-butanol degrading enzymes and all of them might be used as candidates for construction of high n-butanol producing strains. Strains YY-10 and YY-29 showed strong n-butanol degradation efficiency (31 and 20 %, respectively), and might be used for n-butanol bioremediation. Furthermore, the isolated strains were identified by the 16S rRNA gene sequences comparative analysis.