An assessment of serial co-cultivation approach for generating novel Zymomonas mobilis strains

Abstract

Objective The alphaproteobacterium Zymomonas mobilis is an efficient ethanol producer. By utilizing its distinctive physiological features, Z. mobilis-based biorefinery shows great potential for large scale industrial biofuel production. Serial co-cultivation is an emerging approach that promotes inter-species interactions which can improve or rewire the metabolic features in industrially useful microorganisms by inducing frequent mutations. We applied this method to assess if adaptation to long term co-culture improves or rewires the desirable physiological features of Z. mobilis.Results We performed serial co-culture of Z. mobilis with the baker’s yeast, Saccharomyces cerevisiae. We observed filamentation of Z. mobilis cells in the co-culture, indicating that the Z. mobilis cells were exposed to a selective pressure due to the presence of a competitor. After 50 times of serial transfers, we characterized the generated Z. mobilis strains. The analysis showed that long term co-culture did not drive significant changes in either the growth or profile of excreted metabolites in the generated strains. In line with this, whole genome sequencing of the generated Z. mobilis strains revealed only minor genetic variations from the parental strain. The result indicates that co-culture method needs to be carefully optimized for Z. mobilis strain improvement.