An Assessment of Serial Co-cultivation Approach for Generating Novel Zymomonas Mobilis Strains

Abstract ObjectiveThe alphaproteobacterium Zymomonas mobilis is an efficient ethanol producer.Utilizing its distinctive physiological features, Z. mobilis-based biorefinery shows a great potential for an industrial biofuel production at large scale.Serial co-cultivation based adaptation that promotes species-interaction has been an emerging approach to improve or rewire 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 rewire the desirable physiological features of Z. mobilis.ResultsWe have performed serial co-culture of Z. mobilis mixed with the baker yeast Saccharomyces cerevisiae. We observed filamentation of Z. mobilis cell in the co-culture, indicating that Z. mobilis cells were stressed due to the presence of competitor and that there appeared to be a selective pressure. 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 growth or excreted metabolites profile of generated strains. In line with this, whole genome sequencing of the generated Z. mobilis strains revealed only minor genetic variations from parental strain. The result indicates that co-culture method should be carefully optimized for Z. mobilis strain improvement.