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

Abstract

ObjectiveThe alphaproteobacterium Zymomonas mobilis is an efficient ethanol producer.Utilizingits distinctive physiological features, Z. mobilis-based biorefineryshows a great potential foran industrial biofuel production at large scale.Serial co-cultivation based adaptationthat promotes species-interactionhas been an emerging approach to improveor rewire metabolic featuresinindustrially useful microorganisms by inducing frequent mutations. We applied this methodto assess ifadaptation to longterm co-cultureimprovesor rewire the desirablephysiological features ofZ. 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 competitorand 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.