Mechanism Of Butanol Tolerance In Synechocystis Sp. PCC6803

Photosynthetic cyanobacteria have been recently proposed as a microbialfactory to produce butanol due to their capability to utilize solar energy and CO2asthe sole energy and carbon sources, respectively. However, to improve theproductivity, one key issue needed to be addressed is the low tolerance of thephotosynthetic hosts to butanol. The mechanism of butanol tolerance in Synechocystissp. PCC6803will help Synechocystis improve its tolerance to butanol. Futhermore，the understanding of the mechanism of butanol tolerance in Synechocystis sp. PCC6803will facilitate the research to engine Synechocystis sp. PCC6803improve itsbutanol tolerance as a valuable host.In this study, we first applied a quantitative transcriptomics approach based onthe next-generation RNA sequencing technology to identify gene targets relevant tobutanol tolerance in a model cyanobacterium Synechocystis sp. PCC6803. The resultsshowed that278genes were induced upon the butanol exposure at all three samplingpoints through the growth time course. We then applied GC-MS based metabolomicsanalysis to determine the metabolic changes associated with the butanol exposure.The results showed that46out of73chemically classified metabolites weredifferentially regulated by butanol treatment. Notably,3-phosphoglycerate, glycine,serine and urea related to stress responses were elevated in butanol-treated cells. Tovalidate the potential targets, we constructed gene knockout mutants for selected genetargets. The comparative phenotypic analysis confirmed that these genes wereinvolved in the butanol tolerance. Finallly, we cloned some up-regulated genes fromSynechocystis sp. PCC6803according to transcriptomics data and overexpressed themrespectively in Escherichia.coli.The integrated OMICS analysis provided a comprehensive view of thecomplicated molecular mechanisms employed by Synechocystis sp. PCC6803againstbutanol stress, and allowed identification of a series of potential gene candidates fortolerance engineering in cyanobacterium Synechocystis sp. PCC6803.