(62l) Protoplast Fusion Between Escherichia Coli and Lactobacillus Brevis Toward the Engineering of Butanol-Tolerant Strains

One obstacle to the production of butanol from microorganisms is butanol's toxicity: organisms that produce butanol are unable to grow in high butanol concentrations. Escherichia coli can be engineered to produce butanol but experiences severely hindered growth in butanol concentrations above 1%. In comparison, Lactobacillus brevis is more butanol-tolerant, but L. brevis requires more nutritious media to sustain growth than E. coli requires. Protoplast fusion between E. coli and L. brevis was used to engineer bacteria that are more butanol-tolerant than E. coli but are able to grow in less nutritious media than that required by L. brevis. Five fusants were isolated that could sustain growth on both LB and MRS medium over long periods of time. Three of these fusants contained the 16S rRNA sequence of E. coli, and two contained the 16S rRNA sequence of L. brevis. Three of the fusants were able to grow in M9 minimum media. Finally, three of them had higher relative growth rates in the presence of butanol than wild-type E. coli, and one of the other fusants was able to grow to a higher cell density in 2% butanol than E. coli.