Improved method of protoplast fusion between marine luminescent bacterium and Escherichia coli cultivated with fatty acid

An attempt was made to improve the stability toward centrifugation of protoplast fusion between Shewanella sp. and Escherichia coli. Stability of the cell membrane is an important factor in protoplast fusion. In order to change the fatty acid composition of the cell membrane phospholipids, eight fatty acids [caprylic acid, capric acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid] were added to each nutrient medium of Shewanella sp. and E. coli. The protoplasts were treated with lysozyme, and fusion occurred in the presence of a polyethylene glycol solution. The stability of the protoplast of Shewanella sp. decreased after EPA was added to the culture medium, and the stability of the protoplast of E. coli increased after the addition of linoleic acid or linolenic acid. Some fusant colonies that developed on the regenerated medium selected for E. coli with antibiotic tolerance. The efficiency of this fusion was higher than that of initial condition using protoplasts from Shewanella sp. and E. coli incubated without fatty acids. Protoplasts improved the fatty acid composition of the phospholipids. Cell membrane stability can change in order for the weak cells to be taken in by strong cells. These results suggested that the fatty acid composition of cell membrane phospholipids affected the fusant yield of the fusion of these bacteria.