Fatty acid composition of lipids of Escherichia coli W 1655 F+ and its stable protoplast type L-form

The comparative fatty acid analysis of extractable and non-extractable lipids of Escherichia coli W 1655 F+ and its stable protoplast type L-form shows quantitative as well as qualitative differences. From 10 different fatty acids obtained 16:0, 17:0, and 18:0 are present at about the same quantities in the lipid fractions of the bacterial and L-form. The absence of larger amounts of 12:0, 14:0, and 14:βOH fatty acids in non-extractable L-form lipids reflects the loss of the cell wall in L-form cells. 16:1 fatty acid was found in L-form lipids only. This qualitative difference and the 2–3 times higher content of 18:1 in L-form lipids and the 7 times lower content of cyc 19:0 in extractable lipids of the L-form may be interpreted as alterations characteristic for the changed composition of the cytoplasmic membrane in L-form cells.