The rate of
biosynthesis and turnover o f the acetone mobile polar lipids was 0.080 and -0.018
mg/hour respectively. Phospholipids did not get turned over, and their rate of
biosynthesis was 0.019 mg/hour. The biosynthesis o f ethylketones accumulated 29.1 mg
(Table 9), thus their rate o f synthesis was 0.15 mg/hour during the exponential growth
phase. As there were no ethyl ketones detected during the stationary phase, they must
have turned over before the stationary phase was detected. These ethyl ketones may be an
intermediate carbon pool for the synthesis of other lipids or used as a source o f energy.