Efficiency of a soil Mycobacterium during growth on hydrocarbons and related substrates

Hydrocarbon‐utilizing bacteria retained the ability to readapt to propane utilization after prolonged transfer on a non‐hydrocarbon substrate. The organism studied most thoroughly (Mycobacterium vaccae strain JOB5) required 12–15 hr to readapt to propane oxidation. The amount of growth with propane as substrate by strain JOB 5 was proportional to the initial propane concentration when neither O2 nor substrate was limiting. Maximal cell yields were attained with an initial atmospheric O2 concentration of 40% when the propane concentration was 50%. The generation time for strain JOB 5 was 5 hr with propane and 3.5 hr with propionate as substrate. The molar growth yield with strain JOB 5 on gaseous alkanes and related substrates was consistently lower than predicted values.