Adaptation of Bacteria from One Type of Hydrocarbon to Another

Abstract

THE ease with which various bacteria assimilate hydrocarbons is known to vary with the structure of the hydrocarbon¹. As part of an investigation of the fermentation of hydrocarbon material by bacteria we have investigated the relative rates of bacterial growth on liquid hydrocarbons of different structures. About thirty different kinds of bacteria, including Pseudomonas fluorescens and several species of Corynebacterium, have been isolated from soil samples taken from industrial oil and chemical spillage areas and from garden soils. The most rapid growth of fresh isolates from soil samples occurred with the normal paraffins C₈ – C₁₈, but growth on normal C₅ – C₈ hydrocarbons was much less rapid. This may be explained by the known toxicity of the lower alkanes to bacteria because of their lipid solvent properties. The hydrocarbons listed as follows are classified in decreasing order of ability to support bacterial growth: Class 1. n-Paraffins (C₈–C₁₈). Class 2. Branched chain alkanes (3-methylheptane; 2,2,4-trimethylpentane; pentamethylheptane; 2,2,4,4,6,-8,8,-heptamethylnonane; propylene tetramer). Class 3. n-Paraffins (C₅–C₈). Class 4. Cyclic hydrocarbons (cyclohexane, methyl-cyclohexane, decalin, benzene, m-xylene).