title: Microbial growth on hydrocarbons: terminal branching inhibits biodegradation.
abstract: A variety of octane-utilizing bacteria and fungi were screened for growth on some terminally branched dimethyloctane derivatives to explore the effects of iso- and anteiso-termini on the biodegradability of such hydrocarbons. Of 27 microbial strains tested, only 9 were found to use any of the branched hydrocarbons tested as a sole carbon source, and then only those hydrocarbons containing at least one iso-terminus were susceptible to degradation. Anteiso-or isopropenyl termini prevented biodegradation. None of the hydrocarbonoclastic yeasts tested was able to utilize branched-hydrocarbon growth sustrates. In the case of pseudomonads containing the OCT plasmid, whole-cell oxidation of n-octane was poorly induced by terminally branched dimethyloctanes. In the presence of a gratuitous inducer of the octane-oxidizing enzymes, the iso-branched 2,7-dimethyloctane was slowly oxidized by whole cells, whereas the anteiso-branched 3,6-dimethyloctane was not oxidized at all. This microbial sampling dramatically illustrated the deleterious effect of alkyl branching, especially anteiso-terminal branching, on the biodegradation of hydrocarbons.
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D005658:Fungi / Q000254:growth & development / Q000378:metabolism*; D009795:Octanes / Q000378:metabolism*; D010957:Plasmids; D011549:Pseudomonas / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D013045:Species Specificity
chemical_list: D009795:Octanes