Open AccessDegradation of unsaturated hydrocarbons by methanogenic enrichment cultures
Author(s) -
Schink Bernhard
Publication year - 1985
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1985.tb01133.x
Subject(s) - methanogenesis , chemistry , biodegradation , naphthalene , squalene , toluene , enrichment culture , organic chemistry , environmental chemistry , methane , bacteria , biology , genetics
The biodegradability of hydrocarbons under anaerobic conditions was studied in enrichment cultures using mineral media inoculated with sewage sludge or sediment samples of limnic and marine origin. No indication of methanogenic degradation was obtained with either n ‐hexane, n ‐hexadecane, n ‐heptadecane, 1‐hexene, cis ‐2‐hexene, trans ‐2‐hexene, isoprene, 1‐hexine, benzene, toluene, xylene, cyclohexene, cycloheptatriene, cyclopentadiene, styrene, naphthalene, azulene, or β‐carotene. Squalene was incompletely converted to methane and carbon dioxide. Complete degradation was observed with 1‐hexadecene. Methanogenic subcultures were maintained on 1‐hexadecene and squalene. Both enrichments contained after several transfers Methanospirillum hungatei and Methanothrix soehngenii as prevalent methanogenic bacteria. Acetate (≤80 μ M) was the only intermediary product detected indicating that degradation proceeded via hydrogen‐dependent syntrophic β‐oxidations. Short rods on hexadecene and cocci on squalene were found to be associated with substrate degradation. The results indicate that terminal double bonds can be sufficient to allow methanogenic degradation of hydrocarbons whereas branching and terminal ring closures may significantly contribute to hydrocarbon stability in anoxic environments.