Effects of pH, Temperature, and Nutrients on Propionate Degradation by a Methanogenic Enrichment Culture.

Enrichment cultures were used to determine the conditions promoting fastest methanogenic propionate degradation and growth by adapting the cultures to various physical and chemical conditions and measuring the specific growth rate. We found that the fastest growth of propionate oxidizers occurred at pH 6.8 to 8.5 and 32 to 45 degrees C. Acetate-degrading populations showed narrower optima for fastest growth (pH 6.8 to 7.2 and 37 to 43 degrees C). Enrichment cultures grew as well in minimal medium as in complex medium, although individual microbial populations appeared to require growth factors which could be met by cross-feeding.