Syntrophic Association by Cocultures of the Methanol- and CO 2 -H 2 -Utilizing Species Eubacterium limosum and Pectin-Fermenting Lachnospira multiparus During Growth in a Pectin Medium

Lachnospira multiparus grew very well in an anaerobic 0.2% pectin medium, whereasEubacterium limosum , which utilizes methanol, H2 -CO2 , and lactate, did not. Cocultures of the two species grew at a somewhat more rapid growth rate than didL. multiparus alone and almost doubled the amount of growth as measured by optical density. In model experiments with cultures transferred once a day with a 2-day retention time,L. multiparus produced mainly acetate, methanol, ethanol, formate, lactate, CO2 , and H2 from pectin. The coculture produced one-third more acetate, and butyrate and CO2 were the only other significant end products. The results are discussed in relationship to microbial metabolic interactions and interspecies hydrogen transfer.