Effects of methanol on the growth of gastrointestinal anaerobes

The effects of methanol on the growth of representative, predominant, anaerobic gut bacteria were studied. Growth yields and rates were determined in a base medium to which methanol was added to produce media with methanol concentrations varying, in twofold steps, over a concentration range of 0.01 to 25%, by volume. The growth of many of the organisms was completely inhibited by a methanol concentration equal to, or less than, 6.2%. Isolates representing cellulolytic species were completely inhibited at a methanol concentration of 3.1%, and inhibitory effects on the yield of some cellulolytic isolates were found at a methanol concentration as small as 0.01%. Although most of the organisms studied were inhibited at relatively small methanol concentrations, isolates of Selenomonas ruminantium, Bacteroides ovatus, and Fusobacterium necrophorum were relatively methanol resistant. A methanol concentration of 12.5% was required to completely inhibit S. ruminantium. Substantial growth of B. ovatus was obtained in media containing 12.5% methanol, and for F. necrophorum, substantial growth occurred in media containing 25% methanol. The yields of F. necrophorum strain B85 and S. ruminantium strain PC18 were enhanced by relatively small methanol concentrations and reduced with further methanol concentration increase Anaerobic, nonsporing gut bacteria exhibit a diversity of responses to methanol.