Anaerobic stimulated mixed culture system.

A compartmented, autoclavable culture vessel has been developed for the purpose of studying interactive associations of microorganisms which are essential to the anaerobic decomposition of sewage sludge. The unit employs sterile filter membranes to subdivide the interior culture space into individual compartments. Bacteria cultured in one compartment are denied access to adjacent compartments, even though rapid interchange of nutrients and metabolic waste products occurs throughout the unit. The obligate methane-forming anaerobe, Methanobacillus omelianskii has been successfully grown and concentrated in this system by use of a synthetic medium reduced with sodium sulfide. The feasibility of using this system to study microbial interactions was, in part, demonstrated by growing M. omelianskii in a thoroughly aerated medium which had been biologically reduced by Escherichia coli prior to inoculation with the anaerobe. Under this condition of simulated mixed culture growth, the cell yield of both microorganisms, as well as specific metabolic activities ascribed to each organism, was readily monitored.