DECOMPOSITION OF PROTEIN SUBSTRATES AT LOW-TEMPERATURES BY THE MICROFLORA IN PIG MANURE

We studied the time-course of decomposition, at low temperatures (6-28 -degrees-C), of protein substrates (peptone, gelatin, casein, and fibr in) by the microflora in the sediment from a piggery manure run-off, a nd compared it with the self-fermentation of the sediment. The breakdo wn of protein substrates at the low temperatures was not the limiting factor in the anaerobic degradation of the manure. Ammonia fixation an d acid generation proceeded rapidly and were only slightly temperature -dependent. Acetoclastic methane generation rates fell perceptibly alr eady at 20-degrees-C, while low temperatures affected lithotrophic met hane generation to a lesser degree. The repression of lithotrophic met hane generation in the course of protein substrate fermentation may ha ve been due to the competition for available hydrogen between the lith otrophic methane generation and the processes involving the Stickland reaction. We obtained an enriched culture of apsychrotrophic homoaceta te bacterium, and isolated two morphologically distinct strains of psy chrotrophic methanosarcina.