ISOLATION AND IDENTIFICATION OF THERMOPHILIC BACTERIA FROM SEWAGE-SLUDGE COMPOST

Twelve strains of thermophilic bacteria were isolated from a sewage sludge compost under aerobic or anaerobic conditions at 60-degrees-C. On the basis of their physiological and biochemical characters, and in comparison with authentic strains, nine strains were identified as belonging to Bacillus stearothermophilus and two strains were tentatively identified as Thermus sp. One anaerobe was still not identified. These isolates were able to grow in the temperature range from 40-degrees-C to 78-degrees-C, with their optimum growth temperature range being from 60-65-degrees-C. The isolated bacilli grew reasonably on sewage sludge in a mixed culture. Since an extract from the mixed culture was able to digest freeze-dried sewage sludge, the isolated bacilli were thereby concluded to be the dominant microflora in the sewage sludge composting process.