Isolation and cellulolytic. Activities of bacteria from a cattle waste anaerobic digester and the properties of some Clostridium species

Abstract

Bacteria were isolated from a cattle-waste digester on eleven occasions by dilution culture in solid media containing powdered barley straw, ‘delignified’ straw or filter-paper. Clearing of the medium iaround colonies was taken as primary evidence for cellulolytic activity and 390 isolations were made from different samples and dilutions on this basis. Most (367) of the isolates were screened for cellulolytic activity by incubating with filter-paper strips and a range of activities was found. A number (128) of the isolates of higher activities and two isolates of low activity were tested for their ability to degrade straw and again, a range of activities was found. There were only slight correlations between filter-strip disintegration activities, or initial isolation medium, and straw degradation activities. The results show that a cattle-waste digester contains a heterogeneous cellulolytic bacterial population. Of the eleven groups investigated in detail, five had properties which suggested that the bacteria were strains of the known Clostridum species butyricum, beijerinckii, acetobutylicum, bifermentans and sprogenes.