The isolation of fungi from barley straw under alkaline conditions and their utilization as agents of biodegradation

Abstract

By employing selective techniques, cellulolytic, xylanolytic and ligninolytic fungi have been isolated from barley straw under alkaline pH conditions and at a range of incubation temperatures. The most common isolates were identified as Alternaria tenuis, Aspergillus fumigatus, Chaetomium globosum, Cephalosporium sp. Coprinus cinereus, Fusarium sp., Scopulariopsis brevicaulis and Streptomyces sp. The fungi Aspergillus fumigatus and Cephalosporium sp. have been isolated at all the temperatures used (20ºC., 25° C., 30ºC, 35°c., 40°c., 45°C and 50°C); the rest of the fungi have been reported up to 35°C. Fourteen different vegetation samples were collected from various regions of Birmingham, in the summer 1976. Subsequently the isolation of Coprini from these samples showed the presence of C. cinereus and C. lagopus while two isolates of Coprini were not identified to species levels. Isolated fungi were assessed for the utilization of different carbon sources, i.e. cellulose, xylan, ball-milledstraw, phenolic acids including gallic acid and tannic acid,and lignins (lignosulphonate, Indulin A-R, and the ligninprepared by 72% H2SOq4 method). Some of the fungi such as A.fumigatus, C. globosum, C. cinereus, and Botryotrichum piluliferum have shown extensive growth and very strong activities on the media supplemented individually with either of the above mentioned carbonaceous compounds as the sole sources. The fungi which showed good utilization of different carbon sources were tested for the colonisation on the barley straw under alkaline pH conditions and at a range of incubation temperatures using aseptic and septic techniques. The most rapid substrate colonisation under these circumstances were shown by C. cinereus or by B. piluliferum. Nevertheless, their substrates colonisation rates were gradually decreased above 35°C. Synergistic and antagonistic actions of some of the rapid substrate colonisers were studied. C. cinereus or B. piluli-~ferum were found to be the most dominant colonisers on straw and responsible for the suppression of other fungi when either of these fungi was inoculated with them under sterile conditions.However, when non-sterile conditions prevailed, the rapid growth of C. cinereus or B. piluliferum on straw almost totally suppressed the appearance of most of the other fungi.