An investigation into the microbial bioconversion of cellulosic waste

Abstract

A low technology fermentation systam for biodegradation of cellulose based waste material is described. Using a substrate of thermally bonded paper plastic laminate in a defined mineral salts - medimn the cellulolytic nicrofungus Trichoderma viride XXI 2% 458 was shown to effect the separation of the laminate into its components by .enzynic degradation of the paper. This aicrobially indSced t..separation occurred within 14 days compared to up:to 90 days by purely iphysical meanè. Growth of the fungus within the fermentation syitan was found to provide conditions that control the growth of Tcontaxninating
microorganisms.
Carbonolytic enzyme activity of Trichoderma viride was investigated by measurenent of substrate weight hiss and by -reduction.. in the viscosity of soluble substrate analogues when acted npon:by filtrate front-the fermentation systais. An investigation of the:effect of changes in carbon to nitrogen ratios during fermentation Indicated that maxim*n carbonolytic enzyme activity occurred -at a carbon to nitrogen ratio of 0.6:1 within this systam.
An examination of three other cellulolytic fungi in order to assess their potential as biodegradative organisms within the fernentaticin syatom showed that under microthermophiic conditions only Acrenoni*nn stricturn approached the biodegradative activity of Trichoderma viride at mesophiic tomperatures.
The products of fermentation by Trichodenua viride were examined; protein levels in the residual cellulolytic substrate following biodegradation of paper plastic laminate were determined and found to reach levels of up to 9% following 35 days fermentation. The amino acid composition of protein produced by Trichoderma viride when grown on a range of substrates was determined and found to contain a wide range of essential and non essential amino acids. An investigation of mycotoxins both in the culture medium and residual paper component was undertaken. Comparisons with eleven common mycotoxin standards revealed no positive identifications under the - àonditions investigated.