Saccharification of Cellulose from Wastewater Sludge and Subsequent Conversion to Organic Acids by Corynebacteria

Abstract

Wastewater sludge containing cellulose from a paper manufacturing facility was saccharized using Meicelase (cellulase from Trichoderma viride). As a result of process optimization, maximum saccharification was obtained at pH 4.0, 40deg, and 0.1 % enzyme concentration. After neutralization of hydrolysis products by acid, a Corynebacterium glutamicum inoculum and cultivation medium were added to the solution. Lactic acid and succinic acid, as major metabolic products, were synthesized in this reaction under anaerobic conditions by bubbling of carbon dioxide gas. Lactic acid was identified to be of L-form, which is useful as a starting material for the manufacture of biodegradable polymers such as poly lactic acid. Both these organic acids can also be converted to a wide variety of organic products. This production of organic acids was thus accompanied by CO2 fixation. Paper sludge saccharification and organic acid production were done in the same reactor to reduce the reaction time and simplify the overall process by using Celluzyme (cellulase from Humicola microorganism), whose optimum activity is at around pH7. This study illustrates the use of biodegradable wastes in prevention of global warming.