Production of lactic acid from industrial waste paper sludge using Rhizopus oryzae MTCC5384 by simultaneous saccharification and fermentation

Abstract

Petrochemical plastics have become a basic requisite in today’s world. Their production has increased dramatically since the last few decades owing to the increase in their demand. Sustainable green plastics produced from polylactic acid have proven to be an alternative to conventional plastics pertaining to their tendency of biodegradability; they are disintegrated by microorganisms and are utilized as carbon sources by plants and other primitive organisms. Rhizopus species is appropriate for the biosynthesis of lactic acid, which is the basic raw material of polylactic acid could be obtained from lignocellulosic biomass since the fungus has the ability to grow on and ferment various carbon sources like cellulose, starch and so on. This research paper deals with the effective biosynthesis of lactic acid from Paper Sludge (PS) through the method of simultaneous saccharification and fermentation (SSF), along with the optimization of various parameters like temperature, pH and initial substrate concentration. An economical and an alternative methodology was opted to prepare cellulase enzyme necessary for the fermentation process, considering the fact that commercially available cellulase are exorbitant. Various combinations of the above enzymes were tested to determine the optimal cellulase cocktail suitable for these conditions. Finally, lactic acid productivity of 27 g/L was achieved when using a blended cellulase cocktail at 50:50 proportion of commercial and fabricate cellulase using a feed concentration of 75 g/L at 40 °C and 6 pH after144 hr by SSF.