Pretreatments of agroellulosic waste for microbial biomass production with a defined mixed culture

Abstract

This study describes an attempt to produce microbial protein from the Egyptian sugar can bagasse. An alkali plus gamma irradiation and an acid plus gamma irradiation pretreat‐ment method was applied on the sugar can bagasse. The fermentations were carried out in an aerated 5 L fermentor on the pretreated substrates using a mixed culture of the cellulo‐lytic fungus Trichoderma viride and the yeast Candida utilis. The growth of the tow organisms was followed by production of biomass protein and the in vitro rumen digestibility. The biomass production contained 35.5% crude protein and had an in vitro rumen digestibility of 69.8%. The biomass contained all the essential and nonessential amino acid and compared well with other protein sources. It was concluded that the C.utilis may be grown together with T.viride on the pretreated cane bagasse substrate. The presence of C. utilis dose not cause a more extensive hydrolysis of polysaccharides in the cane bagasse, but it enhances the protein production.

Key words:

• Food industry waste
• Pretreatments
• Mixed culture
• Microbial protein
• Egypt