High solid saccharification using mild alkali-pretreated rice straw by hyper-cellulolytic fungal strain

Background: The aim of this study was to use traditional mutagenesis to generate hyper-cellulolytic mutants with emphasis on stable, non-spore formers, shorter enzyme producing times and higher saccharification efficiency at high solid loadings. An in-house isolated strain of Aspergillus terreus (At) was identified, fingerprinted and mutated. A sequential process of mutation followed by stringent selection generated mutant At9, which produced optimal cellulase at day 4 instead of day 7, was non-spore former with high stability and grew on a lower pH than parental strain. At9 cellulases were used successfully at high solid loads [up to 25 % (w/v)] in a modified system at 50°C with reduced hydrolysis times compared to parent strain. Conclusion: In current work ultra violet (UV) mutagenesis and intelligent screening design combined with growth on a cheap substrate for enzyme production was demonstrated. With this work we present a single organism enzyme system with substantially lower production time and decreased saccharification time at high solid loads. © 2015 Dixit et al.