Simultaneous Biological Pretreatment and Saccharification of Rice Straw by Ligninolytic Enzymes from Panus neostrigosus I9 and Commercial Cellulase

Abstract

The utilization of rice straw for biofuel production is limited by its composition. The pretreatment process is required to improve the enzymatic accessibility of polysaccharides in the biomass prior to enzymatic saccharification. In this study, simultaneous biological pretreatment and saccharification (SPS) of rice straw starting from laccase production by Panus neostrigosus I9 was operated in a 2-L fermenter. It was found that fungal physiology was strongly influenced by the agitation, and that the highest laccase production was obtained at an agitation speed of 750 rpm (209.96 ± 0.34 U/L). The dilution rate of 0.05 h−1 was set in continuous fermentation which resulted in laccase activity of 678.49 ± 20.39 U/L, approximately three times higher than that in batch culture. Response surface methodology (RSM) was applied to achieve the condition for maximum percentage of delignification. The maximum percentage of delignification of 45.55% was accomplished after pretreatment of rice straw with laccase enzyme 39.40 U/g rice straw at 43.70 °C for 11.19 h. Reducing sugar of 3.85 ± 0.15 g/L was obtained from the digested rice straw in a SPS reactor, while non-pretreated rice straw gave only 1.13 ± 0.10 g/L within 12 h of incubation. The results indicated that simultaneous biological pretreatment and saccharification (SPS) of rice straw by laccase helped to improve the accessibility of cellulose by cellulolytic enzymes.

Antimicrobial Properties and Characterization of Secondary Metabolites Obtained from Curvularia lunata, an Endophyte of Azadirachta indica

“…The endophyte isolated was subjected to solid-state fermentation in a 1 L Erlenmeyer flask containing sterilized rice medium which was prepared by autoclaving a mixture of 100 g of unpolished rice and 200 mL of distilled water 19 . Blocks of actively developing pure fungal isolates were transferred to rice media under aseptic conditions, blocked with cotton wool and foil, and kept on the fermentation shelf for 21 days after chilling.…”

Exploring the cellulolytic and hemicellulolytic activities of manganese peroxidase for lignocellulose deconstruction

“…Combining the biological pretreatment with the subsequent saccharification steps will be a lower energy and less time process than sequential steps, which can be achieved by mixing ligninolytic enzymes with cellulolytic enzymes in a single step for simultaneous biological pretreatment and saccharification process (SPS) [ 10 ]. Although several successful enzymatic SPS methods have been reported [ 11 – 13 ], poor efficiency and higher production cost make the enzymatic SPS process unpopular. These issues can be solved by utilizing more robust and multifunctional enzyme systems.…”