Organic acids associated with saccharification of cellulosic wastes during solid-state fermentation

Area of Science:

• Biotechnology and Bioengineering
• Microbial Fermentation
• Agricultural Waste Valorization

Background:

• Cellulosic wastes are abundant but underutilized resources.
• Enzyme production for saccharification is crucial for biofuel and biochemical applications.
• Solid-state fermentation (SSF) offers an efficient method for microbial biomass and enzyme production.

Purpose of the Study:

• To investigate the saccharification potential of various agricultural wastes using specific cellulolytic fungi.
• To optimize conditions for glucose and enzyme production through SSF.
• To analyze the production of organic acids during the fermentation process.

Main Methods:

• Laboratory-scale solid-state fermentation (SSF) of rice husks, wheat bran, corn cobs, wheat straw, and rice straw.
• Utilized three fungal strains: Aspergillus glaucus MN1, Aspergillus oryzae MN2, and Penicillium purpurogenum MN3.
• Assessed enzyme activities (FP-ase, CMC-ase, β-glucosidase, α-amylase) and organic acid concentrations.

Main Results:

• Optimal incubation for glucose production was 10 days.
• Penicillium purpurogenum on rice husks yielded maximal cellulase and β-glucosidase activities.
• Aspergillus glaucus on rice husks showed high FP-ase, CMC-ase, and β-glucosidase productivities.
• Addition of rock phosphate and ammonium sulfate influenced pH, enzyme induction, and phytase production.
• Significant concentrations of levulinic and oxalic acids were detected.

Conclusions:

• Agricultural wastes, particularly rice husks, are viable substrates for glucose and enzyme production via SSF.
• Fungal strain selection and substrate type significantly impact saccharification efficiency and enzyme profiles.
• The process generates valuable organic acids, adding to the overall valorization potential.