Biodegradation of wheat straw by Ochrobactrum oryzae BMP03 and Bacillus sp. BMP01 bacteria to enhance biofuel production by increasing total reducing sugars yield

Abstract

Pretreatment is a vital step to enhance the yield of total reducing sugars and biofuel production from lignocellulose biomass. An effective new lignin-degrading and polysaccharide-hydrolyzing bacteria, Ochrobactrum oryzae BMP03 and Bacillus sp. BMP01 strains, were isolated and identified from wood-feeding termite’s guts. Wheat straw was biodelignified by Ochrobactrum oryzae BMP03 bacteria strains to degrade lignin and to release the trapped cellulose and hemicellulose. The biodelignified wheat straw was hydrolyzed by Bacillus sp. BMP01 strains. Ochrobactrum oryzae BMP03-Bacillus sp. BMP01 consortia were also performed to analyze the effect of the simultaneous system. It was shown that the production of total reducing sugars in a separate hydrolysis system by Bacillus sp. BMP01 strain achieved 439 mg/g at 16 days of hydrolysis time, which is 9.45% higher than the simultaneous system. About 44.47% lignin was degraded by the Ochrobactrum oryzae BMP03 strain after 16 days of biotreatment. This also contributed for increment in cellulose content by 22.38% and hemicellulose content by 18.64%. The simultaneous system converted 368 mg of reducing sugars/g of wheat straw. Separate biodelignification and hydrolysis have an advantage over the simultaneous system in terms of hydrolysis efficiency and vice versa in terms of biotreatment time. Scanning electron microscope, mid-infrared analysis by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis confirmed the change in composition due to biotreatment. The biotreatment improved hydrolysis efficiency, which reduces the cost of biofuel production and increases the yield of biofuel. These results indicate the possibilities of biofuel production from wheat straw by employing Ochrobactrum oryzae BMP03 and Bacillus sp. BMP01 bacteria strains.