Asian Journal of Microbiology and Biotechnology
 

Asian Journal of Microbiology and Biotechnology, ISSN No. : 2456-8341, Vol.: 3, Issue.: 2

Original Research Article

HYDROTHERMAL ASSISTED Bacillus sp. AY8 PRETREATMENT ON LIGNOCELLULOSE FOR THE LIQUEFACTION AND ENHANCEMENT OF ENZYMATIC HYDROLYSIS

 

MD. AZIZUL HAQUE1*, DHIRENDRA NATH BARMAN2, SNYGDHA RANI DAS1, MD. YEASIN PRODHAN1, ABU KHAYER MD. MUKTADIRUL BARI CHOWDHURY3, MD. BOKHTAIR RAHMAN1, MD. ATIQUL HAQUE4 and HAN DAE YUN5

1Department of Biochemistry and Molecular Biology, Hajee Mohammad Danesh Science and Technology University, Dinajpur 5200, Bangladesh.

2Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali 3814, Bangladesh.

3Department of Crop Physiology and Ecology, Hajee Mohammad Danesh Science and Technology University, Dinajpur 5200, Bangladesh.

4Department of Microbiology, Hajee Mohammad Danesh Science and Technology University, Dinajpur 5200, Bangladesh.

5Research Institute of Agriculture and Life Science, Gyeongsang National University, Chinju 660-701, Republic of Korea.

Abstracts

Lignocellulose liquefaction by bacterial treatment is a quite challenging task yet. The microstructural changes and liquefaction efficiency of hydrothermal associated Bacillus sp. AY8 treated lingo-cellulosic straw have been focused in this study. The straws (5%) of rice, barley, and wheat were treated at 170°C, 180°C and 190°C for 30 min in biomass digester. The optimum hydrothermal treatment conditions to complete liquefaction of rice, wheat, and barley straws with Bacillus sp. AY8 were obtained at 180°C, 190°C and 190°C for 30 min, respectively. In minimal nutrient media, the Bacillus sp. AY8 degraded aromatic dyes and lignin derivatives when those were utilised as sole carbon and energy sources by the strain. The scanning electron microscopy exhibited the porous structure of the rice straw due to the loss of lignin and other impurities. Moreover, Fourier transformed infrared spectroscopy demonstrated that the lignin-associated peaks at 1516 and 1325 cm-1 intensities were almost disappeared due to the removal of lignin wrapping on the surface of cellulose fibers of treated samples. The crystalline index of the rice straw was 78.30, 63.69, 57.16, and 36.10 on 0, 4, 6, and 8 days treatment respectively with Bacillus sp. AY8. The liquefaction of lignocelluloses was observed likely due to a combination of extracellular enzymes of Bacillus sp. AY8. The Bacillus sp. AY8 treated rice straw yielded maximum 73.5% reducing sugar after 72 h in saccharification. This is the first report that suggests hydrothermal associated bacterial pretreatment to liquefy lignocellulose that has opened a new route of biomass pretreatment.

Keywords :

Bacterial pretreatment; lignocellulose liquefaction; microstructural changes; saccharification.