Exploring the potential of ligninolytic Bacillus sp. TSA-4 in wheat straw pretreatment for efficient methane production: A genomic perspective

Abstract

The study aimed to remove lignin from wheat straw, which hinders the methane yield during fermentation. For lignin removal, a lignin-degrading strain [Bacillus sp. Strain TSA-4], 1 %H₂SO₄, 1 % NaOH were tested separately, and in combination. A lignin degrading bacteria Bacillus sp. Strain TSA-4 was isolated and it showed 76.63 % of lignin and 78.60 % Remazol Brilliant Blue R dye decolorization respectively. The strain showed lignin peroxidase (LiP), laccase (Lac), and cellulase activities of 58.1 U/mL, 27.3 U/mL, and 20.2 U/mL, respectively, at pH 5–6 and 50 °C. Different pretreatment test of 1 % H₂SO₄, 1 % NaOH, Bacillus sp. Strain TSA-4 and combinations were evaluated for the breakdown of lignin and cellulose of wheat straw. The combine AKT [1 %H₂SO₄ + 1 % NaOH + Bacillus sp. TSA4] pretreatment showed 84.98 % lignin degradation, and 68–70 % glucose and soluble sugar from pretreated wheat straw sample compared to the untreated wheat straw samples (17–18 %). The wheat straw pretreated with (1 % H2SO4 + 1 % NaOH + Bacillus sp. TSA4) AKT produced a cumulative biogas yield of 431.9 mL/gVS wheat straw, which is higher than other single treatment conditions. The AKT treatment enhanced 98.5 % cumulative methane yield compared to the untreated wheat straw sample. The genomic characterization of Bacillus sp. Strain TSA-4 has revealed the presence of multiple genes that encode lignocellulolytic enzymes. This confirms its cellulolytic potential and ability to break down lignocellulosic biomass. These findings emphasize the potential of Bacillus sp. Strain TSA-4 in the production of sugars and the utilization of lignocellulosic biomass in various industrial applications.