Abstract

Lignin is a natural polyphenol material found incomplex with cellulose and hemicellulose in every terrestrialand some aquatic plant species. They are recalcitrant andprevent easy access to cellulose; an energy-rich, versatile,promising biomaterial for several eco-friendly and cheapproducts. The lignin-degrading potential of microbes isolatedfrom degraded wood in an environment in Egypt wasinvestigated. In this study, four bacteria were screened using amethylene blue decolorization test, growth on media with ligninas carbon source, and cellulolytic screening using CMC-Congored test. The screened isolates were used to treat sorghum stemstalks to ascertain the level of degradation of the lignin content.The four bacterial isolates were positive to the decolorization ofmethylene blue with percentage decolorization: (23%, 8%, 34%,and 24%) after 24 hrs. respectively. Similarly, the four isolateswere able to grow on minimal salt media with lignin as carbonsource. The optical densities values measured ranged from(0.030–0.165, −0.040–0.080, 0.040–0.121, −0.039–0.054) after12 h for the four bacterial isolates, respectively. Also, the fourbacterial isolates showed negative results for the cellulase test.FT-IR spectrum for the bacterial-treated sorghum stalksrevealed a reduction in peaks at wavelengths indicative of ligninfunctional groups. Similarly, proximate analysis of thelignocellulose content after treatment recorded were extractives(E) (9, 9, 13.5, 9.5, and 10) %, hemicellulose content (H) (29.5,26.0, 31, 26, and 30) %, Klason lignin (L) (39, 31, 33, 24, and26) %, and cellulose (C) (22.2, 33.5, 21.3, 40.5, and 33.5) % forcontrol and the four bacterial isolates, respectively. Thep-values estimated from the average values for the extractiveand hemicellulose content were not significantly different,whiles that of Lignin and Cellulose was significantly different.The four bacterial isolates showed potential for havingligninolytic enzymes for lignin depolymerization.