Isolation of Thermophilic Bacteria from Hot Spring and Exploring its Role in Lignin Valorization

Abstract

Lignin, the second-most prevalent natural polymer, is mainly produced as a byproduct of the pulp and paper industry. About 50 million tons of it are produced annually, and only 2% of it is utilized for high-value products, and the rest of it is released as a waste in the form of black liquor. The effective breakdown of lignin at high temperatures is essential for the effective removal of pulping effluent. Therefore, there is an urgent need to find appropriate eco-friendly techniques to get beyond this environmental limit and utilize this waste for the production of value-added products. The current study focuses on the potential of novel and unidentified thermophilic bacteria SP2 (10) isolated from hot springs, Chitral in lignin degradation, and its role in lignin valorization. The morphological depictions and biochemical characterization suggest that the strain SP2(10) belongs to family Enterobacteriaceae. The strain SP2(10) effectively reduced the target parameters (lignin 44% and color 47%) of BL effluent at 50◦C and pH 8 which was further revealed by FTIR. Moreover, Gas chromatography-mass spectrometry analysis of the untreated and treated BL samples revealed the reduction of the majority of toxic chemicals and the production of high-value products after biological treatment with SP2(10). Furthermore, toxicological studies have also supported the bacterial detoxification of black liquor. Moreover, the active fractions of the Lignin biodegradable extracts were separated via column chromatography, and the phenolic compounds in the active fractions were evaluated using HPLC. HPLC analysis detected the presence of gallic acid and caffeic acid in the fractions C and D of EAE with a specific RT. These results highlight the importance of this unknown strain in relation to sustainable bioprocessing and lignin valorization. By unlocking the bacterium's lignin-degrading abilities, new and intriguing methods for transforming lignin, a historically underutilized waste product, into a regenerative source of useful compounds are made possible.