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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Bioproducts Research » Research » Publications at this Location » Publication #346428
Research Project: Technologies for Improving Industrial Biorefineries that Produce Marketable Biobased Products

Location: Bioproducts Research

Title: Isolation of ligninolytic Bacillus sp. strains for depolymerization of alkali lignin

Author
item SHAH, TAWAF - National Institute Of Biotechnology And Genetic Engineering (NIBGE)
item TABASSUM, ROMANA - National Institute Of Biotechnology And Genetic Engineering (NIBGE)
item Orts, William
item Lee, Charles

Submitted to: Journal of Environmental Progress and Sustainable Energy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2018
Publication Date: 5/13/2019
Citation: Shah, T.A., Tabassum, R., Orts, W.J., Lee, C.C. 2019. Isolation of ligninolytic Bacillus sp. strains for depolymerization of alkali lignin. Journal of Environmental Progress and Sustainable Energy. 38(3):e13036. https://doi.org/10.1002/ep.13036.
DOI: https://doi.org/10.1002/ep.13036

Interpretive Summary: Lignocellulosic biomass represents a rich source for supplying many of the world’s chemical and fuel stock needs. One of the most difficult steps in converting biomass into useful products is the breakdown of the lignin component of this recalcitrant substrate. In nature, microorganisms have evolved a variety of organisms to accomplish this task. In this paper, we have screened various environments for microorganisms that produce high levels of lignin-degrading enzymes. We have characterized these enzymes and determined the optimal conditions for expressing high levels of the enzymes.

Technical Abstract: In biofuel production, a rate-limiting step is the hydrolysis of lignin from lignocellulosic biomass. In this study, we isolated microbes from soil, wood compost, and waste sludge and screened for activity against lignin and synthetic dye substrates. Seven of the most active strains were classified as Bacillus sp. strains TL4, TL6, TL8, TL24, TL26, TL27, and TL33. These strains effectively decolorized alkali lignin and the synthetic dyes Azure B, Congo red, and methylene blue. In flask experiments using lignin or Azure B dye, the Bacillus sp. strains exhibited up to 92% and 97% substrate decolorization, respectively. All strains were found to secrete lignin peroxidase (LiP) and laccase (Lac) enzymes. Optimum yields of LiP were achieved at 2 days at pH 3, whereas the highest levels of Lac was obtained at 5 days at pH 5. The highest extent of lignin degradation (85.7%) was exhibited by Bacillus sp. strain TL33 at pH 5. This study highlights the potential of using Bacillus sp. strains in the degradation of lignin which could improve overall biofuels production from biomass substrates.