Degradation of lignocellulose and lignin by Paenibacillus glucanolyticus

• Paenibacillus glucanolyticus SLM1 and 5162 can grow on lignin as the sole carbon source.
• These strains can grow on hardwood and softwood flour as the sole carbon source.
• Both strains can reduce the molecular weight and chain length of BioChoice lignin.
• P. glucanolyticus 5162 can degrade lignin only under anaerobic conditions.
• P. glucanolyticus SLM1 can degrade lignin under aerobic and anaerobic conditions.

Lignocellulose is an abundant renewable carbon source that has been used for fuel and chemical production. Lignocellulose refers to the plant cell wall and is composed of cellulose, hemicellulose, and lignin. Lignin is a recalcitrant amorphous aromatic compound. Paenibacillus glucanolyticus SLM1, a facultative anaerobe that grows optimally at pH 9, was isolated from pulp mill waste. Initial characterization showed that this bacterium could degrade cellulose and hemicellulose and also suggested that it may be able to degrade lignin. This work examines the ability of P. glucanolyticus SLM1 and the type strain P. glucanolyticus 5162 to degrade lignocellulose, lignin, and aromatic lignin-related compounds using growth studies, dye degradation assays, GC–MS, and GPC. Our results show that both strains of P. glucanolyticus can degrade aromatic lignin-related compounds under aerobic and anaerobic conditions. These strains can also degrade polymeric lignin under anaerobic conditions. However, only P. glucanolyticus SLM1 can also degrade polymeric lignin under aerobic conditions.