Biodegradation of kraft lignin by a bacterial strain Comamonas sp. B-9 isolated from eroded bamboo slips.

ABSTRACT

AIMS: The aim was to obtain evidences for lignin degradation by unicellular bacterium Comamonas sp. B-9. METHODS AND RESULTS: Comamonas sp. B-9 was inoculated into kraft lignin-mineral salt medium (KL-MSM) at pH 7·0 and 30°C for 7 days of incubation. The bacterial growth, chemical oxygen demand (COD) reduction, secretion of ligninolytic enzymes and productions of low-molecular-weight compounds revealed that Comamonas sp. B-9 was able to degrade kraft lignin (KL). COD in KL-MSM reduced by 32% after 7 days of incubation. The maximum activities of manganese peroxidase (MnP) of 2903·2 U l(-1) and laccase (Lac) of 1250 U l(-1) were observed at 4th and 6th day, respectively. The low-molecular-weight compounds such as ethanediol, 3, 5-dimethyl-benzaldehyde and phenethyl alcohol were formed in the degradation of KL by Comamonas sp. B-9 based on GC-MS analysis. CONCLUSIONS: This study confirmed that Comamonas sp. B-9 could utilize KL as a sole carbon source and degrade KL to low-molecular-weight compounds. SIGNIFICANCE AND IMPACT OF THE STUDY Comamonas sp. B-9 may be useful in the utilization and bioconversion of lignin and lignin-derived aromatic compounds in biotechnological applications. Meanwhile, using Comamonas sp. B-9 in treatment of wastewater in pulp and paper industry is a meaningful work.