Isolation and characterization of Streptomyces spp. strains F-6 and F-7 capable of decomposing alkali lignin

Abstract

Biodegradation and bioconversion of lignin are the result of the combined action of fungi, bacteria and actinomycetes. Through screening from forest soil, two novel isolated actinomycete strains were identified as Streptomyces spp. strains F-6 and F-7 by their morphology, cultural characteristics and high homology to the 16S rRNA gene. Both strains possessed laccase and manganese peroxidase activities. Laccase activity produced by strain F-6 was up to 935.4 U g⁻¹ dry cell weight. More than 50% of alkali lignin was removed by strains F-6 and F-7 in 12 days of incubation. GC-MS analysis of the biodegraded products showed strain F-6 converted lignin into phenol and broken phenol compounds. The two strains could co-culture with white-rot fungus, and the combined actinonycete–fungus system decomposed alkali lignin effectively.

Keywords:

• Streptomyces
• alkali lignin
• biodegradation
• co-culture
• GC-MS analysis

Acknowledgements

We are grateful to Dr.Yuan Xinmin for his correction of the English language of the manuscript. This work was supported by the National Key Scientific and Technology Project for Water Pollution Treatment (2008 ZX07208-004-2).