Genetic improvement of Kraft lignin degrading bacteria via mutation induction and protoplast fusion

Pulp and paper manufacturing wastes have been recognized as a significant point source of pollution since they have high levels of lignins and their derivates. Wild type Bacillus subtilis subsp. Subtilis and Citrobacter farmeri isolated from the pulp and paper manufacturing effluent contaminated soil and water were found to be effective towards lignin degradation. Mutant strains were obtained from the acclimatized species by random mutagenesis using various Ethidium Bromide (EthBr) and the physical mutagen Ultra Violet (UV) and after that mutant strains were tested for lignin degradation. It was found that the maximum degradation rates was achieved by treatment with 100 µg EthBr for strain B. subtilis and 150 µg EthBr for strain C. farmeri. Genetic Improvement of lignin degradation by these mutant strains was carried out via Protoplast Fusion aiming to isolate new recombinants (fusants) with high capacity of lignin degradation.