Abstract
Lignin next to cellulose, it is the second most abundant compound in the plant biomass. Partial decay of lignin provides numerous monomers that have attracted attention as renewable resources of certain chemicals traditionally derived from petroleum. Bioconversion of lignin is one of the most important trends in biotechnology. Decomposition of the lignin-cellulose complex in fodder plants improves the digestibility and nutritional value of the materials for livestock feeding, enriching it with physiologically active substances. The objective of this research was to biodegradation of lignin, where found in pulp mill effluent (450 mg/l) and agriculture wastes: leaves tree, corn stalks and wheat straw by selected strains of thermophilic bacteria and optimize physiological conditions required for better lignin degradation by bacteria. Biodegradation experiments were carried out in L-MSM (1g KL/L. MSM) at pH 7.5. Kraft lignin (KL) concentration is greater than that found in pulp mill effluent (450 mg/l). Samples were withdrawn periodically at one day intervals for seven days and determine the bacterial growth, reduction of colour and residual KL content. It was found that, colour reduction ratio for the best two thermophilic strains Bacillus subtilis, Bacillus licheniformis were 86.6 and 75.4 %, respectively and lignin degradation ratio were 73.0, and 64.2 %, respectively.