ISOLASI DAN KARAKTERISASI BAKTERI PENDEGRADASI LIGNIN DARI BEBERAPA SUBSTRAT ALAMI = ISOLATION AND CHARACTERIZATION OF LIGNIN DEGRADING BACTERIA FROM SEVERAL NATURAL SUBSTRATES

Pulp and paper mill effluent contain of black ,liquor with high concentration of lignin. Biologi¬cal treatment of this effluent could be done by inoculation of lignin degrading microorga¬nisms. The objective of this study was to obtain bacterial isolates able to degrade lignin. Several kind s of natural substances containing lignin were used as the source of isolates. Isolation was done using plating method in specific agar medium. Lignin degrading bacterial colonies was indicated by formation of brown color around the colony. Quantitative selec¬tion of lignin degradation ability was based on specific enzymatic activity and degradation of lignin containing in black liquor. Examination of their lignin degradation activity was conduc¬ted using several concentration of black liquor as the sole of carbon source. The selected isolate were identified until genus level. Five teen strains of lignin degrading bacteria were isolated from the sample materials. Based on the ratio between diameter of brown color and diameter of bacterial colony, six strains of bacteria that were isolated from domestic solid waste and decomposed wood, were chosen and examined quantitatively their ability to degrade lignin. The data showed that two bacterial isolates (coded as SPH-9 and SPH-10) were able to produce vanillin much higher then the other, i.e. 2994.93 and 2991.27 g/ml, with specific enzyme activity 0.65 and 0.56 unit/mg protein, respectively. Lignin degra¬dation showed that within 14 days incubation period by using black liquor as the sole of carbon source indicated that SPH-9 and SPH-10 able to degrade lignin around 23 to 76% depend on black liquor concentration. Maximal degradation of lignin was in black liquor concentration of 10%. Bacterial identification showed that SPH-9 and SPH-10 was the member of Micrococcus and Bacillus, respectively. Key words: bacteria, lignin, degradatio