Pencirian pencilan bakteria anaerob selulolitik dan ligninolitik dalam biodegradasi sisa batang pisang / Nurul Fatehah Binti Abdul Ghafar

Thesis (Ijazah Sarjana Sains Bioteknologi) -- Universiti Malaysia Pahang - 2012

Bibliography : p.96-107

Plant biomass is a major renewable source of lignocellulosic biomass which is rich in organic components and it represents a large part of municipal and agricultural wastes in all countries around the world. To overcome the environmental pollution problem due to wastes accumulation, these agricultural wastes can be used as a biomass source to generate alternative source of energy such as biomethane (biogas) through anaerobic digestion process. Lignocellulosic wastes comprise of three major components i.e. lignin, cellulose, and hemicellulose. Lignin is an aromatic polymer synthesized from phenylpropanoid precursor and highly resistant to microbial degradation due to its complex structure. Thus, in order to increase the biogas production, lignin removal must be done to enhance the efficiency of microbial enzymatic action on the cellulose. The aims of this research are to isolate, identify and characterize soil anaerobic bacteria from banana plantation soil which has been acclimatized in banana stem waste and might have a great potential on lignin degradation and cellulose hydrolysis of banana stem wastes. Five (5) potent cellulolytic bacteria (CB) were selected after screening by using carboxymethylcellulose (CMC) agar plate assay based on the diameter size of lysis zone and designated as CB 10, CB 19, CB 120, CB 65, and CB 67. Another five (5) potential ligninolytic bacteria (LB) were selected and named as LB 2, LB 8Y, LB 9, LB 8, and LB 35 after screening the ability of bacteria to grow efficiently in Kraft-lignin medium. All selected mesophilic isolates are Gram positive (although they have also exhibited Gram variability reaction), rod-shape, and spore-former except CB 19 isolate which is coccus in shape and non-spore. Furthermore, 16S rRNA gene sequencing results revealed that all the selected isolates come from four different genera of bacteria i.e. Clostridium, Staphylococcus, Paenibacillus, and Bacillus. Anaerobic delignification of banana stem waste has been carried out and showed that isolate of LB 2 (Clostridium beijerinckii JCM 8026) and LB 8Y (uncultured composed bacterium clone PS3079) were able to selectively delignify the waste with lignin removal of 14.44% and 12.05% with cellulose degradation of 20.60% and 32.79% respectively. The isolate of CB 19 (Stapylococcus sp. DG9) and CB 10 (C. beijerinckii NCIMB 8052) were not able to catalyze the hydrolysis reaction of cellulose from undelignified waste. Meanwhile, the syntrophic digestion of waste by co-culture CB 19 and LB 8Y had showed inconclusive data recovery where cellulose degradation was present while delignification on waste was absent by these co-culture. As a conclusion, only LB 2 and LB 8Y were succesful in displaying lignin and cellulose degradation performance in production of sugar from banana stem waste.