Isolation and Characterization of Cellulase- and Xylanase-Producing Microbes Isolated from Tropical Forests in Java and Sumatra

摘要

Efficiency of cellulases enzyme is one of determining factors in bioethanolfrom-biomass production. However, it could be hampered by the presence of xylan. Employing microbes that can produce both cellulase and xylanase may help to overcome the current challenges in bioethanol production. Biodiversity of microorganisms in tropical forests offers more possibility for obtaining the potential microbes for this purpose. This research, therefore, was aimed to collect, screen, characterize and identify potential cellulase- and xylanase- producing microbes from five different tropical forest ecosystems in Java and Sumatra. Numbers of 553 isolates that have been collected from the fields were screened using selective media (i.e. CMC- and Xylan- agar) in order to determine the potency of microbes in producing cellulase and xylanase which were indicated by clear zones exhibited around the cultures. This qualitative screening showed that 304 isolates were positive producing cellulase and 323 isolates were positive producing xylanase. Eight potential isolates which showing greater cellulo- and xylano- lytic indexes were subjected to enzyme activity tests and DNA analyses for species identification. The assay for enzymatic activity of cellulase and xylanase were determined based on the release of glucose and xylose respectively that were detected using dinitrosalycylic acid (DNS). The potential isolates were identified as Rhizomucor variabilis, Fusarium sp., F. solani, Aspergillus niger, Bacillus thuringiensis, and Sphingobacterium daejeonense. Other two bacterial isolates (FORDA-CC 3128, 3171) were remains unidentified due to faint PCR results. Fusarium sp. And F. solani showed greater cellulase activity than the commercial cellulase after 19 hours of incubation. B. thuringiensis, FORDA-CC 3128 and 3171 showed greater cellulase and xylanase activities than the commercial enzymes after 15 min incubation. Stability of cellulase and xylanase activities was still an issue to be solved in the next experiments. Optimization of pH and temperature are suggested.