Bioprospecting of Xylanolytic Fungi Isolated from Degraded Corn Cobs for Xylooligosaccharides (XOs) Production

摘要

Xylooligosaccharides (XOS) act as prebiotics because they are not digested in the upper gastrointestinal tract and increase the population of beneficial gut microflora like Lactobacilli and Biofidobacteria. XOS with these importances are emerging as important oligosaccharide with rise in demand worldwide. For use of xylanase in the production of XOs, xylanolytic fungi were isolated from degraded corn cobs, screened for enhanced xylanase production with cultural and nutritional conditions optimized using one factor at a time approach. It was found that among the llfungal isolates, isolate SKF-4 which was identified as Aspergillus fumigatus produced highest level of xylanase and lowest level of 2-xylosidase i.e. 143.0 IU/ml and 0.01 IU/ml respectively. The selected fungus A. fumigatus SKF-4 produced enhanced level of xylanase with wheat bran and proteose peptone as carbon and nitrogen source respectively at pH 5.0 and temperature 30°C. The partially purified enzyme from A. fumigatus SKF-4 showed highest xylanase activity at pH 5.0 and temperature 45°C. Partially purified xylanase of A. fumigatus SKF-4 could produce 1.44±0.4 mg/ml of xylobiose and low amount of xylose 0.25+0.1 mg/ml from beechwood xylan after 24hr. Xylanase from A. fumigatus SKF-4found to be promising for xylooligosaccharides production.