Optimization of conditions for laboratory scale production and partial characterization of xylanase from selected fungal culture for poultry feed

Xylanases are hydrolases that is primarily involved in depolymerizing the plant cell wall component-xylan. The goal to produce such enzyme under laboratory state was carried out first, by selection process involving species of Aspergillus _ A. niger MNH (van Tieghem), A. oryzae BTSo-7 (Ahlburg) Cohn, A. terreus FC03 (Thom) and Trichoderma _ T. harzianum QM 9639 (Rifai) and T. reesei NRRL 11485 (Simmons) obtained from the Philippine National Collection of Microorganisms (PNCM) at BIOTECH. After five days of shakeflask fermentation of ambient temperature (30 +- 2 deg C), xylanase activity of 976 U/ml for A. niger MNH was significantly highest among other activities gathered. For that reason, succeeding production experiments were accomplished using A. niger MNH. Optimization studies performed thereafter revealed that induction was numerically highest using 4% xylan. There was a decrease in the production of xylanase when high concentrations of glucose was offered as carbon source which was probably due to catabolite repression. Peptone concentration,initial pH of the medium and aeration were found to have no influence on xylanase production. Restricted Random Balance Design (RRBD) experiment revealed that except for medium no.1, the basal medium was better compared to other media designed. Medium no.1 was selected for production for practical reasons. Time course of fermentation indicated that enzyme production corresponded closely to the growth of the organism and that it required low initial pH favor enzyme synthesis. Optimization of conditions and process parameters enabled high xylanase productions at a relatively shorter time. The optimal temperatures and pHs for xylanase activity were 40 and 50 deg C and 3.5, 5.0 and 6.0, respectively. Xylanase produced was stable at 30 deg C for one hour and at 40 deg C for 2.5 hours. It was likewise stasble at pH 6.0 for 2.5 hrs. Limited poultry feeding study showed that enzyme supplementation, whether commercial or laboratory-produced, failed to significantly improve dry matter, crude protein, nitrogen free extract (NFE) and crude fiber digestibilities of the feed: A significant improvement on fat digestibility was observed through, using crude xylanase. In terms of apparent metabolizable energy (AME), a slight improvement of only 0.3% on energy content of feed supplemented with laboratory-produced enzyme was noticed, though the numerical differences observed from all the treatmens were not statistically significant. Therefore, enzyme supplementation failed to improve the amount of energy of the wheat-based diet fed to the broilers.