In vitro Evaluation of Feed Enzyme Compound Produced by Aspergillus sulphureus in Solid-state Fermentation

Three trials were conducted to analyze a multi-enzyme compound produced by Aspergillus sulphureus in solid-state fermentation (SSF) as a potential feed additive. The results of the first trial showed that there were at least 5 non-starch polysaccharide enzymes: xylanase, b-glucanase, pectinase, mannase and carboxy methyl cellulase (CMCase) contained in the compound. Xylanase and b-glucanase showed good activities at pH 2.5-7.0, which were in the range of 649-1046 U/g and 444-648 U/g, respectively. Pectinase showed good activity in acidic solution (pH 2.5-3.0), which ranged from 195 to 917 U/g. Mannase showed high activity of 235- 298 U/g at pH 3.5-4.5 and the activity of CMCase was relatively constant at pH 2.5-7.0, which was in the range of 38.2-78.6 U/g. The second trial was aimed to test the stability of the enzymes in gastric liquor (pH 2.6) of finishing pigs and Na₂HPO₄-gastric liquor (pH 5.5). After 6 h incubation at 40°C in gastric liquor, the retained activity of xylanase, b-glucanase, pectinase, mannase and CMCase was 26.3%, 65.0%, 71.0%, 74.8% and 85.6%, respectively. While after 6 h incubation at 40°C in Na₂HPO₄-gastric liquor, the retained activity of xylanase, b-glucanase, pectinase, mannase and CMCase was 87.9%, 91.1%, 92.3%, 95.0%, and 97.5%, respectively. The third trial was carried out in a jejunum liquor (pH 5.8, 200mL), which contained 0.2 g of the multi-enzyme compound and 10 g of soybean hull or wheat bran, respectively. After 8 h incubation at 40°C, 18.7% of soybean hull and 20.1% of wheat bran could be degraded to soluble saccharide, respectively. Compared with the traditional methods for feed enzyme testing which involve feeding animals for 1-3 months, enzyme assay in this way was relatively convenient.