Selection of microorganism producing hydrolytic enzymes for improving silage quality

Since the hydrolytic enzyme has an important role in improving silage quality, 162 bacterial isolates were screened for the activity of CM-cellulase, xylanase, and pectinase at high temperature stability and wide range of optimal pH and temperature stability and wide range of optimal pH and temperatures. Only the isolate OM261 and GN156 possessing CM-cellulase activity showed 60 percent higher relative activity and stability at pH 3.7-7.2, temperature of 30-60 deg C. Study on corn and grass degradation resulted that hydrolytic enzyme produced by OM261 and GN156 showed the effective hydrolysis on corn and grass, respectively. Both isolates were identified as Bacillus subtilis. To study ensiling, 10-20 mm chopped corn and grass were ensiled by pouch method with and without evacuation. Then the designed treatments were performed as ensiling alone with hydrolytic enzyme from the selected isolates, commercial enzyme, or lactic acid bacteria and ensiling with the combination treatment of hydrolytic enzymes and lactic acid bacteria. 20 days corn silage under evacuation condition, the combination of hydrolytic enzyme from the isolate OM261 and Pediococcus acidilactici M6 provided good silage quality comparing to the standard on as pH 3.8, 7.26 percent lactic acid contents (as dry weight), 2.75 percent ammonia nitrogen contents (as total nitrogen), and not found butyric acid. In addition, protein contents were 9.28 percent higher than fresh corn crop. The corn silage ensiled without evacuation had a quality which was inferior to the one with evacuation as pH, lactic acid contents (as dry weight), and ammonia nitrogen contents (as total nitrogen) of 4, 3.62 percent and 2.27 percent respectively. However, the silage quality was still shown at standard level. In addition, protein contents were 27.8 percent higher than fresh corn crop. For grass ensiling, Lactobacillus sp. I4 and hydrolytic enzymes from GN156 were tested in the same conditions. The result showed that the combination treatment had a higher lactic acid content and lower pH than the control. However, the grass silage quality was under standard level.