Crude Xylanase Production in Bacteria using Corn Husk as Substrate in Submerged Fermentation

Abstract

Management of crop waste is important for sustainable agriculture. We investigated xylanase producing strains of local bacteria using corn husk as a substrate in submerged fermentation. Soil samples were collected from corn silage waste areas in Mae Sai, Rong Kwang District, Phrae Province, Thailand. Primary screening of crude xylanase producing isolates was made with the enrichment method in Mineral Salt Medium (MSM) containing 1% (w/v) corn husk on a shaking incubator at 150 rpm at 37??C for 7 days. In order to select potential isolates for further study, the serial dilution method was employed using MSM solid agar supplemented with xylan 0.1% (w/v). The enrichment method gave 236 bacterial isolates and these were used to determine their crude xylanase activity in spot diffusion and gel diffusion assays. Eleven isolates presented clear zones between 30 - 35 mm in diameter. The quantity of reducing sugars released in the supernatant in submerged fermentation was measured with the alkaline 3,5-dinitrosalicylic acid method. A gram negative isolate A023 had the highest crude xylanase activity with a value of 21.67 ?? 0.38 Unit/mL in corn husk containing medium. Factors affecting xylanase expression and yield will be investigated further with this isolate.