การใช้วัสดุเหลือใช้ทางการเกษตรสำหรับผลิตเดกซ์แทรนเนสโดย Penicillium sp. สายพันธุ์ 61 / สุภาพร ชาติวรพงศา = Utilization of agricultural wastes for the production of dextranase by Penicillium sp. strain 61 / Suphaporn Chatworapongsa
Agricultural wastes including rice straw, rice husk, rice bran and sugarcane bagasse sized into 50 mesh were pretreated with various methods both physical and/or chemical means. The pretreated materials were further digested with cellulose from Trichoderma reesei and β-glucosidase from Aspergillus niger. The most appropriate condition for pretreating rice straw and bagasse judging from amount of reducing sugar released was 1% NaOH at 121℃. and 15 lbs/in2 for 15 minutes while in case of rice husk and bran was 1% NaOH at room temperature for 30 and 10 minutes respectively. Afterthat they were subjected to hydrolysed by cellulose and β-glucosidase at 656 and 16 units/gram dry weight of material yielding reducing sugar equivalent to 897.5, 1040.5, 30.5 and 372.5 mg/gram of material for rice straw, bagasse, rice husk and rice bran respectively. The optimum conditions for cellulose and β-glucosidase activities upon a 4% solution of pretreated materials (w/v) were at 40 and 60 units/gram of pretreated substrate in 0.05 M acetate buffer, pH 4.8, 40℃. for 24 hrs. with agitation rate of 200 rpm. It was observed that hydrolysate from bagasse could be used for cultivating Penicillium sp. strain 61 for dextranase production. The modified medium contained 0.1% bagasse hydrolysate (w/v equivalent to glucose) as C-source, 1.0% dextran as inducer, 0.2% NaNo3 as N-source with initial pH of 6.0 supplemented with 0.2% yeast extract when used for cultivation of the above organism could give dextranase in range or 35-42 units/ml.
