Screen Of The High Cellulase-producing Fungi And The Research On Its Enzymatic Characteristics

Cellulose is the most abundant, cheapest renewable carbon source in the world. It can be converted to energy, food, feed and chemical raw materials, etc. Cellulase activity is not high and excessive use.That are the main restricting factors in the widely used cellulose.Therefore, the selection of good performance and stable enzyme production strains is not only the basic way of reducing the cost of cellulase production, but also the key to solve the problem of effective utilization of cellulose.This study includes screening of strains, optimizing fermentation conditions, researching on enzymatic characteristics and identification of strains. The main contents and results are as follows:1. Screen of strainsSix strains from different areas were screened by using CMC plate screening and rescreening fermentation.In the same level condition, A2 strain has the best ability to produce enzyme. D19 strain produces enzyme in low temperature .2. Optimizing fermentation conditions(1) The optimal culture conditions of A2 were as follows:temperature 33℃, inoculation amount 7%, fermentation time 4 days, initial pH 4.0, microcrystalline cellulose and wheat bran proportions15:5, the content of (NH₄)₂SO₄ is 6g/l.(2) The optimal culture conditions of D19 were as follows:temperature 23℃, inoculation amount 9%, fermentation time 6 days, initial pH 4.0, microcrystalline cellulose and wheat bran proportions15:5, the content of (NH₄)₂SO₄ is 2g/l.3. Research on enzymatic characteristics(1) The optimal reaction temperature of A2 enzyme was 45℃and the high stability of enzyme was found at temperature 40℃⁵5℃. The optimal reaction pH of A2 enzyme was 5.0 and the high stability of enzyme was found at pH 5.0⁶.0.(2) The optimal reaction temperature of D19 enzyme was 30℃and the high stability of enzyme was found at temperature 25℃ 35℃. The optimal reaction pH of D19 enzyme was 5.5and the high stability of enzyme was found at pH 4.5⁶.0.4. identification of strains (1) A2 was identified as Penicillium by morphologic taxonomy.(2) D19 was identified as Aspergillus by morphologic taxonomy.