Production of raw cassava starch-degrading enzyme by Penicillium and its use in conversion of raw cassava flour to ethanol.
A newly isolated strain Penicillium sp. GXU20 produced a raw starch-degrading enzyme which showed optimum activity towards raw cassava starch at pH 4.5 and 50 °C. Maximum raw cassava starch-degrading enzyme (RCSDE) activity of 20 U/ml was achieved when GXU20 was cultivated under optimized conditions using wheat bran (3.0% w/v) and soybean meal (2.5% w/v) as carbon and nitrogen sources at pH 5.0 and 28 °C. This represented about a sixfold increment as compared with the activity obtained under basal conditions. Starch hydrolysis degree of 95% of raw cassava flour (150 g/l) was achieved after 72 h of digestion by crude RCSDE (30 U/g flour). Ethanol yield reached 53.3 g/l with fermentation efficiency of 92% after 48 h of simultaneous saccharification and fermentation of raw cassava flour at 150 g/l using the RCSDE (30 U/g flour), carried out at pH 4.0 and 40 °C. This strain and its RCSDE have potential applications in processing of raw cassava starch to ethanol.
Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, 530004 Nanning, Guangxi, People's Republic of China.
Hai-Juan
HJ
Lin
Liang
L
Xian
Qiu-Jiang
QJ
Zhang
Xue-Mei
XM
Luo
Qiang-Sheng
QS
Xu
Qi
Q
Yang
Cheng-Jie
CJ
Duan
Jun-Liang
JL
Liu
Ji-Liang
JL
Tang
Jia-Xun
JX
Feng
D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005433:Flour; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism; D006868:Hydrolysis; D002365:Manihot / Q000737:chemistry*; D010407:Penicillium / Q000201:enzymology*; D013213:Starch / Q000378:metabolism*
D000431:Ethanol; D013213:Starch; D005087:Glucan 1,4-alpha-Glucosidase