The β-glycosidase (BG) of Rhizopus stolonifer TZ-03, which obtained by UV mutagenesis combined with ethyl methanesulfonate (EMS) mutagenesis, was 10.53 IU/mL (152% higher than that of wild strain TP-02). In order to investigate the difference of β-glycosidase production of TZ-03, the transcription level of bgl and bgl4 was compared, the gene bgl4 encoding β-glycosidase was cloned and structural modeling and analysis was conducted by an array of bioinformatics software, Swiss model and Discovery Studio 3.0. Results showed that improved effect of β-glycosidase might cause by the increased expressing quantity probably due to the higher translation level of bgl4 (90.19% higher than that of bgl) after induction. And the conformational change of active sites might facilitate the binding of BG-cellobiose, which also had a certain promotion effect on BG. In order to improve the yield of β-glycosidase, the optimal medium in shake flask was confirmed as follows: Avicel 20 g/L, peptone 10 g/L, glutamate 1 g/L, CaCl2 2 g/L,KH2PO4 3 g/L, MgSO4·7H2O 4 g/L, PEG-4000 0.25 g/L, wheat bran extract 2.5%, Tween 80 200 μL/L, trace element solution 1 mL/L. Under the condition, the BG was peaked at 22.15 IU/mL in 108 h. The amplification experiment was carried out in 10 L fermentor with the control of fermentation process, and the maximum of β-glycosidase was 41.62 IU/mL at 84 h. In this paper, the possibility of structural and function change of β-glycosidase after mutagenesis was analyzed and increased production of β-glycosidase was achieved by the optimization of fermentation conditions. All of these results provided certain support for modification of β-glucosidase gene and industrial application of β-glucosidase.
ZHENG Xian-jin
,
TANG Bin
. Research on the structure and function of β-glycosidase from the Rhizopus stolonifer mutant and optimization of its fermentation[J]. Food and Fermentation Industries, 2018
, 44(11)
: 42
-48
.
DOI: 10.13995/j.cnki.11-1802/ts.017560
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