Screening of High-efficiency Cellulose-degrading Microorganism from Spent Lentinula edodes Substrate and Optimization of Its Enzyme Production

doi:10.13560/j.cnki.biotech.bull.1985.2021-1120

Abstract

Abstract:

Utilizing spent Lentinula edodes substrate to develop organic fertilizer is major trend of converting waste bacterial residue into resources. In order to compost the spent L. edodes substrate,a high efficient cellulose-degrading strain DGW1 was isolated from the spent L. edodes substrate,the conditions of cellulase production were optimized,and the degradation capacity of the spent L. edodes substrate was evaluated,which lays a foundation for the subsequent composting fermentation of spent L. edodes substrate to produce bio-organic fertilizer. The strains were preliminarily screened by CMC-Na culturing method and Congo red dyeing and re-screened in combination with filter paper disintegration test and cellulase activity test. The strain was identified by morphological observation and 18S rDNA molecular biology,and the conditions of producing cellulose-degrading enzyme by the strain DGW1 were optimized. The results showed that the highly cellulolytic strain DGW1 was identified as Trichoderma reesei. The filter paper strips were degraded to paste in the 7 d. The optimal conditions of the strain DGW1 were temperature 30℃,time 4 d,the filter paper activity（FPase）was 112.71 U/g,and the high enzyme activity at pH 4-7 was not lower than 96 U/g. The degradation rate of the strain DGW1 on spent L. edodes substrate was 31.14%（14 d）. Therefore,the strain DGW1 can effectively degrade spent L. edodes substrate,and its cellulase activity was high,which has great application potential for composting of spent L. edodes substrate and preparation of bio-organic fertilizer.

Key words: spent Lentinula edodes substrate, Trichoderma reesei DGW1, enzyme activity, enzyme production condition

TAO Zhi-dong, HE Yan-hui, DENG Zi-he, SUN Lin-lin, WU Zhan-sheng. Screening of High-efficiency Cellulose-degrading Microorganism from Spent Lentinula edodes Substrate and Optimization of Its Enzyme Production[J]. Biotechnology Bulletin, 2021, 37(11): 158-165.

Figures/Tables 8

Fig.1 Qualitative screening results of Congo red staining A:Transparent circle size. B:Staining of some strains

Table 1 Filter strip degradation by 22 isolated strains

菌株编号 Strain No.	滤纸条崩解程度 Degradation degree of filter paper	筛选温度 Screening temperature/℃	菌株编号 Strain No.	滤纸条崩解程度 Degradation degree of filter paper	筛选温度 Screening temperature/℃
DF1	+	28	YD3	+++	28
GF1	++	45	YG4	++	45
GF2	+	45	YD2	++	28
YG1	+	45	DGW1	++++	28
DG3	+	28	FYG2	+	45
GF3	+++	45	FYG3	++	45
YG3	+	45	FFD1	+	28
YD4	++++	28	FYG1	++	45
GG1	+	45	FDY2	+	28
YG2	+++	45	FGF1	++	45
YD1	++	28	FFD2	+	28

Fig.2 FPase of cellulose-degrading microorganism

Fig.3 Agarose-gel electrophoresis picture of 18S rDNA

Fig.4 Phylogenetic tree of strain DGW1 based on 18S rDNA sequence homology

Fig.5 Morphology of the strain DGW1 A:Morphology of the strain DGW1;B:spore morphology of strain DGW1;C:mycelial morphology of strain DGW1;D:mycelial morphology of strain DGW1 under SCM

Fig.6 Enzyme activity of strain DGW1 under different conditions A:Enzyme activity of strain DGW1 at different pH. B:Enzyme activity of strain DGW1 at different temperature. C:Enzyme activity of strain DGW1 at different times

Fig.7 Rates of different strains degrading spent mushroom substrate

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