β-Glucosidases from the Fungus Trichoderma: An Efficient Cellulase Machinery in Biotechnological Applications

Table 2

Studies comprising of the enhancement strategies used for β-glucosidase production.

S. no.	Strain used and enzymes	Enhancement strategies	Conclusion	Reference
1	Aspergillus aculeatus β-glucosidase 1	A recombinant T. reesei strain, X3AB1 under the control of xyn3 promoter	63- and 25-fold higher β-glucosidase activity against cellobiose	[38]
2	β-glucosidase from Periconia spp.	Heterologous expression in T. reesei	Around 10.5-fold (23.9 IU/mg) higher β-glucosidase activity; A very high total cellulase activity (about 39.0 FPU/mg)	[63]
3	T. reesei, Bgl2	Mutational studies and engineering of active site residues	Mutants, P172L, and P172L/F250A showed enhanced 𝑘cat/𝐾𝑚 and 𝑘cat values by 5.3- and 6.9-fold; Also, mutant L167W had the best synergism with T. reesei in cellulosic biomass degradation	[32]
4	T. reesei (bglI)	Overexpression in P. pastoris GS115 under methanol-inducible alcohol oxidase promoter and S. cerevisiae secretory signal peptide.	β-glucosidase expression was 0.3 mg/mL and the maximum activity was 60 U/mL	[39]
5	β-glucosidase 1 (BGL1)	Use of xyn3 and egl3 promoters through homologous recombination	4.0- and 7.5-fold higher β-glucosidase activity	[70]
6	T. citrinoviride mutants	Mutational studies, use of ethidium bromide and ethyl methyl sulphonate as mutagens	Secretion of endoglucanase, β-glucosidase and cellobiase was found to be 2.14-, 2.10-, 4.09-, and 1.73-fold higher	[28]
7	Thermostable β-glucosidase (cel3a)	cel3a from Talaromyces emersonii was expressed in T. reesei	High specific activity against p-nitrophenyl-β-D-glucopyranoside (𝑉max, 512 IU/mg) and was competitively inhibited by glucose (ki, 0.254 mM) and displayed transferase activity	[40]
8	BGL4 from H. grisea	Overexpression of BGL4 in T. reesei or; T. viride	Improvement in cellulose saccharification by 1.4–2.2 times	[43]
9	T. reesei Rut C-30	Temperature and pH profiling studies	0.02% Tween-80 concentration was optimum, pH 5.0 and temperature (31°C) initially (for 18 h) was optimum for maximum production of cellulase and β-glucosidase	[89]