Addressing challenges in production of cellulases for biomass hydrolysis: Targeted interventions into the genetics of cellulase producing fungi

Halder

Syst Microbiol and Biomanuf

2021

Cellulose is the utmost plenteous source of biopolymer in our earth, and fungi are the most efficient and ubiquitous organism in degrading the cellulosic biomass by synthesizing cellulases. Tailoring through genetic manipulation has played a substantial role in constructing novel fungal strains towards improved cellulase production of desired traits. However, the traditional methods of genetic manipulation of fungi are time-consuming and tedious. With the availability of the full-genome sequences of several industrially relevant filamentous fungi, CRISPR-CAS (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein) technology has come into the focus for the proficient development of manipulated strains of filamentous fungi. This review summarizes the mode of action of cellulases, transcription level regulation for cellulase expression, various traditional strategies of genetic manipulation with CRISPR-CAS technology to develop modified fungal strains for a preferred level of cellulase production, and the futuristic trend in this arena of research.

“…A maximum number of TFs participated in such regulatory mechanisms (Fig. 1 ), particularly from the Zn2Cys6 zinc binuclear cluster family, specifically in fungi [ 16 ].…”

Section: Molecular Mechanisms Behind the Cellulase Expressionmentioning

confidence: 99%

Section: Genetic Manipulation For Intensified Cellulase Productionmentioning

confidence: 99%

See 1 more Smart Citation

Tailoring in fungi for next generation cellulase production with special reference to CRISPR/CAS system

Halder

Syst Microbiol and Biomanuf

2021

“…Several transcriptional factors of cellulose-degrading pathways have been identified in cellulolytic fungi. CreA/Cre1/Cre-1, AceI, AceII, Ace3, and AmyR were reported to play a negative role in the cellulase and xylanase regulatory network [10]. CreA/Cre1/Cre-1 is a regulator of carbon catabolite repression that plays a pivotal role in the activation or inhibition of cellulose deconstruction [11].…”

Section: Introductionmentioning

confidence: 99%

GlSwi6 Positively Regulates Cellulase and Xylanase Activities through Intracellular Ca2+ Signaling in Ganoderma lucidum

Lian

Shi

Zhu

et al. 2022

JoF

Ganoderma lucidum is a white-rot fungus that produces a range of lignocellulolytic enzymes to decompose lignin and cellulose. The mitogen-activated protein kinase (MAPK) pathway has been implicated in xylanases and cellulases production. As the downstream transcription factor of Slt2-MAPK, the function of Swi6 in G. lucidum has not been fully studied. In this study, the transcription factor GlSwi6 in G. lucidum was characterized and shown to significantly positively regulate cellulases and xylanases production. Knockdown of the GlSwi6 gene decreased the activities of cellulases and xylanases by approximately 31%~38% and 54%~60% compared with those of the wild-type (WT) strain, respectively. Besides, GlSwi6 can be alternatively spliced into two isoforms, GlSwi6A and GlSwi6B, and overexpression of GlSwi6B increased the activities of cellulase and xylanase by approximately 50% and 60%, respectively. Further study indicates that the existence of GlSwi6B significantly increased the concentration of cytosolic Ca2+. Our study indicated that GlSwi6 promotes the activities of cellulase and xylanase by regulating the Ca2+ signaling. These results connected the GlSwi6 and Ca2+ signaling in the regulation of cellulose degradation, and provide an insight for further improvement of cellulase or xylanase activities in G. lucidum as well as other fungi.

“…The mixed enzyme preparation produced by Aspergillus niger can achieve a better peeling effect on citrus paradisi peel by vacuum perfusion [9]. Generally, Penicillium and Aspergillus can generate enzymes for the degradation of lignocellulose [10]. Research shows that new strains of black Aspergilli can produce multiple hydrolytic enzymes, including cellulase, pectinase and tannase [11].…”

Section: Introductionmentioning

confidence: 99%

Safety Evaluation and Whole Genome Sequencing of Aspergillus japonicas PJ01 Reveal Its Potential to Degrade Citrus Segments in Juice Processing

Qian

Gao

Wang

et al. 2021

Foods

Aspergillus japonicas PJ01 (A. japonicas PJ01) is a strain isolated from the rotten branches. In previ-ous studies, it was shown that it can produce complex enzymes to degrade polysaccharide com-ponents. In this study, we evaluated the safety of its crude enzyme solution. Acute oral toxicity, subchronic toxicity, micronucleus and sperm malformation tests all validated the high biologi-cal safety for the crude enzymes. Secondly, we carried out the citrus segment degradation ex-periment of crude enzyme solution. Compared with the control group, the crude enzyme solu-tion of A. japonicas PJ01 can completely degrade the segments in 50 min, which provides the basis for enzymatic peeling during juice processing. The whole genome sequencing showed that the genome of A. japonicus PJ01 has a GC content of 51.37% with a size of 36204647 bp, and encoded 10070 genes. GO, COG, KEGG and CAZy databases were used in gene annotation analyses. Pathway enrichment showed many genes related to carbohydrate metabolism, rich in genes re-lated to pectinase, xylanase and carboxylcellulase. Therefore, the complex enzyme produced by A. japonicus PJ01 can be used in gizzard juice processing to achieve efficient enzymatic decapsu-lation.