Transcriptomic Analysis of the White-rot Basidiomycete Lentinus Squarrosulus to Provide Insights Into Its Lignocellulose Biodegradation Ability

BackgroundBasidiomycetes are of special interest in biotechnological research for their versatile potential in the degradation of lignocellulosic biomass, chiefly attributed to ligninolytic enzymes along with exo, endo β-glucanases, xylanases, esterases, pectinases, mannanases, cellobiohydrolases, polysaccharide monooxygenases. Relatively little is known about the metabolic process and the subsequent polysaccharide degradation. Transcriptomic analysis of lignicolous fungi grown on different substrates, although attempted by researchers, has focused on a fairly small group of species reporting the expression of fungal genes in response to lignocellulosic biomass as a substrate. This study accordingly reports analysis of transcriptome of a white-rot Basidiomycete L.squarrosulus grown in simple potato dextrose broth supplemented with aromatic compound, reactive black dye to gain an insight into the degradation ability of the fungus. RNA was sequenced using Illumina NextSeq 500 to obtain 6,679,162 high-quality paired-end reads that were assembled de novo using CLC assembly cells to generate 25,244 contigs. Putative functions were assigned for the 10,494 transcripts based on sequence similarities through BLAST2GO 5.2 and Function annotator.ResultsFunctional assignments revealed enhanced oxidoreductase activity through the expression of diverse biomass-degrading enzymes and their corresponding coregulators. CAZyme analysis through dbCAN and CUPP revealed the presence of 6 families of polysaccharide lyases, 51 families of glycoside hydrolases, 23 families of glycoside transferases, 7 families of carbohydrate esterases and 10 families of auxiliary activities. Genes encoding ligninolytic enzymes and auxiliary activities among the transcript sequences were identified through gene prediction by AUGUSTUS and FGENESH. Biochemical analysis of several biomass-degrading enzymes substantiated the functional predictions.ConclusionIn essence, L. squarrosulus grown in a simple medium devoid of lignocellulosic substrate demonstrated the presence of a repertoire of lignocellulose-degrading enzymes, simplying that a source of lignocellulose is not required for the expression of these biomass-degrading enzymes. This study on the transcriptome analysis of L. squarrosulus revealed significant facts on this front and will definitely enhance the knowledge about the biodegradative ability of this fungus, potentially paving the way for efficient biotechnological applications utilizing its potency in biomass degradation and its future functional exploitation in biomass conversion applications.

Co-culture of Vel1-overexpressed Trichoderma asperellum and Bacillus amyloliquefaciens: An eco-friendly strategy to hydrolyze the lignocellulose biomass in soil to enrich the soil fertility, plant growth and disease resistance

Background Retention of agricultural bio-mass residues without proper treatment could affect the subsequent plant growth. In the present investigation, the co-cultivation of genetically engineered T. asperellum and B. amyloliquefaciens has been employed for multiple benefits including the enrichment of lignocellulose biodegradation, plant growth, defense potential and disease resistance. Results The Vel1 gene predominantly regulates the secondary metabolites, sexual and asexual development as well as cellulases and polysaccharide hydrolases productions. Overexpression mutant of the Trichoderma asperellum Vel1 locus (TA OE-Vel1) enhanced the activity of FPAase, CMCase, PNPCase, PNPGase, xylanase I, and xylanase II through the regulation of transcription regulating factors and the activation of cellulase and xylanase encoding genes. Further, these genes were induced upon co-cultivation with Bacillus amyloliquefaciens (BA). The co-culture of TA OE-Vel1 + BA produced the best composition of enzymes and the highest biomass hydrolysis yield of 89.56 ± 0.61%. The co-culture of TA OE-Vel1 + BA increased the corn stover degradation by the secretion of cellulolytic enzymes and maintained the C/N ratio of the corn stover amended soil. Moreover, the TA OE-Vel1 + BA increased the maize plant growth, expression of defense gene and disease resistance against Fusarium verticillioides and Cohilohorus herostrophus. Conclusion The co-cultivation of genetically engineered T. asperellum and B. amyloliquefaciens could be utilized as a profound and meaningful technique for the retention of agro residues and subsequent plant growth.

Co-culture of Vel1-overexpressed Trichoderma asperellum and Bacillus amyloliquefaciens: An eco-friendly strategy to hydrolyze the lignocellulose biomass in soil to enrich the soil fertility, plant growth and disease resistance

Background: Retention of agricultural bio-mass residues without proper treatment could affect the subsequent plant growth. In the present investigation, the co-cultivation of genetically engineered T. asperellum and B. amyloliquefaciens has been employed for multiple benefits including the enrichment of lignocellulose biodegradation, plant growth, defense potential and disease resistance. Results: The Vel1 gene predominantly regulates the secondary metabolites, sexual and asexual development as well as cellulases and polysaccharide hydrolases productions. Overexpression mutant of the Trichoderma asperellum Vel1 locus (TA OE-Vel1) enhanced the activity of FPAase, CMCase, PNPCase, PNPGase, xylanase I, and xylanase II through the regulation of transcription regulating factors and the activation of cellulase and xylanase encoding genes. Further, these genes were induced upon co-cultivation with Bacillus amyloliquefaciens (BA). The co-culture of TA OE-Vel1 + BA produced the best composition of enzymes and the highest biomass hydrolysis yield of 89.56 ± 0.61%. The co-culture of TA OE-Vel1 + BA increased the corn stover degradation by the secretion of cellulolytic enzymes and maintained the C/N ratio of the corn stover amended soil. Moreover, the TA OE-Vel1 + BA increased the maize plant growth, expression of defense gene and disease resistance against Fusarium verticillioides and Cohilohorus herostrophus. Conclusion: The co-cultivation of genetically engineered T. asperellum and B. amyloliquefaciens could be utilized as a profound and meaningful technique for the retention of agro residues and subsequent plant growth.