Secretome diversity and quantitative analysis of cellulolytic Aspergillus fumigatusZ5 in the presence of different carbon sources

Abstract

BackgroundAspergillus fumigatus Z5 has a strong ability to decompose lignocellulose biomass, and its extracellular protein secretion has been reported in earlier studies employing traditional techniques. However, a comprehensive analysis of its secretion in the presence of different carbon sources is still lacking. The goal of this work was to identify, quantify and compare the secretome of A. fumigatus Z5 in the presence of different carbon sources to understand in more details the mechanisms of lignocellulose decomposition by Aspergillus fumigatus Z5.ResultsCellulolytic A. fumigatus Z5 was grown in the presence of glucose (Gl), Avicel (Av) and rice straw (RS), and the activities of several lignocellulosic enzymes were determined with chromatometry method. The maximum activities of endoglucanase, exoglucanase, β-glucosidase, laminarinase, lichenase, xylanase and pectin lyase were 12.52, 0.59, 2.30, 2.37, 1.68, 15.02 and 11.40 U·ml-1, respectively. A total of 152, 125 and 61 different proteins were identified in the presence of RS, Av and Gl, respectively, and the proteins were functionally divided into glycoside hydrolases, lipases, peptidases, peroxidases, esterases, protein translocating transporters and hypothetical proteins. A total of 49 proteins were iTRAQ-quantified in all the treatments, and the quantification results indicated that most of the cellulases, hemicellulases and glycoside hydrolases were highly upregulated when rice straw and Avicel were used as carbon sources (compared with glucose).ConclusionsThe proteins secreted from A. fumigatus Z5 in the present of different carbon source conditions were identified by LC-MS/MS and quantified by iTRAQ-based quantitative proteomics. The results indicated that A. fumigatus Z5 could produce considerable cellulose-, hemicellulose-, pectin- and lignin-degrading enzymes that are valuable for the lignocellulosic bioenergy industry.

On-Site Production of Enzymatic Cocktails Using a Non-conventional Fermentation Method with Agro-Industrial Residues as Renewable Feedstocks

“…Despite the fact that glucose is an acknowledged cellulase inhibitor [46,47] and can also cause catabolic repression in fungi [11,48,49], the present findings revealed that at a concentration of 10 gÁL -1 the addition of glucose to the cultivation medium resulted in a suitable environment for both A. niger growth and enzyme production. The glucose promoted rapid fungal growth at the beginning of the cultivation, which was followed by the production of hydrolytic enzymes after the total consumption of glucose by the fungus.…”

“…Comparative secretome studies have been performed using a wide range of fungal strains and substrates, and have demonstrated that complex lignocellulosic materials can induce a greater variety of enzymes, compared to pure substrates [11,[19][20][21]. However, the development of bioprocesses using complex substrates such as agricultural residues is hampered by the fact that the composition and structure of lignocellulosic materials vary significantly from one plant to another, and even among plants of the same species.…”

“…Cellulases (endoglucanases, exoglucanases, and b-glucosidases) and xylanases are the main enzymes involved in lignocellulose deconstruction, and act in synergy with accessory enzymes that assist lignocellulose degradation, such as pectinases, manganese peroxidase, lignin peroxidase, and expansins, among others [10,11]. However, the high costs of these enzymes remain a major difficulty in large-scale 2G ethanol production [12,13].…”

A Novel Exo-Glucanase Explored from a <i>Meyerozyma</i> sp. Fungal Strain

“…The results indicated that various types of enzymes (e.g., isozymes) with diverse characteristics might produce from the strain #58 when it was cultured under different pH and temperature conditions. A previous study had suggested that productions of lignolytic enzymes from a basidiomycetous fungal strain were dissimilar under different culture conditions [23]; and, another report had indicated that Aspergillus fumigates Z5 produced different proteins after cultivation with various carbon sources (i.e., glucose, avicel, and rice straw) [24]. It was surmised some cellulolytic enzymes might not be produced or might just be produced at very low level under inappropriate culturing conditions.…”

Genomics Review of Holocellulose Deconstruction by Aspergilli

“…Thus, we considered only GH12 and GH74 XEGs from aspergilli, due to the lack of characterized gene models for the GH5, GH16, and GH44 families. Furthermore, XEGs from these families were not identified in secretomes of aspergilli growing on biomass (10,14,203,204). Table 9 shows that aspergilli contain one or no GH74 xyloglucanases but several GH12 enzymes.…”