Secretomic Insight into Glucose Metabolism of Aspergillus brasiliensis in Solid-State Fermentation

Abstract

The genus Aspergillus is ubiquitous in nature and includes various species extensively exploited industrially due to their ability to produce and secrete a variety of enzymes and metabolites. Most processes are performed in submerged fermentation (SmF); however, solid-state fermentation (SSF) offers several advantages, including lower catabolite repression and substrate inhibition and higher productivity and stability of the enzymes produced. This study aimed to explain the improved metabolic behavior of A. brasiliensis ATCC9642 in SSF at high glucose concentrations through a proteomic approach. Online respirometric analysis provided reproducible samples for secretomic studies when the maximum CO production rate occurred, ensuring consistent physiological states. Extracellular extracts from SSF cultures were treated by SDS-PAGE, digested with trypsin, and analyzed by LC-MS/MS. Of 531 sequences identified, 207 proteins were analyzed. Twenty-five were identified as the most abundant unregulated proteins; 87 were found to be up-regulated and 95 were down-regulated with increasing glucose concentration. Of the regulated proteins, 120 were enzymes, most involved in the metabolism of carbohydrates (51), amino acids (23), and nucleotides (9). This study shows the high protein secretory activity of A. brasiliensis under SSF conditions. High glucose concentration favors catabolic activities, while some stress-related proteins and those involved in proteolysis are down-regulated.

Physiological Characteristics and Comparative Secretome Analysis of Morchella importuna Grown on Glucose, Rice Straw, Sawdust, Wheat Grain, and MIX Substrates

“…Secretomes of some plant pathogens, mycorrhizal symbiotic fungi, and some micro-ascomycetes, such as Aspergillus , Trichoderma sp., Penicillium sp., Botrytis sp., etc . have also been systematically studied ( Shah et al, 2009 ; Jun et al, 2011 ; Liu et al, 2013 ; Volke-Sepulveda et al, 2016 ). However, studies on macro-ascomycetes are limited.…”

An Effective Protocol for Proteome Analysis of Medaka (Oryzias latipes) after Acute Exposure to Ionizing Radiation

“…For example, the spectral counts obtained after filtering the data with ProteoIQ can be used to evaluate the levels of protein expression and compare the control versus the treated samples. Relative spectral counts can be used to identify upregulation or repression in comparison to control using, for example, the relative spectral abundance factor (RSAF) [36,37]. In the current dataset, we observed that organs and intestines are more likely to be affected by IR exposure than carcasses, since only 39 proteins present in carcasses have an increase or decrease in relative spectral counts two-fold or greater, as compared to 200 in intestines and 264 in organs.…”

Omics Approaches for Understanding Biogenesis, Composition and Functions of Fungal Extracellular Vesicles

“…A. oryzae ( Oda et al, 2006 ) secreted 4-6x more protein in SSF. A. brasiliensis ATCC9642 in SSF produces several differentially expressed proteins which lack secretion signals, suggesting an alternative route of secretion such as EVs ( Volke-Sepulveda et al, 2016 ). Dissecting the molecular trafficking of EVs formation would create a novel compartment for enzyme delivery, or bioproduct collection from a culture without specialized transport proteins.…”