Do cultural conditions induce differential protein expression: Profiling of extracellular proteome of Aspergillus terreus CM20.
The present study reports the diversity in extracellular proteins expressed by the filamentous fungus, Aspergillus terreus CM20 with respect to differential hydrolytic enzyme production profiles in submerged fermentation (SmF) and solid-state fermentation (SSF) conditions, and analysis of the extracellular proteome. The SSF method was superior in terms of increase in enzyme activities resulting in 1.5-3 fold enhancement as compared to SmF, which was explained by the difference in growth pattern of the fungus under the two culture conditions. As revealed by zymography, multiple isoforms of endo-β-glucanase, β-glucosidase and xylanase were expressed in SSF, but not in SmF. Extracellular proteome profiling of A. terreus CM20 under SSF condition using liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) identified 63 proteins. Functional classification revealed the hydrolytic system to be composed of glycoside hydrolases (56%), proteases (16%), oxidases and dehydrogenases (6%), decarboxylases (3%), esterases (3%) and other proteins (16%). Twenty families of glycoside hydrolases (GH) (1, 3, 5, 7, 10, 11, 12, 15, 16, 28, 30, 32, 35, 43, 54, 62, 67, 72, 74 and 125), and one family each of auxiliary activities (AA7) and carbohydrate esterase (CE1) were detected, unveiling the vast diversity of synergistically acting biomass-cleaving enzymes expressed by the fungus. Saccharification of alkali-pretreated paddy straw with A. terreus CM20 proteins released high amounts of glucose (439.63±1.50mg/gds), xylose (121.04±1.25mg/gds) and arabinose (56.13±0.56mg/gds), thereby confirming the potential of the enzyme cocktail in bringing about considerable conversion of lignocellulosic polysaccharides to sugar monomers.
Division of Microbiology, Indian Agricultural Research Institute, New Delhi 110 012, India.
Saritha
S
M
Division of Microbiology, Indian Agricultural Research Institute, New Delhi 110 012, India.
Surender
S
Singh
Division of Microbiology, Indian Agricultural Research Institute, New Delhi 110 012, India.
Rameshwar
R
Tiwari
Central Instrumentation facility, University of Delhi, South Campus, Benito Juarez Road, New Delhi 110 021, India.
Renu
R
Goel
Division of Microbiology, Indian Agricultural Research Institute, New Delhi 110 012, India. Electronic address: latarajat@yahoo.co.in.
Lata
L
Nain
D001230:Aspergillus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism*; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D006868:Hydrolysis; D020543:Proteome; D040901:Proteomics / Q000379:methods; D012997:Solvents
D005656:Fungal Proteins; D020543:Proteome; D012997:Solvents
Aspergillus terreus; Extracellular proteome; Glycoside hydrolase; LC-MS/MS; Solid-state fermentation; Submerged fermentation