Submitted to: Process Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 11, 2003
Publication Date: June 1, 2004
Citation: Saha, B.C. 2004. Production, purification and properties of endoglucanase from a newly isolated strain of Mucor circinelloides. Process Biochemistry. 39:1871-1876. Interpretive Summary: In the USA, the production of fuel alcohol from corn starch reached about 2.1 billion gallons in 2002. Research emphasis is to use various waste and underutilized agricultural residues as low-cost feedstock for production of fuel alcohol. One constraint is the high cost and low effectiveness of cellulase enzymes which breakdown cellulose to glucose. There is a lot of interest to find new enzymes with superior properties. The author isolated a fungal strain from natural sources which produces cellulase enzymes. One cellulase enzyme from this newly isolated fungal strain has been purified and characterized. The enzyme has potential to be used in fuel ethanol production from cellulose containing feedstock.
Technical Abstract: A newly isolated strain of the fungus, Mucor circinelloides (NRRL 26519), when grown on lactose, cellobiose, or Sigmacell 50, produces a complete cellulase (endoglucanase, cellobiohydrolase, and ß-glucosidase) system. The extracellular endoglucanase (EG) from this fungal strain was purified to homogeneity from the culture supernatant by ethanol precipitation (75%, v/v), CM Bio-Gel A column chromatography, and Bio gel A-0.5m gel filtration. The purified EG (specific activity 43.33 U/mg protein) was a monomeric protein with a molecular weight of 27,000. The optimum temperature and pH for the action of the enzyme were at 55 deg C and 4.0-6.0, respectively. The purified enzyme was fully stable at pH 4.0-7.0 and temperature up to 60 deg C. It hydrolyzed carboxymethyl cellulose and insoluble cellulose substrates (Avicel, Solka-floc, and Sigmacell 50) to soluble cellodextrins. No glucose, cellobiose, and short chain cellooligosaccarides were formed from these substrates. The purified EG could not degrade oat spelt xylan and larch wood xylan. It bound to Avicell, Solka-floc, and Sigmacell 50 at pH 5.0, and the bound enzyme was released by changing the pH to 8.0. The enzyme activity was enhanced by 27 ± 5 and 44 ± 14% by the addition of 5 mM MgCl2 and 0.5 mM CoCl2, respectively, to the reaction mixture. Comparative properties of this enzyme with other fungal EGs are presented.