Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/13/2006
Publication Date: 1/24/2007
Citation: Anandan, D., Marmer, W.N., Dudley, R.L. 2007. High-level cellular protease production by aspergillus tamarii NRRL 20818 using solid-state fermentation. Journal of Industrial Microbiology and Biotechnology. 34:339-347. Interpretive Summary: The dehairing of cattle hides is a step in the conversion of the hides into leather. Dehairing generates large quantities of waste that are of environmental concern. Replacement of the traditional dehairing protocol, based on the use of the chemical sodium sulfide, with an enzymatic (protease) dehairing protocol would reduce the amount of hazardous chemicals in a tannery's waste stream. One drawback to dehairing using a protease has been the unavailability of bulk quantities of effective enzyme. We have demonstrated that the protease isolated from Aspergillus tamarii fungus is capable of removing most of the hair from cattle hides. We have optimized the growth conditions of the fungus, making it possible to produce bulk quantities of the protease. The isolated enzyme will be used in developing an effective and economic protocol for enzymatic dehairing.
Technical Abstract: Aspergillus tamarii expresses an extracellular protease that we showed to be an effective dehairing agent. Large quantities of the enzyme will be required for the optimization of the enzymatic dehairing process. The growth conditions for maximum protease expression by A. tamarii were optimized for both solid state culture on wheat bran and for broth culture. Optimal protease expression occurred, for both cultural media, at initial pH 9; the culture was incubated at 30 deg C for 96 h and using a 5% inoculum to inoculate the growth media. Supplementation of the solid-state culture with 1% glucose or peptone, or 0.5% ammonium nitrate, increases A. tamarii protease expression. Supplementation of the broth culture with 1% glucose, or peptone, or skimmed milk or 0.5% ammonium nitrate increased A. tamarii protease production. Protease expression in broth culture was inhibited when the media was enriched with phosphorus.