Influence of the Nitrogen Source on the Productions of α-Amylase and Glucoamylase by a New Trichoderma sp. from Soluble Starch

R. A. Pacheco Chávez, L. C. Tavares, A. C. S. C. Teixeira, J. C. M. Carvalho, A. Converti and S. Sato

Abstract
The influence of the nitrogen source on the production of extra–cellular amylolytic enzymes by a new Trichoderma sp. isolate was investigated. Preliminary tests performed using a mixture of urea and ammonium sulfate demonstrated that this microorganism was able to effectively degrade ungelatinized soluble starch (20 g l–1) yielding 420±30 U l–1 α–amylase and 130 ± 20 U l–1 glucoamylase. Tests were also performed using different nitrogen sources at the optimum level of 0.80 g l–1 nitrogen, specifically ammonium citrate, yeast extract, urea, ammonium sulfate, ammonium sulfate plus urea, peptone, and corn steep liquor. Corn steep liquor was shown to be the best nitrogen source for the simultaneous activities and productivities either of α–amylase (aa,max = 520 ± 4U l–1; Pa = 5.0 ± 0.5 U l–1 h–1) or glucoamylase (ag,max = 1100 ± 70 U l–1; Pg = 15 ± 1 U l–1 h–1).

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Keywords
α-amylase, glucoamylase, nitrogen source, soluble starch, Trichoderma sp.