REPLACEMENT OF THE NITROGEN SOURCE IN THE FERMENTATION PROCESS OF CANDIDA UTILIS AT LABORATORY SCALE

Abstract

Introduction:
In the forage yeast production process, nitrogen-contributing salts represent a high impact on production costs due to their high prices in the market.
Objective:
To evaluate nationally produced ammonium nitrate as a source of nitrogen in the growth of Candida utilis (C. utilis) in final molasses and vinasses media at laboratory scale.
Materials and Methods:
A comparative study was carried out beween the tradicional scheme with ammonium sulfate and ammonium nitrate as a nitrogen source. The C.utilis NRRL Y-1084 strain was used. Simple ANOVA analysis and Fisher's LSD multiple range test were performed on Statgraphics Centurion XVII to determine whether there are significant differences or not. Each experimental condition was performed in triplicate.
Results and Discussion:
The C. utilis responds favorably in the presence of ammonium nitrate with values of net gain of biomass in honey medium of 5.90 and 7.22 g.L-1 and in vinasse medium of 4.45 and 4.12 g.L-1. The yield based on the consumption of ART was 22 and 25%, higher than that obtained in the traditional scheme with ammonium sulfate (15%). The COD removal levels achieved are higher (29.21% and 34.39%) than that obtained with ammonium sulfate (28.92%).
Conclusions:
Ammonium nitrate as a nitrogen source does not cause changes in the propagation of the strain and represents a saving in production costs by raw materials buy of 2,534,654 CUP/year.