Production, characterization and application of new phytase by Saccharomyces cerevisiae

Author(s)

Edi Franciele Ries

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2010-10-26

Examining board members

Gabriela Alves Macedo; Helia Harumi Sato; Ranulfo Monte Alegre; Leila Picolli da Silva; Maria de Lourdes Teixeira de Moraes Polizeli

• Advisor: Gabriela Alves Macedo

Abstract

Most of the phosphorus in grains and seeds are stored in the form of phytate. However, in the diet, phytate is an anti-nutritional factor because of its capacity to chelate metals and link protein, thus preventing the absorption of nutrients and nutritionally important minerals. Although the phytate serve as the main source of energy and phosphorus for seed germination, two thirds of this mineral is unavailable to monogastric animals, so animal feeds are supplemented with inorganic phosphate, or alternatively, with enzymes capable of hydrolyzing phytate - phytases. The enzyme is widely distributed in nature, and can be found in animals, plants and microorganisms. Since phytases of yeast produced without the use of genetic engineering are yet not commercially available, this study sought a new source of yeast able to produce thermostable phytase aimed to be used in animal feed. Saccharomyces cerevisiae (S. cerevisiae) strain zi(EU188613) was selected from 140 yeasts isolated from soil by screening with a gradual increase in temperature to 48 °C, maintaining the capacity to hydrolyze phytate. Phytase production by S. cerevisiae increased about 10-fold after optimization of culture medium composition and fermentation parameters by experimental design techniques, compared to production in a non-optimized medium. The enzyme from S. cerevisiae showed desirable characteristics for application in the production of animal food as activity increases in a wide pH range, high resistance to the action of proteases, broad substrate specificity and optimum activity and thermal stability in wider ranges (37-80 ° C). The implementation of the new phytase S. cerevisiae in grass carp (Ctenopharyngodon idella) meals confirmed the efficiency of the enzyme by the hydrolysis of phytic acid in rice bran used in the food preparation. The metabolic responses obtained compared to the control diet with meal without enzyme treatment and the addition of dicalcium phosphate suggest that the effect of the new phytase at a concentration of 550 FTU / kg does not require supplementation with external sources of inorganic phosphorus. The new phytase, produced by S. cerevisiae, has relevant biochemical characteristics, furthermore the use of this microorganism in food is recognized to be safe (AU)