|788-1||PRODUCTION AND CHARACTERIZATION OF EXTRACELLULAR PHYTASE BY Rhizopus microsporus var. microsporus BIOFILMS|
|Autores:||Vanessa Sayuri Sato (IQ/UNESP - INSTITUTO DE QUÍMICA/UNIVERSIDADE ESTADUAL PAULISTA) ; João Atílio Jorge (FFCLRP-USP - UNIVERSIDADE DE SÃO PAULO) ; Luís Henrique Souza Guimarães (FFCLRP-USP - UNIVERSIDADE DE SÃO PAULO) |
Currently, biotechnology research accompanied by functional, structural and application of enzymes combined with the use of genetic engineering has been carried out in microorganisms for the production of enzymes for industrial purposes. Within the broad range of existing enzymes derived from microorganisms, the phytases (EC 22.214.171.124) catalyze the hydrolysis of phytate (myo-inositol hexakisphosphate) to myo-inositol and inorganic phosphate. These enzymes have been used in animal feed, since in most monogastric animals phytase is absent in the digestive tract is a process completely dependent on enzymes produced by intestinal flora. According to this the aim was to study the phytase production by R. microsporus var. microsporus under Submerged Fermentation (SF) and Biofilm fermentation (BF) as well as to characterize the phytase produced. The biofilm morphology, analyzed by scanning electron microscope, after 48 hours growth is characterized by multiple interconnected hyphae, which form an ordered array with the formation of channels that allow efficient exchange of nutrients from the microbial cells and the environment. R. microsporus var. microsporus produced good levels of extracellular enzyme (34.9 U/mg) under BF (2.48 g), at 30oC for 2 days (40-60 rpm), with sugarcane bagasse as substrate/carbon sources. In submerged fermentation the production was 18 U/mg of protein for 72 hours with addition of 2% (m/V) rye flour as carbon source. The induction of enzyme production was analyzed. The phytase production was strictly regulated by phosphorus when it was used modified Khanna medium containing high concentrations of phosphate (0-20 mM) suggesting that the enzyme is synthesized under Pi-limiting conditions and there-before is called Pi-repressible (optimal expression at 0.5 mM). The phytase demonstrated optimal temperature of activity at 40°C and two optimal apparent pH (4.5 and 6.5) using BF. Under SF the enzyme showed optimal pH of 5.0 and temperature of 50°C. The biofilm fermentation was an efficient system for phytase production and it is hold promise for further enzymatic production optimization. Our results suggest that R. microsporus var. microsporus is better producer of phytase under BF if compared to SF. It can be a new form to produce this enzyme using low cost substrate that is very attractive for animal feed industries.
Palavras-chave: phytase, Rhizopus microsporus var. microsporus, biofilm