Phytase-Producing Fungi from Processed Cheese: Isolation, Screening, and Optimization of Production Parameters

: Phytic acid is a prevalent anti-nutrient in human and animal diets, neutralized effectively by the enzyme phytase. This enzyme, extensively used in the food industry and livestock production, was the focus of our study to identify phytase-producing fungal species among contaminants in ultra-refined white cheeses. We evaluated the enzymatic activity of each isolate in phytase screening medium (PSM) and Luria bertani Broth (LB) media, determining optimal production conditions such as temperature and pH for the isolate with the highest activity. Initial screening from 110 mold isolates, representing 10 different species, identified 28 isolates across 6 species capable of producing phytase. These included Aspergillus niger, Aspergillus oryzae, Penicillium commune, Penicillium chrysogenum, Paecilomyces variotii, and Cladosporium cladosporioides, discernible by halo zones around their colonies. The highest activity levels were recorded for P. commune (133.76 U/mL) and P. variotii (216.7 U/mL) in PSM and LB media, respectively. Remarkably, this study is the first to document phytase production by P. variotii, showcasing the highest activity among the isolates and presenting a new opportunity for industrial phytase production. The enzyme isolated from P. variotii demonstrated stability and optimum activity at temperatures from 20°C to 70°C and pH 4.0 to 7.0, peaking at 50°C and pH 6.0. Its unique properties suggest significant potential for industrial applications, positioning it as a novel candidate for further exploration in industrial phytase production.