Proteolytic and Phytase Activity in Sourdough Lactic Acid Bacteria

ABSTRACT

Twenty-six strains of lactic acid bacteria (LAB) isolated from French and Bulgarian sourdoughs were screened for their enzymatic activities, to elucidate their possible roles during the fermentation process. Phytase and phosphatase activities were measured. These activities were determined spectrophotometrically by using p-nitrophenyl phosphate and sodium phytate as substrates. SDS-PAGE and zymograme were performed to prove phytase activities and evaluate molecular weight of purified proteins. The enzyme responsible for these activities was an acid phosphatase, with a molecular mass of 70 kDa. Proteolytic activity were measured with casein and asocasein in model system and also in modified media with gluten as only one nitrogen source. Several strains have shown an interesting combination of proteolytic and phytase activities, suggesting their possible roles during dough fermentation.

Keywords:

• gluten hydrolysis
• phytase
• sourdough microflora