Selection and immobilization of the optimal phytase-producing probiotic: a comparative in silico analyses of five autochthonous lactic acid bacteria

Abstract

Phytic acid and its salts are the major storage form of both phosphate and myo-inositol, especially in cereals. Phytic acid chelates multivalent cations, which decreases the solubilized form of these nutrients and their dietary bioavailability for absorption and assimilation. Increasing micronutrient bioavailability from the economic phytate-rich food can be achieved by subjecting this food to fermentation by phytase-producing bacteria. A total of 8 lactic acid bacteria were isolated from different fermented food samples. Among the bacteria tested for their ability to produce phytase, only five isolates were selected as promising producers. The results revealed that isolate No. 4 produced the highest phytase levels of 411 U/mL. The five isolates were differentially able to tolerate acidic, alkaline, heat, surfactant, osmotic, bile, and pancreatic enzyme stresses, with the superiority of isolate No. 4, which demonstrated the most desirable probiotic potentials as confirmed by principal component analysis (PCA), heat map, and network analysis. Isolate No. 4 was identified by 16S rRNA sequencing and later confirmed as Pediococcus pentosaceus strain NMP4762Ch under the accession number MZ413646. Moreover, the active cells of P. pentosaceus were immobilized in alginate; the reusability of the immobilized active cells resulted in continuous production with an optimum phytase activity of 432.0 U/mL after 14 days, which decreased with time to reach 142.5 U/mL after 56 days. The maximum shelf stability was also observed, 557.5 U/mL, after 14 days and declined with time, reaching 133.5 U/mL by the end of the 56th day. Since humans don’t naturally produce phytase, utilizing probiotics for phytase production is important to combat mineral deficiencies.