Recherche d’activités phytasiques chez des bactéries isolées à partir de différents sols

Abstract

Enzymes are proteins that catalyze chemical reactions within living organisms. Among the different Enzymatic classes, hydrolases play a major role in industry, accounting for approximately 75% of industrial enzymes. Within this class, phytases have attracted particular interest. These are phosphatases capable of hydrolyzing phytate, the main form of organic phosphorus found in soils. Although phytases are found in various organisms (plants, animal tissues, etc.), those produced by bacteria are of great interest, particularly in the industrial sector.In this study, we investigated and characterized the phytase activity of four bacterial strains isolated from different soils. The study focused on enzymatic kinetics, as well as the influence of temperature and pH on enzyme activity. Thermostability and stability in acidic and basic media were also evaluated. The results revealed that the four studied isolates exhibited notable phytase activity. The phytases from the ISV, ISR, and ISN isolates had an optimal activity temperature of 30 °C, while that of the ISP isolate was 35 °C. Regarding pH, the phytases from the ISV and ISP isolates had optimal activity at pH 5, that of the ISR isolate at pH 7, and that of the ISN isolate at pH 9.As for thermal stability, most of the phytases lost their activity after 1 hour of treatment at 90 °C, except for those from the ISP isolate, which retained high activity. After 2 hours of treatment, all phytases had lost their activity, except for that of the ISV isolate, which still showed a low residual activity. Finally, the study of stability in acidic and basic environments showed that all phytases are sensitive to extreme pH conditions, with a significant loss of activity after 1 or 2 hours of treatment.