Biotechnological potential of bacteria isolated from cattle environments of desert soils in Sonora Mexico

Abstract

The aim of this research was to study the hydrolytic potential of bacteria isolated from cattle environments of two desert soils in one of the driest and hottest zones in America. A total of 26 points were sampled, 144 strains were isolated, and 50 strains were selected for the characterization of esterase, lipase, protease, and amylase activities and for 16S rRNA identification. Strains of the Bacillus, Pseudomonas, Acinetobacter, Enterobacter, Providencia, Escherichia, and Pantoea genera were identified. Comparisons of the proteolytic activity of the secretome from 14 strains (Bacillus n = 7, Escherichia n = 2; Providencia, Pseudomonas, Enterobacter, Pantoea and Acinetobacter n = 1) were performed. Four strains of Bacillus showed the highest proteolytic activity. These strains were characterized through a comparative analysis of pH and temperature as well as the effects of salt concentration on protease activity. Maximum proteolytic activity occurred in the range of pH 7–9 and temperatures between 50 and 70 °C for B. subtilis WD01, B. tequilensis WS11, B. tequilensis WS13, and B. tequilensis WS14. At a 20% NaCl concentration, the proteolytic activity retained was 71.4%, 65%, and 79.8% for WD01, WS11, and WS13, respectively; the activity of strain WS14 increased with 45% NaCl. Protease production by B. tequilensis WS14 with wheat, fish, and bone flours as low-cost substrates showed no differences between bone and fish flours and showed a decrease in protease production with wheat flour. The proteolytic activity in flour extracts with 20% NaCl was 82%, 75.61% and 38.04% for fish, bone and wheat flours, respectively. Data obtained in this work allow us to propose that strains isolated from environments with extreme conditions have a biotechnological potential.