Isolation and Characterization of Protease Producing Bacteria from Quebec Soil and Water Samples

Seventy-four bacterial isolates were recovered from 10 protein rich soil and water samples collected from Quebec City. On the basis of colony size, texture, and microscopic characteristics, the isolates were categorized into 33 types. Among these, five isolates showed good proteolytic activity $(>5)$ , eight isolates showed moderate activity (between $>3.0$ and $<5.0$ ), 12 isolates showed poor activity (between $>2.0$ and $<3.0$ ), and eight isolates exhibited very poor activity (below 2.0). The five promising isolates were identified as Bacillus strains, which produced higher amount of protease and maximum cell concentration in fermentor than a shake flask in a shorter time. The enzyme produced by five strains of Bacillus showed similar thermal activity and stability. The proteases retained 31 and 10% of their original activity after $2\mathrm{h}$ at 50° and $60°\mathrm{C}$ , respectively, but lost all activity at $70°\mathrm{C}$ . However, the optimum pH and pH stability of proteases was from 6.0 to 9.0 and 6.0 to 8.0, respectively. The enzyme activities were accelerated by the addition of ${\mathrm{Mg}}^{2+}$ , ${\mathrm{Ca}}^{2+}$ , ${\mathrm{Mn}}^{2+}$ , ${\mathrm{Fe}}^{2+}$ , ${\mathrm{Co}}^{2+}$ , ${\mathrm{Cu}}^{2+}$ , and ${\mathrm{Na}}^{+}$ , whereas these were inhibited by ${\mathrm{Hg}}^{2+}$ and EDTA. Thus, all evaluated isolates were suitable for the production of protease.