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[Combined effect of temperature a(W) and pH on proteases from Pseudomonas and Bacillus spp]
C Klug1, K Fehlhaber, U Müller
1Institut für Lebensmittelhygiene, Veterinärmedizinischen Fakultät, Universität Leipzig.
Abstract:
The factors affecting protease activity were investigated on certain media. Five strains of Bacillus (B.) cereus, four strains of B. subtilis, five strains of Pseudomonas (Ps.) aeruginosa and two strains of Ps. fluorescens produced the proteases that were tested. The enzyme activity was evaluated under 32 different combinations of temperature (2 and 7 degrees C), water activity (aw) (0.80-0.98) and pH (4.0-7.3). A decrease in water activity and pH and/or temperature caused a decrease in protease activity. It appeared that the combined effect of temperature, aw and pH influences enzyme production significantly compared with the influence of single environmental factors. Temperature plays the crucial role in these reactions. Enzyme activities could be observed even at low temperature. Although the exoprotease of Ps. spp. showed intense activity at refrigeration temperature, low pH and aw, Bacillus proteases were comparably less active under the same conditions, but nevertheless proved to be significant.
Insights
Protease activity is significantly influenced by temperature, pH, and water activity. Pseudomonas proteases show high activity at refrigeration temperatures, unlike Bacillus proteases.
Area of Science:
- Microbiology
- Enzymology
- Biochemistry
Background:
- Proteases are essential enzymes with diverse industrial applications.
- Understanding protease activity under various environmental conditions is crucial for optimizing their use.
- Bacillus and Pseudomonas species are known producers of extracellular proteases.
Purpose of the Study:
- To investigate the impact of temperature, water activity (aw), and pH on protease activity from selected bacterial strains.
- To compare the protease activity profiles of Bacillus and Pseudomonas species under different environmental conditions.
Main Methods:
- Protease activity was assessed from five Bacillus cereus, four Bacillus subtilis, five Pseudomonas aeruginosa, and two Pseudomonas fluorescens strains.
- Enzyme activity was evaluated across 32 combinations of temperature (2-7°C), water activity (0.80-0.98), and pH (4.0-7.3).
Main Results:
- Protease activity decreased with lower temperature, water activity, and pH.
- The combined effect of these factors significantly impacted enzyme production more than individual factors.
- Pseudomonas proteases exhibited high activity at refrigeration temperatures, low pH, and low aw.
- Bacillus proteases showed lower activity under these specific conditions but remained significant.
Conclusions:
- Temperature is a critical factor influencing protease activity, with activity observed even at low temperatures.
- Environmental factors like pH and water activity modulate protease production and activity.
- Pseudomonas exoproteases are more adapted to low-temperature, low-aw, and low-pH environments compared to Bacillus proteases.