Effect of Varying Environmental Conditions on the Growth and Viability of Selected Microorganisms using Conventional Cultures

Abstract

Four experiments were conducted to examine the effect of heat, temperature, pH, and salt concentration on the growth and viability of Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli, and Staphylococcus aureus using nutrient agar plate cultures. The heating effect was checked at 50 and 80 oC for 0, 10, 20, 30, and 60 min, while temperature effects were examined at 4, 25, 30, 37, and 45 oC. Results showed that P. aeruginosa could grow well at 50 oC for 1 h while only surviving at 80 oC for 10 min. Growths were recorded from 25 oC for all the bacteria tested. No growth was recorded at pH 11 for P. aeruginosa. In contrast, others exhibited growth at all the pH tested except for S. aureus that could not survive pH 3. All organisms could not survive any of the salt concentrations tested. However, some growth was recorded between 5 – 10 % salt for others, with S. aureus showing the highest tolerance to salt. A study of the effect of environmental conditions on the growth and viability of microorganisms is necessary in thr future. These findings provide a more realistic estimation of food safety risks and valuable quantitative data to develop processes for safer food products.

Keywords

• Microbes;
• Growth;
• Environment;
• temperature;
• Salt;
• pH