The Effect of Environmental Factors Such as Temperature, Osmotic Pressure, Oxygen Concentration and Ph on Microbial Growth and Survival

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The effect of environmental factors such as temperature, osmotic pressure, oxygen concentration and pH on microbial growth and survival

Abstract:
Microbial growth can be affected by different environmental factors such as temperature, osmotic pressure, oxygen concentration and pH. Six experiments were carried out in this report testing for microbial growth against different environmental factors. Good aseptic techniques were used to prevent contamination, resulting in a uniform set of results that are in line with the literature.

Introduction
Bacteria vary greatly in terms of their characteristics and morphology. Colonies can be classified according to their colour, form, elevation, margin and size. Pure cultures of microorganisms
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Broth cultures of E.coli, Micrococcus luteus and Vibrio natriegens were streaked onto the respective sections. The plate was then incubated at 37oC for 48 hours. The process was then repeated on nutrient agar plates with 5, 6.5 and 10% salt.

Experiment 5: Effect of oxygen concentration on bacterial growth
A fresh pipette was used to transfer 0.5ml of broth culture of E. coli, to be inoculated, into a tube of molten agar previously boiled to drive off oxygen. The tube was then rolled to distribute the bacteria and allowed time for the agar to harden. The tube was incubated at 37oC for 48 hours. The procedure was repeated for broth cultures of the bacterium Clostridium sporogenes and B. Subtilis.

Experiment 6: Effect of environmental factors on microbial growth - pH
A sterile pipette was used to add 0.1ml of E. coli culture to the pH 3.0 tube. This was then repeated for the tubes at pH 7.0 and pH 9.The tubes were then incubated at 37oC for 48 hours. This was then repeated for saline culture of Saccharomyces cerevisiae but incubated for 72 hours at 25oC.

Results

Six experiments were carried in this report concerning the effect that different environmental factors have on microbial growth. The results were recorded into tables where (+) symbolises growth and (–) symbolises no growth.
Experiment 1: Streak plate technique to

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