Control by UV and heat of microorganisms

Introduction


One of the most prevalent non-living entities on the planet is the microorganism. Microorganisms increase the danger of a variety of diseases infecting people and plant life. Microorganisms can be divided into three groups: bacteria, viruses, and fungi. Microorganisms are a frequent occurrence for people in their daily lives. Because most microbes are tiny (1 cell thick) and cannot be seen without a microscope, most humans come into contact with them without detecting them (microorganisms). Therefore, it's critical to restrict the growth of these creatures that endanger human life. Two distinct ways can help get the existence of microorganisms in check; these are by eliminating them physically, that is, killing the microorganisms or by use of chemicals (D’ans, Gottlieb & Kokotovic, 1972).

Controlling Microorganism Growth


This experiment is based on controlling the growth of bacteria by heat and UV. Heat and broth can be distinctively used to control bacterial growth in that the heat and UV interferes with the composition of control media that enhances the growth of a certain microorganism. UV is rays directly from the sun, while heat for this case is an artificial means which man has devised to increase the temperatures of the surrounding to control bacterial growth according to Kirchman, Rex, Malmstrom, and Matthew (2005). Heat can indicate a vast range in temperature ranging to high values more than a hundred degrees Celsius based on Thingstad and Lignell (1997). Heat can be generated in two forms, namely, dry and moist heat. Dry heat comes directly from the source of heat maybe fire, while moist heat entails use of steam or water baths. Extreme temperatures kill microorganisms thus making heat a viable means of sterilizing equipments.

Materials and Methods


This experiment was done in three parts whereby in the first part the effects of temperature on the growth of bacteria for both Serratia marcescens and Bacillus subtilis were determined. In the second part of the experiment UV rays were used on the growth of bacteria for Escherichia coli and Bacillus subtilis. The last part of the experiment entailed controlled growth of bacteria using heat for Bacillus subtilis and Escherichia coli. The experiments were carried out in different Soy broth tubes which were labeled using marker pens. The Soy broth tubes were divided into equal halves where the bacterium was placed. The first experiment was set at three different temperatures; one part was refrigerated at 4 degrees Celsius while the remaining two parts were incubated at 25 and 37 degrees Celsius respectively. The second experiment was done in line with controls for both Bacillus subtilis and E. Coli. The third experiment was done at three different temperatures (40, 55, and 50 degrees Celsius) and time schemes. The sources of heat for these experiments were water baths at indicated temperatures and Bunsen burner. Sterile swabs were used to avoid contamination of results.

Results


Setup for the first experiment was as follows:

S. marcescens/ B. subtilis refrigerated at 4 degrees Celsius

(ii) S. marcescens/ B. subtilis incubated at 25 degrees Celsius

S. marcescens/ B. subtilis incubated at 37 degrees Celsius

The second experiment was setup as follows

B. subtilis with the left side exposed to light and the right side is the control

E. Coli with the left side exposed to light and the right side is the control.

The results of the third experiment were negative for both time schemes, that is, 20 and 10 minutes for E. Coli at 55 degrees Celsius.

Conclusion


Lack of sensitivity can lead to a bacterial population being described as resistant because of continuous exposure to the same controlled growth conditions which makes the body mechanism of the bacteria develop a defensive mechanism against the stipulated controlled growth conditions. The main source of UV rays is the sun; the intensity of the rays can be reduced due to existence of the ozone layer leading to gross effects while carrying out preventive bacterial growth on various media. Heat requires more input on economical basis, therefore a viable source that is less costly is required and the source must be able to produce high temperatures to counter the growth of microorganisms. UV and heat prevent reproduction of microorganisms hence short living their existence in a certain locality. UV light from the sun and heat from source such as Bunsen burner inhibits the growth of endospores generated by Bacillus species.


References


D’ans, G., Gottlieb, D., & P. Kokotovic. (1972). Optimal control of bacterial growth. Automatica 8.6: 729-736.


Kirchman, David L., Rex R. Malmstrom, & Matthew T. Cottrell. (2005). Control of bacterial growth by temperature and organic matter in the Western Arctic. Deep Sea Research Part II: Topical Studies in Oceanography 52.24: 3386-3395.


Thingstad, T. F., & R. Lignell. (1997). Theoretical models for the control of bacterial growth rate, abundance, diversity and carbon demand. Aquatic Microbial Ecology 13.1: 19-27.

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