Microbiology: Environmental Circumstances Essay

Question:

Discuss about the Microbiology for Environmental Circumstances.

Answer:

Introduction

Microorganism are present everywhere they are said to be ubiquitous in this world. It is possible for them to survive and grow in a wide range of environmental circumstances. If the environmental condition is unfavourable then these microorganism form spores and thus survives in such unfavourable condition (Gaballa et al., 2014). Bleach or sodium hypochlorite is an agent which is responsible for the destruction or killing of these spores. Therefore bleach is consider as a disinfectant which possess the ability to kill the vegetative cell as well as can destroy the spores of microorganism (Thorn et al., 2013).

Name of the chemical

classification

Spectrum of activity

(Gram +, - or broad)

Mechanism of action

Domestic bleach or Sodium hypochlorite

Disinfectant

Active against all gram positive and gram negative bacteria (Mouloud et al., 2013).

Sodium hypochlorite destroys the coat of the spore of the bacteria and thus makes it vulnerable to the unfavourable condition of the environment which subsequently results in the death of the organism.

Mode of Action

Bleach or Sodium hypochlorite does not kill the bacteria by damaging the DNA of the bacteria rather it destroys the coat of the bacterial spore (Seier-Petersen et al., 2014). The major factor which is responsible for making the spores resistant to the antimicrobial agents is the spore coat. The killing of the spore of the bacteria by Sodium hypochlorite or bleach mainly makes the spores unable and defective for germination, because of the severe damaged is caused to spore’s inner membrane (Subha et al., 2013). This chemical is more active against young cell than the older cells. The reason behind this that the metabolic rate of the younger cells is very high in comparison to the older cells as a result of that the young cell have thin cell membrane and the old culture cells have a thick cell membrane and so the young cell appears to be more vulnerable to Sodium hypochlorite. The damaged can be caused to a thin layer very easily in comparison to a thick layer. But this chemical has some limitation this includes it can only be used or applied to non-living things only (Setlow et al., 2013).

Materials Required

  1. Two Nutrient Agar plates.
  2. 20% bleach solution.
  3. Cotton swab.
  4. Bacillus subtilis
  5. BOD incubator.
  6. Laminar air flow.

Methods and Procedure

  1. At first the culture of the Bacillus subtilis was collected in a cotton swab from broth culture tubes.
  2. The entire surface of the two agar plates is to be streaked with the cotton swabs at least three times and rotating the plates between each of them. ( In this respect it should be noted that the surfaces of the nutrient agar plates should be completely inoculated).
  3. One bleach soaked discs should be placed on each swabbed plate aseptically.
  4. The discs are removed after 10 minutes from the 10 minutes labelled plate and after 30 minutes from the 30 minutes labelled plate.
  5. As soon as the disc are removed the lid are to be placed again on the plates and the plate’s edge are to be sealed with parafilm.
  6. Then the plates are to be incubated at 37degreecentigrade for 48 hours.

Results

Zone of inhibition was observed in both the cases but the zone of inhibition of the plate where the bleach solution disc was place for 30 minutes was larger than the zone of inhibition in the plate where bleach solution disc was kept for 10 minutes.

Table 2 Result of the bleach over bacterial culture

Bacteria

E. coli

B. subtilis

Time of Bleach (Min)

10

30

10

30

Concentration of the Bleach (%)

10

+++

+++

+++

+++

20

-

-

-

-

25

-

-

-

-

35

-

-

-

-

45

-

-

-

-

Discussion

Zone of inhibition was present in both the cases of bleach for 10 minutes and 30 minutes. However, the zone of inhibition is larger in the case of the plate where the bleach disc is kept for 30 minutes in comparison to the zone of inhibition of the plate where the bleach disc is kept for 10 minutes. The reason behind this is that bleach solution when kept for more time it will also diffuse radially throughout a larger zone of the plate than the plate where less time is given. As the inoculating organism was taken from the same mother source therefore the reason behind the difference in the zone of inhibition is time given for the bleach solution to diffuse. As the bleach solution was of same concentration its diffusion rate will also be same.

Conclusion

As the bleach solution is of same percentage in both the cases that is 20% of bleach solution and the inoculant culture was taken from the same mother culture of Bacillus subtilis culture. Therefore it can concluded that the reason behind the difference in the size of the zone of inhibition is the time of application given of the bleach solution to diffuse. The bleach solution which was allowed to diffuse for 30 minutes will diffuse to more extent than the bleach solution that is allowed to diffuse only for 10 minutes.

Reference

Gaballa, A., Chi, B. K., Roberts, A. A., Becher, D., Hamilton, C. J., Antelmann, H., & Helmann, J. D. (2014). Redox regulation in Bacillus subtilis: the bacilliredoxins BrxA (YphP) and BrxB (YqiW) function in de-bacillithiolation of S-bacillithiolated OhrR and MetE. Antioxidants & redox signaling, 21(3), 357-367.

Mouloud, G., Daoud, H., Bassem, J., Atef, I. L., & Hani, B. (2013). New bacteriocin from Bacillus clausii strainGM17: purification, characterization, and biological activity. Applied biochemistry and biotechnology, 171(8), 2186-2200.

Seier-Petersen, M. A., Jasni, A., Aarestrup, F. M., Vigre, H., Mullany, P., Roberts, A. P., & Agers?, Y. (2014). Effect of subinhibitory concentrations of four commonly used biocides on the conjugative transfer of Tn916 in Bacillus subtilis. Journal of Antimicrobial Chemotherapy, 69(2), 343-348.

Setlow, B., Yu, J., Li, Y. Q., & Setlow, P. (2013). Analysis of the germination kinetics of individual Bacillus subtilis spores treated with hydrogen peroxide or sodium hypochlorite. Letters in applied microbiology, 57(4), 259-265.

Subha, N., Prabhakar, V., Koshy, M., Abinaya, K., Prabu, M., & Thangavelu, L. (2013). Efficacy of peracetic acid in rapid disinfection of Resilon and gutta-percha cones compared with sodium hypochlorite, chlorhexidine, and povidone-iodine. Journal of endodontics, 39(10), 1261-1264.

Thorn, R. M. S., Robinson, G. M., & Reynolds, D. M. (2013). Comparative antimicrobial activities of aerosolized sodium hypochlorite, chlorine dioxide, and electrochemically activated solutions evaluated using a novel standardized assay. Antimicrobial agents and chemotherapy, 57(5), 2216-2225.

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