Instructions:

This document provides data corresponding to the Microbiology 3023L (section 911288) lab exercises in which we evaluated the effect of physical forces (i.e. Temperature, UV light, and pH), on bacterial growth. The graphs listed below are accompanied with questions for you to answer and submit by email (friveram@mdc.edu) to Prof. Rivera-Mariani no later than Friday March 8th by 11:59 pm. When submitting your answers, in the subject of the email, write Answers to Lab Report (Pipetting Techniques). In the body, for example, for question 1 letter a, write 1.a: and your answer . Write answers in complete sentences in order to be awarded full grade for your answers. The total points of this lab report is 10 points.

This document was created with the open-course statistical software R (https://www.r-project.org/). If you would like to take at code for this document, feel free to visit Prof. Rivera-Mariani’ online repository four our course at https://github.com/friveramariani/mcb3023L-2015-2.

## Warning: NAs introduced by coercion

## Warning: NAs introduced by coercion

## Warning: NAs introduced by coercion

Note: disregard the warning messages above as this report was created through a series of programming codes using the open-source statistical software R (https://www.r-project.org/).

The three histograms above represent the distributions of Growth observations reported by the students. Recall that we reported the Growth variable as follows: 0 = No Growth, 1 = Poor Growth, 2 = Medium Growth, 3 = Lots of Growth.

From the histograms above for each of the physical forces tested (i.e. Temperature, UV light, and pH),

  1. Which observation was recorded the most?
  2. Do all three histograms look similar? Why or why not?
  3. Do you notice any pattern when you examine the histograms individually?
  4. Do you notice any pattern when you examine the histograms as a group?

The three boxplots above report the students’ observations for each of the three physical forces: temperature, UV light, and pH. On the temperature (Figure A) boxplot, temperature was plotted against Growth; on the UV (Figure B), exposure (0 = UV exposure, 1 = UV exposure) was plotted against Growth; on the pH (Figure C), the different pH levels tested were plotted against Growth.

  1. When you look at each physical force individually, is there any noticeable pattern(s)?
  2. When you look at all of the boxplot graph as a group, what can you conclude?

In the two boxplots above, the Growth for the temperature and UV experiments, respectively, were plotted against exposure time.

  1. When you look at temperature and the UV boxplots individually, is there any noticeable pattern(s)?
  2. When you look at both boxplots as a group, what can you conclude?

In the three boxplots above, the growth variable was plotted for each of the bacterial for each of the three physical forces tested.

  1. Which bacteria was the least resistant to physical forces tested?
  2. Which bacteria was the most resistant to the physical forces tested?
  3. For the bacterial species you selected for question 1, based on your microbiological knowledge, which property(or properties) may be helping this bacterial species to be the most resistant to the physical forces tested?

Final Question:

If you were asked to provide an expert consultation on which physical force to use to effectively disinfect against the most resistant bacterial species (i.e. most resistant according to your answer above), which physical force would you recommend? (Support your answer)

## [1] "This document was created for the Microbiology Lab Course (MCB3023L, section 911288), taught at Miami Dade College, by prof. Rivera-Mariani on 2016-04-04 21:48:18"