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

The colonies were smooth, translucent, and had a white brownish color. The Gram stain resulted in Gram positive cocci. After the Gram stain was completed, the bacteria were streaked on a Mannitol-Salt Agar plate and a Catalase test was performed. After these test were completed a Phenol Red Dextrose Fermentation tube was inoculated, and a SIM Tube inoculated.

PH can affect the way fermentation occurs due to the irregularity of the acidity or alkalinity within the glucose solution. This is an enzyme-based reaction that is susceptible to pH. The aim of this experiment was to determine how pH affects the yeast fermentation rate by performing the experiment numerous times with a different pH of glucose solution which included pH 3, 5, 7, 9, 11. The hypothesis was ‘If the pH is lower than the neutral point then the fermentation reaction will occur faster?’ The experiment conducted was to measure the amount of C02 produced by the yeast going into fermentation, however varying the pH of glucose solution by using different pHs . To test this every 5 minutes the volume of gas in the test tube was observed and recorded until a period of 30 minutes had been. The end results

In the S. cerevisiae specimen, moderate growth was expected and observed based on the knowledge that most microbes desire this type of environment for growth. The same was expected although a larger amount of growth was observed for the S. epidermidis specimens in the 1% NaCl solution than expected. The 1% NaCl solution provided the best environment for the growth of both microbes. Minimal growth of S. cerevisiae and moderate growth of S. epidermidis was observed from the 7% NaCl solutions. The S. epidermidis is used to a slightly salty environment on the surface of skin which may account for the higher growth over S. cerevisiae in this environment. Lastly, no growth was noted in either specimen of 15% NaCl. This type of environment does not support the growth of most microbes due to the increase in salt content and the hypertonic environment it creates.

The first result of importance was the result of the Gram stain. The observations of the unknown bacteria from the slant culture after Gram staining showed that the unknown bacteria were Gram negative bacilli (Image 1). After determining the unknown bacteria was Gram negative, an oxidase test was conducted on a sample from the slant culture. The cotton swap with the sample of bacteria did not change color when the oxidase reagent was applied, thus providing a negative result. With a negative oxidase test, further tests were conducted to determine various characteristics of the unknown bacteria. A MR-VP broth was inoculated with a sample from a slant culture of unknown bacteria. After incubation, the methyl red reagent was added to the broth, and the broth turned red, providing a positive result (Image 2). An EMB agar streak plate was inoculated with a sample from a slant culture of the unknown bacteria, and after incubation, growth was found on the plate, providing a positive result (Image 3). A Citrate agar slant was inoculated, and after incubation, growth was found on the media, providing a positive result (Image 4). A Urea agar slant was inoculated, and after incubation, the agar had changed from a peach color to a bright pink color, providing a positive result (Image 5). Using the flowchart (Figure 1) developed from the Table of Expected Results, the lab partners started at the oxidase test. Given the negative result of the oxidase test, the flowchart is

The conditions needed for the growth of micro-organisms are: Micro - organisms need food to survive. They like high protein food to survive, eg. Poultry & fish. Most micro - organisms need warmth & grow best at 20-40c. They need moisture to multiply. They need air to multiply, though some can without. A single Micro-organism becomes two every twenty minutes.

(Biology Dept.). 0.1 ml of E.coli K or 0.1ml of E.coli B was added to the 10 fold dilution. Using soft agar technique, the growth media mixture with E.coli was plated and incubated.

In this lab, the organism that we have been working with is the bacterium, Serratia marcescens. S. marcescens is a member of the Enterobacteriaceae family, and tends to grow in damp environments. S. marcescens is an ideal bacterium to work with in the lab because it reproduces quicker than other bacterium. This bacterium produces a special pigment called prodigiosin, which is red in color. The prodigiosin pigment is intensified when S. marcescens is grown at higher densities. During our experiment, temperature, pH, salinity concentration and oxygen requirements were tested on S. marcescens to measure their optimal growth and prodigiosin production.

Background information: In this lab you will be looking at the growth of bacteria under different conditions to see the how populations of bacteria grow. Read about cells in the text or e-text. For everyone, in your e-text read chapter 13, sections 13.3 and 13.4 to learn more about bacteria. Then answer the questions below.

It is the y value posted in the upper right hand corner. The following data was obtained from the “Closed-System Growth” experiment:

When reflecting back to experiment 3, Aseptic Technique and Culturing Microbes, I realized the large amount of microorganisms that can be found in everyday life. Many different types are found with in the human body. Theses experiments focused on two types of bacteria. First was Staphylococcus epidermidis, found on the skin, and second was Lactobacillus acidophilus, found in the gastrointestinal tract. Both have similar needs for growth when it comes to temperature, however, different growth environments are used.

Fungi were collected from the air and selected for using different media types in order to demonstrate the principle of selection. This was done using two different types of media with differing pH levels. The Mycophil plate had a pH of 5 and selected for fungal growth while the Tryptic Soy Agar plate, with a pH of 7, served as a general growth medium. The plates were exposed for 5 minutes outside of the Food Science Building at Rutgers University. High fungal percentages were found on the Mycophil plates, and low fungal percentages with more bacteria present were found on the Tryptic Soy Agar plates after incubation at room temperature. This proved that fungal growth favors a more acidic pH, while bacterial growth favors a neutral pH.

A few different factors that affect bacterial growth are the availability of resources and nutrients, temperature and pH. (Act For Libraries) stated in the above paragraph, once the resources and nutrients are

Another purpose of this experiment is to stress the importance of knowing the identity of a microorganism. Knowing the species of microorganism present in a sample provides a

The purpose of the two experiments was to determine the fundamental effects that temperature has on the growth and survival of bacteria. During the first experiment five different bacterial broth cultures of Escherichia coli, Pseudomonas fluorescens, Enterococcus faecalis, Bacillus subtilis and Bacillus stearothermophilus were individually incubated at temperatures of 5, 25, 37, 45 and 55°C for one week in an aim to distinguish the effect temperature has on growth and survival of the five different species. After one week they were observed for distinguishable changes by the turbidity showing an indication of bacterial growth, or the clarity an indication of no survival.

This experiment was performed to test the hypothesis if LB nutrient broth, +pGLO and -pGLO Ampicillin, and Arabinose was placed in the E. coli plates, then there will be a significant growth in the newly transformed bacteria and it will possess the ability to glow under UV light. The measurements were recorded from the bent glass tube in each glass test tube. The transformation protocol tested for the newly possessed traits in E.coli bacteria. Throughout the experiment there were many probable reasons for failure. If the pipettes and sterile loop were not thrown out in between each use, a cross contamination could cause a miscalculation in the experiment causing the data results to fail. The hypothesis that was tested was validated due to the positive results with each experiment stating that newly transformed organisms due in fact pass on traits.