Introduction
Bacteria can be differentiated with specific metabolic activities. There are a variety of reagents and methods that can be used to distinguish species. The purpose of this experiment was to determine the characteristics of four different bacteria through four unique tests. The bacteria tested include: Escherichia coli (Ec), Pseudomonas aeruginosa (Pa), Bacillus subtilis (Bs) and Proteus vulgaris (Pv). Four types of tests were performed to understand the metabolic activities of the four bacteria.
The first test executed was the fermentation of carbohydrates. The objective of this particular test is to identify the ability of microorganisms to ferment a specific carbohydrate (Reiner, 2012). The test can be used to identify three different ways in which bacteria can ferment simple carbohydrates. Bacteria can be tested for acidity, alkalinity, whether or not it remains neutral and gas formation (Reiner, 2012). To conduct the carbohydrate fermentation test, a pH indicator, bromocresol purple, is used to indicate an acidic characteristic (Reiner, 2012). Bromocrescol purple indicates carbohydrate fermentation media by turning a deep purple if it’s an uninoculated media, yellow if it’s acidic and purple if it’s alkaline (Reiner, 2012). Durham tubes are placed inside the tubes containing the media and bacteria to detect gas production (Reiner, 2012). Three different carbohydrates were tested for fermentation during this test: glucose, sucrose and lactose for each of the
The following tests according to the lab manual were performed: gram stain, fermentation tubes, methyl red, vogues proskauer, sulfur, indole, motility and growing it up on MacConkey agar. The gram stain was performed incorrectly the first time. This is because the decolorizer was not on the bacterium slide for long enough, giving a false outcome.
This laboratory experiment’s objective was to take a pure culture and isolate it from a mixed culture. The other part of the objective was to ascertain what species of bacteria that the pure culture was. The hypothesis made stated that so long as lab protocol was followed, the unidentified culture would be positively recognized/identified. An isolated pure colony of the unknown culture was obtained using the quadrant streak plate method. Afterward, the culture was Gram stained, and the results showed that it was Gram positive. Motility tests were done on the unknown using a filter paper bridge on a petri dish that contained TTC with agar. The unknown was revealed to not be motile, which meant that it did not possess flagella. The last test done was to learn the metabolic capabilities of the unknown bacteria. There were tests done for citrate utilization, the mixed fermentation pathway, catalase presence, carbohydrate fermentation in mannitol, lactose and glucose, urease production and the butanediol fermentation pathway in order to better identify the unknown bacteria. The results from each of the metabolic tests in conjunction with the motility and Gram staining tests were ultimately compared to results from database containing many different kinds of results from various bacteria. The unknown from the mixed culture was identified as Staphylococcus
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
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
Often scientists work with bacteria that do not come in a labeled test tube— for example, bacterial samples taken from infected human tissue or from the soil—and the scientist must then identify the unknown microorganism in order to understand what behavior to expect from the organism, for example, a certain type of infection or antibiotic resistance. However, because of the relatively few forms of bacteria compared to animals and because of the lack of bacterial fossil records due to their asexually reproductive nature, the taxonomy used to classify animals cannot be applied to bacteria (Brown 275). In order to classify unknown bacteria, a variety of physiological and metabolic tests are available to narrow a sample down from the fathomless number of possibilities into a more manageable range. Once these tests have been performed, the researcher can consult Bergey’s Manual of Determinative Bacteriology, a systematically arranged and continually updated collection of all known bacteria based on their structure, metabolism, and other attributes.
The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible
The purpose of the following study is to determine where the two unknown bacteria acquired in Microbiology lab should be classified in regards to temperature, pH level, and osmoregularity. It is important to classify bacteria in order to identify them. Identification of bacteria is important because they are not only useful but potentially dangerous as well. The identification of bacteria can lead to breakthroughs in healthcare regarding treatment of old and new diseases alike. Identifying bacteria can also be used in many other areas from better crop production through microbial pesticides to biological warfare. Their uses are endless as are their abilities to evolve and adapt to changing environments. That is why it is so important
The main idea of this experiment was to correctly identify the unknown bacteria, #3. Identification of unknown bacteria yields multiple benefits in many different areas in the research of microorganisms. In this experiment I performed many different test dealing with things such as the presence of enzymes, fermentation abilities and different chemical reactions. Observations made from the tests were then compared to a gram negative unknown chart in order to identify the bacteria. Based off of my results and the chart, I concluded the bacteria #3 was the bacteria Escherichia coli. E. coli is most commonly found in the intestines of warm blooded organisms. Most E. coli strands are non pathogenic however, there are strands
For this experiment we will be testing four different bacteria with four different tests, using glucose, lactose, and sucrose. Hopefully we will use the information from those test to be able to identify the organisms in each of the samples from the case studies. We will use the results from the four different tests along with the information of how different bacteria react to match up to the case scenario and identify the bacteria, then check to see if our guess was correct. The findings are that we were able to identify, by process of elimination, the four different test bacteria.
The oxidation fermentation test was used to differentiate if the organism utilizes lactose, mannitol, glucose and citrate aerobically (oxidation) or anaerobically (fermentation). A methyl red test was performed to determine if the organism carried out mixed-acid fermentation when supplied glucose. A Voges-Proskauer test was performed to evaluate if the unknown was able to ferment glucose into butanediol. A citrate test was performed to determine if the unknown organism was able to break down citrate into ammonia. An oxidase test was then performed to determine if the unknown culture was oxidase positive or negate.
The purpose of this project was to identify the identities of two unknown bacteria in a mixed broth culture by using several separation methods. To separate the organisms, a four-way streak plate technique was used to isolate the two unknown bacteria into separate visible colonies. Then after each colony were clearly isolated; the two unknowns were processed through Gram staining test to determine the Gram stain and morphology. After Gram staining, a carbohydrate test was performed on each unknown to determine if it had glucose, sucrose, or lactose fermentation. The results of the sugar test help determining which biochemical test should be performed next. The Gram positive organism was tested through a carbohydrate fermentation test, then further tested to confirm its identity through an indole and catalase test. The Gram negative organism was tested through carbohydrate fermentation test, then further tested to confirmed its identity through an indole, and TSIA test. After running four biochemical tests, the results conclude that the Gram positive unknown was Staphylococcus aureus. S. aureus was identified based on the fermentation results of the glucose test, negative indole test, and a positive catalase production. S. aureus is a Gram positive circular shaped bacterium that is very common in the U.S and is normally found in the nose, respiratory tract, and on the skin. This bacterium is usually the most common cause of infections after injury or surgery.
Microorganisms need energy and that is generated through these metabolic activities (Jurtshuk, 1996). Through this experiment, it is shows that all the bacteria experienced different metabolic activities in different mediums.
Introduction: A frequent matter in the science, medical and pharmaceutical world is identifying unknown bacteria. Throughout the past months of this class we have learned lab technique and how to do a variety of different tests on bacteria. Microbiology is not only an academic understanding of microorganisms but learning how to practically use lab procedures to properly identify and test organisms. There are several reasons one might need to identify a bacteria. It could be to find out the causative agent in a patients disease or to figure out the antibiotics that need to be administered.
The energy sources an organism’s uses can also be determined to classify the metabolism of the unknown organism. For instance, the ability to use citrate as the sole carbon source can be assessed by growing cells in a medium with citrate as the only carbon source and a pH indicator that which changed color when the pH increases as a result of citrate metabolism (7). Similarly, the indicator methyl red can be added to a medium containing the unknown sample and various carbon sources. If the sample uses mixed acid fermentation, generating cellular energy by using more than one carbon source, then the drop in pH due to the accumulation of various acidic products will cause the indicator to turn red (7). Another such example is the use of a pH
In this bacteria growth lab, students from Mrs. Bronson’s biology class collected bacteria samples from around the school and grew them in petri dishes filled with agar which were prepared one day before in advance with the expectation that after one week, distinct bacterial colonies will grow larger in numbers so that the human can see them. These single-celled prokaryotes were grown on agar as it is easy to culture and grow bacterial colonies in nutrient agar, a gelatin-like substance with a semi solid surface on which bacteria can grow and reproduce quickly while consuming added nutrients in the agar mixture. The petri dishes were then incubated for a period of one week, so that students can examine the significant bacterial growth and compare observations of various samples collected by students.