1.4.1 Discovery and abundance of homoacetogens
Homoacetogens are strict anaerobic bacteria that produce acetate from CO2 as a diagnostic end-product of metabolism (Drake 1994, Muller 2003). They can grow on different substrates such as hydrogen, hexoses, formate, carbon monoxide, methoxylated compounds, and alcohols. Depending on what energy sources they are growing with, products in addition to acetate can be formed, and some can produce butyrate from CO2 using the same basic pathway as used for acetate formation. They are known as “homoacetogens” (organisms generating only acetate), “reductive acetogens”, “CO2-reducing acetogens”, or simply as “acetogens”. These different terminologies are confusing, and misleading, since they do not only produce acetate, and acetogens could form acetate by any pathway. In this thesis, the term “homoacetogen” will be used, because it is a simple one word descriptor for this taxonomically-diverse group of bacteria unified by using the Wood-Ljundahl pathway to form acetate from CO2. The term “homoacetogenesis” will be used for this metabolism, and “homobutyrogenesis” for the process in which butyrate is formed from CO2.
In 1932,
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2008). The formation of butyrate using CO2 and H2 by homoacetogens is referred to as “homobutyrogenesis” (equation (3)). In addition to the use of eight H2 to generate two moles of acetate, and additional two moles of H2 are used to reduce two acetate to butyrate via acetoacetate, 3-hydroxybutyrate, and crotonate, all as CoA derivatives (Kerby et al. 1983). Members of genera Acetonema and Eubacterium are some of the known homoacetogens that produce butyrate as well as acetate from H2 and CO2 (Schiel-Bengelsdorf & Dürre
There are many differents ways to identify a bacterial unknown and many different situations where identification would be beneficial. One way to identify bacterial unknowns is to perform biochemical tests. In this experiment multiple biochemical tests were done, by performing these tests on the bacterial unknown received the two different bacteria were then identified. The citrate test is done to test the ability of organisms to use citrate as a carbon source. This test uses Simmons citrate agar, the agar contains sodium citrate as the only carbon source and has bromothymol blue as the pH indicator. The organisms that use citrate as a carbon source use the enzyme to transport the citrate into the cell. The cells converts ammonium dihydrogen
Acetobacter aceti is an aerobic (requiring oxygen) bacteria strain that produces acetic acid and gluconic acid. It is always found in kombucha. Acetobacter strains also build the SCOBY mushroom. Acetobacter xylinoides and acetobacter ketogenum are two strains that you might find in kombucha.
Respiration is a chemical process by which organic compounds release energy. There are two types of respiration reactions that cells use to provide themselves with energy: aerobic and anaerobic (fermentation). (Chemistry for Biologists: Respiration. 2015) Both processes are similar within the initial steps of the reaction- beginning with glycolysis. However, in fermentation instead of the pyruvic acid being converted to acetyl coenzyme A, it’s converted into both ethanol and carbon dioxide in yeast and some plants and lactic acid in animal cells. Another distinct difference between the two processes is that anaerobic respiration uses oxygen
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.
Yeast is a fungus that can generate glucose into energy without using any oxygen molecules. We tested the fermenting ability of yeast from two different carbon sources: glucose and aspartame. We hypothesized that yeast is unable to use the carbon sources of aspartame. To do this, we decided to use both carbon sources in the same concentration. Each carbon source was mixed with the same amount of yeast solution. The experiment group of 5.5 mM aspartame solution was compared with the control group of 5.5mM glucose solution. We recorded the rate of fermentation for glucose and aspartame in the Vernier Lab Quest. The fermentation rate of aspartame is a negative number, and glucose is a positive number. Our results show that yeast was unable to ferment aspartame as yeast fermented glucose. The results indicate that aspartame has no effect on yeast fermentation rate because yeast do not catabolize aspartame because it does not have the appropriate enzymes to break it down.
Cellular respiration is the series of metabolic process by which living cells produce energy through the oxidation of organic substances. Cellular respiration takes place in the mitochondria. Fermentation is the process by which complex organic compounds such as glucose, are broken down by the action of enzymes into simpler compounds without the use of oxygen. The significance of these pathways for organisms is to allow for an organism to be able to generate ATP. Some organism that undergo cellular respiration are bacteria and fungi. Some organism that undergo fermentation are yeast and muscle cells. In cellular respiration, glucose is oxidized and releases energy. In cellular respiration, glucose produces ATP and 3-carbon molecules of pyruvate. The pyruvate is then further broken down in the mitochondria where it becomes oxidized and releases CO2 (Upadhyaya 2014). In the fermentation process oxygen does not play a part. This process converts glucose into pyruvate and produces ATP. From there pyruvate breaks down into CO2 and acetaldehyde (Upadhyaya 2014) Monosaccharides are known as simple sugars and their main function is being the source of energy for organisms. Disaccharides are two monosaccharides joined by a covalent bond and their primary function is to provide food to monosaccharides. Some disaccharides
The citric acid cycle has been described as “the hub of the metabolic wheel”. Discuss the roles of the citric acid cycle in the oxidation of various fuel molecules and the provision of carbon skeletons for biosynthesis.
Bacteria groups or species can be differentiated by the fermentation patterns. The end-product of carbohydrate fermentation is an acid or acid with gas production and is dependent on the organism involved in the fermentation process. The carbohydrate fermentation tests detect if an organism is able to utilize glucose, lactose and sucrose. Phenol red is used as a pH indicator because it can indicate a change in pH when acid products are formed. Bacteria can utilize certain sugars resulting in an alkaline by-product which changes the color of the carbohydrate broth from red to yellow. Bubbles trapped within the Durham tube indicate the production of gas. The Phenol red carbohydrate fermentation tests determine that my organism E. coli can utilize glucose, lactose and sometimes sucrose but can only produce gas in glucose and lactose. (Phenol red carbohydrate fermentation lab
In this lab we tried to find what fuels yeast could metabolize and what the yields of the carbon dioxide gas that were produced from the different sugars used. We used 6 different yeast and sugar mixtures. The different yeast and sugar mixtures we used were control, glucose, sucrose, fructose, starch, and saccharin. The results for the 6 different results are presented in Tables 1-6 and Graph 1. Graph 1 is a graph of all the information in Tables 1-6. Each Table and graph is labeled approximately.
The medium contains sodium citrate that serves as sole carbon source and ammonium phosphate as the sole nitrogen source. These organisms produce the enzyme citrate-permease that can transport the citrate into the cell and produce pyruvate from it. Bromthymol blue dye is used as an indicator that is green at pH 6.9 and blue at pH 7.6 and above (Leboffe and Pierce). A positive result is obtained if the color is blue meaning that bacteria utilize the citrate and convert the ammonium phosphate into ammonia and ammonium hydroxide.
Purpose of Bergy’s Manual: based on ribosomal RNA sequences, which presumably reflect phylogenetic (evolutionary) relationships. Used for the identification of prokaryotes. 2nd edition on classification of prokaryotes.
Morganella morganii is a gram-negative bacillus with no special arrangement. It is the third member of the tribe Proteeae. This bacterium was first discovered in the year 1906 by a British bacteriologist by the name of He. De R. Morgan. In the late year of 1939, the bacterium was named Proteus morganii, and again changed some years later due to findings that this bacterium did not obtain the ability to ferment all carbohydrates like the genus Proteus was capable of doing. Instead, researchers found the bacterium to have the capabilities of ferment only glucose and therefore its name had been changed one final time to Morganella (its own genus) morganii. While testing M. morganii, findings show that it has its own special characteristics that differ from the usual Proteea. M. morganii does not swarm on a nutrient agar plate like the typical Proteus would. It also does not produce the black precipitate found in Hydrogen Sulfide gas tests. M. morganii produces phenylalanine deaminase, which is the enzyme that wipes out the amino group, resulting in a phenyl pyruvic acid. It is a facultative anaerobe meaning that it is capable of producing energy in the form of ATP by aerobic respiration if oxygen is present in its environment. If oxygen is not present in the environment, the bacteria is fully capable of producing energy in anaerobic environments as well. Morganella morganii can be found in the soil, water, and feces. The bacteria is a common resident to the
Prokaryotes are ubiquitous, successfully adapting to diverse environments as well as developing symbiotic relationships with host organisms (Lengeler, Drews, & Schlegel, 1999). Prokaryotes may have both autotrophic and heterotrophic characteristics. A cyanobacteria is photosynthetic, commonly called blue-green algae, and may produce toxins (Crayton, 1993). Bacteria are most commonly associated in the general
Sugars are vital to all living organisms. The eukaryotic fungi, yeast, have the ability to use some, but not all sugars as a food source by metabolizing sugar in two ways, aerobically, with the aid of oxygen, or anaerobically, without oxygen. The decomposition reaction that takes place when yeast breaks down the hydrocarbon molecules is called cell respiration. As the aerobic respiration breaks down glucose to form viable ATP, oxygen gas is consumed and carbon dioxide is produced. This lab focuses on studying the rate of cellular respiration of saccharomyces cerevisiae, baker’s yeast, in an aerobic environment with glucose, sucrose, lactose, artificial sweetener, and water as a negative control. A CO2
As the diagram on the right displays, one molecule of Glucose produces two molecules of carbon dioxide and two molecules of ethanol. The fermentation of glucose to ethanol is only possible if oxygen is absent otherwise instead of producing ethanol and carbon dioxide, lactic acid is produced instead.