Method of Staining Bacterial Cells - Essay Example

Microbiology Questions al Affiliation Microbiology Questions In 1835, Bassi showed that a fungus caused a silkworm disease, and in 1865 Pasteur discovered that a protozoan caused another silkworm disease. Why do we use Kochs postulates instead of Bassis or Pasteurs postulates? In 1835 Agostino Bassi discovered a causal relationship between a fungus and the silkworm disease. This was just a mere connection of the two variables he used. Explicitly, the 1935 research just proved the hypothesis that can be framed as, is there a connection between fungus and silkworm (Tortora 40). However, the results were not particular even though his study gave a preliminary foundation for the germ theory. Additionally, in 1965, Louis Pasteur discovered that silkworm was caused by a protozoan and this added more information on the prior discovery of the 1935. However, there were still limitations as the results were general instead of being particular. Koch’s discovery was so particular in his results that a particular disease is caused by a particular organism. Truly, Koch did not only isolate the causal pathogen, but he also correlated a specific pathogen to a specific disease. Again Koch provided experimental steps and guideline to prove that a bacterium caused anthrax by using a specimen of purified culture of anthrax isolated from dead animals. In the modern era, Koch’s postulates have been used to assert the causation of infectious diseases through pathogenic microorganism culture and with the aid of electronic microscopes. He was awarded a Nobel Peace prize in 1905 for his work on microbiology. 2. In 1884, Hans Christian Gram described a method of staining bacterial cells while not staining surrounding animal tissues; however, he thought the staining method he developed was faulty because not all bacteria stained. In a letter to the editor of the journal in which Gram published his findings, write your response to Grams concern. His discovery was not a faulty one in any way, it just had some limitations. To prove the reality, the stain work in some of the bacteria specimen he used. However, the failure in the other cases opened a new research question, why not in all bacteria? It has been discovered in modern science that there are almost countless bacteria, each possess a different characteristics. Some bacteria secret a chemical substance the reacts with Hans’s stained to blur vision. Now it has been discovered that the chemical mycolic acid. Mycolic acids produced by the bacteria interfere with the dye, deterring the dye to stain. The acid is a species of bacteria known as mycolata. It gives the species a gross morphological trait referred to as “cording” for example members of genus Rhodococcus. The members need sophisticated methods to stain, which had not been discovered by Hans Christian. 3. You look in the refrigerator and find an orange drink you had forgotten was there. The drink now has an off taste and it bubbles. What is the most likely explanation for the changes in the drink? Refrigerators are conditioned to prevent food spoilage which is caused by bacteria and other microorganisms. Therefore, very cold temperatures and conditions of no oxygen do not allow bacteria to survive. However, when orange juice is stored for a long time, flavor is reduced with time. First, the minerals and ingredients used to flavor orange juice breaks down with time and the process is accelerated in cold temperatures. Furthermore, the loss of taste is rapid when there is no oxygen. During manufacturing process, microorganism enzymes are used to create the sweet taste of orange juice the drink is pasteurized to make the microorganism harmless when consumed. Additionally the enzymes maintain the flavor, however, at cold temperatures the enzymes are denatured and die hence the taste is lost. Bubbles then evolve as the microorganisms precipitate out. The orange flavor is made up of 0.02% of the total weight: 1% esters, 1% ketones, 0.6-0.7% aldehydes, 1-5% alcohols, and 75-98%hydrocarbons for conventionally pasteurized orange juice. These compounds are only active to form a complex flavor chain at relatively warm conditions. However cold conditions affect their chemistry and they precipitate out, which cause bubbles to evolve. The bubbles can also be produced due to increase in the total soluble solids (TSS), which increase when orange juice is stored for a long time. 4. Identify the catabolic pathways used by the following bacteria: i) Pseudomonas Oxidizes glucose These pathways are used in genomic or flux analysis which occurs via simultaneous operation, which follow three pathways converging at a level of 6-photogulutanate. The metabolism is done by Eda and Edd Entner enzymes into central metabolites. Glucose enters a periplasmic space via specific OprB porins, and then either become internalized in the cytoplasm or oxidized to glutamate. Glucose is transported to the cytoplasm through mediation by an uptake system called ABC, which is encoded by reading frames PP1015 to PP1018. It is then phosphorylated using glucokinase and changed by glucose-6-phosphate dehydrogenase to 6-phosphogluconate. Periplsmic glutamate I s transported to the cytoplasm and phosphorilated using gluconokinase into 6-phosphogluconate. Alternatively it can be oxidized to 2-ketogluconate, transported and phosphorilated in the cytoplasm and reduced 6-phosphogluconate. ii) Lactobacillus Ferments glucose The ethanolic fermentation by yeast can be altered due a number of changes done in a culture medium. The presence of sodium sulfite makes acetaldehyde to be trapped as bisulfite addition complex, therefore, glycerol is the major product formed. Glucose + HSO3-→Glycerol + acetaldehyde-HSO3- + CO2 Under the conditions, acetaldehyde cannot serve as hydrogen acceptor. Dihydroxyacetone phosphate therefore is the preferred hydrogen acceptor, producing Glycerol-3-phosphate then hydrolyzed to form glycerol and Pi. The fermentation Isn’t shifted wholly in the direction of glycerol formation because there is no possibility of adding sufficient bisulfite for binding of the acetaldehyde without additional toxic effects. Thus, some ethanol will be found among the products. Under alkaline conditions, another pattern of fermentation pattern is observed 2glucose→2glycerol+acetate+ethanol+2CO2 Again, under the conditions, dismutation reaction takes place where 1 mol of acetaldehyde becomes oxidized into acetate and another one is reduced to form ethanol. The sequence is catalyzed using 2 NAD-linked dehydrogenases, which requires a balance on the following reactions: CH3CHO+NAD++H2O→CH3COOH+NADH+H+ CH3 CHO+NADH+H+→CH3CH2OH+NAD+ GA-3-P+Pi+NAD+→1,3-diphosphoglycerate+NADH+H+ Dihydroxyacetone-P+NADH+H+→glycerol-3-P+NAD+ Series of reactions are sometimes called the glycerol-3-phosphate shuttle. Oxidation of acetaldehyde to acetate yields does not produce ATP, because the reaction proceeds directly with no intermediary production of acetyl-CoA iii) Alcaligenes Neither oxidizes nor ferments glucose Nonfermenters Oxidative Gram-Negative Bacilli, which also include Pseudomonas spp., release acid from glucose and carbohydrates only when oxygen is present (nonfermenters). It is wort noting that, Enterobacteriaceae , Vibrio andAeromonas are fermentative which utilize carbohydrates when oxygen is absent. Again, Pseudomonas aeruginosa oxidizes but it does not do glucose fermentation. However, Alcaligenes faecalis does not ferments or oxidizes glucose. iv)Escherichia Oxidizes and ferments glucose. Glycerol and glucose is fermented in redox routes by which are regulated by oxidizing and reducing reagents at different pHs. Cell growth is followed by reduction of pH together with redox potential (E h. Glycerol utilization at pH 7.5 ∆pH, the difference between initial and end pH, was lower compared with glucose fermentation. In case of glycerol H2 is evolved at a middle log phase while during glucose fermentation H2 was produced at an early log phase. In glycerol utilization, oxidizer called potassium ferricyanide (1 mM) inhibits cell growth and H2 formation. Reducing reagents called dl-dithiothreitol (3 mM) and dithionite (1 mM) inhibit growth but stimulate H2 production. Therefore Escherichia Creates the reductive conditions for H2 production and glycerol fermentation. 5. Rhodopseudomonas is an anaerobic photoautotroph that uses organic compounds as an electron donor. It is also capable of chemo heterotrophic metabolism. Diagram the metabolic pathways of this bacterium. R. palustris can to switch between different modes of metabolism which support life: photoautotrophic, and photoheterotrophic, but also chemoautotroph and chemoheterotrophic. Therefoe, the bacterium can grow in the presence or abscene of oxygen. It uses inorganic or organic compounds to produce. Also, it acquires carbon from carbon dioxide fixation or sometimes from compounds of green plant. Furthermore it fixes nitrogen, hence used in many biotechnological applications. Fig: Diagram the metabolic pathways of Rhodopseudomonas References Tortora, G. J., Funke, B. R., & Case, C. L. (2012). Microbiology: An introduction. San Francisco, Calif: Benjamin Cummings. Read More