Positive starch hydrolysis test. Serratia marcescens & Bacillus cereus Report Essay Example for Free 2019-01-22
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Biochemical characters and antibiotic susceptibility of Staphylococcus aureus isolates
In the starch hydrolysis test, the test bacteria are grown on agar plates containing starch. Alpha-amylase 1,4 alpha D-Glucan-glucanohydrolase acts upon large polymers of starch at internal bonds and cleaves them to short glucose polymers. Other symptoms may include abdominal pain and headache. It also differentiates lactose-fermenting bacteria from non-lactose-fermenting bacteria. This process takes place in two sequential reactions.
This indicates the organism is a motile, anaerobe that ferments glucose with no gas. Multiple results, see results page. The absence of coagulation after 24 hours of incubation is a negative result, indicative of an avirulent strain. The enzyme amylase is an extra cellular enzyme produced by microorganism which hydrolyses the starch breaking α 1,4 glycosidic bond to produce dextrin, maltose and glucose molecules. This gave a profile of drug susceptibility vis-à-vis antibiotic resistance.
Push the leaf to the bot … tom of a test tube and cover it with alcohol ethanol. Certain bacteria use citrate as the sole carbon source. Its pH is determined using a pH paper or pH meter and adjusted to 7. This black line or tube indicates a positive H 2S reaction; absence of a black precipitate indicates a negative reaction. After going through some of the literatures, including the prescribed college book itself; I found the lines: 1. Specimen 1 initially appeared to be gram-positive diplococci.
There was heavy gray growth on this enriched medium. Simple staining is used to study the morphology of all microorganisms Fig 1. Bacterial alpha-amylase is particularly suited for industrial usage since it is inexpensive and isothermally stable. It is now thought that iodine-iodide mixture combines with the starch to form an infinite polyiodide homopolymer. The diameter of zone of bacterial growth inhibition surrounding the disc including the disc was measured and compared with the standard for each drug. Enriched media are media that have been supplemented with highly nutritious materials such as blood, serum or yeast extract for the purpose of cultivating fastidious organisms. The streak plate is a qualitative isolation method; quadrant streaking is mostly done to obtain pure colonies.
Clearing of the agar around the bacterial growth indicates casein hydrolysis. Incubate for 48 hours, observe results 3. It may be due to inactivation of the antibiotic as a result of structural modification by enzymatic action, prevention of access to target by altering the outer membrane permeability, alteration of the antibiotic target site, efflux pump which pumps out the antibiotic, and target enzyme bypass or over production. This indicates lysis of red blood cells occurred, which is beta-hemolysis. Due to the building of acid during fermentation, the pH falls. The starch agar plate was inoculated with isolates 1 and 2 using a sterile loop. If the organism can release gelatinase enzymes the gelatin is broken down or liquefied.
Biochemical Test and Identification of Staphylococcus aureus
Incubate at optimum temperature for at least 48 hours. Phenol Red Fermentation Broth Procedure: 1. Observations were made at 15 minutes. Hence the counter stain Safranin has no action on gram positive cells. The present study aimed to observe the biochemical characters of isolated S. The growth on this streak plate is bright red and white.
Several other tests were done, such as for detection of hemolysis and glucose fermentation. For example, if you have a piece of potato and you put a tiny bit of Iodine on the sample, if it goes orange, then you know that the potato has starch, however if it remains purple, then that means there is no starch in the sample. There being no growth and no change in appearance of the medium for either organism, this indicates there was no mannitol fermentation and they do not tolerate salt. Note the pink rods, indicating a Gram negative bacillus. To flip the current card, click it or press the Spacebar key. Failure of deep pink colour to develop is evidence of a negative reaction.
Sign up Already a StudyStack user? Then put in boiling water. Reddish pink or red colour of test tube was regared as positive. Introduction The purpose of this study is to differentiate and identify two unknown organisms provided by the instructor in a nutrient broth. The fact of the matter is that they absolutely can both be positive. Organisms which hydrolyze gelatin will cause the gelatin to liquefy. Then the tube was placed on ice for about 15 min or in the fridge for about 30 min, to determine liquefaction.
Serratia marcescens & Bacillus cereus Report Essay Example for Free
With the color contrast, the separation of organisms is certain and pure cultures can be grown. Epidemiology The patient presenting with vomiting likely has food poisoning due to the contamination of a starchy dish such as pasta salad or rice. If a blue-black color appears, it means starch is present. This step as well as the sterilization of the petri dishes at step 6 is omitted, if oven-sterilized petri dishes are used directly. The bacterial cells can then take up these amino acids and use them in their metabolic processes. Incubate for 48 hours, observe results then incubate for 5 more days and observe results again. A positive result is indicated by diffuse or cloudy growth mainly at the top and bottom of the stabbed region.
As expected, isolate 1 bubbled nicely, indicating the presence of catalase and allowing the conclusion that 1 is a facultative anaerobe instead of a strict anaerobe. Indole test: Indole tests looks for the presence or absence of tryptophanase enzyme production of the bacteria. Bad Bug Book: Foodborne Pathogenic Microorganisms. The plate with three inoculations showed similar results. Hence they are the main causative agents of intestinal infection. Dear Imaobong James Thank you so much for your comment.
