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    Home > Biochemistry News > Microbiology News > IMVIC and hydrogen sulfide test

    IMVIC and hydrogen sulfide test

    • Last Update: 2021-01-24
    • Source: Internet
    • Author: User
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    IMVIC and hydrogen sulfide testFirst, the purpose requiresto understand the principle of IMVIC and hydrogen sulfide reaction and its significance in the identification of enterobacteria., basic principles IMVIC is the indol test, methyl red test, Voges-Prokauer test, V. P. test) and the abbreviation of the citrate test. These four trials are mainly used to identify E. coli and enterobacteria, and mainly for bacteriological examination of water, because E. coli is not pathogenic bacteria, but in drinking water if more than a certain number of E. coli means contaminated feces, and E. coli is widely found in nature, therefore, when examining water to distinguish between the two.sulfide test is also a bio-bio-chemical test to
    intestinal
    bacteria.test. Some bacteria contain tryptophan enzymes that break downin proteins to produce pyridine. When it is combined with metformin, a red rose pyridine is formed.trysine hydrolysis reaction:and reaction to metformin:to metformin formaldehydeE. coli positive, gas-producing E. coli negative.meth red test. Some bacteria in the process of sugar metabolism,
    culture
    -based sugar first broken down into acetone acid, acetone acid and then broken down into foric acid, acetic acid, lactic acid, etc. , so that
    -culture
    acid, with methyl red indicator (pH4. 2 (Red) -6. 3 (yellow) to change the culture from orange to red, i.e. methyl red positive. E. coli is positive and E. coli is negative.-Pu test. Some bacteria can use glucose to produce acetone acid, acetone acid for contraction, dehydration into acetyl methyl methanol, which can be oxidized into diacetyl by oxygen in the air under alkaline conditions. Diacetyl and the proteinin the arginine-based action, the production of red
    compound
    , that is, volt-pu-positive, no red compound produced is negative. The reaction process is as follows:positive for E. coli volt-pu, E. coli volt-pu reaction negative.the citric acid test. Some bacteria can use sodium citrate as a carbon source, such as E. coli, while others cannot use sodium citrate, such as E. coli. After the bacteria break down the citric acid and ammonium phosphate in the culture base, the bacteria produce alkaline compounds, which raise the pH of the culture base, which changes from green to dark blue with a blue indicator of 1% brominated vanilla. The indicative range of brominated vanilla phenol blue is: pH is less than 6. 0 is yellow and pH is 6. 0-7. 6 is green, pH is greater than 7. It's blue at 6 p.m. hydrogen sulfide test. Some bacteria can break down sulfur-containing
    organized
    , such as cysteine, cysteine, methionine, etc. to produce hydrogen sulfide, hydrogen sulfide in the culture base of lead salt or iron salt, etc. , to form a black lead sulfide or iron sulfide sediment, so as to determine the production of hydrogen sulfide. cysteine as an example, the chemical reaction process is as follows: CH2 SHCHNH2 COOH H2 O→ CH3 COCOOH H2 S H2 S Pb (CH3 COO) 2 →PbS 2CH3 COOH (black) E. coli is negative and E. coli is positive. III, equipment E. coli, E. coli production; protein water culture, glucose protein water culture, citric acid sloped culture, lead acetate culture, methyl red
    reagents
    ,40% KOH, 5% α-phenol, ethyl ether, pyridine, etc. , the operation step 1. Inoculation and culture (1) with vaccination needles to E. coli, E. coli-producing bacteria punctured into 2 lead acetate mediums, 37 degrees C greenhouse culture for 48 hours. (2) inoculated the above-mentioned bacteria in 2 proteins water mediums (to do the sterilization test) and cultured in a greenhouse at 37 degrees C for 2 days. (3) inoculated the above-mentioned bacteria in 2 glucose water mediums (do methyl red test and volt-pu test) and cultured in a greenhouse at 37 degrees C for 2 days. (4) inoculated the above two bacteria into 2 citric acid slope mediums. It is cultured in a greenhouse at 37 degrees C for 2 days. 2. Observations hydrogen sulfide production was observed after 48 hours of culture. (2) lye test in the culture 48 hours after the protein water culture plus 3-4 drops of ether, shake several times, sit for 1-3 minutes, waiting for ether to rise, along the pipe wall slowly added 2 drops of pyridine reagents, between ether and culture to produce a red ring positive reaction. (3) After 48 hours of methyl red test culture, the glucose protein water culture was divided into two small tubes (one tube was left for volt-pu test), in one tube added methyl red reagent 2 drops, the culture base turned red positive, yellowing negative. (4) Volt-P test in the above left a small
    test tube
    culture to add 40% KOH5-10 drops, and then add the same amount of 5% α-phenol solution, force oscillation, and then put in a 37 degrees C temperature tank insulation 15-30 minutes, to speed up the reaction speed. If the culture is red, it is vo-pu-positive. (5) the citric acid test cultured for 48 hours to see if the citric acid culture base has any bacterial growth and color change. Blue is positive and green is negative. , the experimental report 1. Results the results of the experiment are filled in the table below. ""indicates a positive reaction;" -" indicates a negative reaction. 2. Question : (1) What is
    the
    bio-chemical reaction of microorganisms? (2) what are the similarity and similarity between the initial and final products of the methyl red test and the Volt-P test? Why does the end product differ?
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