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    Home > Biochemistry News > Microbiology News > Have you seen these biochemical reactions in the microbiological identification?

    Have you seen these biochemical reactions in the microbiological identification?

    • Last Update: 2020-06-20
    • Source: Internet
    • Author: User
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    Some microbial bacteria have the ability to synthesize amylase and can secrete extracellular amylaseAmylase can make starch hydrolysis for maltose and glucose, starch hydrolysis after iodine no longer becomebluethe fat enzymes produced by bacteria that break down the fat in the medium to produce glycerin and fatty acidsFatty acids can reduce the medium pH and can be tested by adding neutral red sinnuse to the grease mediumThe neutral red indication range is pH6.8 (red) to 8.0 (yellow)When bacteria break down fat to produce fatty acids, red spots appear in the media around the colonysome bacteria secrete proteases to break down gelatin, producing small moleculesIf the bacteria have the ability to break down gelatin, the medium can be turned into a liquid state from the original solid statemilk mainly contains lactose, casein and other ingredientsThe use of milk by bacteria mainly refers to the decomposition and utilization of lactose and caseinIn cow's milk, stinx is often added as an acid-base indicator and a redox indicatorWhen neutral, is lilac, red when acidic, blue when alkaline, and partially or completely decolorized when restoredThe use of bacteria on cow's milk can be divided into three kinds of conditions:(1) acid coagulation effect: bacteria fermented lactose, produce a lot of acid, so that the oxave milk red, when the acidity is very high, can make cow's milk solidified, this is called acid coagulation(2) coagulase coagulation: Some bacteria can secrete lactase, which solidifies casein in cow's milk, which occurs in a neutral environmentUsually the bacteria also have the ability to hydrolyze proteins, thus producing alkaline substances such as ammonia, which turns the stone molygmtonasis blue(3) hypsotic: casein is hydrolysated to turn cow's milk into a clear, transparent liquid The anticitise can be performed under acidic or alkaline conditions, and the general stone pigment is reduced and faded experimental materials 1, living materials: E coli, Bacillus subtilis, Staphylococcus aureus, enterosphere sein( Enterocoster aero, alcaligenium (Alcaligenes viscolactis), copper cytoma (Psumonas) 2, medium: starch medium: beef paste protein medium plus 0.2% soluble starch; grease medium: beef paste protein medium with peanut oil 10mL, 0.6% neutral red water solution 1mL; gelatin liquidization medium: protein 5g, gelatin 150g, water 10000mL, pH7.2 to 7.4, 115 degrees C sterilization 20min Stone cow milk medium: milk powder 100g, stone 0.075g, water 1000 mL, pH6.8, 121 oC sterilization 15 min 3, Reagent: Lugo iodine fluid experimental supplies flat dishes, vaccination rings, alcohol lamps, test tubes, vaccination needles, etc experimental method (i) starch hydrolysis test 1, prepare starch medium plate: the melted cooling to about 50 degrees C of starch medium poured into a sterile flat dish, to be solidified to make a flat plate 2, inoculation: with a marker pen at the bottom of the plate divided into two parts, in each part of the name of the bacteria, with the vaccination ring to take a small number of bacteria to be tested, dot in the center of the corresponding part of the surface of the medium, one of the bacteria should be bacillus as a control bacteria 3, culture: the inoculated flat dish in a 28-degree c constant temperature box culture 24h 4, detection: take out the plate, open the flat dish cover, drop a small amount of iodine on the plate, gently rotate, so that the iodine liquid is evenly spread throughout the plate If a colorless transparent ring appears around the colony, the starch has been hydrolyzed, indicating that the bacteria has the ability to break down the starch The strength of the hydrolysis ability of the test strain can be used to illustrate the size of the transparent ring (ii) grease hydrolysis test 1, the triangular bottle filled with grease medium in a boiling water bath to melt, remove and fully oscillate, so that the grease is evenly distributed, and then poured into a sterile flat dish, to be solidified into a flat 2, inoculation: on both sides of the same flat dish, one of which is Staphylococcus aureus as a control bacteria Placed in a 37-degree c constant temperature tank culture 24h, after removal to observe the color of flat-bed moss, if there is a red spot, that means that the fat is hydrolysised, this reaction is positive reaction The size of the red spots indicates the strength of the ability to test the hydrolysis fat of the strain (iii) gelatin liquefaction test 1, vaccination: with puncture vaccination method to inoculate E coli or gas-producing E coli in gelatin medium 2, culture: put 20 degrees C thermostat box to cultivate 48h If the bacteria do not grow at the optimum temperature at 20 degrees C 3, observation results: observe the medium for liquefaction and the shape after liquefaction because gelatin solidified at less than 20 degrees C, higher than 25 degrees C when self-liquefaction, if the bacteria cultured at more than 20 degrees C, observation should be placed in the ice bath observation, if gelatin is liquefyed by bacteria, even at low temperature gelatin will not solidify (four) stone milk test 1, inoculation: the mucous coyle and copper-green pseudomonasina bacteria inoculated into the stone cow milk medium 2, culture: after vaccination test tube at 37 degrees C constant temperature culture 7d, and retain a non-inoculated stone cow milk medium as a control 3, results observation: remove the culture, with no injection of any bacteria test tube as a control, to observe the changes after the growth of different bacteria
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