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Why cant the ONPG test be substituted for the determination of lactose fermentation?
Wiki User
∙ 11y ago
ONPG test detects only presence of beta galactosidase enzyme whereas lactose fermentation requires the presence of permease as well as beta galactosidase enzyme.
Wiki User
∙ 11y ago
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Why are some organisms positive in the ONPG Test but negative when tested for the ability to metabolize lactose?
ONPG is for the detection of delayed lactose fermentation.
Can shigella sonnei be a lactose non fermenter My tests are as followed TSI KA Methyl red VP - citrate - urea - NO3 degraded to NO2 H2S - motility -. all points to shigella but it's nonferm?
S.sonnei is not a true lactose fermenting bacteria (see.. http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=271578&blobtype=pdf)But is a delayed lactose fermenter as it does not have the enzyme permease to transport lactose through its cell wall.However an ONPG lactose fermenting test does not require permease to allow the bacterium to ferment lactose so in an ONPG test the shigella sonnei will appear as lactose fermenting positive.Hope this helps!!2nd year BMS student
Does bacillus subtilis have a positive reaction for ONPG Test?
yes it have positive reaction for ONPG test
Biochemical tests for Salmonella and Shigella?
urease - negative ONPG - positive Lysine - positive
Motility is best seen with a?
Wet mount, hanging drop slide, or motility tube (SIMS, ONPG-PAM)
Why beta Galactosidase produce yellow color?
beta galactosidase breaks onpg into galactose and ortho-nitrophenol which gives a yellow colour
Why incubate ONPG?
too see transcription and translation speed - u plot it against time (A400 - A550*1.65) / 0.0075
How does an API test work?
The API 20E System is a miniatuized version of conventional tsts that is used for the identification of members of the family Enterobacteriaceae and other gram-negative bacteria. This system utilizes a plastic strip with 20 separated compartments. Each compartments consists of a depression, or cupule, and a small tube that contains a specific dehydrated medum. After you inoculated each compartment with an unknown bacteria, a reaction will occur within 24 hours. The results of each reaction are tabulated and then given a number based on the results. The unknown bacteria is identified by searching through a book, Analytical Profile Index (may be in other book), and searching for the number corresponding to your unknown.The test consists of the following:ONPG: galactosidaseADH: Arginine DiHydolaseLDC: LysineDeCarboxylaseODC: Ornithinine DeCarboxylaseCIT: Citrate utilizationH2S: Hydogen sulfide productionURE: UreaaseTDA: Tryptophane DeAminaseIND: Indole ProductionVP: acetoin production (Voges Proskauer)GEL: GelatinaseGLU: fermentaion / oxidation (Glucose)MAN: fermentaion / oxidation (Mannitol)INO: fermentaion / oxidation (Inositol)SOR: fermentaion / oxidation (Sorbitol)RHA: fermentaion / oxidation (Rhamnose)SAC: fermentaion / oxidation (Saccharose)MEL: fermentaion / oxidation (Melibiose)AMY: fermentaion / oxidation (Amygdalin)ARA: fermentaion / oxidation (Arabinose)Supplemental Test also may be done with the API testOXI:NO2:N2 GAS:MOT:MAC:OF-O:OF-F:The reactions of each compartment are given a (+) or (-). Each compartment has a corresponding points. If a reaction for a certain compartment, like GLU, is possible then the points are counted.Every 3 compartment (or test) is given a number. The points of every 3 set is 1, 2, and 4 (in order)... Do not get mixed up with points and number. Each test has a corresponding points and Every 3 tests is given a number based on the results...For example:ONPG (1), ADH (2), and LDC (4)If ONPG and LDC are positive and ADH reaction is negative, then the number given to this set is 5 (1pt from ONPG and 4pt from LDC; No point is given to ADH because the result is negative)THERE SHOULD BE 9 NUMBERS[27 tests/compartments divided into 3 groups each is 9]A test result for a specific bacteria of Eshcerichia coli (E. coli) is+ - + + - - - - + - - + + - + + - + - + - + - + + + +5 1 4 4 5 5 2 5 7The number is 514455257An important thing to remember is that they have a lot of bacteria. Some bacterias have different strains, so there may be more than 1 number that identifies to be E. coli. It's just they are different strains of E. coliInformation taken from Benson's MICROBIOLOGY APPLICATIONS Tenth edition by Alfred E. BrownPosted by 13K
