gram negative bacteria in gelatin hydrolysis test

If the tube is colorless (picture on the right)Īfter the addition of Zn this indicates a positive test. If there is no color change in the tube after the addition of nitrate I and Turns red (tube pictured on the left) after the addition of Zn, this indicates a negative

Nitrate II are added, this color indicates a positive result. If the nitrate broth turns red (tubes pictured in the center) after nitrate I and Be sure to indicate the number of hours of that the nutrient gelatin deep had been incubated prior to assessing hydrolysis. Upon addition of zinc then this means that the NO 3 - was converted to NO 2 - and then was converted to some other undetectable form of nitrogen (a positive result). For the control and each species listed below, indicate with a + if gelatin has been hydrolyzed (a positive result) or a - if it has not (a negative result). Zinc will convert any remaining NO 3 - to NO 2 - thus allowing nitrate I and nitrate II to react with the NO 2 - and form the red pigment (a verified negative result). In order to determine which of the preceding is the case, elemental NO 3 - has not been converted to NO 2 - (a negative result), or that NO 3 - was converted to NO 2 - and then immediately reduced to some other, undetectable form of nitrogen (also a No red color forms upon addition of nitrate I and II, this indicates that either the If nitrite is present in the media, then it will react with nitrate Testing includes the addition of sulfanilic acid (often called nitrate I) and dimethyl-alpha-napthalamine Testing is necessary to determine if reduction of nitrate has occurred. However, in many cases gas is produced by fermentation and further In the case of nonfermenters, this is indicative of reduction of nitrate

This test is important in the identification of both Gram-positiveĪfter incubation, these tubes are first inspected for the presence of gas in theĭurham tube. Reducing nitrate (NO 3 -) to nitrite (NO 2 -) or other nitrogenous compounds via the action of the enzyme nitratase (also called It is used to determine if an organism is capable of

Gram negative bacteria in gelatin hydrolysis test