triple sugar iron test Question and answer 100% solved

triple sugar iron test Question and answer 100% solvedwhat is the purpose of the triple sugar iron test? -the TSI test is designed to differentiate among the different groups or genera of the Enterobacteriaceae, which are all gram-negative bacilli capable of fermenting glucose with the production of acid, and to distinguish the Enterobacteriacase from other gram-negative intestinal bacilli. What is the enterobacteriacase? -all gram negative bacilli capable of fermenting glucose with the production of acid. what is the differentiation based on? The differentiation is made on the basis of the differences in carbohydrate fermentation patterns and hydrogen sulfide production. what kind of tool does this test use? -agar slant (contains lactose and sucrose (1%) & glucose (0.1%)) -pH indicator (phenol red) used to detect acid produced during fermentation what happens if only glucose is fermented? -if only glucose is fermented by the bacterium tested, only a small amount of acid will be produced, turning just the butt (bottom) of the slant yellow. -this is because there is only a little amount of glucose available (0.1% vs 1%) what happens if either lactose or sucrose are fermented? -if either lactose or sucrose are fermented, their greater concentration will allow greater acid production resulting in the ENTIRE butt and slant turning yellow. Thus, we can use the amount of acid produced to distinguish bacteria that ONLY ferment glucose (Enterobacteriaceae) from bacteria that ferment lactose and/or sucrose (other intestinal bacilli) how are TSI inoculated? -using inoculating needle -first, the butt of the slant is stabbed by pushing the needle into the agar to within 0.5 cm of the bottom of the tube. -then, as the needle is removed from the butt, the surface of the slant is streaked by dragging the needle lightly across the slanted surface of the agar in a zig-zag motion. After inoculating the TSI slants for 24-48 hours, what are the reactions? -yellow butt and red slant = fermentation of ONLY glucose. The slant remains red because of the limited glucose substrate and thus, limited acid production. -yellow butt and yellow slant = fermentation of lactose and/or sucrose. the excessive concentration of these sugars lead to ecvessive acid production turning the entire slant and butt yellow. -gas formation indicated by splitting or cracks in the agar or lifting of the agar from the bottom of the tube. -hydrogen sulfide production indicated by blackening of the agar. -red butt and red slant indicating that none of the sugars were fermented, and neither gas nor hydrogen sulfide were produced. j what bacteria would you use the TSI test for? -enterobacteriaceae how would you identify an acidic slant? -the slant turns yellow if acidic. why is there more lactose and sucrose in TSI agar than glucose? -we can use the acid produced to distinguish bacteria that ONLY ferment glucose (enterobacteriaceae) from bacteria that ferment lactose and/or sucrose (other intestinal bacilli) red slant/red butt no fermentation red slant/yellow butt glucose fermentation