be sure to use very clear writing Inoculation of a broth After sterilizing an in
ID: 205940 • Letter: B
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be sure to use very clear writing
Inoculation of a broth After sterilizing an inoculation loop, obtain a small sample of the target organism. Remove the lid from the broth tube and gently stir the loop in the broth close to the glass side of the container Remove the inoculation loop and replace the cap. Gently flick the tube to mix the organism into the broth. 1. 2. 3. :Lactose Broth Fermentation (3pts) Obtain 4 tubes of lactose broth. Make sure that each tube contains a Durham tube. The Durham tube will catch gas produced by bacteria that ferment lactic acid. What is the fourth tube for? Inoculate E. coli into one tube, S. marcescens into the second, and P. aeruginosa into the third. Be sure to label them well. The incubator will be very crowded. Incubate the tubes for 24 hours. Recording your observations: If you need to make a comparison between tubes, the volume of the Durham tube is approximately 0.5 ml. You may estimate the volume to make a comparison, otherwise just enter a "+" for the presence of gas and " "for the absence of gas. Even if you see a bubble the size of the head of a pin, that is a positive result. 1. 2. 3. 4. Lactose Fermentation Gas Present Organism Eschericia coli Serratia marcescens Psuedemonas aeruginosaExplanation / Answer
According to given data, fermentation of lactose takes place in absence of oxygen .Lactose is broken down into lactic acid by the activity of bacterial species like E.coli,Pseudomonas etc.Gram negative bacteria like Pseudomonas,E.coli does not produce any bubble or gas during culture, while gram positive producing gas during their culture .Serratia is also a gram negative and not producing any gas.Lactose fermentation take place only in anaerobic condition and bacteria like E.coli are aerobic and don't grow in anaerobic conditions.
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