True or False:
Pasteurization uses high temperatures over a period of 5-15 minutes to sterilize, and therefore preserve, food.
Gram positive bacteria in the lag phase of their growth curve are the most sensitive to penicillin.
Bacteria that tolerate high concentrations of NaCl, up to 10% are halotolerant.
Answer 1:
Pasteurization uses high temperatures over a period of 5-15 minutes to sterilize, and therefore preserve, food. TRUE
Explanation: Pasteurization is one of the methods of food preservation where the pathogens and spoilage causing organisms are killed with the help of high temperature and the food item is preserved for a considerable period of time.
It can not be called as sterilization as the spores are not killed by this method. Pasteurization involves either of the two methods
Answer 2: Gram positive bacteria in the lag phase of their growth curve are the most sensitive to penicillin. FALSE
Explanation: Lag phase is when the bacteria are not increasing in number but only growing in size. It is the phase before log phase or exponential phase.
Action of penicillin is by binding to cell wall proteins of the Gram positive bacteria. Penicillin inactivates the proteins in the cell wall in such a way that cross linking needed for cell wall formation will not take place and cell wall will not be formed resulting in inhibiting growth of the organism.
so the bacteria would be more sensitive to penicillin during log phase of growth and not the lag phase of growth.
Answer 3 : Bacteria that tolerate high concentrations of NaCl, up to 10% are halotolerant. TRUE
Explanation: Halotolerant bacteria can tolerate high salt concentrations but they are not halophiles. Halotolerant bacteria can grow in absence of salt as well as in presence of salt concentration as high as 10%. Example of halotolerant bacteria is Staphylococcus aureus As against this Halophiles require high salt concentration for their growth.
True or False: Pasteurization uses high temperatures over a period of 5-15 minutes to sterilize, and...
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