Question

Examine patterns of microbial death by completing each sentence. F value The death of microbial populations is typically plotted as log values. and linear The reflects the time required to kill 90% of the microbes in a sample. lag phase D value The , however, is the temperature change needed to kill 90% of the microbes in a sample in a specific length of time. Z value It should be noted that some cells act as persisters, resisting control methods, in a state considered exponential VBNC T value near death

Answer 1

Ans 1: Exponential- During the death phase there is a decline in the no. of viable cells that occurs exponentially as the cells dies at a constant rate.

Ans 2: D value- D value or decimal reduction time is defined as the time required to kill or destroy 90% of the viable microorganisms or endospores under specific experimental conditions.

Ans 3: Z value- Z value is defined as the change in temperature at a given D value that results in the reduction of microbial population by 90%.

Ans 4: VBNC- VBNC is defined as the viable but nonculturable cells where the cells become metabolically inactive and forms a tough coat around itself called as endospores when the environemntal conditions becomes extremely harsh for their survival. Once the favorable condition returns, these cell may then resume their growth. Such VBNC cells forming tough endospores are difficult to kill and resist various control methods since they are made to survive various harsh environmental conditions.

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