 In this module we will continue our discussion on sterilization kinetics. As we have seen that in our previous module that the value of Nt the survivors is less than 1 if we draw the kinetics then there is the possibility then we can achieve that there will be the value of the Nt is 0.1. So 0.1 is the either the survivors either the viable organism so this implies the probability of one organism surviving the treatment is 1 in 10. So 1 tenth is the probability. So this may be better expressed in practical terms as a risk of one batch in 10 becoming contaminated. So if we run 10 different batch then we can say that one time of contamination possibility. So that how many number of the batches that what will be the possibility of the contamination to be carried out. So in this case the value of the K is not the species dependent but it depend upon the physiological form of the cells because there are 2 different forms of the cells. Number 1 is the vegetative form and other form is the spore or resting or a resistant form. For example the endospores of the genus bacillus are more heat resistant than the vegetative cells. So if there is a presence of the vegetative cells in the fermentation medium then there will be another kind of sterilization kinetics but in case of the endosperm forming cells then the nature of the sterilization kinetics is different. So in next slide you can see the figure in which that show that how the heat treatment on the survival of the population in a bacterial endospores population. So in this slide you can see that draw the plot between the log of nature of Nt over N naught against the time you can see here the trend then there is upper side and then the graph go down what happened by this. So initial population increase resulting from the heat activation of the spores in early stage of the sterilization because when there is a more heat endosperm burst and that start germinated. So that is why there is an increase of the survivors because they are very heat resistant and then that heat required to just give the activation of the spores. So that is why this kind of the graph we achieved. So in other case the activation of the spores is balanced by the spores death. So you can see the difference between the previous graph to this graph is here is the state line because there is no more uprise because the sterilization treatment is carried out and in process then if there is an increase and then there will be a death. So that makes the balanced equation. So in this case we can say that an initial stationary period is observed during the sterilization treatment due to the death of the spores that is being completely compensated by the heat activation of the spores. So in this case the activation of spores is less than the spore death. In first case the activation of the spores is more than the death rate. But in second the death rate and the activation are equal then we can say the balance stage but in this case when we say that the activation of the spores is less than the spore death then we can see such kind of the graph. So there is a slight so this can happen when we are dealing with the cultures having contamination with adenospore forming bacteria or any organism. So the deviation from an immediate exponential decline in viable spore number is only due to the heat activation of the spores that is the induction of the spore germination by the heat and the moisture of the initial period of the sterilization process. Because when there is a heat and then there is a wet condition then immediately the spores start germination. So as we have discussed the three different possibilities in case of the sterilization kinetics dealing with the second form of the cell which we called as endospoming cells. But in case of only the vegetative cells we have only a straight line as we have seen in our previous module.