 In this module, we will talk about again the microbial growth kinetics which one is the seventh module of batch culture for kinetics. In previous modules of batch culture kinetics, we discussed about the relationship of biomass to time and then the substrate change during the fermentation process and then how the substrate concentration effect on biomass with respect to time and then we conclude the whole kinetics with respect to x with respect to s and then in finally, we discussed the process kinetics the overall effect in product formation. So, in this module, we will talk about different phases of the growth during the fermentation process with respect to product. In previous module, we talk about four different phases of the growth with respect to biomass and we discuss in detail all four phases depend upon the ratio between the birth and the death of the cell. So, in this way, but when we talk about the different phases during the fermentation especially in batch fermentation, then Barrow et al 1961 divided the growth of the organism into several phases. As you can see in this slide that Barrow et al discussed first of all the balanced phase which is equivalent to the early and the middle exponential phase of the first four which I have already told you lag log stationary and decline phase. But the balanced phase referred to the early and middle exponential phase or we can say that the early and the middle log phase. But as concerned the second which we called as the storage phase, storage phase equivalent to the late exponential phase where increase in the mass is due to the accumulation of the lipid and the carbohydrates inside the cell. And the third stage that referred to the maintenance phase, so this one is also equivalent to the stationary phase of the previous discussed phases. So, in short we can say that the exponential phase can be further divided into two balanced phase and storage phase and the maintenance phase can be called as stationary phase can be called as maintenance phase according to Barrow et al. So, as concerned with respect to Boo log et al 1965 he tried to they tried to discuss different growth phases with his own respect. He divided the growth phase into two major phases that first one is tropophase and the second one is ideophase which will you will see in the later slide. So, the tropophase referred to the exponential phase in which the primary metabolites are produced. So, the classification of Boo log et al basically based upon the type of the products formed. So, as we discussed in the range of products during the fermentation process we discussed that there are different types of metabolites produced primary metabolites, secondary metabolites, tertiary metabolites. But Boo log et al divided the growth phase into two the first one which I have already told you tropophase and tropophase referred to that phase in which only the primary metabolites will be produced. But as concerned the ideophase the ideophase usually referred to the stationary or the death phase during that lag log and other two phases. So during the ideophase mostly the cell formed the secondary metabolites or other metabolites which can be further classified at tertiary metabolites other than primary metabolites. So, when we talk about with respect to the product formation so the different phases can be expressed in different way as by borrow et al by three different phases but according to Boo log et al having two major phases. So actually the four different phases lag phase is we can say only that acclimatization phase but major phase is exponential phase that is mostly referred for the production of primary metabolites. But on other hand the stationary and decline phase referred to the phases in which the scanty and other products can be formed.