 As concerned, the effect of sterilization time and the temperature on the medium component and which is just in our previous module that if we want to have a short holding time having a high temperature, then it will be preferable of a continuous steam. So, as concerned the sterilization process, we can classify the sterilization into various types. One is in-stitue sterilization and other is ex-stitue sterilization. What is in-stitue sterilization? In-stitue sterilization of the fermenter on the same place where the fermenter is. So, we just supply the steam to the fermenter and then to sterilize and that is known as in-stitue sterilization. As concerned the ex-stitue sterilization that only help only a small scale or a shake flask level because we keep our material or a fermenter vessel into the autoclave and then we sterilize. So, this is known as ex-stitue sterilization. You know that we discuss in detail the in-stitue and ex-stitue sterilization while discussing the scale of fermentation because when we say the lab scale fermentation that only include that only have ex-stitue sterilization, but on pilot scale and industrial fermentation we have only the in-stitue sterilization. But here on other hand the sterilization can be divided into two types on the base of the mode of sterilization. One is batch mode and other one is the continuous mode. So, each mode has its own limitations. Some are the benefit, some are the we can say that the disadvantages. So, the relative merit of the batch and continuous sterilization. So, what is batch? So, if we sterilize in a batches I mean all the medium on a same time either we sterilize the medium in a stream and then we gradually feed into the fermentation medium that is known as continuous sterilization process. So, as concerned that advantages of the continuous sterilization over the batch sterilization. So, we can say that the continuous sterilization is superior maintenance for medium quality. So, in this case we can give a high temperature for a short time. So, it is better to maintain the medium quality. So, in this case it is easy of scale up, easier automatic control, reduction of surge capacity for steam, reduction of sterilization cycle time as can the six under certain circumstances the reduction it reduce the fermentor collision. Because fermentor is just only have no medium and then we can sterilize by the steam and then if we have not the sterilization cycle time by time that increase the life cycle life of the fermentor. So, as concerned the advantages of the batch sterilization over the continuous sterilization it require low capital investment, low risk of contamination because the process require the aseptic transfer of sterile growth to the sterile vessel. Because in continuous culture we need a some condemn lines. So, if we our sterilization process that is very good, but there is any leakage in those lines then there is more risk. So, in batch culture the risk is less than the continuous, but in batch culture it is easier to handle. So, manually it is easy to control in batch culture in batch sterilization. As concerned the batch sterilization it is easier to use medium containing with the high proportion of solid matter. Because continuous sterilization can only be applied when there is a less thick and there is more flow, but those media which have a viscous and have a less flow then there is will be the batch sterilization option. So, as concerned the early continuous sterilizers were constructed as a plate heat exchangers and these were unsuitable for two account. Number one the failure of the gasket between the plates resulted in the mixing of sterile and unsterile steam. Because when there is a heat exchangers and then there is a plate between the two and if there is any leakage then the mixture can happen of the sterilized and unsterilized medium. So, the particular component in the medium would block the heat exchangers. So, because there are the very small passages so sometimes when there is a viscous medium and then that can block the heat exchanger then there will be a more loss. So, as concerned the modern continuous sterilizers are double spiral heat exchangers in which the two streams are separated. When there is a chance of mixing of the sterilized and unsterilized streams then in the modern case the sterilizers have a separate we can say that double spiral heat exchangers in which the two streams are separated by the continuous steel divisions. So, then the spiral exchangers are far less susceptible to the blockage, but the major limitation to the adaptation of the continuous sterilization was the precision of control necessary for its success. So, this precision has been achieved with the development of sophisticated computerized monitoring and the control system resulting in the continuous sterilization being very widely used and it is now be the method of choice in fermentation in a industrial type fermentations. So, the nevertheless of the batch sterilization that is the steel use so if we can say that the continuous sterilization has its own advantages, but due to the more cost capital cost and then most of the fermentation and most of the industrial fermentation use batch sterilization. So, we will discuss in detail in our later module about.