 In this module, we will talk about a very important part of the industrial fermentation medium that is chelators. What are chelators? Chelators are actually are the sequesting agent that squeeze that sequest the metal content in the medium . So, as we know that fermentation process needs sterilization and mostly the sterilization in industrial scale involve in stew process . So, in stew sterilization need the autoclaving process in which the temperatures has to rise up to 121 degrees Celsius and having the pressure of 15 pound per inch square. But in case when the media contain number of mineral compounds and even the water that has some which we said that hard water containing bivalent ions like calcium and magnesium ions in that. So, in the presence of all these there are some metals are also present in that medium when especially when we utilize when we use complex parts or complex ingredients complex medium. So, in case of a sterilization what happen the media become cloudy just due to the precipitations that is formed due to the interaction of those metals and some salts to each other. So, as reported by Gunt et al 1984 they demonstrated that when the medium of metals and vapour was autoclaved a white precipitate a metal ion were formed. So, that contain almost iron and most of the calcium magnesium and zinc present in the medium. So, in such case when there is such kind of the chances and then there is chance of precipitation and the metal presence then we have to use some chelating compound just to have the overcome of such problems in which the compounds and the metals phosphates become insoluble. So, in case of that we use some chelating compounds you can see here the different examples of chelating compounds in case of ethylene, diamine, acetic acid, EDTA, citric acid, polyphosphates that mostly added into a very low concentration in the medium that act as the chelators. So, these chelating agents preferentially form complexes with the metal ions in the medium and hinders to give them the negative effect on the growth and their availability because in the presence of those metal ions the enzymatic system of that organism will be affected. So, then metal ions may be gradually utilized if they are required. So, in case you can see here that Gunt et al that able to show the precipitates were eliminated in the same media as reported by the Mandel and Weber's just by the addition of EDTA having 25 milligram per liter. So, that is that act as the chelating agent. So, in many media particular those are commonly used on a large scale processes they are the chance and there is the need of the chelating compounds especially I will give you an one example in which we mostly use the molasses and those especially those products and byproducts which we can say that industrial byproducts that we utilize as a industrial fermentation especially very golden example of such as molasses. So, molasses are the byproduct of sugarcane industry. So, molasses contain a heavy concentration of iron particles and other unwanted metal compounds. So, maximum part of such unwanted particles that will be removed that has to removed before using in the medium but then there is a chance of trace amount of or a high amount of such metal compounds then there is a need of using chelating agent. So, in the present of the chelating agent then we can say that suitable and ideal and favorable conditions that need for the production of our desired product in the medium. So, the chelators are the need of the medium especially when we are using some agriculture byproducts, industrial byproducts are in case of complex nitrogen sources because that contain and that might be the chance of the presence of the metal compounds which can have the effect on the product formation through industrial fermentation.