Whey is the major by-product obtained during the preparation of dairy products such as cheese. The nutrient composition of whey is based on the nutrient composition of milk from which it is derived, which in turn is affected by many factors including how the milk was processed. Lactose is the major component comprising about 70 % of the total solids of whey. Whey also contains a pool of nutrients and growth factors that have the potential to stimulate the growth of microorganisms but the suitability of whey for EPS production highly depends on the ability of the microorganism to utilize lactose. Cheese whey has been used as carbon and nitrogen source for xanthan [59] and gellan [40] production. Mozzarella cheese whey has been used for xanthan production by two different X. campestris strains and although both strains reached comparable yields, the polymers were found to differ in their chemical characteristics [59]. The low yields were attributed to the low capacity of the X. campestris strains to utilize lactose. On the other hand, Fialho et al. [40] evaluated the gellan gum production by the S. paucimobilis ATCC 31461 strain in media containing lactose, glucose, and sweet cheese whey as substrates. The strain was known to grow on lactose and to produce highly viscous gellan directly from lactose [76]. Sweet cheese whey obtained from the industry was neutralized and disinfected by three cycles of heat treatment at 80 °C for 30 min. A maximum gellan yield of 7.9 g/L could be recovered from the flask cultures after 100 h of fermentation period [40]. Cheese whey has also been investigated as a potential substrate for dextran production by L. mesenteroides NRRL B512 cultures [37]. For this, proteins were removed from whey by precipitation through autoclaving and then centrifugation. Though lactose in the supernatant was found to repress the dextransucrase activity, 7.23 g/L dextran could be produced when carob extract was also present in the medium [37].