Syrups and molasses have long been used as substrates for fermentative production of commercial polysaccharides such as pullulan [46-49], xanthan [57], dextran [38], scleroglucan [32], levan [33, 41, 42], and gellan [39] due to their many advantages like high sucrose and other nutrient contents, low cost and ready availability, and ease of storage. Using molasses in crude form resulted in low pullulan [46] and scleroglucan [32] yields which in turn pointed out the need for pretreatments. Pre­treatment of sugar beet molasses with sulfuric acid has been reported for pullulan

[47] and levan [33] production but, when acid treatment was combined with activated carbon treatment, significant improvements in pullulan [48,49] and levan [33] yields

were obtained, most probably due to the removal of heavy metals and colored sub­stances. Activated carbon is particularly known for its efficiency in removing heavy metal pollutants [64]. However, after a systematic study on the effect of different pretreatments on the heavy metal distribution of starch and beet molasses samples, Kuquka§ik et al. [33] reported a drastic increase in the dissolved iron (Fe2+) content after the activated carbon treatment. This has been attributed to the reduction of iron from its impregnated Fe3+ form to its soluble form since this increase in soluble iron was more profound when acid treated samples were subjected to activated carbon treatment [33]. Same authors suggested tricalcium phosphate (Ca3(PO4)2,TCP) treat­ment as an effective method for selective removal of iron and zinc from molasses or other mixtures of comparable composition. Heavy metals like iron, zinc, and nickel are known to enter the apatite crystal structure of TCP by replacing the Ca atom

[65] . Goksungur et al. [49] applied potassium ferrocyanide (K3[Fe(CN)6]) treatment to precipitate heavy metals. For the microbial levan production with Paenibacillus polymyxa NRRL B-18475, clarified sugar cane syrup and crude sugar beet molasses resulted in very low yields. Therefore, peptone was added to the cane syrup and beet molasses was subjected to various expensive pretreatments like passing it through gel filtration and anion exchange columns in order to increase the levan yields to levels comparable with sucrose [41]. To produce levan from Zymomonas mobilis, both sug­arcane molasses and sugarcane syrup were clarified by centrifugation followed by filtration and then used at 250 g/L carbohydrate concentration [42]. For levan produc­tion by halophilic Halomonas sp. cultures, sugar beet molasses, and starch molasses were subjected to five different physical and chemical pretreatment methods and their combinations, that is, clarification, pH adjustment, sulfuric acid, TCP and activated carbon treatment [33]. In both molasses types, pretreatments like clarification, pH adjustment were not adequate as also reflected by the low EPS production yields due to the retained undesirable constituents (e. g., heavy metals, impurities) which influence the growth of microorganism and associated polysaccharide production [47, 66, 67]. Highest levan yields were obtained with sugar beet molasses pretreated with TCP followed by acidification with sulfuric acid and then subjected to activated carbon pretreatment [33]. On the other hand, Kalogiannis et al. [57] applied various treatment methods to sugar beet molasses including aeration, acid, activated carbon, K3[Fe(CN)6] treatments, and ion exchange chromatography, however, none of the pretreatments improved the xanthan yield of X. campestris ATCC 1395 cultures and the highest production was obtained with the untreated crude molasses. Crude beet molasses is also used to produce dextran by L. mesenteroides bacterial cultures and the yields were comparable to those of media containing pure sucrose [38]. Banik et al. [39] used Response surface methodology to optimize the production of gellan gum by S. paucimobilis ATCC-31461 using crude sugarcane molasses and reported a maximum yield of 13.81 g/L gellan. Survase et al. [32] used various dilutions of coconut water, sugarcane molasses, and sugarcane juice for scleroglucan production by filamentous fungi S. rolfsii MTCC 2156 and obtained the highest yields (23.87 g/L in 72 h) from sugarcane juice that was obtained from a local market and hence did not require any pretreatments before use. Coconut water and sugarcane juice were also used for EPS production by Lactobacillus confusus cultures [68].