جستجوی مقالات مرتبط با کلیدواژه « cheese whey » در نشریات گروه « زیست شناسی »

Xanthan gum is produced by Xanthomonas bacteria. This gum is    widely used in various industries. Random mutagenesis of xanthan-producing strains can increase xanthan production capacity several times. This study aimed to evaluate Xanthomonas mutant strains with high xanthan production capacity.Materials &

The native strain of Xanthomonas citri K37 was affected by nitrogenic acid mutagen and after initial screening, the mutant strains were selected based on the appearance and diameter of the colony formed on the c dye medium. Whey-based production medium was used to produce xanthan gum and then production indices such as beta-galactosidase activity, sugar consumption, production rate, and viscosity of xanthan gum were selected in selected mutant strains.

A total of 8 mutant strains were selected among all treated colonies. Two high-yielding strains named R3 and R8 and two low-yielding strains called M2 and M6 were selected to evaluate the activity of beta-galactosidase enzyme and glucose consumption. Strain R3 increased viscosity and amount of xanthan compared to wild strain equivalent to 200 cp and 2 g / l,  espectively, and mutant M6 lost the ability to produce xanthan.

From the native Xanthomonas citri K37 isolate, a new R3 strain was created during mutagenesis, which can be effective in low cost cheese whey as a xanthan-producing strain.

Xanthan is an extracellular polysaccharide produced by Xanthomonas genus. Because of high viscosity and other properties, this gum is used in various industries. Hence, the use of cheap carbon sources such as whey can be economically feasible to produce Xanthan gum with positive lactose strains of Xanthomonas.

In this study, the native strain of Xanthmonas citri 386 was used to produce xanthan gum in cheese whey medium. The strain was cultured in a yeast extract lactose broth (YL) and then inoculated into production medium, the fermentation process was investigated in 5 days’ time in terms of production variables such as growth, consumption of lactose, viscosity and amount of xanthan. The content of pyruvate and acetate of product were compared with standard xanthan and the FTIR method was used to determine the functional groups.

The strain used was the ability to use lactose in cheese whey. At the end of the fermentation process, the amount and viscosity of xanthan were estimated to be 20.3 g/L and 2066.5 centipoise respectively. The acetate and pyruvate content was acceptable in comparison with standard xanthan, and the FTIR study confirmed the position of the functional groups of the xanthan structure.

In this study, for the first time, the native isolate of Xanthomonas citri 386 was evaluated for the production of xanthan in whey. This strain showed high potential for lactose consumption in whey and produced a significant amount of xanthan with an optimum viscosity. Therefore, at an industrial scale, the use of this native isolate, can be suitable for the production of xanthan by low-priced whey medium. Keywords: Xanthan gum, Xanthomonas citri, cheese whey, acetate and Pyruvate