Xanthan Production Using Wastewaters from Rose Wine Industry: Screening of Xanthomonas euvesicatoria Isolates

Wastewaters, as the major waste stream of the wine industry, are usually disposed in crude form due to the lack of sustainable treatments, which poses rising environmental threat. Considering biodegradability, nutrients content and other specific characteristics, winery wastewaters are suitable for utilization in xanthan production. In this study, the screening of local wild-type Xanthomonas euvesicatoria strains, isolated from pepper leaves, for xanthan production on medium containing wastewaters from rose wine industry, with initial sugar content of 25 g/L, was performed. Bioprocess success was estimated based on the quantity and quality of separated biopolymer. Additionally, composition of collected wastewaters was determined, and the obtained data indicate the importance of their proper management. The results of screening experiments suggest that applied X. euvesicatoria isolates have a statistically significant effect on xanthan concentration in cultivation medium, its molecular weight, as well as on apparent viscosity of xanthan aqueous solution. According to the obtained results, xanthan concentration varied from 4.0 g/L to 10.0 g/L, while the values of average molecular weight of xanthan and apparent viscosity of its solution ranged from 2.5 ∙ 105 g/mol to 8.5 ∙ 105 g/mol and from 40 mPa ∙ s to 60 mPa ∙ s, respectively. The results from this study suggest that X. euvesicatoria PL2 isolate showed the greatest potential for xanthan production on medium containing wastewaters from rose wine industry because of determined quantity of good-quality biopolymer. Further research is necessary in order to improve proposed bioprocess as sustainable biotechnological solution for winery wastewaters utilization.