The effect of cultivation time on xanthan production by Xanthomonas spp. on glycerol containing medium

Abstract

In this study, the influence of cultivation time on xanthan biosynthesis by different Xanthomonas strains, reference strain and crucifers? and pepper leaves? isolates, was examined. Biopolymer was produced by submerged cultivation of fourteen producing strains on medium with glycerol as a sole carbon source. Each experiment was performed at a laboratory level under aerobic conditions at 30?C and 150 rpm for 168 h and 240 h. Bioprocess efficacy was estimated based on the xanthan quantity and its average molecular weight that was selected as quality parameter. According to the obtained results, it can be concluded that all applied strains have a statistically significant effect on xanthan concentration in medium and on its average molecular weight, while cultivation time significantly affect the bioprocess efficacy only when biosynthesis is performed by Xanthomonas strains isolated from crucifers. Further, when only Xanthomonas strains isolated from crucifers are observed, statistically obtained data suggest that the largest amount of the best quality xanthan in applied experimental conditions can be accomplished by the cultivation of CB strain for 240 h. On the other hand, when it comes to Xanthomonas strains isolated from pepper leaves, the highest productivity is shown by PL 2, PL 4 and PL 5 strains regardless of the cultivation time, while the PL 3 strain was responsible for the synthesis of biopolymers with the highest average molecular weight. The results obtained in this study represent valuable information for development of biotechnological process for xanthan production on glycerol containing media using new producing strain.

Screening of Local Wild Xanthomonas Species for Xanthan Production on Crude Glycerol-based Medium

“…The results presented in Fig. 2 (a) indicate that there is a statistically significant difference in xanthan concentration in media when cultivation of X. campestris strains isolated from crucifers on crude glycerol-based medium was conducted for 168 h and 240 h. According to graphically presented results, higher xanthan content was obtained when cultivation of X. campestris strains was performed for 240 h. This result is in agreement with findings gained in the previous study where higher xanthan concentration in media was obtained after 240 h of cultivation of Xanthomonas strains isolated from crucifers on commercial glycerol containing medium, under similar experimental conditions [28]. This may be due to the greater time needed by the applied strains to adapt to the glycerol as a sole carbon source in cultivation media [6].…”

“…Graphically presented results in Fig. 2 (b) indicate that there is no statistically significant difference in xanthan concentration in media when cultivation of X. euvesicatoria strains isolated from pepper leaves on crude glycerol-based medium was performed for 168 h and 240 h. The results obtained in this research confirm findings of the previous research, where aforementioned strains were cultivated on commercial glycerol containing media for 168 h and 240 h and there was insignificant difference in xanthan concentration at the end of biosynthesis [28]. Comparing to the previously discussed results presented in Fig.…”

“…4 (a), X. campestris strains isolated from crucifers produce xanthan of higher average molecular weight for 240 h of cultivation. Taking into account the presented results and the results obtained in previous research [28], it can be concluded that X. campestris strains isolated from crucifers need more time (240 h) to produce xanthan of higher average molecular weight on crude glycerol-based media comparing to biosynthesis on commercial glycerol containing media. Considering aforementioned results presented in Fig.…”

Xanthan production on crude glycerol-based medium by local Xanthomonas isolate: Optimization of inoculum incubation time

“…At the end of bioprocess, the xanthan was separated from the supernatant of cultivation medium by precipitation with cold 96% (v/v) ethanol in the presence of the potassiumchloride as electrolyte as described in previous research (18). The concentration of the produced biopolymer was evaluated by determining the weight of the dry product per litre of cultivation medium.…”

“…Results from previous study indicate that Xanthomonas strains need a certain period to adapt to glycerol as a sole carbon source in the cultivation medium in order to produce xanthan (18). Accordingly, it is considered that the duration of the inoculum preparation may affect the success of xanthan biosynthesis on crude glycerol-based medium.…”