Biosynthesis of Xanthan Gum by Xanthomonas campestris Using Cane Molasses as a Carbon Source

The objective of the present study was to study the optimization conditions for the production of xanthan by Xanthomonas campestris from pre-treated sugarcane molasses. In the study, the optimization was carried out for different parameters including pH, temperature, and incubation time for the pre-treated sugarcane molasses. The age of inoculums and time of culture growth (6, 12, 18 and 24 hrs), size of inoculums (2%, 5%, 7.5% and 10%), pH (6.6, 6.8, 7.0 and 7.2) and temperature (25°C, 28°C, 30°C, 32°C and 37°C) were studied. It was observed that the xanthan production was maximal with 7.5% (v/v) inoculums, pH. 7 at 30°C for 48 hrs. The study suggested that cane molasses is an appropriate agro-industrial substrate for xanthan gum fermentations, and further scale-up study is needed for gum production in the stirred fermenter.

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

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.

Semi-pilot production of xanthan gum using nejayote as culture medium substrate

Background: Xanthan gum is an industrialized polysaccharide produced by Xanthomonas genus. Alternative carbon sources for Xanthomonas culturing may help reducing its production cost. Nejayote, a residue from maize nixtamalization process, is an alternative culture medium substrate to produce xanthan. In this study, industrial and semi-industrial nejayote alone or in combination with supplements, were tested for xanthan production by Xantomonas campestris (1 × 108 cells/mL inoculum), using YGC medium as control, in 100 mL and 1 L volumes. Cellular growth was determined by the colorimetric MTT reduction assay (OD 540 ). Xanthan pyruvate and acetyl groups from nejayote plus supplement cultures in the bioreactor were evaluated (OD 570). Results: Industrial nejayote steadily produced up to 4 g/L xanthan, as compared with YGC medium control, which increased its production over time up to 9.3 g/L at 96 h. Cellular activity assay revealed that the highest values after 24 h (3.88 and 2.71 OD 540 for YGC and industrial nejayote, respectively). Nejayote supplemented with MgSO4 •7 H2O resulted in the highest xanthan production (10.8 g/L), but low cell growth (3.6 and 1.82 OD 540 for YGC and nejayote plus supplement, respectively), after 96 h of culture. Furthermore, gum yield reached up to 6 g/L and 1.9 OD 540, after 96 h of nejayote plus supplement culture, using a 14 L bioreactor. Xanthan pyruvate and acetyl groups from nejayote plus supplement cultures in the bioreactor resulted in similar amounts (0.107 and 0.130 OD 570 , respectively), compared with a commercial biopolymer (0.148 and 0.127 OD 570 respectively). Conclusions: X. campestris effectively grew and produced industrial-quality xanthan gum in nejayote substrate-containing culture medium, thus providing an inexpensive alternative for bioremediation.

Potential of different Xanthomonas campestris strains for xanthan biosynthesis on waste glycerol from biodiesel production

A rapid expansion of the biodiesel industry has created various ecological issues relative to crude glycerol disposal. Xanthan biosynthesis is considered one of the sustainable solutions for minimizing the adverse effects of waste crude glycerol on the environment. The initial phase of xanthan production on crude glycerol entails the screening of producing microorganism. Therefore, the purpose of this study is to examine the possibility of xanthan production on a crude glycerol-based medium using different Xanthomonas campestris strains. The bioprocesses performed were assessed according to the rheology of the media considered, amounts of xanthan produced and conversion degrees of the most important nutrients present. The pseudoplastic behavior of all the media considered, the amounts of xanthan produced (5.22-7.67 g/L) and the degrees of crude glycerol, total nitrogen and phosphorus conversion (34.44-57.61 %, 23.04-30.35 % and 18.20-22.28 %, respectively) suggest that crude glycerol, after additional bioprocess optimization, can be a suitable raw material for the industrial production of xanthan.

Xanthan gum production by Xanthomonas axonopodis pv. mangiferaeindicae from glycerin of biodiesel in different media and addition of glucose

Biodiesel production has been increasing yearly in Brazil. A large amount of glycerin is generated in this process and needs a correct destination. One possible use of this glycerin in crude form is in biotechnological processes. Xanthan gum is a commercial gum used primarily in the pharmaceutical and food industries as thickener, emulsifier and stabilizer. It is synthetized by species of the bacterium Xanthomonas generally from glucose. However, current research shows that species of this bacterium have the capacity to grow and synthesize the gum using glycerin from biodiesel. The aim of this study was to produce xanthan gum using glycerin from biodiesel production in medium with different nitrogen content, named complex and simple media. The kinetics of fermentation in simple medium showed a two-fold increase in gum production (3.16 kg.m-3) compared to the one in complex medium (1.46 kg.m-3) after 120 hours. The gum generated in this study showed chemical and rheological characteristics of xanthan gum. Glucose supplementation did not show an increase in xanthan production but did increase the consistency index and the behavioral index of solutions of this gum.