Glycerol as a carbon source for xantan production by Xanthomonas campestris isolates

Abstract

The success of xanthan biosynthesis depends on several factors, most importantly the genetic potential of the production microorganism and cultivation media composition. Cultivation media composition affects the yield and quality of the desired product as well as production costs. This is why many studies focus on finding cheap alternative raw materials, especially carbon sources, to replace commercially used glucose and sucrose. In addition to the Xanthomonas campestris ATCC 13951 which is the primary industrial production microorganism, other Xanthomonas strains can produce xanthan as well. Under the same conditions, different strains produce different amounts of the biopolymer of varying quality. The aim of this paper is to compare producibility of phytopathogenic X. campestris strains, isolated from the environment with the reference X. campestris ATCC 13951 strain and to estimate the possibility of xanthan production using alternative glycerol-based media than the synthetic glucose-based media. Submerged cultivation on the medium based on glucose or glycerol (2.0 %w/v) was performed using the reference strain and eight isolated X. campestris strains. In order to assess the success of biosynthesis, xanthan yield and rheological properties were determined. Strains isolated from the environment produced yields between 2.98 g/L and 12.17 g/L on the glucose-based medium and 1.68 g/L and 6.31 g/L on the glycerol-based medium. Additionally, X. campestris ATCC 13951 provided the highest yield when using glucose (13.24 g/L), as well as glycerol-based medium (7.44 g/L). The obtained results indicate that in the applied experimental conditions and using all tested strains, glycerol is viable as a carbon source for the production of xanthan.

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

“…The quality of xanthan can be estimated based on several parameters, such as the viscosity of its solutions, the composition of the macromolecules, the molecular weight, etc. [18]. In this study, the quality of the xanthan produced in applied experimental conditions was estimated based on its average molecular weight.…”

“…Besides the producing strain, cultivation time also has significant effect on xanthan quantity and quality [17]. Generally, fermentation time for xanthan production on glycerol containing media ranges from 48 h to 168 h [14,18,19]. The results from earlier studies show that after the cultivation of certain Xanthomonas strains on glycerol-based media for 96 h [14] and 120 h [18], glycerol conversion was about 50% or less.…”

“…Generally, fermentation time for xanthan production on glycerol containing media ranges from 48 h to 168 h [14,18,19]. The results from earlier studies show that after the cultivation of certain Xanthomonas strains on glycerol-based media for 96 h [14] and 120 h [18], glycerol conversion was about 50% or less. The applied producing strains did not metabolize all available amount of glycerol probably due to lack of time to adapt to glycerol and produce xanthan in a sufficient quantity.…”

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

“…So, there is also a need to determine the optimal cultivation time for new producing strains (18) in order to achieve successful efficacy of examined biotechnological process. The usual fermentation time for xanthan production is from 72 h to 120 h (15,19,20), and in one study, xanthan biosynthesis was performed on glycerol containing medium up to 168 h (7). The results from the available literature where xanthan biosynthesis was performed on glycerol containing media show that the applied producing strains did not metabolize all available amount of glycerol during the cultivation of 96 h (15) and 120 h (20), and glycerol conversion was about 50% or less.…”

Utilization of wastewaters from red wine technology for xanthan production in laboratory bioreactor

“…Comparing the results obtained in this study (Table 3) with the amount of biopolymer produced by the reference producing strain on the traditionally applied medium with glucose (Bajić et al., 2015), the success of xanthan biosynthesis on the selected wastewater from red wine technology can be estimated in the best way. As the amount of accumulated xanthan in the medium prepared with wastewater generated during fermentation tank washing was 20% higher, it is indisputable that the selected winery effluent represents a very good substitute for standard semisynthetic medium.…”