Simultaneous production of polyhydroxyalkanoate and xanthan gum: From axenic to mixed cultivation

In the present study, mixed and axenic submerged cultures of Cupriavidus necator and Xanthomonas campestris were performed for simultaneous and individual PHA and XG productions using palm oil (Elaeis guineensis) as substrate. Rotational Central Compound Design (RCCD) was successfully used in the optimization of individual productions of PHA (3.39 g L^-1, Mw = 692.6 kDa) and XG (1.77 g L^-1, Mw = 36.6 × 10⁵ kDa). Novel simultaneous production of PHA (6.43 g L^-1, Mw = 629.2 kDa) and XG (1.98 g L^-1, Mw = 25.0 × 10⁵ kDa), executed in bacterial co-cultivation, revealed to be a successful strategy to increment polymer synthesis, especially PHA. XG bioconversions followed a general trend of lower production in co-culture. Culture configurations also altered polymers properties and characteristics.

Impact of Preservation Conditions on Fatty Acids, Xanthan Gum Production and Other Characteristics of Xanthomonas campestris pv. mangiferaeindicae IBSBF 2103

The conditions of storage, cultivation and maintenance of microbial cultures should preserve the microbiological homogeneity, phenotypic and genotypic characteristics to ensure better reproducibility of metabolic production. To evaluate the influence of the storage condition on the composition of cell fatty acids, genetic profile and biochemical characteristics of Xanthomonas campestris pv. mangiferaeindicae IBSBF 2103, as well as, to identify its relationship with the yielding and viscosity of the xanthan gum produced, this study monitored the strain preserved in two simple and widely used conditions, ultra-freezer (-80 °C) and refrigeration (3-8 °C) during 5 months. Were identified and quantified 13 fatty acids. The cells preserved at -80 °C showed more stable concentration of all fatty acids, producing more xanthan gum and with higher viscosity. The chromosomal analysis obtained with the enzyme XbaI revealed 17 distinct fragments with maximum size of 485 kilobases, without variations among the subcultures maintained in both storage conditions. The X. campestris pv. mangiferaeindicae subcultures preserved at -80 °C showed less pronounced phenotypic variations, which had positive influence in the qualitative and quantitative characteristics of the xanthan gum produced.