Iron-binding characterization and polysaccharide production by Klebsiella oxytoca strain isolated from mine acid drainage

Abstract

Aims:To investigate Klebsiella oxytoca strain BAS-10 growth on ferric citrate under anaerobic conditions for exopolysaccharide (EPS) production and localization on cell followed by the purification and the EPS determination of the iron-binding stability constant to EPS or biotechnological applications.Methods and Results:Klebsiella oxytoca ferments ferric citrate under anaerobic conditions and produces a ferric hydrogel, whereas ferrous ions were formed in solution. During growth, cells precipitate and a hydrogel formation was observed: the organic material was constituted of an EPS bound to Fe(III) ions, this was found by chemical analyses of the iron species and transmission electron microscopy of the cell cultures. Iron binding to EPS was studied by cyclic voltammetric measurements, either directly on the hydrogel or in an aqueous solutions containing Fe(III)-citrate and purified Fe(III)-EPS. From the voltammetric data, the stability constant for the Fe(III)-EPS complex can be assumed to have values of approx. 1012–1013. It was estimated that this is higher than for the Fe(III)-citrate complex.Conclusions:The production of Fe(III)-EPS under anaerobic conditions is a strategy for the strain to survive in mine drainages and other acidic conditions. This physiological feature can be used to produce large amounts of valuable Fe(III)-EPS, starting from a low cost substrate such as Fe(III)-citrate.Significant and Impact of the Study:The data herein demonstrates that an interesting metal-binding molecule can be produced as a novel catalyst for a variety of potential applications and the EPS itself is a valuable source for rhamnose purification.

A bio-generated Fe(iii)-binding exopolysaccharide used as new catalyst for phenol hydroxylation

“…17 In our opinion, the use of this bio-generated iron complex could be worthy of investigation as a catalyst; therefore, research to verify its catalytic ability in a model oxidation reaction, such as the hydroxylation of phenol with H 2 O 2 (Scheme 1), was carried out.…”

Metabolic Changes in Klebsiella oxytoca in Response to Low Oxidoreduction Potential, as Revealed by Comparative Proteomic Profiling Integrated with Flux Balance Analysis

“…At high culture ORP (Ϫ150 mV), YMU2 cells were regular short rods and their cytoplasms were evenly distributed ( Fig. 2A), as reported during anaerobic growth in citrate sodium media (43). In contrast, low ORP (Ϫ240 mV) induced irregularities in cell shape and aggregation of intracellular components (Fig.…”

Mechanisms Controlling the Expression of the Exopolysaccharide of Burkholderia and Role in Niche Adaptation

“…Ferreira and co-authors also demonstrated a protective effect of cepacian on Burkholderia isolates exposed to metal ion stress (Ferreira et al, 2010). The protection conferred by EPS to toxic concentrations of metal ions was also demonstrated in other bacteria as it is the case of Klebsiella oxytoca (Baldi et al, 2009). The metal-binding properties of EPS might be due to the occurrence of carbonyl, carboxyl and hydroxyl groups within the EPS matrix that attach cations and scavenge metals (Potts, 1994).…”