Exopolysaccharide (EPS) prodcution is a general mechanism employed by bacteria to thrive under
stressful conditions. We report an increase in the production of EPS by Lelliottia amnigena
strain LABEM through CuSO4 exposure along with the use of low-cost carbon sources, namely sucrose
(SUC) and crude glycerin (CG). The production of EPS was analyzed in relation to yield, and
characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy
(SEM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis. L. amnigena
grew in up to 1.0 mM CuSO4, with a maximum EPS yield of 51.8% at 0.6 mM CuSO4. The absence
of copper detection in the enhanced EPS batches is innovative, indicating a potential reduction in
purification steps and heavy metal removal from the produced EPS. This suggests a possible low
copper affinity of the produced EPS until the production of 0.8 mM CuSO4. Microbial supplementation
with CuSO4 also enhanced EPS thermostability and surface roughness, showcasing intriguing
properties applicable to drilling fluids and pharmaceutical uses. High-performance liquid
chromatography (HPLC) and FTIR showed the polysaccharide nature of the products and the
presence of the highly valuable EPS constituent fucose. The results illustrate the relationship between
exopolysaccharide and heavy metal exposure, with a focus on enhancing bioprocesses.
This expands our understanding and applications beyond heavy metal adsorption and removal.
EPS properties and composition suggest diverse applications, such as food additives and in other
processes that employ fucose polymer. Future experiments should explore the various applications
of this exopolysaccharide and the scale-up of the technology.
The authors would like to thank LABPETRO/DQUI/CCE/UFES (Brazil) for performing FTIR and TGA measurements (Technical
Cooperation Agreements number 0050.0022844.06.4 – Equipment UFES/PETROBRAS). The authors would also like to thank the Laboratório de Ultraestrutura Celular Carlos Alberto Redins (LUCCAR)/CCS/UFES, as well as edital MCT/FINEP/CT-INFRA – PROINFRA January 2006 for the SEM images and EDS analyses and the support from the Foundation for Research and Innovation Support of Espírito Santo (FAPES) and the National Council for Scientific and Technological Development (CNPq).
