Sticky bacteria: Combined effect of galactose and high ferric iron concentration on extracellular polymeric substances production and the attachment of Acidithiobacillus ferrooxidans on a polymetallic sulfide ore surface

Abstract

Adaptation and microbial attachment mechanisms for the degradation of sulfide ores are mediated by the production of extracellular polymeric substances (EPS) and their role in biofilm formation. EPS production responds to induction mechanisms associated with environmental conditions. In this study, the double induction of EPS with galactose and high ferric iron concentrations in planktonic cells of Acidithiobacillus ferrooxidans, and their attachment on the surface of a polymetallic sulfide ore from Bella Rica-Azuay in Ecuador were evaluated. A. ferrooxidans cells were previously adapted to different concentrations of galactose [0, 0.15, and 0.25% (w/v)], using two ferrous iron concentrations as an energy source (9 and 18 g L–1) in a 9K culture medium. EPS production and its effect on mineral attachment were determined at the time point of maximal growth. The results obtained show a maximum cell attachment of 94.1% within 2 h at 0.15% of galactose and 18 g⋅L–1 of ferric iron concentration, compared to 71.4% without galactose and 9 g⋅L–1 of ferric iron. The maximum concentration of EPS was obtained with a 0.25% galactose concentration; however, it did not result in greater attachment compared to 0.15% galactose concentration. Through the combined induction of low galactose concentration and high ferric iron concentration, the percentage of bacterial attachment can be increased and, therefore, a possible increase in the rate of biooxidation and bioleaching could be obtained.

Effect of silicon dioxide nanoparticles on the rheology properties of fresh and mechanically degraded hydrolyzed polyacrylamide polymer solutions

“…Throughout the experiment, the column temperature was maintained at 30°C. The chromatograms were recorded and processed using the Agilent OpenLab software (version 2.5) 44 …”

“…Approximately 5 μL of the dispersion was placed on a formvar/carbon‐coated TEM grid. The sample was stained with 0.1% phosphotungstic acid (PTA) for 1 s to enhance the contrast between the nanoparticles and the polymer molecules 44 …”

“…The sample was stained with 0.1% phosphotungstic acid (PTA) for 1 s to enhance the contrast between the nanoparticles and the polymer molecules. 44…”

Roles and Regulation of Quorum Sensing of Acidophiles in Bioleaching: A Review

“…EPS mainly comprises proteins, polysaccharides, fatty acids, and metal ions, and multiple components promote mineral leaching [ 116 , 117 , 118 , 119 , 120 ]. EPS interacts with iron-containing minerals through the formation of P-O-Fe bonds, thereby inducing microbial adhesion and EPS accumulation [ 97 ].…”