Making sticky cells: effect of galactose and ferrous iron on the attachment of Leptospirillum ferrooxidans to mineral surfaces

Publication date: Available online 1 September 2018Source: Research in MicrobiologyAuthor(s): Paulina Aguirre, Karlo Guerrero, Aminael Sánchez-Rodríguez, Juan Carlos Gentina, Axel SchippersAbstractThe purpose of this study was to compare the efficacy of galactose and high initial ferrous iron concentrations as inducers for extracellular polymeric substances (EPS) production in planktonic cells of Leptospirillum ferrooxidans and to study cell attachment to a mineral surface in comparison to cells not exposed to such substances. Leptospirillum ferrooxidans was successfully adapted to grow in a modified 9K medium at different concentrations of galactose (0.15, 0.25, 0.35%) and also at different initial ferrous iron concentrations (18, 27, 36 g/L), which are higher than 9K medium (9 g/L). The experiments were done in shake flasks using ferrous iron as energy source. A comparison of growth kinetics showed a decreasing of maximum specific growth rate of Leptospirillum ferrooxidans with increasing concentrations of galactose and initial ferrous iron. The EPS content increased and the EPS chemical composition (relative abundance of carbohydrates, proteins and ferric iron) changed with increasing concentrations of galactose and initial ferrous iron. Results revealed that the increase of the bacterial adhesion rather depended on the chemical composition, i.e. relative abundance of the constituents of the EPS, than on the total amount of EPS. The EPS induced by galactose seemed to be ...
Source: Research in Microbiology - Category: Microbiology Source Type: research