Producción de sustancias poliméricas extracelulares de los microorganismos acidófilos Leptospirillum ferrooxidans y Acidithiobacillus thiooxidans en medio puro y modificado con un mineral aurífero refractario.

Abstract

In the industry biooxidation is used as a pre-treatment for gold recovery. The extracellular polymeric substances (EPS) are related to biofilm formation and, together, with the ferric ions they oxidize the mineral. For this reason the main objective of this research was inducting the production of EPS in microbial cultures of the species Leptospirillum ferrooxidans and Acidithiobacillus thiooxidans. The microorganisms used were Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans, which grew at pH = 1.8 and 1.3 respectively and with a temperature of 30 °C. They were also adapted to different galactose concentrations of (0, 0.15, 0.25 and 0.35%), iron (9, 18, 27 and 36 g / L) and 2% p/v of ore. Growth kinetics, EPS production, oxidation of iron and sulphates were determined. The highest amounts of EPS in Acidithiobacillus thiooxidans cultures were obtained using 0.25% of galactose, while for the Leptospirillum ferrooxidans cultures the highest production of EPS was obtained with an iron concentration of 27 g/L. The mineral induces the production of EPS, but in a fewer extent to the inducers mentioned before.