The Effect of Metal Ions on the Growth and Ferrous Iron Oxidation by <i>Leptospirillum ferriphilum</i> CC Isolated from Armenia Mine Sites

• Main Authors: Anna Khachatryan, Narine Vardanyan, Arevik Vardanyan, Ruiyong Zhang, Laura Castro
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Metals
• Subjects: <i>leptospirillum ferriphilum</i>; iron-oxidizing kinetics; specific grow rate; saturation constant; tolerance to metal ions
• Online Access: https://www.mdpi.com/2075-4701/11/3/425

The aim of this study is to investigate the potential of newly isolated strain <i>Leptospirillum</i> (<i>L.</i>) <i>ferriphilum</i> CC for bioleaching of pyrite and chalcopyrite in pure or mixed culture with other iron- and/or sulfur-oxidizing bacteria. In this paper, kinetics of ferrous iron (Fe²⁺) oxidation by newly isolated strain <i>Leptospirillum</i> (<i>L.</i>) <i>ferriphilum</i> CC was studied. The effect of initial Fe²⁺ in the concentration range of 50–400 mM on bacterial growth and iron oxidation was studied. It was shown that microbial Fe²⁺ oxidation was competitively inhibited by Fe³⁺. The influence of copper, zinc, nickel and cobalt ions on the oxidation of Fe²⁺ by <i>L. ferriphilum</i> CC was also studied. Minimal inhibitory concentrations (MIC) for each metal ion were determined. The toxicity of the ions was found to be as follows: Co > Zn > Ni > Cu. The comparison of iron oxidation kinetic parameters of <i>L. ferriphilum CC</i> with other strains of <i>L. ferriphilum</i> indicates the high potential of strain <i>L. ferriphilum </i>CC for biogenic regeneration of concentrated ferric iron (Fe³⁺) in bioleaching processes of ores and ore concentrates. Bioleaching tests indicated that the newly isolated <i>L. ferriphilum</i> CC can be a prospective strain for the bioleaching of sulfide minerals in pure culture or in association with other iron- and/or sulfur-oxidizing bacteria.