Metagenomic analysis reveals adaptations to a cold-adapted lifestyle in a low-temperature acid mine drainage stream

Abstract

An acid mine drainage (pH 2.5-2.7) stream biofilm situated 250 m below ground in the low-temperature (6-10°C)Kristineberg mine, northern Sweden, contained a microbial community equipped for growth at low temperature and acidicpH. Metagenomic sequencing of the biofilm and planktonic fractions identified the most abundant microorganism to besimilar to the psychrotolerant acidophile, Acidithiobacillus ferrivorans. In addition, metagenome contigs were most similar toother Acidithiobacillus species, an Acidobacteria-like species, and a Gallionellaceae-like species. Analyses of the metagenomesindicated functional characteristics previously characterized as related to growth at low temperature including cold-shockproteins, several pathways for the production of compatible solutes and an anti-freeze protein. In addition, genes werepredicted to encode functions related to pH homeostasis and metal resistance related to growth in the acidicmetal-containing mine water. Metagenome analyses identified microorganisms capable of nitrogen fixation and exhibitinga primarily autotrophic lifestyle driven by the oxidation of the ferrous iron and inorganic sulfur compounds contained in thesulfidic mine waters. The study identified a low diversity of abundant microorganisms adapted to a low-temperature acidicenvironment as well as identifying some of the strategies the microorganisms employ to grow in this extreme environment. © FEMS 2015.