Abstract

Microrganisms are well known for their unique ability to thrive in different lifestyles (e.g. planktonic or sessile) and environments, even within extreme ones. The most common and widespread lifestyle of microbes on earth is in form of biofilms, associated colonies of microorganisms embedded in a matrix of extracellular polymeric substances (EPS). Extremely acidophilic metal/sulfur-oxidizing microorganisms (AMOM) thrive in special ecological niches characterized by harsh conditions such as low pH (below 3) and high concentration of heavy metals across a broad range of temperatures. The molecular mechanisms controlling biofilm formation in acidophilic leaching bacteria are starting to be elucidated while these operating in archaea are far less explored. In this chapter we provide an overview about the biofilm lifestyle of AMOM. This includes surface sciences, microscopy, cell-cell communication, interspecies interactions as well as molecular and high-throughput studies. Current knowledge on the EPS composition and biofilm visualization of acidophiles is also included. Future perspectives in this field include the elucidation of EPS biosynthesis pathways and a comprehensive analysis of the chemical nature of the EPS polymers. Cell-cell communication and microbial interactions within multispecies biofilms of acidophiles are considered to be crucial determinants in controlling the metabolic activity of AMOM. Either for their biotechnological applications in biomining or in mitigation of acid mine drainage (AMD) generation, further studies in both fields may presumably reveal key perspectives to influence and control bioleaching of sulfide minerals.