Comparative genomics of the oxidative stress response in bioleaching microorganisms

摘要

Bioleaching acidophiles inhabit environments with unusually high concentrations of iron that can potentially cause oxidative stress via the Fenton reaction in which dangerous reactive oxygen species (ROS) are generated. ROS can cause damage to proteins, nucleic acids, lipids and other macromolecules and thus have deleterious effects on cell growth and survival. Many of these microorganisms are chemolithotrophs with unusually high oxygen consumption rates that may exacerbate the problem of oxidative stress. Although some knowledge has been gained in recent years regarding the oxidative stress response in a few acidophiles, the general strategies used by them to face ROS challenges are still inadequately understood. Comparative genomics and multiple bioinformatic tools were used to explore 43 sequenced genomes of acidophilic bacteria and archaea in an attempt to reconstruct their individual oxidative stress responses and to look for conserved strategies. The analyses revealed that acidophiles lack genes encoding typical oxidative stress response regulators and have an underrepresentation of classical ROS consumption enzymes ( e. g. catalases) and an overrepresentation of repair systems compared to phylogenetically related neutrophiles. This suggests that stress mitigation is an active strategy in acidophiles confronting unavoidable ROS formation in their environment. Insights into the oxidative stress response in bioleaching acidophiles may in the long run contribute to a better understanding of both basic and applied issues that influence the efficiency of heap bioleaching.