Transcriptomic Analysis of the Dual Response of Rhodococcus aetherivorans BCP1 to Inorganic Arsenic Oxyanions
Abstract
Bacterial strains belonging to the genus Rhodococcus are able to degrade various toxic organic compounds and tolerate high concentrations of metal (loid)s. We have previously shown that Rhodococcus aetherivorans BCP1 is resistant to various levels of the two arsenic inorganic species, arsenite [As(III)] and arsenate [As(V)].
However, while arsenite showed toxic effects at concentrations as low as 5 mM, arsenate at 30 mM boosted the growth rate of BCP1 cells and was toxic only at concentrations of .100 mM. Since such behavior could be linked to peculiar aspects of its metabolism, the transcriptomic analysis of BCP1 cells exposed to 5 mM As(III) and 30 mM As(V) was performed in this work.
The aim was to clarify the mechanisms underlying the arsenic stress response of the two growth phenotypes in the presence of the two different oxyanions. The results revealed that As (III) induced higher activity of reactive oxygen species (ROS)-scavenging enzymes than As(V) in relation to the expression of enzymes involved in cellular damage recovery and redox buffers/cofactors (ergothioneine, mycofactocin, and mycothiol).
Further, As(III) downregulated pathways related to cell division, while both oxyanions downregulated genes involved in glycolysis. Notably, As(V) induced the expression of enzymes participating in the synthesis of metallophores and rearranged the central and energetic metabolism, also inducing alternative pathways for ATP synthesis and glucose consumption.
This study, in providing transcriptomic data on R. aetherivorans exposed to arsenic oxyanions, sheds some light on the plasticity of the rhodococcal response to arsenic stress, which may be important for the improvement of biotechnological applications.