Shotgun proteomics study of early biofilm formation process ofAcidithiobacillus ferrooxidansATCC 23270 on pyrite

Abstract

Acidithiobacillus ferrooxidans is a chemolithoautotrophic, mesophilic Gram-negative bacterium able to oxidize ferrous iron, sulfur, and metal sulfides. It forms monolayer biofilms where extracellular polymeric substances are essential for cell attachment and metal sulfide leaching. High-throughput proteomics has been applied to study the early process of biofilm formation on pyrite by At. ferrooxidans ATCC 23270. After 24 h contact with the mineral, planktonic and sessile (biofilm) cell subpopulations were separated and proteins extracted. In total, 1319 proteins were detected in both samples. Sixty-two of these were found to be increased in biofilms. Additionally, 25 proteins were found to be decreased in the biofilm cell subpopulation. Three transcriptional factors were found to be increased or decreased among both cell subpopulations, suggesting their potential involvement in the regulation of these processes. Although no significant differences were observed for the known proteins related to ferrous iron and sulfur oxidation pathways among both cell subpopulations, the results presented here show that the early steps of At. ferrooxidans biofilm formation consist of a set of metabolic adaptations following cell attachment to the mineral surface. Functions such as extracellular polymeric substances biosynthesis seem to be pivotal. This first high-throughput proteomic study may also contribute to the annotation of several unknown At. ferrooxidans proteins found.

Response to copper of Acidithiobacillus ferrooxidans ATCC 23270 grown in elemental sulfur

“…In addition, a putative nucleotide-diphosphate reductase protein (NrdA) (AFE_2638) was overexpressed in A. ferrooxidans cells grown in sulfur in the presence of copper (Table 2). Very recently, an increased level of (NrdA) (AFE_2638) was reported in biofilms of A. ferrooxidans ATCC 23270 grown in pyrite [57]. On the other hand, this protein did not change its levels in the presence of copper in ferrous iron-grown cells (Table 5).…”

Manipulation of pyrite colonization and leaching by iron-oxidizing Acidithiobacillus species

“…These changes may be related to a glutathione-driven response against an increased exposure of cells to ROS after 24 h contact with pyrite. Also, in the PP, a thiol-dependent peroxidase (OsmC/Ohr family), probably involved in defense against oxidative stress caused by exposure to organic hydroperoxides, was found increased (Vera et al 2013a). In addition, A. ferrooxidans T GR gene expression was previously found to be induced after bacterial exposure to copper, suggesting its involvement in recovering GSH pools and cell homeostasis (Xia et al 2011).…”

“…By high-throughput proteomics, it was shown that A. ferrooxidans T undergoes several metabolic adaptations after 24 h of biofilm formation on pyrite. Functions such as EPS synthesis and biosynthesis of electron-carriercontaining molecules as well as osmotic and oxidative stress responses were enhanced in biofilm cells (Vera et al 2013a).…”

The Confluence of Heavy Metal Biooxidation and Heavy Metal Resistance: Implications for Bioleaching by Extreme Thermoacidophiles

“…Early biofilm formation involves capsular polysaccharide production (CPS), up-regulation of genes related to pili and EPS production, motility and quorum sensing, synthesis of cell wall structures, specific proteases, stress response chaperons, and mixed acid fermentation [316][317][318][319]. Proteomic analysis revealed similar results with the addition of increased production of osmolarity sensing, outer-membrane efflux, iron uptake, sulfate uptake and assimilation, glutathione/coenzyme/cofactor biosynthesis, lipoproteins, and nucleotidases [320].…”