Acidithiobacillus thiooxidans secretome containing a newly described lipoprotein Licanantase enhances chalcopyrite bioleaching rate

Abstract

The nature of the mineral–bacteria interphase where electron and mass transfer processes occur is a key element of the bioleaching processes of sulfide minerals. This interphase is composed of proteins, metabolites, and other compounds embedded in extracellular polymeric substances mainly consisting of sugars and lipids (Gehrke et al., Appl Environ Microbiol 64(7):2743–2747, 1998). On this respect, despite Acidithiobacilli—a ubiquitous bacterial genera in bioleaching processes (Rawlings, Microb Cell Fact 4(1):13, 2005)—has long been recognized as secreting bacteria (Jones and Starkey, J Bacteriol 82:788–789, 1961; Schaeffer and Umbreit, J Bacteriol 85:492–493, 1963), few studies have been carried out in order to clarify the nature and the role of the secreted protein component: the secretome. This work characterizes for the first time the sulfur (meta)secretome of Acidithiobacillus thiooxidans strain DSM 17318 in pure and mixed cultures with Acidithiobacillus ferrooxidans DSM 16786, identifying the major component of these secreted fractions as a single lipoprotein named here as Licanantase. Bioleaching assays with the addition of Licanantase-enriched concentrated secretome fractions show that this newly found lipoprotein as an active protein additive exerts an increasing effect on chalcopyrite bioleaching rate.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-010-3063-8) contains supplementary material, which is available to authorized users.

Stoichiometric modeling of oxidation of reduced inorganic sulfur compounds (Riscs) in Acidithiobacillus thiooxidans

“…Culture purity and quantification was assessed from purified genomic DNA extracted by phenol:chloroform:isopropyl alcohol method by specific q‐PCR determinations with primers designed for specific 16S rRNA gene of At. thiooxidans DSM 17318 and total bacteria as proposed previously (Bobadilla et al, 2011) with comparable values for both determinations in the same order of magnitude.…”

“…At. thiooxidans DSM 17318 (strain patented by BioSigma ‘S.A.’ for its use in bioleaching processes) was grown in a 1 L bioreactor (Model BioFlo 110; New Brunswick, Edison, NJ) operated at 30°C and fed in batch cyclic mode (withdrawal of 500 mL of culture followed by replacement with the same volume of fresh medium every 48 h) with a based medium (pH 1.8) as described previously (Bobadilla et al, 2011) supplemented with 1% sulfur (99.5% purity; Sigma–Aldrich, St. Louis, MO). The culture was continuously aerated (1 L/min) and stirred (250 rpm).…”

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

“…thiooxidans/At. ferrooxidans metasecretomes has been partially purified and its external addition slightly enhanced chalcopyrite bioleaching .…”

Assessment of Bioleaching Microbial Community Structure and Function Based on Next-Generation Sequencing Technologies

“…In leaching processes, iron oxidation and sulfur reduction by bioleaching microbes occur mainly in the extracellular space. In agreement with this, several proteomics studies revealed protein-associated molecules present in the extracellular polymeric substance (EPS) layers that are able to accumulate sulfur and enhance the bioleaching of metal sulphides [15]. Researchers determined the differential response in the proteome of the acidophilic halophile, Acidihalobacter prosperus DSM 14174 (strain V6) at low and high chloride ion level, to thus understand the mechanism of tolerance to high chloride ion stress in the presence of low pH [16].…”