Heat and phosphate starvation effects on the proteome, morphology and chemical composition of the biomining bacteria Acidithiobacillus ferrooxidans

Abstract

Acidithiobacillus ferrooxidans is a Gram negative, acidophilic, chemolithoautotrophic bacterium that plays an important role in metal bioleaching. During bioleaching, the cells are subjected to changes in the growth temperature and nutrients starvation. The aim of this study was to gather information about the response of the A.ferrooxidans Brazilian strain LR to K2HPO4 starvation and heat stress through investigation of cellular morphology, chemical composition and differential proteome. The scanning electron microscopic results showed that under the tested stress conditions, A. ferrooxidans cells became elongated while the Fourier transform infrared spectroscopy (FT-IR) analysis showed alterations in the wavenumbers between 850 and 1,275 cm(-1), which are related to carbohydrates, phospholipids and phosphoproteins. These findings indicate that the bacterial cell surface is affected by the tested stress conditions. A proteomic analysis, using 2-DE and tandem mass spectrometry, enabled the identification of 44 differentially expressed protein spots, being 30 due to heat stress (40°C) and 14 due to K2HPO4 starvation. The identified proteins belonged to 11 different functional categories, including protein fate, energy metabolism and cellular processes. The upregulated proteins were mainly from protein fate and energy metabolism categories. The obtained results provide evidences that A. ferrooxidans LR responds to heat stress and K2HPO4 starvation by inducing alterations in cellular morphology and chemical composition of the cell surface. Also, the identification of several proteins involved in protein fate suggests that the bacteria cellular homesostasis was affected. In addition, the identification of proteins from different functional categories indicates that the A. ferrooxidans response to higher than optimal temperatures and phosphate starvation involves global changes in its physiology.

Phosphate starvation enhances the pathogenesis of Bacillus anthracis

“…Moreover, confocal microscopic data unveiled the fact that in low phosphate conditions, the cells were more elongated as compared to cells grown under normal phosphate conditions. This is concordant with what observed in other bacteria like M. tuberculosis (Rifat et al, 2009), Acidithiobacillus ferrooxidans (Ribeiro et al, 2011), Staphylococcus aureus (Watson et al, 1998), Vibrio cholerae (Holmquist and Kjelleberg, 1993), where cell elongation under phosphate limitation was found to be a strategy to meet their phosphate demand by increasing the surface to volume ratio (Young, 2006). Further studies also revealed that phosphate starved B. anthracis, become more tolerant toward replication and translation inhibitors.…”

Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions

“…prosperus T was cultured in high salt conditions; and a serine protease, DO/DeqQ family protein (2.0 fold) that has a chaperone function and also has a higher concentration in the At. ferrooxidans response to heat stress (Ribeiro et al, 2011). Finally, the major outer membrane protein 40 had 1.8 fold lower concentration in high salt conditions, potentially to reduce the influx of chloride (Csonka and Hanson, 1991).…”

Kinetics of anaerobic elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans and protein identification by comparative 2-DE-MS/MS

“…remains unclear. Several proteomic studies of A. ferrooxidans have been already performed to characterize protein expression under different environmental conditions including phosphate starvation (Jerez et al 1992), pH perturbations (Amaro et al 1991), copper and other heavy metals exposure (Novo et al 2000), oxidation of metal sulfides, thiosulfate, elemental sulfur and ferrous iron (Bouchal et al 2006;Chi et al 2007;He et al 2005;Ramirez et al 2004), and recently temperature adaptation (Mykytczuk et al 2011;Ribeiro et al 2011). Ohmura et al (2002) purified significant amounts of an acid-stable 28-kDa monomer c-type cytochrome under anaerobic conditions in A. ferrooxidans strain JCM 7811.…”