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 1,275cm−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.
–Scanning electron microscopy–Fourier transform infrared spectroscopy–Proteome–Stress
World Journal of Microbiology and Biotechnology 04/2012; 27(6):1469-1479. · 1.53 Impact Factor