Traditional methods of obtaining arsenic have disadvantages such as high cost and high energy
consumption. Realgar is one of the most abundant arsenic sulphide minerals and usually treated as waste in
industry. The aim of the present study was to screen an arsenic tolerant bacterium used for bioleaching arsenic
An acidophilic iron-oxidizing bacterium BYQ-12 was isolated from Wudalianchi volcanic lake in
northeast China. BYQ-12 was a motile, rod-shaped gram-negative bacterium with an optimum growth at 30°C
and pH 2.5. 16S rDNA phylogeny showed that BYQ-12 was a new strain of Acidithiobacillus ferrooxidans
inhibitory concentrations (ICs) of arsenite and arsenate were 32 and 64 mM, respectively. A significant
second-order model was established using a Box–Behnken design of response surface methodology
(BBD-RSM) and it estimated that a maximum arsenic bioleaching rate (73.97%) could be obtained when the
pulp concentration, pH and initial ferrous ion concentration were set at optimized values of 0.95% w/v
and 3.68 g/L, respectively. SEM, EDS and XRD analyses also revealed that there was direct bioleaching besides
indirect electrochemical leaching in the arsenic bioleaching system.
Fromthis workwe were successful in isolating an acidophilic, arsenic tolerant ferrous iron-oxidizing
bacterium. The BBD-RSM analysis showed that maximum arsenic bioleaching rate obtained under optimum
conditions, and the most effective factor for arsenic leaching was initial ferrous ion concentration. These
revealed that BYQ-12 could be used for bioleaching of arsenic from arsenical minerals.