Isolation selleck of chromate-resistant and reducing bacteria was performed as described [34]. The abilities of the chromate-resistant bacteria to reduce Cr(VI) (K2CrO4) were determined using a spectrophotometric method using the reagent 1, 5-diphenylcarbazide (DPC) [34]. Several chromate-resistant bacteria were isolated and strain SJ1 was chosen for this study. The 16 S rDNA of strain SJ1 was obtained from the genome sequence (see below) and analyzed by BlastN searching tools http://​www.​ncbi.​nlm.​nih.​gov/​blast. Cell morphologies were examined under a scanning electron microscope (SEM; JSM-6390, JEOL,

Japan) with 20,000 V accelerating voltage and 15,000 times enlargement. Determination of the minimal inhibitory concentrations (MICs) of heavy and transition metals and metalloids The MIC, defined as the lowest concentration of heavy metals that inhibited growth in R2A broth (Becton Dickinson, MD, USA), was performed with strain SJ1. A 1% inoculum of an overnight

culture was introduced into R2A medium amended with different concentrations of CuCl2, NiCl2, Co(NO3)2, Na2HAsO4, NaAsO2, HgCl2, CdCl2 and AgNO3, incubated at 37°C on a rotary shaker at 200 rpm for 3 days. MIC values were determined spectrophotometrically at OD600. Chromate resistance and reduction assays The exponential phase cultures of uninduced, and induced with 1 mM K2Cr2O6 for 8 h, were adjusted to the same OD600. One hundred microliters of each culture Selleckchem Selumetinib was added to 10 ml fresh LB medium with increasing amounts of K2CrO4, and incubated at 37°C with 200 rpm shaking for 3 days. The OD600 values were then determined spectrophotometrically. For chromate reduction, the uninduced and induced cultures were prepared as above and inoculated into 100 ml LB medium amended with 1 mM

K2CrO4 and incubated at 37°C on a rotary shaker at 200 rpm for about 60 h. The residual Cr(VI) concentration was monitored as described above. LB medium with 1 mM K2CrO4 without bacterial cells was incubated Metalloexopeptidase as a negative control to monitor abiotic chromate reduction. Sequencing of the B. cereus SJ1 genome High-molecular-mass genomic DNA isolated from B. cereus SJ1 using Blood & Cell Culture DNA Mini Kit (Qiagen, MD, USA) was used to construct a 4 kb to 40 kb random genomic library. Whole genome shotgun sequencing was performed by the University of Arizona Genetics Core facility, using a Roche 454 Genome Sequencer FLX instrument. The B. cereus SJ1 DNA sample was loaded onto one region of a standard four-region plate. A local Linux computing cluster was used for signal processing on the images produced by the FLX instrument. The Roche gsassembler software version 2.0.01 was used for de novo assembly of the 271,408 reads. Using the default assembly parameters, 141 contigs of length greater than 500 bp were built, along with 127 shorter contigs. These 268 contigs were submitted to the RAST annotation server [35] for subsystem classification and functional annotation.