Figure 3 Comparison of genetic determinants

of chromate resistance in other bacterial strains versus Protein Tyrosine Kinase inhibitor B. cereus SJ1. (a) Genetic context of the chromate operon chrIA and arsenic resistance operon arsRBCDA in B. cereus SJ1. (b) Genetic context of the chromate operon chrIA1 in B. thuringiensis serovar konkukian str. 97-27. B. thuringiensis str. 97-27 [GenBank: AE017355]; B. anthracis str. Ames Ancestor [GenBank: AE017334]; B. anthracis str. Ames [GenBank: NC003997]; B. anthracis str. Sterne [GenBank: AE017225]; B. cereus E33L [GenBank: CP000001]; B. thuringiensis str. Al Hakam [GenBank: NC008600] and B. cereus ATCC 10987 [GenBank: AE017194]. Heavy metal tolerance of B. selleck screening library cereus SJ1 and putative genes responsible for heavy metal resistance Since B. cereus SJ1 was isolated from industrial wastewater containing various toxic elements in addition to chromium, the MICs of B. cereus SJ1 for these heavy metals were determined. For B. cereus SJ1, the highest resistance was found for As(V), while Hg(II) was the most toxic compared

to the other metal ions. When B. cereus SJ1 was incubated with increasing As concentration, no viable cells were recovered at concentrations above 50 mM As(V) and 4 mM As(III). The MICs of B. cereus SJ1 for Cu(II), Co(II), Ni(II), Cd(II), Ag(I) and Hg(II) were 0.9 mM, 0.8 mM, 0.7 mM, 0.2 mM, 0.02 mM and 0.007 mM, respectively. In order to survive in such unfavorable habitat, B. cereus SJ1 must have various determinants to tolerate such harsh conditions. For example, the copper concentration of the wastewater was as high as 0.65 mM and the MIC of B. cereus SJ1 to copper was 0.9 mM in R2A medium. When we analyzed the genome sequence of B. cereus SJ1, several genes related to copper resistance including copper-exporting P-type ATPase CopA, copper export protein CopC, copper resistance protein CopD, copper homeostasis protein CutC and two multicopper oxidases were identified. Furthermore, many other putative heptaminol heavy metal resistance

genes including those for As, Zn, Mn, Co, Cd, Te and Hg were also identified in the B. cereus SJ1 draft genome (Additional file 2). Chromate reduction is constitutive The difference in chromate reducing ability of B. cereus SJ1 with and without Cr(VI) induction was not significant (Figure 4A). Although less rapid chromate reduction was observed in B. cereus SJ1 cells induced before inoculation during the first 32 h, both cultures emerged at approximately 85% chromate reduced within 55 h. No abiotic Cr(VI) reduction was observed in LB medium without bacterial inoculation. Induction of genes possibly responsible for chromate reduction was also evaluated by RT-PCR. As shown in Figure 5, all the four nitR genes and the azoR gene were expressed constitutively.