Genome sequence of the arsenite oxidizing strain Aliihoeflea sp. 2WW

Introduction Bacterial transformation of arsenic has a high impact on the arsenic cycle in soil and water, threatening public health in both developing and industrial countries. Biological oxidation of the more mobile and toxic arsenite [As(III)] to the less toxic arsenate [As(V)] helps to alleviate this problem, due to subsequent adsorption of As(V) to metal oxides in ground waters. Here we report the draft genome sequence and annotation of Aliihoeflea sp. strain 2WW, the first reported As(III) oxidizing bacterium belonging to the genus Aliihoeflea. Methods Strain 2WW was isolated from a biofilter treating arsenic contaminated groundwater in the Northern part of Italy (Cremona, Lombardia). The genome sequence of Aliihoeflea sp. strain 2WW was obtained by Illumina paired-end and mate-pair sequencing. Results Aliihoeflea sp. strain 2WW oxidized As(III) completely to As(V) in the early exponential growth phase within 24 h at 30°C, 96 h at 15° C and within 350 h at 5°C. The draft genome was assembled into 273 contigs with a genome size of 4,122,965 bp and it was assembled in 10 scaffolds. It had a GC content of 64.37%, 4,139 putative coding sequences (CDS). Genome analysis indicated that Aliihoeflea sp. strain 2WW possessed two different genetic islands: one including 4 genes of the ars operon for arsenic resistance (arsR for regulatory protein, ACR3(2) for As(III) efflux pump, arsC for As(V) reductase and arsH for protein conferring high resistance to As(V)); the second containing an As(III) oxidase aioBA. Although strain 2WW possessed arsC, it was not able to reduce As(V) to As(III). In addition, many genes encoding putative metal (lead, cadmium, zinc, mercury and copper) transporters and cobalt-zinc-cadmium resistance protein (CzcD) were also identified in the genome. Conclusions These results indicate that Aliihoeflea sp. strain 2WW is an efficient psychrotolerant As(III) oxidizer that could be used in combination with iron-based materials for arsenic adsorption and removal from contaminated groundwater. The draft genome of strain 2WW provides information to explore arsenic as well as multiple metal resistance mechanisms. The draft genome sequence of strain 2WW has been deposited at GOLD database under the identification code Gi21948. Acknowledgments This work was supported by CARIPLO Foundation project 2010-2221 and by PRIN-MIUR 2010 project 2010JBNLJ7_004.