Electron micrograph by Dr. Patrick Viollier, Case Western Reserve University.

Caulobacter strain K31 is a stalked bacterium isolated from low temperature, chlorophenol-contaminated groundwater that may shed light on new mechanisms for biological chlorophenol degradation and bioremediation.

Caulobacter strain K31 was isolated in an enrichment culture for chlorophenol-tolerant bacteria in groundwater from Karkola, Finland, which percolates through nutrient-poor silt and clay, and is cold (7-8oC), oxygen-deficient, iron-rich, and mildly acidic (pH 6-6.5). The aquifer had been contaminated with high levels of chlorophenols for decades by a sawmill using polychlorophenol as a fungicide for lumber treatment. Genomic analysis of Caulobacter K31 may shed light on microbial chlorophenol metabolism and adaptations to subsurface aquatic niches, which may be useful in designing bioremediation strategies stalked bacteria of the Caulobacter family are ubiquitous in low nutrient aquatic habitats, particularly in biofilms. The polar stalk enhances nutrient uptake, while the holdfast organelle at the tip of the stalk anchors cells to substrates. Comparative analysis of nutrient acquisition, polar organelle development, and biofilm formation in strain K31, the freshwater strain Caulobacter crescentus, and the marine strain Maricaulis maris (also sequenced at JGI) will shed light on these features, while revealing adaptations to each niche. These include (for example) a novel pathway for D-xylose metabolism shared by K31 and C. crescentus, but absent in M. maris.