, 2002; Schäfer et al., 2005). The fact that some marine methyl halide-degrading bacteria do employ an enzyme system such as CmuA, which is specific for the degradation of the related compounds methyl chloride and methyl bromide, suggests ABT-263 ic50 that methyl halide degradation in the marine environment is not just a case of co-metabolism or detoxification of these compounds. On a scale relevant to microorganisms, and considering the vicinity of methyl halide-producing phytoplankton as potential hotspots of higher local concentrations, these trace gases may potentially be of selective advantage
for specialised bacterial populations that could utilise methyl halides as an energy and/or carbon source. Recent work by Halsey et al. (2012) suggests that degradation of C1 compounds including methyl chloride by the methylotrophic bacterium HTCC2181 may indeed be primarily linked to energy gain rather than carbon Z-VAD-FMK purchase assimilation. The enzymatic basis of methyl chloride degradation in strain HTCC2181 is as yet unidentified, and the genome sequence of strain HTCC2181 does not contain a gene encoding CmuA. Also of interest is the wide geographic and environmental distribution of some highly similar cmuA
sequences. Clade 2 was detected in the Arabian Sea, Plymouth coastal waters and Aminobacter spp. isolated from soils. Given the enrichment methods used, it is not possible to associate particular sequences or clades of cmuA with biogeochemical data from the research cruise in the Arabian Sea. The Arabian Sea, at the time of sampling, had a gradient of nutrient levels, from oligotrophic waters in the South to strongly eutrophic waters in the North. It is interesting to note that all station 1 (oligotrophic) clones grouped in clade 3, whereas clones from stations 4 and 9 (higher nutrient 17-DMAG (Alvespimycin) HCl levels) fell into clade 1. Further work with a higher resolution of cmuA diversity would be required to investigate whether this might indicate distinct ecological niches for these cmuA clades. The ecology and diversity of marine methyl
halide-degrading microorganisms and their role in the biogeochemical cycling of methyl halides remains a challenging field of biological oceanography. Further work is required to determine the extent to which methyl bromide is oxidised to CO2 or assimilated into microbial biomass in seawater. The diversity and activity of methyl halide-utilising bacteria in these environments should also be studied in more detail. Stable isotope probing with 13C-methyl bromide is a potential approach for detecting active methyl halide-degrading bacteria based on the assimilation of methyl halide carbon during growth-linked catabolism and has been used to detect bacteria related to Roseobacter and Methylophaga in samples from the English Channel (Neufeld et al., 2008).