Methyl halide production by cultures of marine proteobacteria erythrobacter and pseudomonas and isolated bacteria from brackish water

Abstract

Bacteria were investigated for the production of methyl chloride, methyl bromide, and methyl iodide from brackish water. Bacteria were isolated and incubated at 25°C, and the concentrations of methyl halides in the gas phase above cultured samples were determined using dynamic headspace gas chromatography/mass spectrometry. Bacterial growth was monitored by measuring the optical density at 600 nm. Bacteria isolated from brackish water were identified by 16 Svedberg unit ribosomal-ribonucleic acid (16S rRNA) gene sequence analysis. Five genetically different strains of bacteria belonging to Erythrobacter or Pseudomonas produced methyl chloride, methyl bromide, and methyl iodide for several days in the culture. Cultured strains of these genera also released methyl chloride, methyl bromide, and/or methyl iodide. Maximum production rates for methyl halide were observed in the culture of isolated bacteria (HKF-1) belonging to Erythrobacter. The production rates for methyl chloride, methyl bromide, and methyl iodide by HKF-1 were 537 ±124, 67.4 ± 25.7, and 48.8 ±9.8 pmol L-1 h-1, respectively. Aquatic bacteria could be a new source of methyl halides in marine environments. © 2012, by the Association for the Sciences of Limnology and Oceanography, Inc.