© 2006 Heron Publishing—Victoria, Canada
Cultivation of methanogens from shallow marine sediments at Hydrate Ridge, Oregon
Melissa M. Kendall (1, 2, 3) and David R. Boone (1)
1. Biology Department, Portland State University, P.O. Box 751, Portland, Oregon 97207–0751, USA / 2. Corresponding author ([email protected]) / 3. Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390–9048, USA / Received August 22, 2005; accepted February 20, 2006; published online March 10, 2006
Little is known about the methanogenic degradation of acetate, the fate of molecular hydrogen and formate or the ability of methanogens to grow and produce methane in cold, anoxic marine sediments. The microbes that produce methane were examined in permanently cold, anoxic marine sediments at Hydrate Ridge (44°35' N, 125°10' W, depth 800 m). Sediment samples (15 to 35 cm deep) were collected from areas of active methane ebullition or areas where methane hydrates occurred. The samples were diluted into enrichment medium with formate, acetate or trimethylamine as catabolic substrate. After 2 years of incubation at 4 °C to 15 °C, enrichment cultures produced methane. PCR amplification and sequencing of the rRNA genes from the highest dilutions with growth suggested that each enrichment culture contained a single strain of methanogen. The level of sequence similarity (91 to 98%) to previously characterized prokaryotes suggested that these methanogens belonged to novel genera or species within the orders Methanomicrobiales and Methanosarcinales. Analysis of the 16S rRNA gene libraries from DNA extracted directly from the sediment samples revealed phylotypes that were either distantly related to cultivated methanogens or possible anaerobic methane oxidizers related to the ANME-1 and ANME-2 groups of the Archaea. However, no methanogenic sequences were detected, suggesting that methanogens represented only a small proportion of the archaeal community.
Keywords: cultivation, marine sediments, psychrotolerant.
ISSN 1472-3654 (Online) ISSN 1472-3646 (Print) Copyright © 2002–2007 Heron Publishing