Naegleria fowleri Detected in Grand Teton National Park Hot Springs.

The free-living thermophilic amoeba Naegleria fowleri (N. fowleri) causes the highly fatal disease primary amoebic meningoencephalitis. The environmental conditions that are favorable to the growth and proliferation of N. fowleri are not well-defined, especially in northern regions of the United States. In this study, we used culture-based methods and multiple molecular approaches to detect and analyzeN. fowleri and other Naegleria spp. in water, sediment, and biofilm samples from five hot spring sites in Grand Teton National Park, Wyoming, U.S.A. These results provide the first detections of N. fowleri in Grand Teton National Park and provide new insights into the distribution of pathogenic N. fowleri and other nonpathogenic Naegleria spp. in natural thermal water systems in northern latitudes.

Thermocrinis minervae sp. nov., a hydrogen- and sulfur-oxidizing, thermophilic member of the Aquificales from a Costa Rican terrestrial hot spring.

A thermophilic bacterium, designated strain CR11(T), was isolated from a filamentous sample collected from a terrestrial hot spring on the south-western foothills of the Rincón volcano in Costa Rica. The Gram-negative cells are approximately 2.4-3.9 microm long and 0.5-0.6 microm wide and are motile rods with polar flagella. Strain CR11(T) grows between 65 and 85 degrees C (optimum 75 degrees C, doubling time 4.5 h) and between pH 4.8 and 7.8 (optimum pH 5.9-6.5). The isolate grows chemolithotrophically with S(0), S(2)O(2)(3)(-) or H(2) as the electron donor and with O(2) (up to 16 %, v/v) as the sole electron acceptor. The isolate can grow on mannose, glucose, maltose, succinate, peptone, Casamino acids, starch, citrate and yeast extract in the presence of oxygen (4 %) and S(0). Growth occurs only at NaCl concentrations below 0.4 % (w/v). The G+C content of strain CR11(T) is 40.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence places the strain as a close relative of Thermocrinis ruber OC 1/4(T) (95.7 % sequence similarity). Based on phylogenetic and physiological characteristics, we propose the name Thermocrinis minervae sp. nov., with CR11(T) (=DSM 19557(T) =ATCC BAA-1533(T)) as the type strain.

Anaerobic oxidation of methane: mechanisms, bioenergetics, and the ecology of associated microorganisms.

Microbially mediated anaerobic oxidation of methane (AOM) moderates the input of methane, an important greenhouse gas, to the atmosphere by consuming methane produced in various marine, terrestrial, and subsurface environments. AOM coupled to sulfate reduction has been most extensively studied because of the abundance of sulfate in marine systems, but electron acceptors otherthan sulfate are more energetically favorable. Phylogenetic trees based on 16S rRNA gene clone libraries derived from microbial communities where AOM occurs show evidence of diverse, methanotrophic archaea (ANME) closely associated with sulfate-reducing bacteria, but these organisms have not yet been isolated as pure cultures. Several biochemical pathways for AOM have been proposed, including reverse methanogenesis, acetogenesis, and methylogenesis, and both culture-dependent and independent techniques have provided some clues to howthese communities function. Still, questions remain regarding the diversity, physiology, and metabolic restrictions of AOM-related organisms.