Dechloromonas denitrificans sp. nov., Flavobacterium denitrificans sp. nov., Paenibacillus anaericanus sp. nov. and Paenibacillus terrae strain MH72, N2O-producing bacteria isolated from the gut of the earthworm Aporrectodea caliginosa

Abstract

Earthworms emit nitrous oxide (N2O) via the activity of bacteria in their gut. Four N2O-producing facultative aerobes, ED1T, ED5T, MH21T and MH72, were isolated from the gut of the earthworm Aporrectodea caliginosa. The isolates produced N2O under conditions that simulated the microenvironment of the earthworm gut. ED1T and ED5T were Gram-negative, motile rods that carried out complete denitrification (i.e. the reduction of nitrate to N2) and contained membranous c-type cytochromes. ED1T grew optimally at 30 °C and pH 7. ED1T oxidized organic acids and reduced (per)chlorate, sulfate, nitrate and nitrite. The closest phylogenetic relative of ED1T was Dechloromonas agitata. ED5T grew optimally at 25 °C and pH 7. ED5T grew mainly on sugars, and nitrate and nitrite were used as alternative electron acceptors. The closest phylogenetic relatives of ED5T were Flavobacterium johnsoniae and Flavobacterium flevense. MH21T and MH72 were motile, spore-forming, rod-shaped bacteria with a three-layered cell wall. Sugars supported the growth of MH21T and MH72. Cells of MH21T grew in chains, were linked by connecting filaments and contained membranous b-type cytochromes. MH21T grew optimally at 30–35 °C and pH 7·7, grew by fermentation and reduced low amounts of nitrite to N2O. The closest phylogenetic relatives of MH21T were Paenibacillus borealis and Paenibacillus chibensis. Based on morphological, physiological and phylogenetic characteristics, ED1T (=DSM 15892T=ATCC BAA-841T), ED5T (=DSM 15936T=ATCC BAA-842T) and MH21T (=DSM 15890T=ATCC BAA-844T) are proposed as type strains of the novel species Dechloromonas denitrificans sp. nov., Flavobacterium denitrificans sp. nov. and Paenibacillus anaericanus sp. nov., respectively. MH72 is considered a new strain of Paenibacillus terrae.

Functional Diversity and Electron Donor Dependence of Microbial Populations Capable of U(VI) Reduction in Radionuclide-Contaminated Subsurface Sediments

“…The Betaproteobacteria genera Dechloromonas, Diaphorobacter, Acidovorax, and Castellaniella were abundant during the time points of shifting TEAPs in our microcosms, and these groups were detected previously in ORFRC subsurface sediments (2,15,48,61). Taxa within the Dechloromonas and Diaphorobacter genera reduce nitrate (22,28,29) and are likely responsible for mediating nitrate reduction in the carbon-amended microcosms. Dechloromonas spp.…”

“…Dechloromonas spp. have been shown to reduce sulfate (22), and we suggest that this group is responsible for the overlap in sulfate and U(VI) reduction observed in the ethanol-amended microcosms. The denitrifying bacteria of the genera Acidovorax and Castellaniella have been isolated from the ORFRC site (49,61), and the Acidovorax isolate can reduce U(VI) (49).…”

Clostridiaceae and Enterobacteriaceae as active fermenters in earthworm gut content

“…Alpha-, Beta-and GammaProteobacteria, Bacteroidetes, Actinobacteria and Firmicutes are potentially dominant taxa in the earthworm gut, as determined on the basis of 16S rRNA gene analyses (Furlong et al, 2002;Singleton et al, 2003;Knapp et al, 2009). Furthermore, species related to Aeromonadaceae, Comamonadaceae, Enterobacteriaceae, Flavobacteriaceae, Moraxellaceae, 'Paenibacillaceae', Pseudomonadaceae, Rhodocyclaceae, Sphingobacteriaceae and Actinobacteria have been isolated from the alimentary canals of earthworms (Ihssen et al, 2003;Horn et al, 2005;Byzov et al, 2009;Knapp et al, 2009). These findings show the diverse taxa that might be metabolically active in the earthworm gut, many of which might participate in polymer hydrolysis in situ (MartinCarnahan and Joseph, 2005;Bernadet and Bowman, 2006;Priest, 2009).…”

“…Although the occurrence of H 2 and organic acids is evidence for in situ fermentation, the fermentative microorganisms in the alimentary canal are unknown. Indeed, although diverse bacteria are present in the earthworm gut (Karsten and Drake, 1997;Furlong et al, 2002;Ihssen et al, 2003;Singleton et al, 2003;Horn et al, 2005;Byzov et al, 2009), active bacterial taxa remain unresolved.…”

Paenibacillus konsidensis sp. nov., isolated from a patient

“…nov.); 2, P. macerans DSM 24 T ; 3, P. sanguinis CIP 107938 T ; 4, P. timonensis CIP 108005 T ; 5, Paenibacillus anaericanus ATCC BAA-844 T . The biochemical profile of strain LBY T was determined by using the API 50 CH and API 20NE systems, and those of related species were from Djordjevic et al (2000), Heyndrickx et al (1996), Horn et al (2005) and Roux & Raoult (2004). All strains are catalasepositive.…”