Phylogenetic characterization and quantification of ammonia-oxidizing archaea and bacteria from Lake Kivu in a long-term microcosm incubation

Autors/ores

  • Anna Plasencia Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona.
  • Frederic Gich Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona.
  • Mireia Fillol Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona.
  • Carles M. Borrego Water Quality and Microbial Diversity, Catalan Institute for Water Research (ICRA), Girona.

Paraules clau:

ammonia-oxidizing archaea and bacteria, ammonia monooxygenase alpha subunit (amoA), Lake Kivu, microcosm, multi-color CARD-FISH

Resum

A microcosm cultivation-based method was set up to investigate the growth of ammonia-oxidizing archaea (AOA), isolated from a water sample acquired at a depth of 50 m from the northern basin of Lake Kivu. For this purpose, both CARD-FISH and qPCR targeting of archaeal 16S rRNA and amoA genes were used. Archaeal cell growth at the end of the 246-day microcosm experiment accounted for 35 % of the SybrGold-stained cells, which corresponded to 6.61 × 106 cells/ml and 1.76 ± 0.09 × 106 archaeal 16S rRNA gene copies/ml. Clone libraries and DGGE fingerprinting confirmed the dominance of AOA phylotypes in the archaeal community microcosm. The majority of the identified archaeal 16S rRNA gene sequences in the clone libraries were affiliated with Thaumarchaeota Marine Group 1.1a. Subsequent cultivation of the AOA community on deep-well microtiter plates in medium containing different carbon sources to stimulate archaeal growth failed to show significant differences in archaeal abundance (ANOVA t14 = –1.058, P = 0.308 and ANOVA t14 = 1.584, P = 0.135 for yeast extract and simple organic acids, respectively). The lack of growth stimulation by organic compounds is in concordance with the oligotrophic status of Lake Kivu. Finally, the addition of antibiotics to the growth medium resulted in archaeal cell counts that were significantly lower than those obtained from cultures in antibiotic-free medium (ANOVA t14 = 12.12, P < 0.001). [Int Microbiol 2013; 16(3):177-189]

Keywords: ammonia-oxidizing archaea and bacteria · ammonia monooxygenase alpha subunit (amoA) · Lake Kivu ·
microcosm · multi-color CARD-FISH

Descàrregues

Número

Vol. 16 Núm. 3 (2013)

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Articles

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