Phylogenetic characterization and quantification of ammonia-oxidizing archaea and bacteria from Lake Kivu in a long-term microcosm incubation Authors 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. Keywords: ammonia-oxidizing archaea and bacteria, ammonia monooxygenase alpha subunit (amoA), Lake Kivu, microcosm, multi-color CARD-FISH Abstract 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 Downloads PDF Issue Vol. 16 No. 3 (2013) Section Research Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. The corresponding author signs for and accepts responsability for releasing this material and will act on behalf of any and all coauthors regarding the editorial review and publication process.If an article is accepted for publication in International Microbiology, the authors (or other copyright holder) must transfer to the journal the right–not exclusive–to reproduce and distribute the article including reprints, translations, photographic reproductions, microform, electronic form (offline, online) or any other reproductions of similar nature. Nevertheless, all article in International Microbiology will be available on the Internet to any reader at no cost. The journal allows users to freely download, copy, print, distribute, search, and link to the full text of any article, provided the authorship and source of the published article is cited. The copyright owner's consent does not include copying for new works, or resale. In these cases, the specific written permission of International Microbiology must first be obtained.Authors are requested to create a link to the published article on the journal's website. The link must be accompanied by the following text: "The original publication is available on LINK at <http://www.im.microbios.org>. Please use the appropiate URL for the article in LINK. Articles disseminated via LINK are indexed, abstracted, and referenced by many abstracting and information services, bibliographic networks, subscription agencies, library networks, and consortia.
