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4586

The authors wish to make the following correction to this paper [...]

SummaryThe Candidate Phyla Radiation (CPR) is a very large group of bacteria with no pure culture representatives, first discovered by metagenomic analyses. Within the CPR, candidate phylum Parcubacteria (previously referred to as OD1) within the candidate superphylum Patescibacteria is prevalent in anoxic sediments and groundwater. Previously, we had identified a specific member of the Parcubacteria (referred to as DGGOD1a) as an important member of a methanogenic benzene-degrading consortium. Phylogenetic analyses herein place DGGOD1a within theCandidateclade Nealsonbacteria. Because of its persistence over many years, we hypothesized thatCa. Nealsonbacteria DGGOD1a must serve an important role in sustaining anaerobic benzene metabolism in the consortium. To try to identify its growth substrate, we amended the culture with a variety of defined compounds (pyruvate, acetate, hydrogen, DNA, phospholipid), as well as crude culture lysate and three subfractions thereof. We observed the greatest (10 fold) increase in the absolute abundance ofCa. Nealsonbacteria DGGOD1a only when the consortium was amended with crude cell lysate. These results implicateCa. Nealsonbacteria in biomass recycling. Fluorescent in situ hybridization and cryogenic transmission electron microscope images revealed thatCa. Nealsonbacteria DGGOD1a cells were attached to larger archaealMethanothrixcells. This apparent epibiont lifestyle was supported by metabolic predictions from a manually curated complete genome. This is one of the first examples of bacterial-archaeal episymbiosis and may be a feature of otherCa. Nealsonbacteria found in anoxic environments.

Anaerobic methanotrophic (ANME) archaea can drive anaerobic oxidation of methane (AOM) using solid iron or manganese oxides as the electron acceptors, hypothetically via direct extracellular electron transfer (EET). This study investigated the response of Candidatus “Methanoperedens nitroreducens TS” (type strain), an ANME archaeon previously characterized to perform nitrate-dependent AOM, to an Fe(III)-amended condition over a prolonged period. Simultaneous consumption of methane and production of dissolved Fe(II) were observed for more than 500 days in the presence of Ca. “M. nitroreducens TS,” indicating that this archaeon can carry out Fe(III)-dependent AOM for a long period. Ca. “M. nitroreducens TS” possesses multiple multiheme c-type cytochromes (MHCs), suggesting that it may have the capability to reduce Fe(III) via EET. Intriguingly, most of these MHCs are orthologous to those identified in Candidatus “Methanoperedens ferrireducens,” an Fe(III)-reducing ANME archaeon. In contrast, the population of Ca. “M. nitroreducens TS” declined and was eventually replaced by Ca. “M. ferrireducens,” implying niche differentiation between these two ANME archaea in the environment.

Anaerobic methanotrophic (ANME) archaea have recently been reported to be capable of using insoluble extracellular electron acceptors via extracellular electron transfer (EET). In this study, we investigated EET by a microbial community dominated by “Candidatus Methanoperedens” archaea at the anode of a bioelectrochemical system (BES) poised at 0 V vs. standard hydrogen electrode (SHE), in this way measuring current as a direct proxy of EET by this community. After inoculation of the BES, the maximum current density was 274 mA m–2 (stable current up to 39 mA m–2). Concomitant conversion of 13CH4 into 13CO2 demonstrated that current production was methane-dependent, with 38% of the current attributed directly to methane supply. Based on the current production and methane uptake in a closed system, the Coulombic efficiency was about 17%. Polarization curves demonstrated that the current was limited by microbial activity at potentials above 0 V. The metatranscriptome of the inoculum was mined for the expression of c-type cytochromes potentially used for EET, which led to the identification of several multiheme c-type cytochrome-encoding genes among the most abundant transcripts in “Ca. Methanoperedens.” Our study provides strong indications of EET in ANME archaea and describes a system in which ANME-mediated EET can be investigated under laboratory conditions, which provides new research opportunities for mechanistic studies and possibly the generation of axenic ANME cultures.

Epibiotic bacteria are known to live on and off bacterial cells. Here, we describe the ultramicrobacterial anaerobic epibiont OP3 LiM living on Archaea and Bacteria .

Amaç: Bu çalışmada Elma Çoklu Sürgün Fitoplazma Hastalığı (EÇSF) (Candidatus Pyhtoplasma mali)’nın biyolojik mücadelesinde endofitik fungusların etkinliğinin belirlenmesi amaçlanmıştır. Böylece pratikte kimyasal mücadele olanağı olmayan hastalık etmenine karşı farklı kontrol stratejileri geliştirilebilme olanağının sağlanması hedeflenmiştir. Yöntem ve Bulgular: EÇSF ve endofit fungus izolasyonları için toplam 50 farklı bahçe gezilerek fitoplazma testleri için 360 ağaçtan, endofit funguslar için ise hem sağlıklı hem de fitoplazma ile enfekteli 198 ağaçtan bitki örneği toplanmıştır. Fitoplazma açısından testlenen 360 örnekten 29 tanesi ‘Ca. P. mali’ ile enfekteli bulunmuştur. ‘Ca. P. mali’ ile enfekteli ve sağlıklı elma ağaçlarından endofit fungus türleri izole edilmiş, bu fungusların morfolojik ve moleküler tanısı ile birlikte patojenisite çalışmaları yapılmıştır. Sağlıklı elma ağaçlarından en yaygın olarak izole edilen endofit funguslardan Epicoccum nigrum, Aureobasidium pullulans, Ulocladium consortiale’nin EÇSF hastalığına karşı etkinlikleri incelenmiştir. Her bir fungus izolatının EÇSF hastalık yoğunluğunu farklı düzeylerde etkilediği, en yüksek etkinin A. pullulans’a ait olduğu ve EÇSF hastalık yoğunluğunu uygulama sonrası %34,18 etki değeri ile azalttığı belirlenmiştir. Genel Yorum: EÇSF hastalığının etkili bir kimyasal mücadelesinin bulunmaması ve etmenin karantina listesinde yer alması nedeniyle olası biyolojik mücadele uygulamaları oldukça önemlidir. EÇSF ile enfekteli ağaçlara inokule edilen 3 farklı endofit fungus türünden Aureobasidium pullulans’ın fitoplazma yoğunluğunu diğer 2 etmene göre daha fazla azaltmasından dolayı A. pullulans hastalıkla mücadelede kullanılabilecek biyolojik mücadele ajanı olabilir. Çalışmanın Önemi ve Etkisi: Bu çalışma ile biyolojik mücadele ajanı olan endofit fungusların elmalarda EÇSF hastalığı üzerine etkileri Türkiye’de ilk kez araştırılmış ve hastalığın kontrol stratejilerinin oluşturulmasında önemli ön bulgular elde edilmiştir.

AbstractGeothermal environments, including terrestrial hot springs and deep-sea hydrothermal sediments, often contain many poorly understood lineages of archaea. Here, we recovered ten metagenome-assembled genomes (MAGs) from geothermal sediments and propose that they constitute a new archaeal class within the TACK superphylum, “Candidatus Culexarchaeia”, named after the Culex Basin in Yellowstone National Park. Culexarchaeia harbor distinct sets of proteins involved in key cellular processes that are either phylogenetically divergent or are absent from other closely related TACK lineages, with a particular divergence in cell division and cytoskeletal proteins. Metabolic reconstruction revealed that Culexarchaeia have the capacity to metabolize a wide variety of organic and inorganic substrates. Notably, Culexarchaeia encode a unique modular, membrane associated, and energy conserving [NiFe]-hydrogenase complex that potentially interacts with heterodisulfide reductase (Hdr) subunits. Comparison of this [NiFe]-hydrogenase complex with similar complexes from other archaea suggests that interactions between membrane associated [NiFe]-hydrogenases and Hdr may be more widespread than previously appreciated in both methanogenic and non-methanogenic lifestyles. The analysis of Culexarchaeia further expands our understanding of the phylogenetic and functional diversity of lineages within the TACK superphylum and the ecology, physiology, and evolution of these organisms in extreme environments.

AbstractThe Yessentukskoye deposit of Caucasian mineral waters contains balneologically valuable drinking mineral water, which is extracted from the Upper Cretaceous 1 km subsurface aquifer and is almost unexplored by microbiologists. We have sampled this water via continuously operating production wells, characterized the phylogenetic diversity of its microbial community, and obtained enrichments of thermophilic iron reducers from the source aquifer. From the enrichments, a novel anaerobic thermophilic bacterium, reducing Fe(III) in the mineral ferrihydrite with acetate as the electron donor, was isolated into a pure culture. The novel isolate, designated as strain Es71-Z0220Tbelonging toDeferribacteralesorder, is thermophilic, neutrophilic, halotolerant, motile vibrio. It utilizes synthesized ferrihydrite, fumarate, nitrate or elemental sulfur as the electron acceptors with organic acids as the electron donors. The strain is incapable of soluble Fe(III) complexes reduction and fermentative growth. The draft genome assembly of strain Es71-Z0220Tresulted in 65 contigs with a total size of ca. 2.3 Mb. On the basis of whole-genome phylogenetic reconstruction and physiological characterization, the novel isolate was considered to represent a novel family, genus and species for which the nameDeferrivibrio essentukiensisgen. nov., sp. nov. is proposed. Genome analysis revealed key determinants of anaerobic respiration and carbon substrate utilization pathways in the organism with peculiarities related to putative Fe(III)-reducing electron transfer chain. Considering the revealed metabolic features ofDeferrivibrio essentukiensis, the involvement of the organism in its subsurface environment in biogeochemical by carbon cycling by coupling the organic matter oxidation with Fe(III) minerals reduction is discussed.