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Manzulli V, Schiavone A, Castellana S, Albenzio M, Cafiero MA, Camarda A, Capozzi L, D'Angelo F, Parisi A, Vasco I, Sciancalepore D, Marino L, Serrecchia L, Rondinone V, Campaniello M, Crescenzo G, Galante D, Pugliese N. Psychrobacter raelei sp. nov., isolated from a dog with peritonitis. Int J Syst Evol Microbiol 2024; 74. [PMID: 38683659 DOI: 10.1099/ijsem.0.006353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2024] Open
Abstract
A strain belonging to the genus Psychrobacter, named PraFG1T, was isolated from the peritoneal effusion of a stray dog during necropsy procedures. The strain was characterized by the phylogenetic analyses based on the nucleotide sequences of 16S and 23S rRNA genes and of gyrB, which placed the strain in the genus Psychrobacter. The nucleotide sequence of the chromosome confirmed the placement, showing an average nucleotide identity of 72.1, 77.7, and 77.5 % with the closest related species, namely Psychrobacter sanguinis, Psychrobacter piechaudii, and Psychrobacter phenylpyruvicus, respectively, thus indicating a novel species. The polyphasic characterization by biochemical and fatty acid profiling as well as MALDI-TOF supported those findings. The strain was halotolerant, capable of growing within a temperature range between 4 and 37 °C, it was positive for catalase and oxidase, indole producing, nitrate reducing, and not able to use 5-keto-d-gluconic acid as a carbon source. Taken together, the data suggest that strain PraFG1T could be considered as representing a novel species, with the name Psychrobacter raelei sp. nov. (type strain PraFG1T=CIP 111873T=LMG 32233T).
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Affiliation(s)
- Viviana Manzulli
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Antonella Schiavone
- Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, Valenzano, Italy
- Moredun Research Institute, Edinburgh, UK
| | - Stefano Castellana
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Putignano, Italy
| | - Marzia Albenzio
- Dipartimento di Scienze Agrarie, Alimenti, Risorse naturali e Ingegneria, Università di Foggia, Foggia, Italy
| | - Maria Assunta Cafiero
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Antonio Camarda
- Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, Valenzano, Italy
| | - Loredana Capozzi
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Putignano, Italy
| | - Francesca D'Angelo
- Dipartimento di Scienze Agrarie, Alimenti, Risorse naturali e Ingegneria, Università di Foggia, Foggia, Italy
| | - Antonio Parisi
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Putignano, Italy
| | - Ilaria Vasco
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Dario Sciancalepore
- Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, Valenzano, Italy
| | - Leonardo Marino
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Luigina Serrecchia
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Valeria Rondinone
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Maria Campaniello
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Giuseppe Crescenzo
- Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, Valenzano, Italy
| | - Domenico Galante
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Foggia, Italy
| | - Nicola Pugliese
- Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, Valenzano, Italy
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Prekrasna-Kviatkovska Y, Parnikoza I, Yerkhova A, Stelmakh O, Pavlovska M, Dzyndra M, Yarovyi O, Dykyi E. From acidophilic to ornithogenic: microbial community dynamics in moss banks altered by gentoo penguins. Front Microbiol 2024; 15:1362975. [PMID: 38525081 PMCID: PMC10959021 DOI: 10.3389/fmicb.2024.1362975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 02/21/2024] [Indexed: 03/26/2024] Open
Abstract
Introduction The study explores the indirect impact of climate change driven by gentoo's penguin colonization pressure on the microbial communities of moss banks formed by Tall moss turf subformation in central maritime Antarctica. Methods Microbial communities and chemical composition of the differently affected moss banks (Unaffected, Impacted and Desolated) located on Galindez Island and Сape Tuxen on the mainland of Kyiv Peninsula were analyzed. Results The native microbiota of the moss banks' peat was analyzed for the first time, revealing a predominant presence of Acidobacteria (32.2 ± 14.4%), followed by Actinobacteria (15.1 ± 4.0%) and Alphaproteobacteria (9.7 ± 4.1%). Penguin colonization and subsequent desolation of moss banks resulted in an increase in peat pH (from 4.7 ± 0.05 to 7.2 ± 0.6) and elevated concentrations of soluble nitrogen (from 1.8 ± 0.4 to 46.9 ± 2.1 DIN, mg/kg) and soluble phosphorus compounds (from 3.6 ± 2.6 to 20.0 ± 1.8 DIP, mg/kg). The contrasting composition of peat and penguin feces led to the elimination of the initial peat microbiota, with an increase in Betaproteobacteria (from 1.3 ± 0.8% to 30.5 ± 23%) and Bacteroidota (from 5.5 ± 3.7% to 19.0 ± 3.7%) proportional to the intensity of penguins' impact, accompanied by a decrease in community diversity. Microbial taxa associated with birds' guts, such as Gottschalkia and Tissierella, emerged in Impacted and Desolated moss banks, along with bacteria likely benefiting from eutrophication. The changes in the functional capacity of the penguin-affected peat microbial communities were also detected. The nitrogen-cycling genes that regulate the conversion of urea into ammonia, nitrite oxide, and nitrate oxide (ureC, amoA, nirS, nosZ, nxrB) had elevated copy numbers in the affected peat. Desolated peat samples exhibit the highest nitrogen-cycle gene numbers, significantly differing from Unaffected peat (p < 0.05). Discussion The expansion of gentoo penguins induced by climate change led to the replacement of acidophilic microbiomes associated with moss banks, shaping a new microbial community influenced by penguin guano's chemical and microbial composition.
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Affiliation(s)
| | - Ivan Parnikoza
- Biology and Ecology Department, State Institution National Antarctic Scientific Center, Kyiv, Ukraine
- Department of Cell Population Genetics, Institute of Molecular Biology and Genetics, Kyiv, Ukraine
- Faculty of Natural Science, National University of “Kyiv-Mohyla Academy”, Kyiv, Ukraine
| | - Anna Yerkhova
- Biomedical Institute, Open International University of Human Development Ukraine, Kyiv, Ukraine
| | - Olesia Stelmakh
- Faculty of Molecular Biology and Biotechnology, Kyiv Academic University, Kyiv, Ukraine
| | - Mariia Pavlovska
- Biology and Ecology Department, State Institution National Antarctic Scientific Center, Kyiv, Ukraine
- Faculty of Plant Protection, Biotechnology and Ecology, National University of Life and Environmental Sciences of Ukraine, Kyiv, Ukraine
| | - Marta Dzyndra
- Biology and Ecology Department, State Institution National Antarctic Scientific Center, Kyiv, Ukraine
| | - Oleksandr Yarovyi
- Biology and Ecology Department, State Institution National Antarctic Scientific Center, Kyiv, Ukraine
| | - Evgen Dykyi
- Biology and Ecology Department, State Institution National Antarctic Scientific Center, Kyiv, Ukraine
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Ochoa-Sánchez M, Acuña Gomez EP, Moreno L, Moraga CA, Gaete K, Eguiarte LE, Souza V. Body site microbiota of Magellanic and king penguins inhabiting the Strait of Magellan follow species-specific patterns. PeerJ 2023; 11:e16290. [PMID: 37933257 PMCID: PMC10625763 DOI: 10.7717/peerj.16290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 09/22/2023] [Indexed: 11/08/2023] Open
Abstract
Animal hosts live in continuous interaction with bacterial partners, yet we still lack a clear understanding of the ecological drivers of animal-associated bacteria, particularly in seabirds. Here, we investigated the effect of body site in the structure and diversity of bacterial communities of two seabirds in the Strait of Magellan: the Magellanic penguin (Spheniscus magellanicus) and the king penguin (Aptenodytes patagonicus). We used 16S rRNA gene sequencing to profile bacterial communities associated with body sites (chest, back, foot) of both penguins and the nest soil of Magellanic penguin. Taxonomic composition showed that Moraxellaceae family (specifically Psychrobacter) had the highest relative abundance across body sites in both penguin species, whereas Micrococacceae had the highest relative abundance in nest soil. We were able to detect a bacterial core among 90% of all samples, which consisted of Clostridium sensu stricto and Micrococcacea taxa. Further, the king penguin had its own bacterial core across its body sites, where Psychrobacter and Corynebacterium were the most prevalent taxa. Microbial alpha diversity across penguin body sites was similar in most comparisons, yet we found subtle differences between foot and chest body sites of king penguins. Body site microbiota composition differed across king penguin body sites, whereas it remained similar across Magellanic penguin body sites. Interestingly, all Magellanic penguin body site microbiota composition differed from nest soil microbiota. Finally, bacterial abundance in penguin body sites fit well under a neutral community model, particularly in the king penguin, highlighting the role of stochastic process and ecological drift in microbiota assembly of penguin body sites. Our results represent the first report of body site bacterial communities in seabirds specialized in subaquatic foraging. Thus, we believe it represents useful baseline information that could serve for long-term comparisons that use marine host microbiota to survey ocean health.
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Affiliation(s)
- Manuel Ochoa-Sánchez
- Instituto de Ecología, Universidad Nacional Autónoma de México, CDMX, Mexico
- Centro de Estudios del Cuaternario de Fuego, Patagonia y Antártica (CEQUA), Punta Arenas, Chile
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | | | - Lucila Moreno
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Claudio A. Moraga
- Centro de Estudios del Cuaternario de Fuego, Patagonia y Antártica (CEQUA), Punta Arenas, Chile
| | - Katherine Gaete
- Centro de Estudios del Cuaternario de Fuego, Patagonia y Antártica (CEQUA), Punta Arenas, Chile
| | - Luis E. Eguiarte
- Instituto de Ecología, Universidad Nacional Autónoma de México, CDMX, Mexico
| | - Valeria Souza
- Instituto de Ecología, Universidad Nacional Autónoma de México, CDMX, Mexico
- Centro de Estudios del Cuaternario de Fuego, Patagonia y Antártica (CEQUA), Punta Arenas, Chile
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Update on Novel Taxa and Revised Taxonomic Status of Bacteria Isolated from Nondomestic Animals Described in 2018 to 2021. J Clin Microbiol 2023; 61:e0142522. [PMID: 36533958 PMCID: PMC9945507 DOI: 10.1128/jcm.01425-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Revisions and new additions to bacterial taxonomy can have a significant widespread impact on clinical practice, infectious disease epidemiology, veterinary microbiology laboratory operations, and wildlife conservation efforts. The expansion of genome sequencing technologies has revolutionized our knowledge of the microbiota of humans, animals, and insects. Here, we address novel taxonomy and nomenclature revisions of veterinary significance that impact bacteria isolated from nondomestic wildlife, with emphasis being placed on bacteria that are associated with disease in their hosts or were isolated from host animal species that are culturally significant, are a target of conservation efforts, or serve as reservoirs for human pathogens.
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Song H, Lee K, Hwang I, Yang E, Ha J, Kim W, Park S, Cho H, Choe JC, Lee SI, Jablonski P. Dynamics of Bacterial Communities on Eggshells and on Nest Materials During Incubation in the Oriental Tit (Parus minor). MICROBIAL ECOLOGY 2023; 85:429-440. [PMID: 35094098 DOI: 10.1007/s00248-021-01927-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Abstract
Eggshell bacterial communities may affect hatching success and nestling's condition. Nest materials are in direct contact with the eggshells, but the relationships with the eggshell microbiome during incubation have not been fully elucidated. Here, we characterize eggshell and nest material bacterial communities and their changes during incubation in the Oriental Tit (Parus minor). Bacterial communities on the nest material were relatively stable and remained distinct from the eggshell communities and had higher diversity and greater phylogenetic clustering than the eggshell communities from the same nest, resulting in lower phylogenetic turnover rate of nest material microbiome during incubation than expected by chance. While the species diversity of both communities did not change during incubation, we found significantly greater changes in the structure of bacterial communities on the eggshell than on the nest material. However, eggshell microbiome remained distinct from nest material microbiome, suggesting independent dynamics of the two microbiomes during incubation. We detected an increase in the relative abundance of several bacterial taxa on the eggshell that likely come from the bird's skin, feathers, cloaca/intestine, or uropygial secretion which suggests some exchange of bacteria between the incubating bird and the eggshell. Furthermore, incubation appeared to promote the abundance of antibiotic producing taxa on the eggshell, which may hypothetically inhibit growth of many bacteria including pathogenic ones. Our results suggest that the future studies should focus on simultaneous monitoring of absolute abundance as well as relative abundance in communities on eggshells, nest materials, and the incubating bird's body.
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Affiliation(s)
- Hokyung Song
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
- School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- Division of Life Sciences, Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon, 21990, South Korea
| | - Keesan Lee
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
| | - Injae Hwang
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
| | - Eunjeong Yang
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
| | - Jungmoon Ha
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
| | - Woojoo Kim
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
| | - Sungjin Park
- Office of Planning & Strategy, College of Agriculture & Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea
- Seoul National University Forests, Taehwasan, 572 Docheogwit-ro, Docheok-myeon, Gwangju-si, Gyeonggi-do, South Korea
| | - Hyunjoon Cho
- Division of Life Sciences, Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon, 21990, South Korea
| | - Jae Chun Choe
- Interdisciplinary Program of EcoCreative, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, 03760, Seoul, South Korea
| | - Sang-Im Lee
- Department of New Biology, DGIST, 333 Techno Jungang-daero, 42988, Daegu, South Korea.
| | - Piotr Jablonski
- School of Biological Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 08826, Seoul, South Korea.
- Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679, Warsaw, Poland.
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Bai S, Zhang P, Zhang C, Du J, Du X, Zhu C, Liu J, Xie P, Li S. Comparative Study of the Gut Microbiota Among Four Different Marine Mammals in an Aquarium. Front Microbiol 2021; 12:769012. [PMID: 34745077 PMCID: PMC8567075 DOI: 10.3389/fmicb.2021.769012] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 09/23/2021] [Indexed: 12/18/2022] Open
Abstract
Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet, environment, or host phylogeny has the greatest impact on microbial community structure is still unknown. To fill part of this knowledge gap, we exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas) affiliated with family Monodontidae, Pacific white-sided dolphins (Lagenorhynchus obliquidens) and common bottlenose dolphin (Tursiops truncatus) affiliated with family Delphinidae, and Cape fur seals (Arctocephalus pusillus pusillus) affiliated with family Otariidae. Results show significant differences in microbial community composition of whales, dolphins, and fur seals and indicate that host phylogeny (family level) plays the most important role in shaping the microbial communities, rather than food and environment. In general, the gut microbial communities of dolphins had significantly lower diversity compared to that of whales and fur seals. Overall, the gut microbial communities were mainly composed of Firmicutes and Gammaproteobacteria, together with some from Bacteroidetes, Fusobacteria, and Epsilonbacteraeota. However, specific bacterial lineages were differentially distributed among the marine mammal groups. For instance, Lachnospiraceae, Ruminococcaceae, and Peptostreptococcaceae were the dominant bacterial lineages in the gut of belugas, while for Cape fur seals, Moraxellaceae and Bacteroidaceae were the main bacterial lineages. Moreover, gut microbial communities in both Pacific white-sided dolphins and common bottlenose dolphins were dominated by a number of pathogenic bacteria, including Clostridium perfringens, Vibrio fluvialis, and Morganella morganii, reflecting the poor health condition of these animals. Although there is a growing recognition of the role microorganisms play in the gut of marine mammals, current knowledge about these microbial communities is still severely lacking. Large-scale research studies should be undertaken to reveal the roles played by the gut microbiota of different marine mammal species.
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Affiliation(s)
- Shijie Bai
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Peijun Zhang
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | | | - Jiang Du
- Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Medical University, Haikou, China
| | | | - Chengwei Zhu
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Jun Liu
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Peiyu Xie
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Songhai Li
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
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Comparison of Gut Microbiota between Gentoo and Adélie Penguins Breeding Sympatrically on Antarctic Ardley Island as Revealed by Fecal DNA Sequencing. DIVERSITY 2021. [DOI: 10.3390/d13100500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There are two pygoscelid penguins, the Gentoo (Pygoscelis papua Forster, 1781) and Adélie (P. adeliae Hombron and Jacquinot, 1841) penguins, breeding sympatrically on Ardley Island, Fildes Peninsula region, South Shetlands, Antarctica. Whether the two closely related penguin species with similar dietary habits possess compositional similarity in gut microbiota remains unknown. DNA barcoding of feces is an emerging approach for gut microbiota analysis of protected animals. In the present study, the 16S rRNA gene from penguin feces was sequenced using the Illumina MiSeq platform to investigate the gut microbiota of the two pygoscelid penguin species. The fecal community of Gentoo penguins has higher diversity indices and OTU (operational taxonomic unit) richness compared to Adélie penguins. Besides unclassified bacteria, sequences fell into 22 major lineages of the domain Bacteria: Acidobacteria, Actinobacteria, Armatimonadetes, Bacteroidetes, Chlamydiae, Chloroflexi, Cloacimonetes, Cyanobacteria, Deinococcus-Thermus, Fibrobacteres, Firmicutes, Fusobacteria, Gemmatimonadetes, Ignavibacteriae, Planctomycetes, Proteobacteria, Tenericutes, Verrucomicrobia, and candidate divisions BRC1, SR1, WPS-2, and Saccharibacteria. Among these, Firmicutes (37.7%), Proteobacteria (23.1%, mainly Gamma- and Betaproteobacteria), Fusobacteria (14.3%), Bacteroidetes (7.9%), and Actinobacteria (6.6%) were dominant in the fecal microbiota of the two penguin species. At the same time, significantly higher abundances of Actinobacteria and Cyanobacteria were detected in Gentoo penguins than in Adélie penguins (p < 0.05). Overall, there was a clear difference in the composition of gut microbiota between the Adélie and Gentoo penguins. The results suggested that both the phylogeny of penguin species and the diet could be responsible for the differences in the gut microbiota of the two pygoscelid penguins breeding in the same area.
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Abstract
Host-adapted microorganisms are generally assumed to have evolved from free-living, environmental microorganisms, as examples of the reverse process are rare. In the phylum Gammaproteobacteria, family Moraxellaceae, the genus Psychrobacter includes strains from a broad ecological distribution including animal bodies as well as sea ice and other nonhost environments. To elucidate the relationship between these ecological niches and Psychrobacter's evolutionary history, we performed tandem genomic analyses with phenotyping of 85 Psychrobacter accessions. Phylogenomic analysis of the family Moraxellaceae reveals that basal members of the Psychrobacter clade are Moraxella spp., a group of often-pathogenic organisms. Psychrobacter exhibited two broad growth patterns in our phenotypic screen: one group that we called the "flexible ecotype" (FE) had the ability to grow between 4 and 37°C, and the other, which we called the "restricted ecotype" (RE), could grow between 4 and 25°C. The FE group includes phylogenetically basal strains, and FE strains exhibit increased transposon copy numbers, smaller genomes, and a higher likelihood to be bile salt resistant. The RE group contains only phylogenetically derived strains and has increased proportions of lipid metabolism and biofilm formation genes, functions that are adaptive to cold stress. In a 16S rRNA gene survey of polar bear fecal samples, we detect both FE and RE strains, but in in vivo colonizations of gnotobiotic mice, only FE strains persist. Our results indicate the ability to grow at 37°C, seemingly necessary for mammalian gut colonization, is an ancestral trait for Psychrobacter, which likely evolved from a pathobiont.IMPORTANCE Host-associated microbes are generally assumed to have evolved from free-living ones. The evolutionary transition of microbes in the opposite direction, from host associated toward free living, has been predicted based on phylogenetic data but not studied in depth. Here, we provide evidence that the genus Psychrobacter, particularly well known for inhabiting low-temperature, high-salt environments such as sea ice, permafrost soils, and frozen foodstuffs, has evolved from a mammalian-associated ancestor. We show that some Psychrobacter strains retain seemingly ancestral genomic and phenotypic traits that correspond with host association while others have diverged to psychrotrophic or psychrophilic lifestyles.
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