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Price CTD, Hanford HE, Al-Quadan T, Santic M, Shin CJ, Da'as MSJ, Abu Kwaik Y. Amoebae as training grounds for microbial pathogens. mBio 2024; 15:e0082724. [PMID: 38975782 PMCID: PMC11323580 DOI: 10.1128/mbio.00827-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024] Open
Abstract
Grazing of amoebae on microorganisms represents one of the oldest predator-prey dynamic relationships in nature. It represents a genetic "melting pot" for an ancient and continuous multi-directional inter- and intra-kingdom horizontal gene transfer between amoebae and its preys, intracellular microbial residents, endosymbionts, and giant viruses, which has shaped the evolution, selection, and adaptation of microbes that evade degradation by predatory amoeba. Unicellular phagocytic amoebae are thought to be the ancient ancestors of macrophages with highly conserved eukaryotic processes. Selection and evolution of microbes within amoeba through their evolution to target highly conserved eukaryotic processes have facilitated the expansion of their host range to mammals, causing various infectious diseases. Legionella and environmental Chlamydia harbor an immense number of eukaryotic-like proteins that are involved in ubiquitin-related processes or are tandem repeats-containing proteins involved in protein-protein and protein-chromatin interactions. Some of these eukaryotic-like proteins exhibit novel domain architecture and novel enzymatic functions absent in mammalian cells, such as ubiquitin ligases, likely acquired from amoebae. Mammalian cells and amoebae may respond similarly to microbial factors that target highly conserved eukaryotic processes, but mammalian cells may undergo an accidental response to amoeba-adapted microbial factors. We discuss specific examples of microbes that have evolved to evade amoeba predation, including the bacterial pathogens- Legionella, Chlamydia, Coxiella, Rickettssia, Francisella, Mycobacteria, Salmonella, Bartonella, Rhodococcus, Pseudomonas, Vibrio, Helicobacter, Campylobacter, and Aliarcobacter. We also discuss the fungi Cryptococcus, and Asperigillus, as well as amoebae mimiviruses/giant viruses. We propose that amoeba-microbe interactions will continue to be a major "training ground" for the evolution, selection, adaptation, and emergence of microbial pathogens equipped with unique pathogenic tools to infect mammalian hosts. However, our progress will continue to be highly dependent on additional genomic, biochemical, and cellular data of unicellular eukaryotes.
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Affiliation(s)
- Christopher T. D. Price
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, USA
| | - Hannah E. Hanford
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, USA
| | - Tasneem Al-Quadan
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, USA
| | | | - Cheon J. Shin
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, USA
| | - Manal S. J. Da'as
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, USA
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, USA
- Center for Predictive Medicine, College of Medicine, University of Louisville, Louisville, Kentucky, USA
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Hopkins HA, Lopezguerra C, Lau MJ, Raymann K. Making a Pathogen? Evaluating the Impact of Protist Predation on the Evolution of Virulence in Serratia marcescens. Genome Biol Evol 2024; 16:evae149. [PMID: 38961701 PMCID: PMC11332436 DOI: 10.1093/gbe/evae149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 06/25/2024] [Accepted: 06/30/2024] [Indexed: 07/05/2024] Open
Abstract
Opportunistic pathogens are environmental microbes that are generally harmless and only occasionally cause disease. Unlike obligate pathogens, the growth and survival of opportunistic pathogens do not rely on host infection or transmission. Their versatile lifestyles make it challenging to decipher how and why virulence has evolved in opportunistic pathogens. The coincidental evolution hypothesis postulates that virulence results from exaptation or pleiotropy, i.e. traits evolved for adaptation to living in one environment that have a different function in another. In particular, adaptation to avoid or survive protist predation has been suggested to contribute to the evolution of bacterial virulence (the training ground hypothesis). Here, we used experimental evolution to determine how the selective pressure imposed by a protist predator impacts the virulence and fitness of a ubiquitous environmental opportunistic bacterial pathogen that has acquired multidrug resistance: Serratia marcescens. To this aim, we evolved S. marcescens in the presence or absence of generalist protist predator, Tetrahymena thermophila. After 60 d of evolution, we evaluated genotypic and phenotypic changes by comparing evolved S. marcescens with the ancestral strain. Whole-genome shotgun sequencing of the entire evolved populations and individual isolates revealed numerous cases of parallel evolution, many more than statistically expected by chance, in genes associated with virulence. Our phenotypic assays suggested that evolution in the presence of a predator maintained virulence, whereas evolution in the absence of a predator resulted in attenuated virulence. We also found a significant correlation between virulence, biofilm formation, growth, and grazing resistance. Overall, our results provide evidence that bacterial virulence and virulence-related traits are maintained by selective pressures imposed by protist predation.
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Affiliation(s)
- Heather A Hopkins
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA
- Department of Biology, University of North Carolina Greensboro, Greensboro, NC, USA
| | - Christian Lopezguerra
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA
- Department of Biology, University of North Carolina Greensboro, Greensboro, NC, USA
| | - Meng-Jia Lau
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA
| | - Kasie Raymann
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA
- Department of Biology, University of North Carolina Greensboro, Greensboro, NC, USA
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Rivera J, Valerdi-Negreros JC, Vázquez-Enciso DM, Argueta-Zepeda FS, Vinuesa P. Phylogenomic, structural, and cell biological analyses reveal that Stenotrophomonas maltophilia replicates in acidified Rab7A-positive vacuoles of Acanthamoeba castellanii. Microbiol Spectr 2024; 12:e0298823. [PMID: 38319117 PMCID: PMC10913462 DOI: 10.1128/spectrum.02988-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 01/15/2024] [Indexed: 02/07/2024] Open
Abstract
Acanthamoeba species are clinically relevant free-living amoebae (FLA) ubiquitously found in soil and water bodies. Metabolically active trophozoites graze on diverse microbes via phagocytosis. However, functional studies on Rab GTPases (Rabs), which are critical for controlling vesicle trafficking and maturation, are scarce for this FLA. This knowledge gap can be partly explained by the limited genetic tools available for Acanthamoeba cell biology. Here, we developed plasmids to generate fusions of A. castellanii strain Neff proteins to the N- or C-termini of mEGFP and mCherry2. Phylogenomic and structural analyses of the 11 Neff Rab7 paralogs found in the RefSeq assembly revealed that eight of them had non-canonical sequences. After correcting the gene annotation for the Rab7A ortholog, we generated a line stably expressing an mEGFP-Rab7A fusion, demonstrating its correct localization to acidified macropinocytic and phagocytic vacuoles using fluorescence microscopy live cell imaging (LCI). Direct labeling of live Stenotrophomonas maltophilia ESTM1D_MKCAZ16_6a (Sm18) cells with pHrodo Red, a pH-sensitive dye, demonstrated that they reside within acidified, Rab7A-positive vacuoles. We constructed new mini-Tn7 delivery plasmids and tagged Sm18 with constitutively expressed mScarlet-I. Co-culture experiments of Neff trophozoites with Sm18::mTn7TC1_Pc_mScarlet-I, coupled with LCI and microplate reader assays, demonstrated that Sm18 underwent multiple replication rounds before reaching the extracellular medium via non-lytic exocytosis. We conclude that S. maltophilia belongs to the class of bacteria that can use amoeba as an intracellular replication niche within a Stenotrophomonas-containing vacuole that interacts extensively with the endocytic pathway.IMPORTANCEDiverse Acanthamoeba lineages (genotypes) are of increasing clinical concern, mainly causing amoebic keratitis and granulomatous amebic encephalitis among other infections. S. maltophilia ranks among the top 10 most prevalent multidrug-resistant opportunistic nosocomial pathogens and is a recurrent member of the microbiome hosted by Acanthamoeba and other free-living amoebae. However, little is known about the molecular strategies deployed by Stenotrophomonas for an intracellular lifestyle in amoebae and other professional phagocytes such as macrophages, which allow the bacterium to evade the immune system and the action of antibiotics. Our plasmids and easy-to-use microtiter plate co-culture assays should facilitate investigations into the cellular microbiology of Acanthamoeba interactions with Stenotrophomonas and other opportunistic pathogens, which may ultimately lead to the discovery of new molecular targets and antimicrobial therapies to combat difficult-to-treat infections caused by these ubiquitous microbes.
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Affiliation(s)
- Javier Rivera
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Julio C. Valerdi-Negreros
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
- Programa de Doctorado en Ciencias Biomédicas, UNAM, Mexico City, Mexico
| | - Diana M. Vázquez-Enciso
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
- Programa de Maestría y Doctorado en Ciencias Bioquímicas, UNAM, Mexico City, Mexico
| | - Fulvia-Stefany Argueta-Zepeda
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
- Programa de Maestría y Doctorado en Ciencias Bioquímicas, UNAM, Mexico City, Mexico
| | - Pablo Vinuesa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
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Rayamajhee B, Willcox M, Sharma S, Mooney R, Petsoglou C, Badenoch PR, Sherchan S, Henriquez FL, Carnt N. Zooming in on the intracellular microbiome composition of bacterivorous Acanthamoeba isolates. ISME COMMUNICATIONS 2024; 4:ycae016. [PMID: 38500701 PMCID: PMC10945361 DOI: 10.1093/ismeco/ycae016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/29/2023] [Accepted: 01/22/2024] [Indexed: 03/20/2024]
Abstract
Acanthamoeba, a free-living amoeba in water and soil, is an emerging pathogen causing severe eye infection known as Acanthamoeba keratitis. In its natural environment, Acanthamoeba performs a dual function as an environmental heterotrophic predator and host for a range of microorganisms that resist digestion. Our objective was to characterize the intracellular microorganisms of phylogenetically distinct Acanthamoeba spp. isolated in Australia and India through directly sequencing 16S rRNA amplicons from the amoebae. The presence of intracellular bacteria was further confirmed by in situ hybridization and electron microscopy. Among the 51 isolates assessed, 41% harboured intracellular bacteria which were clustered into four major phyla: Pseudomonadota (previously known as Proteobacteria), Bacteroidota (previously known as Bacteroidetes), Actinomycetota (previously known as Actinobacteria), and Bacillota (previously known as Firmicutes). The linear discriminate analysis effect size analysis identified distinct microbial abundance patterns among the sample types; Pseudomonas species was abundant in Australian corneal isolates (P < 0.007), Enterobacteriales showed higher abundance in Indian corneal isolates (P < 0.017), and Bacteroidota was abundant in Australian water isolates (P < 0.019). The bacterial beta diversity of Acanthamoeba isolates from keratitis patients in India and Australia significantly differed (P < 0.05), while alpha diversity did not vary based on the country of origin or source of isolation (P > 0.05). More diverse intracellular bacteria were identified in water isolates as compared with clinical isolates. Confocal and electron microscopy confirmed the bacterial cells undergoing binary fission within the amoebal host, indicating the presence of viable bacteria. This study sheds light on the possibility of a sympatric lifestyle within Acanthamoeba, thereby emphasizing its crucial role as a bunker and carrier of potential human pathogens.
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Affiliation(s)
- Binod Rayamajhee
- School of Optometry and Vision Science, Faculty of Medicine and Health, UNSW, Sydney, NSW 2052, Australia
| | - Mark Willcox
- School of Optometry and Vision Science, Faculty of Medicine and Health, UNSW, Sydney, NSW 2052, Australia
| | - Savitri Sharma
- Jhaveri Microbiology Centre, Prof Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute (LVPEI), Hyderabad, 500034, India
| | - Ronnie Mooney
- School of Health and Life Sciences, University of the West of Scotland, Blantyre, PA1 2BE, United Kingdom
| | - Constantinos Petsoglou
- Sydney and Sydney Eye Hospital, South-Eastern Sydney Local Health District, Sydney, NSW 2000, Australia
- Save Sight Institute, University of Sydney, Sydney, NSW 2000, Australia
| | - Paul R Badenoch
- College of Medicine and Public Health, Flinders University, Adelaide, 5042, Australia
| | - Samendra Sherchan
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, United States
| | - Fiona L Henriquez
- School of Health and Life Sciences, University of the West of Scotland, Blantyre, PA1 2BE, United Kingdom
| | - Nicole Carnt
- School of Optometry and Vision Science, Faculty of Medicine and Health, UNSW, Sydney, NSW 2052, Australia
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Hoque MM, Noorian P, Espinoza-Vergara G, Adhikary S, To J, Rice SA, McDougald D. Increased iron utilization and oxidative stress tolerance in a Vibrio cholerae flrA mutant confers resistance to amoeba predation. Appl Environ Microbiol 2023; 89:e0109523. [PMID: 37882527 PMCID: PMC10686080 DOI: 10.1128/aem.01095-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/15/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE Persistence of V. cholerae in the aquatic environment contributes to the fatal diarrheal disease cholera, which remains a global health burden. In the environment, bacteria face predation pressure by heterotrophic protists such as the free-living amoeba A. castellanii. This study explores how a mutant of V. cholerae adapts to acquire essential nutrients and survive predation. Here, we observed that up-regulation of iron acquisition genes and genes regulating resistance to oxidative stress enhances pathogen fitness. Our data show that V. cholerae can defend predation to overcome nutrient limitation and oxidative stress, resulting in an enhanced survival inside the protozoan hosts.
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Affiliation(s)
- M. Mozammel Hoque
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Parisa Noorian
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Gustavo Espinoza-Vergara
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Srijon Adhikary
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Joyce To
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
| | - Scott A. Rice
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
- CSIRO Animal, Food and Health Sciences, Westmead, NSW, Australia
| | - Diane McDougald
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, NSW, Australia
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6
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Lin C, Li WJ, Li LJ, Neilson R, An XL, Zhu YG. Movement of protistan trophic groups in soil-plant continuums. Environ Microbiol 2023; 25:2641-2652. [PMID: 37547979 DOI: 10.1111/1462-2920.16477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 07/20/2023] [Indexed: 08/08/2023]
Abstract
Protists, functionally divided into consumers, phototrophs, and parasites act as integral components and vital regulators of microbiomes in soil-plant continuums. However, the drivers of community structure, assembly mechanisms, co-occurrence patterns, and the associations with human pathogens and different protistan trophic groups remain unknown. Here, we characterized the phyllosphere and soil protistan communities associated with three vegetables under different fertilization treatments (none and organic fertilization) at five growth stages. In this study, consumers were the most diverse soil protist group, had the role of inter-kingdom connector, and were the primary biomarker for rhizosphere soils which were subjected to decreasing deterministic processes during plant growth. In contrast, phototrophs had the greatest niche breadth and formed soil protistan hubs, and were the primary biomarkers for both bulk soils and the phyllosphere. Parasites had minimal input to microbial co-occurrence networks. Organic fertilization increased the relative abundance (RA) of pathogenic protists and the number of pathogen-consumer connections in rhizosphere soils but decreased protistan richness and the number of internal protistan links. This study advances our understanding of the ecological roles and potential links between human pathogens and protistan trophic groups associated with soil-plant continuums, which is fundamental to the regulation of soil-plant microbiomes and maintenance of environmental and human health.
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Affiliation(s)
- Chenshuo Lin
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wen-Jing Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Li-Juan Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Roy Neilson
- Ecological Sciences, The James Hutton Institute, Dundee, Scotland, UK
| | - Xin-Li An
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
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Lin C, Li LJ, Ren K, Zhou SYD, Isabwe A, Yang LY, Neilson R, Yang XR, Cytryn E, Zhu YG. Phagotrophic protists preserve antibiotic-resistant opportunistic human pathogens in the vegetable phyllosphere. ISME COMMUNICATIONS 2023; 3:94. [PMID: 37660098 PMCID: PMC10475086 DOI: 10.1038/s43705-023-00302-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 09/04/2023]
Abstract
Food safety of leafy greens is an emerging public health issue as they can harbor opportunistic human pathogens (OHPs) and expose OHPs to consumers. Protists are an integral part of phyllosphere microbial ecosystems. However, our understanding of protist-pathogen associations in the phyllosphere and their consequences on public health remains poor. Here, we examined phyllosphere protists, human pathogen marker genes (HPMGs), and protist endosymbionts from four species of leafy greens from major supermarkets in Xiamen, China. Our results showed that Staphylococcus aureus and Klebsiella pneumoniae were the dominant human pathogens in the vegetable phyllosphere. The distribution of HPMGs and protistan communities differed between vegetable species, of which Chinese chive possessed the most diverse protists and highest abundance of HPMGs. HPMGs abundance positively correlated with the diversity and relative abundance of phagotrophic protists. Whole genome sequencing further uncovered that most isolated phyllosphere protists harbored multiple OHPs which carried antibiotic resistance genes, virulence factors, and metal resistance genes and had the potential to HGT. Colpoda were identified as key phagotrophic protists which positively linked to OHPs and carried diverse resistance and virulence potential endosymbiont OHPs including Pseudomonas nitroreducens, Achromobacter xylosoxidans, and Stenotrophomonas maltophilia. We highlight that phyllosphere protists contribute to the transmission of resistant OHPs through internalization and thus pose risks to the food safety of leafy greens and human health. Our study provides insights into the protist-OHP interactions in the phyllosphere, which will help in food safety surveillance and human health.
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Affiliation(s)
- Chenshuo Lin
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Li-Juan Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Kexin Ren
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
| | - Shu-Yi-Dan Zhou
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, 510650, China
| | - Alain Isabwe
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
| | - Le-Yang Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Roy Neilson
- Ecological Sciences, The James Hutton Institute, Dundee, DD2 5DA, Scotland, UK
| | - Xiao-Ru Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
| | - Eddie Cytryn
- Department of Soil Chemistry, Plant Nutrition and Microbiology, Institute of Soil, Water and Environmental Sciences, The Volcani Institute, Agriculture Research Organization, 7528809, Rishon Lezion, Israel
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China.
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China.
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Tsai CM, Chen CH, Cheng WH, Stelma FF, Li SC, Lin WC. Homeostasis of cellular amino acids in Acanthamoeba castellanii exposed to different media under amoeba-bacteria coculture conditions. BMC Microbiol 2023; 23:198. [PMID: 37495951 PMCID: PMC10373360 DOI: 10.1186/s12866-023-02942-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 07/11/2023] [Indexed: 07/28/2023] Open
Abstract
BACKGROUND Acanthamoeba castellanii is a free-living protist that feeds on diverse bacteria. A. castellanii has frequently been utilized in studies on microbial interactions. Grazing bacteria also exhibit diverse effects on the physiological characteristics of amoebae, such as their growth, encystation, and cytotoxicity. Since the composition of amoebae amino acids is closely related to cellular activities, it can indicate the overall responses of A. castellanii to various stimuli. METHOD A. castellanii was exposed to different culture conditions in low-nutrient medium with heat-killed DH5α to clarify their effects. A targeted metabolomic technique was utilized to evaluate the concentration of cellular amino acids. The amino acid composition and pathways were analyzed by two web-based tools: MetaboAnalyst and Pathview. Then, long-term exposure to A. castellanii was investigated through in silico and in vitro methods to elucidate the homeostasis of amino acids and the growth of A. castellanii. RESULTS Under short-term exposure, all kinds of amino acids were enriched in all exposed groups. In contrast to the presence of heat-killed bacteria, the medium exhibited obvious effects on the amino acid composition of A. castellanii. After long-term exposure, the amino acid composition was more similar to that of the control group. A. castellanii may achieve amino acid homeostasis through pathways related to alanine, aspartate, citrulline, and serine. DISCUSSION Under short-term exposure, compared to the presence of bacteria, the type of medium exerted a more powerful effect on the amino acid composition of the amoeba. Previous studies focused on the interaction of the amoeba and bacteria with effective secretion systems and effectors. This may have caused the effects of low-nutrient environments to be overlooked. CONCLUSION When A. castellanii was stimulated in the coculture system through various methods, such as the presence of bacteria and a low-nutrient environment, it accumulated intracellular amino acids within a short period. However, different stimulations correspond to different amino acid compositions. After long-term exposure, A. castellanii achieved an amino acid equilibrium by downregulating the biosynthesis of several amino acids.
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Affiliation(s)
- Chih-Ming Tsai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chun-Hsien Chen
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Hung Cheng
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Foekje F. Stelma
- Department of Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands
| | - Sung-Chou Li
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
- Department of Nursing, Meiho University, Pingtung, Taiwan
| | - Wei-Chen Lin
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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9
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Hoque MM, Espinoza-Vergara G, McDougald D. Protozoan predation as a driver of diversity and virulence in bacterial biofilms. FEMS Microbiol Rev 2023; 47:fuad040. [PMID: 37458768 DOI: 10.1093/femsre/fuad040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/19/2023] [Accepted: 07/07/2023] [Indexed: 07/27/2023] Open
Abstract
Protozoa are eukaryotic organisms that play a crucial role in nutrient cycling and maintaining balance in the food web. Predation, symbiosis and parasitism are three types of interactions between protozoa and bacteria. However, not all bacterial species are equally susceptible to protozoan predation as many are capable of defending against predation in numerous ways and may even establish either a symbiotic or parasitic life-style. Biofilm formation is one such mechanism by which bacteria can survive predation. Structural and chemical components of biofilms enhance resistance to predation compared to their planktonic counterparts. Predation on biofilms gives rise to phenotypic and genetic heterogeneity in prey that leads to trade-offs in virulence in other eukaryotes. Recent advances, using molecular and genomics techniques, allow us to generate new information about the interactions of protozoa and biofilms of prey bacteria. This review presents the current state of the field on impacts of protozoan predation on biofilms. We provide an overview of newly gathered insights into (i) molecular mechanisms of predation resistance in biofilms, (ii) phenotypic and genetic diversification of prey bacteria, and (iii) evolution of virulence as a consequence of protozoan predation on biofilms.
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Affiliation(s)
- M Mozammel Hoque
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Gustavo Espinoza-Vergara
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Diane McDougald
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Sydney, NSW 2007, Australia
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10
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Lv Z, Xu M, Liu Y, Rønn R, Rensing C, Liu S, Gao S, Liao H, Liu YR, Chen W, Zhu YG, Huang Q, Hao X. Phagotrophic Protists Modulate Copper Resistance of the Bacterial Community in Soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:3590-3601. [PMID: 36811608 DOI: 10.1021/acs.est.2c07136] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Protist predation is a crucial biotic driver modulating bacterial populations and functional traits. Previous studies using pure cultures have demonstrated that bacteria with copper (Cu) resistance exhibited fitness advantages over Cu-sensitive bacteria under the pressure of protist predation. However, the impact of diverse natural communities of protist grazers on bacterial Cu resistance in natural environments remains unknown. Here, we characterized the communities of phagotrophic protists in long-term Cu-contaminated soils and deciphered their potential ecological impacts on bacterial Cu resistance. Long-term field Cu pollution increased the relative abundances of most of the phagotrophic lineages in Cercozoa and Amoebozoa but reduced the relative abundance of Ciliophora. After accounting for soil properties and Cu pollution, phagotrophs were consistently identified as the most important predictor of the Cu-resistant (CuR) bacterial community. Phagotrophs positively contributed to the abundance of a Cu resistance gene (copA) through influencing the cumulative relative abundance of Cu-resistant and -sensitive ecological clusters. Microcosm experiments further confirmed the promotion effect of protist predation on bacterial Cu resistance. Our results indicate that the selection by protist predation can have a strong impact on the CuR bacterial community, which broadens our understanding of the ecological function of soil phagotrophic protists.
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Affiliation(s)
- Zhenguang Lv
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Min Xu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Ying Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Regin Rønn
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christopher Rensing
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Song Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Shenghan Gao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Hao Liao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiuli Hao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
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11
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Environmental Reservoirs of Pathogenic Vibrio spp. and Their Role in Disease: The List Keeps Expanding. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1404:99-126. [PMID: 36792873 DOI: 10.1007/978-3-031-22997-8_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Vibrio species are natural inhabitants of aquatic environments and have complex interactions with the environment that drive the evolution of traits contributing to their survival. These traits may also contribute to their ability to invade or colonize animal and human hosts. In this review, we attempt to summarize the relationships of Vibrio spp. with other organisms in the aquatic environment and discuss how these interactions could potentially impact colonization of animal and human hosts.
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12
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Rayamajhee B, Willcox MDP, Henriquez FL, Petsoglou C, Subedi D, Carnt N. Acanthamoeba, an environmental phagocyte enhancing survival and transmission of human pathogens. Trends Parasitol 2022; 38:975-990. [PMID: 36109313 DOI: 10.1016/j.pt.2022.08.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 01/13/2023]
Abstract
The opportunistic protist Acanthamoeba, which interacts with other microbes such as bacteria, fungi, and viruses, shows significant similarity in cellular and functional aspects to human macrophages. Intracellular survival of microbes in this microbivorous amoebal host may be a crucial step for initiation of infection in higher eukaryotic cells. Therefore, Acanthamoeba-microbe adaptations are considered an evolutionary model of macrophage-pathogen interactions. This paper reviews Acanthamoeba as an emerging human pathogen and different ecological interactions between Acanthamoeba and microbes that may serve as environmental training grounds and a genetic melting pot for the evolution, persistence, and transmission of potential human pathogens.
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Affiliation(s)
- Binod Rayamajhee
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales (UNSW), Sydney, Australia.
| | - Mark D P Willcox
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales (UNSW), Sydney, Australia.
| | - Fiona L Henriquez
- Institute of Biomedical and Environmental Health Research, School of Health and Life Sciences, University of the West of Scotland, Blantyre, South Lanarkshire, G72 0LH, UK
| | - Constantinos Petsoglou
- Sydney and Sydney Eye Hospital, Southeastern Sydney Local Health District, Sydney, Australia; Save Sight Institute, University of Sydney, Sydney, Australia
| | - Dinesh Subedi
- School of Biological Sciences, Monash University, Clayton, Australia
| | - Nicole Carnt
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales (UNSW), Sydney, Australia
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13
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Giddings LA, Kunstman K, Moumen B, Asiama L, Green S, Delafont V, Brockley M, Samba-Louaka A. Isolation and Genome Analysis of an Amoeba-Associated Bacterium Dyella terrae Strain Ely Copper Mine From Acid Rock Drainage in Vermont, United States. Front Microbiol 2022; 13:856908. [PMID: 35677904 PMCID: PMC9169046 DOI: 10.3389/fmicb.2022.856908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 04/21/2022] [Indexed: 11/13/2022] Open
Abstract
Protozoa play important roles in microbial communities, regulating populations via predation and contributing to nutrient cycling. While amoebae have been identified in acid rock drainage (ARD) systems, our understanding of their symbioses in these extreme environments is limited. Here, we report the first isolation of the amoeba Stemonitis from an ARD environment as well as the genome sequence and annotation of an associated bacterium, Dyella terrae strain Ely Copper Mine, from Ely Brook at the Ely Copper Mine Superfund site in Vershire, Vermont, United States. Fluorescent in situ hybridization analysis showed this bacterium colonizing cells of Stemonitis sp. in addition to being outside of amoebal cells. This amoeba-resistant bacterium is Gram-negative with a genome size of 5.36 Mbp and GC content of 62.5%. The genome of the D. terrae strain Ely Copper Mine encodes de novo biosynthetic pathways for amino acids, carbohydrates, nucleic acids, and lipids. Genes involved in nitrate (1) and sulfate (7) reduction, metal (229) and antibiotic resistance (37), and secondary metabolite production (6) were identified. Notably, 26 hydrolases were identified by RAST as well as other biomass degradation genes, suggesting roles in carbon and energy cycling within the microbial community. The genome also contains type IV secretion system genes involved in amoebae resistance, revealing how this bacterium likely survives predation from Stemonitis sp. This genome analysis and the association of D. terrae strain Ely Copper Mine with Stemonitis sp. provide insight into the functional roles of amoebae and bacteria within ARD environments.
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Affiliation(s)
- Lesley-Ann Giddings
- Department of Chemistry, Smith College, Northampton, MA, United States.,Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, United States
| | - Kevin Kunstman
- Research Resources Center, University of Illinois at Chicago, Chicago, IL, United States
| | - Bouziane Moumen
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, UMR7267, Poitiers, France
| | - Laurent Asiama
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, United States
| | - Stefan Green
- Research Resources Center, University of Illinois at Chicago, Chicago, IL, United States
| | - Vincent Delafont
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, UMR7267, Poitiers, France
| | - Matthew Brockley
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, United States
| | - Ascel Samba-Louaka
- Laboratoire Ecologie et Biologie des Interactions, Université de Poitiers, UMR7267, Poitiers, France
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Adaptation to an amoeba host leads to Pseudomonas aeruginosa isolates with attenuated virulence. Appl Environ Microbiol 2022; 88:e0232221. [PMID: 35020451 PMCID: PMC8904051 DOI: 10.1128/aem.02322-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is ubiquitous in the environment, and in humans, it is capable of causing acute or chronic infections. In the natural environment, predation by bacterivorous protozoa represents a primary threat to bacteria. Here, we determined the impact of long-term exposure of P. aeruginosa to predation pressure. P. aeruginosa persisted when coincubated with the bacterivorous Acanthamoeba castellanii for extended periods and produced genetic and phenotypic variants. Sequencing of late-stage amoeba-adapted P. aeruginosa isolates demonstrated single nucleotide polymorphisms within genes that encode known virulence factors, and this correlated with a reduction in expression of virulence traits. Virulence for the nematode Caenorhabditis elegans was attenuated in late-stage amoeba-adapted P. aeruginosa compared to early-stage amoeba-adapted and nonadapted counterparts. Further, late-stage amoeba-adapted P. aeruginosa showed increased competitive fitness and enhanced survival in amoebae as well as in macrophage and neutrophils. Interestingly, our findings indicate that the selection imposed by amoebae resulted in P. aeruginosa isolates with reduced virulence and enhanced fitness, similar to those recovered from chronic cystic fibrosis infections. Thus, predation by protozoa and long-term colonization of the human host may represent similar environments that select for similar losses of gene function. IMPORTANCEPseudomonas aeruginosa is an opportunistic pathogen that causes both acute infections in plants and animals, including humans, and chronic infections in immunocompromised and cystic fibrosis patients. This bacterium is commonly found in soils and water, where bacteria are constantly under threat of being consumed by bacterial predators, e.g., protozoa. To escape being killed, bacteria have evolved a suite of mechanisms that protect them from being consumed or digested. Here, we examined the effect of long-term predation on the genotypes and phenotypes expressed by P. aeruginosa. We show that long-term coincubation with protozoa gave rise to mutations that resulted in P. aeruginosa becoming less pathogenic. This is particularly interesting as similar mutations arise in bacteria associated with chronic infections. Importantly, the genetic and phenotypic traits possessed by late-stage amoeba-adapted P. aeruginosa are similar to those observed in isolates obtained from chronic cystic fibrosis infections. This notable overlap in adaptation to different host types suggests similar selection pressures among host cell types as well as similar adaptation strategies.
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