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1.
Annu Rev Microbiol ; 77: 561-581, 2023 09 15.
Article in English | MEDLINE | ID: mdl-37406345

ABSTRACT

Bacteria are single-celled organisms that carry a comparatively small set of genetic information, typically consisting of a few thousand genes that can be selectively activated or repressed in an energy-efficient manner and transcribed to encode various biological functions in accordance with environmental changes. Research over the last few decades has uncovered various ingenious molecular mechanisms that allow bacterial pathogens to sense and respond to different environmental cues or signals to activate or suppress the expression of specific genes in order to suppress host defenses and establish infections. In the setting of infection, pathogenic bacteria have evolved various intelligent mechanisms to reprogram their virulence to adapt to environmental changes and maintain a dominant advantage over host and microbial competitors in new niches. This review summarizes the bacterial virulence programming mechanisms that enable pathogens to switch from acute to chronic infection, from local to systemic infection, and from infection to colonization. It also discusses the implications of these findings for the development of new strategies to combat bacterial infections.


Subject(s)
Bacteria , Virulence , Bacteria/genetics
2.
EMBO J ; 40(21): e108174, 2021 11 02.
Article in English | MEDLINE | ID: mdl-34636061

ABSTRACT

All bacteria produce secreted vesicles that carry out a variety of important biological functions. These extracellular vesicles can improve adaptation and survival by relieving bacterial stress and eliminating toxic compounds, as well as by facilitating membrane remodeling and ameliorating inhospitable environments. However, vesicle production comes with a price. It is energetically costly and, in the case of colonizing pathogens, it elicits host immune responses, which reduce bacterial viability. This raises an interesting paradox regarding why bacteria produce vesicles and begs the question as to whether the benefits of producing vesicles outweigh their costs. In this review, we discuss the various advantages and disadvantages associated with Gram-negative and Gram-positive bacterial vesicle production and offer perspective on the ultimate score. We also highlight questions needed to advance the field in determining the role for vesicles in bacterial survival, interkingdom communication, and virulence.


Subject(s)
Extracellular Vesicles/metabolism , Gram-Negative Bacteria/metabolism , Gram-Positive Bacteria/metabolism , Microbial Viability/genetics , Secretory Vesicles/metabolism , Virulence Factors/genetics , Animals , Extracellular Vesicles/chemistry , Gene Expression , Gram-Negative Bacteria/genetics , Gram-Negative Bacteria/growth & development , Gram-Negative Bacteria/pathogenicity , Gram-Positive Bacteria/genetics , Gram-Positive Bacteria/growth & development , Gram-Positive Bacteria/pathogenicity , Host-Parasite Interactions/genetics , Humans , Immunity, Innate , Quorum Sensing/genetics , Secretory Vesicles/chemistry , Virulence , Virulence Factors/metabolism
3.
Proc Natl Acad Sci U S A ; 119(41): e2209699119, 2022 10 11.
Article in English | MEDLINE | ID: mdl-36191236

ABSTRACT

Fungi and bacteria often engage in complex interactions, such as the formation of multicellular biofilms within the human body. Knowledge about how interkingdom biofilms initiate and coalesce into higher-level communities and which functions the different species carry out during biofilm formation remain limited. We found native-state assemblages of Candida albicans (fungi) and Streptococcus mutans (bacteria) with highly structured arrangement in saliva from diseased patients with childhood tooth decay. Further analyses revealed that bacterial clusters are attached within a network of fungal yeasts, hyphae, and exopolysaccharides, which bind to surfaces as a preassembled cell group. The interkingdom assemblages exhibit emergent functions, including enhanced surface colonization and growth rate, stronger tolerance to antimicrobials, and improved shear resistance, compared to either species alone. Notably, we discovered that the interkingdom assemblages display a unique form of migratory spatial mobility that enables fast spreading of biofilms across surfaces and causes enhanced, more extensive tooth decay. Using mutants, selective inactivation of species, and selective matrix removal, we demonstrate that the enhanced stress resistance and surface mobility arise from the exopolymeric matrix and require the presence of both species in the assemblage. The mobility is directed by fungal filamentation as hyphae extend and contact the surface, lifting the assemblage with a "forward-leaping motion." Bacterial cell clusters can "hitchhike" on this mobile unit while continuously growing, to spread across the surface three-dimensionally and merge with other assemblages, promoting community expansion. Together, our results reveal an interkingdom assemblage in human saliva that behaves like a supraorganism, with disease-causing emergent functionalities that cannot be achieved without coassembly.


Subject(s)
Biofilms , Saliva , Streptococcus mutans , Candida albicans/metabolism , Child , Disease , Humans , Hyphae/physiology , Population Dynamics , Saliva/microbiology
4.
Proc Natl Acad Sci U S A ; 119(10): e2118227119, 2022 03 08.
Article in English | MEDLINE | ID: mdl-35238645

ABSTRACT

SignificanceHost-emitted stress hormones significantly influence the growth and behavior of various bacterial species; however, their cellular targets have so far remained elusive. Here, we used customized probes and quantitative proteomics to identify the target of epinephrine and the α-adrenoceptor agonist phenylephrine in live cells of the aquatic pathogen Vibrio campbellii. Consequently, we have discovered the coupling protein CheW, which is in the center of the chemotaxis signaling network, as a target of both molecules. We not only demonstrate direct ligand binding to CheW but also elucidate how this affects chemotactic control. These findings are pivotal for further research on hormone-specific effects on bacterial behavior.


Subject(s)
Bacterial Proteins/metabolism , Catecholamines/physiology , Chemotactic Factors/physiology , Chemotaxis/physiology , Vibrio/physiology , Catechols/chemistry , Chemotactic Factors/metabolism , Iron/analysis , Molecular Probes/chemistry , Protein Binding , Proteomics/methods , Signal Transduction
5.
J Bacteriol ; 206(7): e0010424, 2024 Jul 25.
Article in English | MEDLINE | ID: mdl-38899897

ABSTRACT

Glucan-dependent biofilm formation is a crucial process in the establishment of Streptococcus mutans as a cariogenic oral microbe. The process of glucan formation has been investigated in great detail, with glycosyltransferases GtfB, GtfC, and GtfD shown to be indispensable for the synthesis of glucans from sucrose. Glucan production can be visualized during biofilm formation through fluorescent labeling, and its abundance, as well as the effect of glucans on general biofilm architecture, is a common phenotype to study S. mutans virulence regulation. Here, we describe an entirely new phenotype associated with glucan production, caused by a mutation in the open reading frame SMU_848, which is located in an operon encoding ribosome-associated proteins. This mutation led to the excess production and accumulation of glucan-containing droplets on the surface of biofilms formed on agar plates after prolonged incubation. While not characterized in S. mutans, SMU_848 shows homology to the phage-related ribosomal protease Prp, essential in cleaving off the N-terminal extension of ribosomal protein L27 for functional ribosome assembly in Staphylococcus aureus. We present a further characterization of SMU_848/Prp, demonstrating that the deletion of this gene leads to significant changes in S. mutans gtfBC expression. Surprisingly, it also profoundly impacts the interkingdom interaction between S. mutans and Candida albicans, a relevant dual-species interaction implicated in severe early childhood caries. The presented data support a potential broader role for SMU_848/Prp, possibly extending its functionality beyond the ribosomal network to influence important ecological processes. IMPORTANCE: Streptococcus mutans is an important member of the oral biofilm and is implicated in the initiation of caries. One of the main virulence mechanisms is the glucan-dependent formation of biofilms. We identified a new player in the regulation of glucan production, SMU_848, which is part of an operon that also encodes for ribosomal proteins L27 and L21. A mutation in SMU_848, which encodes a phage-related ribosomal protease Prp, leads to a significant accumulation of glucan-containing droplets on S. mutans biofilms, a previously unknown phenotype. Further investigations expanded our knowledge about the role of SMU_848 beyond its role in glucan production, including significant involvement in interkingdom interactions, thus potentially playing a global role in the virulence regulation of S. mutans.


Subject(s)
Bacterial Proteins , Biofilms , Glucans , Streptococcus mutans , Streptococcus mutans/genetics , Streptococcus mutans/metabolism , Streptococcus mutans/enzymology , Biofilms/growth & development , Glucans/metabolism , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Gene Expression Regulation, Bacterial , Ribosomes/metabolism , Mutation , Ribosomal Proteins/metabolism , Ribosomal Proteins/genetics
6.
J Biol Chem ; 299(12): 105376, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37866633

ABSTRACT

Legionella pneumophila is an environmental bacterium, which replicates in amoeba but also in macrophages, and causes a life-threatening pneumonia called Legionnaires' disease. The opportunistic pathogen employs the α-hydroxy-ketone compound Legionella autoinducer-1 (LAI-1) for intraspecies and interkingdom signaling. LAI-1 is produced by the autoinducer synthase Legionella quorum sensing A (LqsA), but it is not known, how LAI-1 is released by the pathogen. Here, we use a Vibrio cholerae luminescence reporter strain and liquid chromatography-tandem mass spectrometry to detect bacteria-produced and synthetic LAI-1. Ectopic production of LqsA in Escherichia coli generated LAI-1, which partitions to outer membrane vesicles (OMVs) and increases OMV size. These E. coli OMVs trigger luminescence of the V. cholerae reporter strain and inhibit the migration of Dictyostelium discoideum amoeba. Overexpression of lqsA in L.pneumophila under the control of strong stationary phase promoters (PflaA or P6SRNA), but not under control of its endogenous promoter (PlqsA), produces LAI-1, which is detected in purified OMVs. These L. pneumophila OMVs trigger luminescence of the Vibrio reporter strain and inhibit D. discoideum migration. L. pneumophila OMVs are smaller upon overexpression of lqsA or upon addition of LAI-1 to growing bacteria, and therefore, LqsA affects OMV production. The overexpression of lqsA but not a catalytically inactive mutant promotes intracellular replication of L. pneumophila in macrophages, indicating that intracellularly produced LA1-1 modulates the interaction in favor of the pathogen. Taken together, we provide evidence that L. pneumophila LAI-1 is secreted through OMVs and promotes interbacterial communication and interactions with eukaryotic host cells.


Subject(s)
Legionella pneumophila , Quorum Sensing , Humans , Bacterial Proteins/genetics , Dictyostelium , Escherichia coli , Legionella , Legionella pneumophila/physiology , Legionnaires' Disease/microbiology
7.
Ecol Lett ; 27(6): e14442, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38844373

ABSTRACT

Highly diverse and abundant organisms coexist in soils. However, the contribution of biotic interactions between soil organisms to microbial community assembly remains to be explored. Here, we assess the extent to which soil fauna can shape microbial community assembly using an exclusion experiment in a grassland field to sort soil biota based on body size. After 1 year, the exclusion of larger fauna favoured phagotrophic protists, with increases up to 32% in their proportion compared to the no-mesh treatment. In contrast, members of the bacterial community and to a lesser extent of the fungal community were negatively impacted. Shifts in bacterial but not in fungal communities were best explained by the response of the protistan community to exclusion. Our findings provide empirical evidence of top-down control on the soil microbial communities and underline the importance of integrating higher trophic levels for a better understanding of the soil microbiome assembly.


Subject(s)
Bacteria , Fungi , Grassland , Microbiota , Soil Microbiology , Fungi/physiology , Animals , Eukaryota/physiology , Soil/chemistry , Body Size
8.
Metabolomics ; 20(4): 75, 2024 Jul 09.
Article in English | MEDLINE | ID: mdl-38980562

ABSTRACT

INTRODUCTION: Microbial communities affect several aspects of the earth's ecosystem through their metabolic interaction. The dynamics of this interaction emerge from complex multilevel networks of crosstalk. Elucidation of this interaction could help us to maintain the balance for a sustainable future. OBJECTIVES: To investigate the chemical language among highly abundant microbial genera in the rhizospheres of medicinal plants based on the metabolomic analysis at the interaction level. METHODS: Coculturing experiments involving three microbial species: Aspergillus (A), Trichoderma (T), and Bacillus (B), representing fungi (A, T) and bacteria (B), respectively. These experiments encompassed various interaction levels, including dual cultures (AB, AT, TB) and triple cultures (ATB). Metabolic profiling by LC-QTOFMS revealed the effect of interaction level on the productivity and diversity of microbial specialized metabolites. RESULTS: The ATB interaction had the richest profile, while the bacterial profile in the monoculture condition had the lowest. Two native compounds of the Aspergillus genus, aspergillic acid and the dipeptide asperopiperazine B, exhibited decreased levels in the presence of the AT interaction and were undetectable in the presence of bacteria during the interaction. Trichodermarin N and Trichodermatide D isolated from Trichoderma species exclusively detected during coexistence with bacteria (TB and ATB). These findings indicate that the presence of Bacillus activates cryptic biosynthetic gene clusters in Trichoderma. The antibacterial activity of mixed culture extracts was stronger than that of the monoculture extracts. The TB extract exhibited strong antifungal activity compared to the monoculture extract and other mixed culture treatments. CONCLUSION: The elucidation of medicinal plant microbiome interaction chemistry and its effect on the environment will also be of great interest in the context of medicinal plant health Additionally, it sheds light on the content of bioactive constituents, and facilitating the discovery of novel antimicrobials.


Subject(s)
Microbial Interactions , Plants, Medicinal , Rhizosphere , Plants, Medicinal/metabolism , Plants, Medicinal/microbiology , Aspergillus/metabolism , Bacteria/metabolism , Trichoderma/metabolism , Bacillus/metabolism , Fungi/metabolism , Metabolomics , Coculture Techniques , Soil Microbiology
9.
Microbiology (Reading) ; 169(3)2023 03.
Article in English | MEDLINE | ID: mdl-36952261

ABSTRACT

Bacteria produce an array of diverse, dynamic and often complex lipid structures, some of which function beyond their typical role in membrane structure. The model organism, E. coli, has three major membrane lipids, which are glycerophosphoglycerol (phosphatidylglycerol), glycerophosphoethanolamine (phosphatidylethanolamine) and cardiolipin. However, it is now appreciated that some bacteria have the capacity to synthesize a range of lipids, including glycerophosphocholines, glycerophosphoinositols, 'phosphorous-free' N-acyl amines, sphingolipids and plasmalogens. In recent years, some of these bacterial lipids have emerged as influential contributors to the microbe-host molecular dialogue. This review outlines our current knowledge of bacterial lipid diversity, with a focus on the membrane lipids of microbiome-associated bacteria that have documented roles as signalling molecules.


Subject(s)
Gastrointestinal Microbiome , Membrane Lipids , Membrane Lipids/chemistry , Escherichia coli/genetics , Escherichia coli/chemistry , Cardiolipins
10.
Appl Environ Microbiol ; 89(12): e0140623, 2023 12 21.
Article in English | MEDLINE | ID: mdl-38014962

ABSTRACT

IMPORTANCE: We applied macro- (forest stand and forest management) and micro-scale (bacterial and fungal community) analyses for a better understanding of the Heterobasidion pathosystem and associated wood decay process. The core microbiome, as defined by hierarchy analysis and a consistent model, and environmental factors correlation with the community assembly were found to be novel.


Subject(s)
Ascomycota , Basidiomycota , Microbiota , Wood/microbiology , Forests
11.
Mol Ecol ; 32(24): 6939-6952, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37902115

ABSTRACT

Despite the known collective contribution of above- (plants) and below-ground (soil fungi) biodiversity on multiple soil functions, how the associations among plant and fungal communities regulate soil multifunctionality (SMF) differentially remains unknown. Here, plant communities were investigated at 81 plots across a typical arid inland river basin, within which associated soil fungal communities and seven soil functions (nutrients storage and biological activity) were measured in surface (0-15 cm) and subsurface soil (15-30 cm). We evaluated the relative importance of species richness and biotic associations (reflected by network complexity) on SMF. Our results demonstrated that plant species richness and plant-fungus network complexity promoted SMF in surface and subsurface soil. SMF in two soil layers was mainly determined by plant-fungus network complexity, mean groundwater depth and soil variables, among which plant-fungus network complexity played a crucial role. Plant-fungus network complexity had stronger effects on SMF in surface soil than in subsurface soil. We present evidence that plant-fungus network complexity surpassed plant-fungal species richness in determining SMF in surface and subsurface soil. Moreover, plant-fungal species richness could not directly affect SMF. Greater plant-fungal species richness indirectly promoted SMF since they ensured greater plant-fungal associations. Collectively, we concluded that interkingdom networks between plants and fungi drive SMF even in different soil layers. Our findings enhanced our knowledge of the underlying mechanisms that above- and below-ground associations promote SMF in arid inland river basins. Future study should place more emphasis on the associations among plant and microbial communities in protecting soil functions under global changes.


Subject(s)
Rivers , Soil , Soil Microbiology , Plants/microbiology , Biodiversity , Fungi/genetics , Ecosystem
12.
Appl Microbiol Biotechnol ; 107(1): 433-446, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36454252

ABSTRACT

Mobile genetic elements (MGEs) are associated with the emergence of multidrug resistance in extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae. This study explores the role of class 1 integrons and IS26 elements in breaching taxonomic barriers. A total of 110 E. coli bacteria were isolated from 300 clinical mastitis milk samples. The 98% E. coli isolates were extended-spectrum beta-lactamase- producers. About 83% of these isolates carried co-resistance for fluoroquinolones. The co-existence of (extended-spectrum beta-lactamase + quinolone resistance determining region mutations) and (extended-spectrum beta-lactamase + plasmid-mediated quinolone resistance genes) was found in 76% and 44% of isolates, respectively. The MGEs were detected in 88% of isolates with IS26 in 82% and class 1 integrase in 40% of isolates. The types of class 1 integron gene cassettes detected includes dfrA7, (dfrA17 + aadA5), and (dfrA1 + aadA1). We discovered 2 and 4 novel variants of the dfrA17 and aadA5 genes, respectively. We report a variant of aadA5 with mutation E235G in the Indian subcontinent earlier reported only in a human clinical isolate from Belgium. About 19 isolates carried IS26 linked to integrase gene intI1 with an internal deletion of 265 bp in the 5`CS of integrase gene intI1, earlier reported only in E. coli ST131 isolates from human clinical, wastewater samples. This study suggests intercontinental dissemination of antibiotic resistant genes (ARGs) across different microbiomes via mobile genetic elements. KEY POINTS: • The role of mobile genetic elements in the emergence of multidrug-resistant E. coli in bovine mastitis. • Novel variants of the aadA5 (aminoglycoside adenyl transferase) and dfrA17 (dihydrofolate reductase) genes were identified in pathogenic E. coli isolated from bovine mastitis in class 1 integron gene cassette. • Sequence analysis of mobile genetic components revealed the physical connection between IS26 and intI1 genes with an internal deletion in 5'CS of class 1 integrase.


Subject(s)
Escherichia coli Infections , Mastitis, Bovine , Quinolones , Cattle , Animals , Female , Humans , Integrons/genetics , Escherichia coli , Mastitis, Bovine/microbiology , Microbial Sensitivity Tests , Escherichia coli Infections/veterinary , Escherichia coli Infections/microbiology , Anti-Bacterial Agents/pharmacology , beta-Lactamases/genetics , Integrases/genetics , Drug Resistance, Bacterial/genetics
13.
Int J Mol Sci ; 24(3)2023 Jan 20.
Article in English | MEDLINE | ID: mdl-36768391

ABSTRACT

Obesity and type 2 diabetes are associated with defects of insulin action in different tissues or alterations in ß-cell secretory capacity that may be triggered by environmental challenges, inadequate lifestyle choices, or an underlying genetic predisposition. In addition, recent data shows that obesity may also be caused by perturbations of the gut microbiota, which then affect metabolic function and energy homeostasis in the host. Maintenance of metabolic homeostasis in complex organisms such as mammals requires organismal-level communication, including between the different organs and the gut microbiota. Extracellular vesicles (EVs) have been identified in all domains of life and have emerged as crucial players in inter-organ and inter-kingdom crosstalk. Interestingly, EVs found in edible vegetables or in milk have been shown to influence gut microbiota or tissue function in mammals. Moreover, there is a multidirectional crosstalk mediated by EVs derived from gut microbiota and body organs that has implications for host health. Untangling this complex signaling network may help implement novel therapies for the treatment of metabolic disease.


Subject(s)
Diabetes Mellitus, Type 2 , Extracellular Vesicles , Animals , Humans , Diabetes Mellitus, Type 2/metabolism , Obesity/metabolism , Extracellular Vesicles/metabolism , Mammals , Communication
14.
Biofouling ; 38(4): 401-413, 2022 04.
Article in English | MEDLINE | ID: mdl-35655421

ABSTRACT

Enterococcus faecalis is the most important agent of persistent apical periodontitis, and recently, Candida albicans has also been implicated in periapical infections. This study aimed to optimize an in vitro E. faecalis and C. albicans dual-species biofilm protocol for endodontic research. Different physicochemical conditions for biofilm formation were tested. Susceptibility assays to antimicrobials, biochemical composition and an ultra-morphological structure analyses were performed. Reproducible dual-species biofilms were established in BHI medium at 35 °C, for 48 h and in a microaerophilic atmosphere. An increase in biomass and chitin content was detected after vancomycin treatment. Structural analysis revealed that the dual-species biofilm was formed by both microorganisms adhered to the substrate. The proposed protocol could be useful for the study of interkingdom relationships and help to find new strategies against periapical infections.


Subject(s)
Anti-Infective Agents , Enterococcus faecalis , Biofilms , Candida albicans
15.
Subcell Biochem ; 97: 509-521, 2021.
Article in English | MEDLINE | ID: mdl-33779931

ABSTRACT

It has been well established that diet influences the health status of the consuming organism. Recently, extracellular vesicles (EVs) present in dietary sources are proposed to be involved in cross-species and kingdom communication. As EVs contain a lipid bilayer and carry bioactive cargo of proteins and nucleic acids, they are proposed to survive harsh degrading conditions of the gut and enter systemic circulation. Following the bioavailability, several studies have supported the functional role of dietary EVs in various tissues of the consuming organism. Simultaneously, multiple studies have refuted the possibility that dietary EVs mediate cross-species communication and hence the topic is controversial. The feasibility of the concept remains under scrutiny primarily owing to the lack of significant in vivo evidence to complement the in vitro speculations. Concerns surrounding EV stability in the harsh degrading gut environment, lack of mechanism explaining intestinal uptake and bioavailability in systemic circulation have impeded the acceptance of their functional role. This chapter discusses the current evidences that support dietary EV-based cross species communication and enlists several issues that need to be addressed in this field.


Subject(s)
Extracellular Vesicles , Biological Transport , Diet , Extracellular Vesicles/metabolism , Proteins/metabolism
16.
Int J Mol Sci ; 23(16)2022 Aug 16.
Article in English | MEDLINE | ID: mdl-36012475

ABSTRACT

Due to the possible co-presence of Pseudomonas aeruginosa and Candida albicans (the most common nosocomial pathogens) in lungs, rapid interkingdom biofilm production is possible. As such, PA+CA produced more dominant biofilms on the pulmonary epithelial surface (NCI-H292) (confocal fluorescent extracellular matrix staining) with dominant psl upregulation, as demonstrated by polymerase chain reaction (PCR), after 8 h of experiments than PA alone. With a proteomic analysis, rhamnosyltransferase RhlB protein (Psl-associated quorum-sensing protein) was found to be among the high-abundance proteins in PA+CA than in PA biofilms, supporting psl-mediated biofilms in PA+CA on the cell surface. Additionally, PA+CA increased supernatant cytokines (IL-8 and IL-13, but not TNF-α, IL-6, and IL-10) with a similar upregulation of TLR-4, TLR-5, and TLR-9 (by PCR) compared with PA-stimulated cells. The intratracheal administration of PA+CA induced a greater severity of sepsis (serum creatinine, alanine transaminase, serum cytokines, and histology score) and prominent biofilms (fluorescent staining) with psl upregulation (PCR). In comparison with PA+CA biofilms on glass slides, PA+CA biofilms on biotic surfaces were more prominent (fluorescent staining). In conclusion, PA+CA induced Psl-predominant biofilms on the pulmonary cell surface and in mice with acute pneumonia, and these biofilms were more prominent than those induced by PA alone, highlighting the impact of Candida on rapid interkingdom biofilm production.


Subject(s)
Candida , Pseudomonas , Animals , Biofilms , Candida/metabolism , Cytokines/metabolism , Lung/metabolism , Mice , Polysaccharides, Bacterial/metabolism , Proteomics , Pseudomonas/metabolism , Pseudomonas aeruginosa/physiology
17.
Infect Immun ; 89(4)2021 03 17.
Article in English | MEDLINE | ID: mdl-33526565

ABSTRACT

The term "microbiota" invokes images of mucosal surfaces densely populated with bacteria. These surfaces and the luminal compartments they form indeed predominantly harbor bacteria. However, research from this past decade has started to complete the picture by focusing on important but largely neglected constituents of the microbiota: fungi, viruses, and archaea. The community of commensal fungi, also called the mycobiota, interacts with commensal bacteria and the host. It is thus not surprising that changes in the mycobiota have significant impact on host health and are associated with pathological conditions such as inflammatory bowel disease (IBD). In this review we will give an overview of why the mycobiota is an important research area and different mycobiota research tools. We will specifically focus on distinguishing transient and actively colonizing fungi of the oral and gut mycobiota and their roles in health and disease. In addition to correlative and observational studies, we will discuss mechanistic studies on specific cross-kingdom interactions of fungi, bacteria, and the host.


Subject(s)
Bacteria , Disease Susceptibility , Fungi , Homeostasis , Host Microbial Interactions , Microbial Interactions , Mycobiome , Animals , Host Microbial Interactions/immunology , Humans , Immune System/immunology , Immune System/metabolism , Metagenome , Metagenomics/methods , Microbiological Techniques , Microbiota , Organ Specificity
18.
Vet Res ; 52(1): 39, 2021 Mar 04.
Article in English | MEDLINE | ID: mdl-33663613

ABSTRACT

Zinc (Zn) is an essential trace element in living organisms and plays a vital role in the regulation of both microbial virulence and host immune responses. A growing number of studies have shown that zinc deficiency or the internal Zn concentration does not meet the needs of animals and microbes, leading to an imbalance in zinc homeostasis and intracellular signalling pathway dysregulation. Competition for zinc ions (Zn2+) between microbes and the host exists in the use of Zn2+ to maintain cell structure and physiological functions. It also affects the interplay between microbial virulence factors and their specific receptors in the host. This review will focus on the role of Zn in the crosstalk between the host and microbe, especially for changes in microbial pathogenesis and nociceptive neuron-immune interactions, as it may lead to new ways to prevent or treat microbial infections.


Subject(s)
Host Microbial Interactions/physiology , Host-Pathogen Interactions/physiology , Nociceptors , Zinc/metabolism , Animals , Nociceptors/immunology , Nociceptors/microbiology
19.
Environ Sci Technol ; 55(18): 12337-12351, 2021 09 21.
Article in English | MEDLINE | ID: mdl-34486373

ABSTRACT

Decomposition by microorganisms of plastics in soils is almost unexplored despite the fact that the majority of plastics released into the environment end up in soils. Here, we investigate the decomposition process and microbiome of one of the most promising biobased and biodegradable plastics, poly(butylene succinate-co-adipate) (PBSA), under field soil conditions under both ambient and future predicted climates (for the time between 2070 and 2100). We show that the gravimetric and molar mass of PBSA is already largely reduced (28-33%) after 328 days under both climates. We provide novel information on the PBSA microbiome encompassing the three domains of life: Archaea, Bacteria, and Eukarya (fungi). We show that PBSA begins to decompose after the increase in relative abundances of aquatic fungi (Tetracladium spp.) and nitrogen-fixing bacteria. The PBSA microbiome is distinct from that of surrounding soils, suggesting that PBSA serves as a new ecological habitat. We conclude that the microbial decomposition process of PBSA in soil is more complex than previously thought by involving interkingdom relationships, especially between bacteria and fungi.


Subject(s)
Ascomycota , Biodegradable Plastics , Microbiota , Biodegradation, Environmental , Soil , Soil Microbiology
20.
Microbiology (Reading) ; 166(4): 335-348, 2020 04.
Article in English | MEDLINE | ID: mdl-32209172

ABSTRACT

Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between bacteria and their animal hosts. The genus Photorhabdus comprises Gram-negative insect pathogenic bacteria that are normally found as symbionts that colonize the gut of the infective juvenile stage of soil-dwelling nematodes from the family Heterorhabditis. The nematodes infect susceptible insects and release the bacteria into the insect haemolymph where the bacteria grow, resulting in the death of the insect. At this stage the nematodes feed on the bacterial biomass and, following several rounds of reproduction, the nematodes develop into infective juveniles that leave the insect cadaver in search of new hosts. Therefore Photorhabdus has three distinct and obligate roles to play during this life-cycle: (1) Photorhabdus must kill the insect host; (2) Photorhabdus must be capable of supporting nematode growth and development; and (3) Photorhabdus must be able to colonize the gut of the next generation of infective juveniles before they leave the insect cadaver. In this review I will discuss how genetic analysis has identified key genes involved in mediating, and regulating, the interaction between Photorhabdus and each of its invertebrate hosts. These studies have resulted in the characterization of several new families of toxins and a novel inter-kingdom signalling molecule and have also uncovered an important role for phase variation in the regulation of these different roles.


Subject(s)
Insecta/microbiology , Photorhabdus/physiology , Photorhabdus/pathogenicity , Rhabditoidea/microbiology , Animals , Bacterial Toxins/genetics , Bacterial Toxins/metabolism , Gastrointestinal Tract/microbiology , Host Microbial Interactions , Insecta/parasitology , Life Cycle Stages , Rhabditoidea/growth & development , Rhabditoidea/pathogenicity , Rhabditoidea/physiology , Signal Transduction , Symbiosis
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