-
Journal of Bacteriology Jun 2020Phage tail-like bacteriocins (tailocins) are bacterially produced protein toxins that mediate competitive interactions between cocolonizing bacteria. Both theoretical...
Phage tail-like bacteriocins (tailocins) are bacterially produced protein toxins that mediate competitive interactions between cocolonizing bacteria. Both theoretical and experimental research has shown there are intransitive interactions between bacteriocin-producing, bacteriocin-sensitive, and bacteriocin-resistant populations, whereby producers outcompete sensitive cells, sensitive cells outcompete resistant cells, and resistant cells outcompete producers. These so-called rock-paper-scissors dynamics explain how all three populations occupy the same environment, without one driving the others extinct. Using as a model, we demonstrate that otherwise sensitive cells survive bacteriocin exposure through a physiological mechanism. This mechanism allows cells to survive bacteriocin killing without acquiring resistance. We show that a significant fraction of the target cells that survive a lethal dose of tailocin did not exhibit any detectable increase in survival during a subsequent exposure. Tailocin persister cells were more prevalent in stationary- rather than log-phase cultures. Of the fraction of cells that gained detectable resistance, there was a range from complete (insensitive) to incomplete (partially sensitive) resistance. By using genomic sequencing and genetic engineering, we showed that a mutation in a hypothetical gene containing 8 to 10 transmembrane domains causes tailocin high persistence and that genes of various glycosyltransferases cause incomplete and complete tailocin resistance. Importantly, of the several classes of mutations, only those causing complete tailocin resistance compromised host fitness. This result indicates that bacteria likely utilize persistence to survive bacteriocin-mediated killing without suffering the costs associated with resistance. This research provides important insight into how bacteria can escape the trap of fitness trade-offs associated with gaining tailocin resistance. Bacteriocins are bacterially produced protein toxins that are proposed as antibiotic alternatives. However, a deeper understanding of the responses of target bacteria to bacteriocin exposure is lacking. Here, we show that target cells of survive lethal bacteriocin exposure through both physiological persistence and genetic resistance mechanisms. Cells that are not growing rapidly rely primarily on persistence, whereas those growing rapidly are more likely to survive via resistance. We identified various mutations in lipopolysaccharide biogenesis-related regions involved in tailocin persistence and resistance. By assessing host fitness of various classes of mutants, we showed that persistence and subtle resistance are mechanisms uses to survive competition and preserve host fitness. These results have important implications for developing bacteriocins as alternative therapeutic agents.
Topics: Bacterial Proteins; Bacteriocins; Drug Resistance, Bacterial; Microbial Viability; Pseudomonas
PubMed: 32312747
DOI: 10.1128/JB.00142-20 -
Scientific Reports Jun 2020To assess the role of core metabolism genes in bacterial virulence - independently of their effect on growth - we correlated the genome, the transcriptome and the...
To assess the role of core metabolism genes in bacterial virulence - independently of their effect on growth - we correlated the genome, the transcriptome and the pathogenicity in flies and mice of 30 fully sequenced Pseudomonas strains. Gene presence correlates robustly with pathogenicity differences among all Pseudomonas species, but not among the P. aeruginosa strains. However, gene expression differences are evident between highly and lowly pathogenic P. aeruginosa strains in multiple virulence factors and a few metabolism genes. Moreover, 16.5%, a noticeable fraction of the core metabolism genes of P. aeruginosa strain PA14 (compared to 8.5% of the non-metabolic genes tested), appear necessary for full virulence when mutated. Most of these virulence-defective core metabolism mutants are compromised in at least one key virulence mechanism independently of auxotrophy. A pathway level analysis of PA14 core metabolism, uncovers beta-oxidation and the biosynthesis of amino-acids, succinate, citramalate, and chorismate to be important for full virulence. Strikingly, the relative expression among P. aeruginosa strains of genes belonging in these metabolic pathways is indicative of their pathogenicity. Thus, P. aeruginosa strain-to-strain virulence variation, remains largely obscure at the genome level, but can be dissected at the pathway level via functional transcriptomics of core metabolism.
Topics: Animals; Gene Expression Regulation, Bacterial; Genes, Bacterial; Host-Pathogen Interactions; Male; Mutation; Pseudomonas aeruginosa; Virulence
PubMed: 32528034
DOI: 10.1038/s41598-020-66194-4 -
Metabolic Engineering Jan 2023In recent years branched short-chain dicarboxylates (BSCD) such as itaconic acid gained increasing interest in both medicine and biotechnology. Their use as building...
In recent years branched short-chain dicarboxylates (BSCD) such as itaconic acid gained increasing interest in both medicine and biotechnology. Their use as building blocks for plastics urges for developing microbial upcycling strategies to provide sustainable end-of-life solutions. Furthermore, many BSCD exhibit anti-bacterial properties or exert immunomodulatory effects in macrophages, indicating a medical relevance for this group of molecules. For both of these applications, a detailed understanding of the microbial metabolism of these compounds is essential. In this study, the metabolic pathway of BSCD degradation from Pseudomonas aeruginosa PAO1 was studied in detail by heterologously transferring it to Pseudomonas putida. Heterologous expression of the PA0878-0886 itaconate metabolism gene cluster enabled P. putida KT2440 to metabolize itaconate, (S)- and (R)-methylsuccinate, (S)-citramalate, and mesaconate. The functions of the so far uncharacterized genes PA0879 and PA0881 were revealed and proven to extend the substrate range of the core degradation pathway. Furthermore, the uncharacterized gene PA0880 was discovered to encode a 2-hydroxyparaconate (2-HP) lactonase that catalyzes the cleavage of the itaconate derivative 2-HP to itatartarate. Interestingly, 2-HP was found to inhibit growth of the engineered P. putida on itaconate. All in all, this study extends the substrate range of P. putida to include BSCD for bio-upcycling of high-performance polymers, and also identifies 2-HP as promising candidate for anti-microbial applications.
Topics: Metabolic Networks and Pathways; Pseudomonas; Pseudomonas aeruginosa; Pseudomonas putida; Carboxylic Acids
PubMed: 36581064
DOI: 10.1016/j.ymben.2022.12.008 -
The Brazilian Journal of Infectious... 2016This work performed a phenotypic and genotypic characterization of 79 clinical isolates of Enterobacteriaceae and Pseudomonadaceae collected in hospitals of Southern...
This work performed a phenotypic and genotypic characterization of 79 clinical isolates of Enterobacteriaceae and Pseudomonadaceae collected in hospitals of Southern Ecuadorin 2013. Our results showed a high incidence of β-lactamases and ESBLs with bla and bla as the prevalent genes, respectively. By direct sequencing of PCR amplicons, the different β-lactamases and variants of the genes were also distinguished. Our results revealed a predominance of TEM-1 β-lactamase and the presence of different CTX-M variants with a prevalence of CTX-M-15. Two infrequent CTX-M variants in South America were also identified. To the best of our knowledge, this is one of the first studies describing the genetic characteristics of β-lactamases in Ecuador.
Topics: Anti-Bacterial Agents; DNA, Bacterial; Disk Diffusion Antimicrobial Tests; Ecuador; Enterobacteriaceae; Genotype; Humans; Phenotype; Pseudomonadaceae; beta-Lactamases
PubMed: 27479052
DOI: 10.1016/j.bjid.2016.07.001 -
Antimicrobial Agents and Chemotherapy Jun 2018Carbapenemase-producing have increasingly been reported worldwide, with an ever-increasing heterogeneity of carbapenem resistance mechanisms, depending on the bacterial...
Carbapenemase-producing have increasingly been reported worldwide, with an ever-increasing heterogeneity of carbapenem resistance mechanisms, depending on the bacterial species and the geographical location. OXA-198 is a plasmid-encoded class D β-lactamase involved in carbapenem resistance in one isolate from Belgium. In the setting of a multicenter survey of carbapenem resistance in strains in Belgian hospitals in 2013, three additional OXA-198-producing isolates originating from patients hospitalized in one hospital were detected. To reveal the molecular mechanism underlying the reduced susceptibility to carbapenems, MIC determinations, whole-genome sequencing, and PCR analyses to confirm the genetic organization were performed. The plasmid harboring the gene was characterized, along with the genetic relatedness of the four isolates. The gene was harbored on a class 1 integron carried by an ∼49-kb IncP-type plasmid proposed as IncP-11. The same plasmid was present in all four isolates. Multilocus sequence typing revealed that the isolates all belonged to sequence type 446, and single-nucleotide polymorphism analysis revealed only a few differences between the isolates. This report describes the structure of a 49-kb plasmid harboring the gene and presents the first description of OXA-198-producing isolates associated with a hospital-associated cluster episode.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Carbapenems; DNA, Bacterial; Microbial Sensitivity Tests; Multilocus Sequence Typing; Plasmids; Pseudomonas aeruginosa; beta-Lactamases
PubMed: 29581118
DOI: 10.1128/AAC.02496-17 -
Applied and Environmental Microbiology Oct 1983Hexavalent chromium [Cr(VI)] is a known carcinogen and mutagen; however, the actual mechanisms of Cr toxicity are unknown. Two approaches were used to isolate... (Comparative Study)
Comparative Study
Hexavalent chromium [Cr(VI)] is a known carcinogen and mutagen; however, the actual mechanisms of Cr toxicity are unknown. Two approaches were used to isolate Cr(VI)-resistant bacteria from metal-contaminated river sediments. Diluted sediments were plated directly onto a peptone-yeast extract (PYE) medium containing 0 to 100 micrograms of Cr(VI) ml-1. Approximately 8.4 x 10(5) CFU g-1 were recovered on 0 microgram of Cr(VI) ml-1, whereas 4.0 x 10(2) CFU g-1 were recovered on PYE plus 100 micrograms of Cr(VI) ml-1. Alternatively, continuous culture enrichment techniques were employed using PYE and 100 micrograms Cr(VI) ml-1 input at dilution rates of 0.02 and 0.10 h-1. After six residence periods, 10(9) CFU were recovered on PYE agar containing 0 microgram of Cr(VI) ml-1 and 10(7) CFU on PYE agar plus 100 micrograms of Cr(VI) ml-1. Of 89 isolates obtained by direct plating onto PYE, 47% were resistant to 100 micrograms of Cr(VI) ml-1, and 29% were resistant to 250 micrograms of Cr(VI) ml-1. When the same isolates were plated onto PYE containing Cr(III), 88% were resistant to 100 micrograms ml-1 but only 2% were resistant to 250 micrograms ml-1. Cr, Co, Sb, and Zn were found in significantly higher concentrations at an industry-related contaminated site than at a site 11 km downstream. Total Cr in the sediments at the contaminated site averaged 586 micrograms (dry weight) g-1, and the downstream site averaged 71 micrograms (dry weight) g-1. The Cr recovered from acid-digested Ottawa River sediment samples was predominantly hexavalent. Five acid digestion procedures followed by atomic absorption spectroscopy were compared and found to be 30 to 70% efficient for recovery of Cr relative to neutron activation analysis. A population of aerobic, heterotrophic bacteria was recovered from sediments containing elevated levels of Cr.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Bacteria, Aerobic; Chromium; Drug Resistance, Microbial; Pseudomonadaceae; Water Microbiology; Water Pollution, Chemical
PubMed: 6639032
DOI: 10.1128/aem.46.4.846-854.1983 -
PloS One 2020Pseudomonas aeruginosa is an opportunistic pathogen causing different types of infections, particularly in intensive care unit patients. Characteristics that favor its...
Pseudomonas aeruginosa is an opportunistic pathogen causing different types of infections, particularly in intensive care unit patients. Characteristics that favor its persistence artificial environments are related to its high adaptability, wide arsenal of virulence factors and resistance to several antimicrobial classes. Among the several virulence determinants, T3SS stands as the most important due to the clinical impact of exoS and exoU genes in patient's outcome. The molecular characterization of P. aeruginosa isolates helps in the comprehension of transmission dynamics and enhance knowledge of virulence and resistance roles in infection process. In the present study, we investigated virulence and resistance properties and the genetic background of P. aeruginosa isolated from ICUs patients at a referral hospital in Brazilian Amazon. A total of 54 P. aeruginosa isolates were characterized by detecting 19 virulence-related genes, antimicrobial susceptibility testing, molecular detection of β-lactamase-encoding genes and genotyping by MLST and rep-PCR. Our findings showed high prevalence of virulence-related markers, where 53.7% of the isolates presented at least 17 genes among the 19 investigated (P = 0.01). The rare exoS+/exoU+ cytotoxic virulotype was detected in 55.6% of isolates. Antimicrobial susceptibility testing revealed percentages of antibiotic resistance above 50% to carbapenems, cephalosporins and fluoroquinolones associated to MDR/XDR isolates. Isolates harboring both blaSPM-1 and blaOXA genes were also detected. Genotyping methods demonstrated a wide genetic diversity of strains spread among the different intensive care units, circulation of international MDR/XDR high-risk clones (ST111, ST235, ST244 and ST277) and emergence of seven novel MLST lineages. Finally, our findings highlight the circulation of strains with high virulence potential and resistance to antimicrobials and may be useful on comprehension of pathogenicity process, treatment guidance and establishment of strategies to control the spread of epidemic P. aeruginosa strains.
Topics: Brazil; Genetic Variation; Hospitals; Humans; Molecular Typing; Prevalence; Pseudomonas aeruginosa; Referral and Consultation; Virulence
PubMed: 32911510
DOI: 10.1371/journal.pone.0238741 -
Molecular Plant-microbe Interactions :... Jul 2021pv. is a causative agent of bacterial blight of crucifers including cabbage, radish, and broccoli. Importantly, pv. can infect not only a wide range of Brassicaceae...
pv. is a causative agent of bacterial blight of crucifers including cabbage, radish, and broccoli. Importantly, pv. can infect not only a wide range of Brassicaceae spp. but, also, green manure crops such as oat. However, pv. virulence mechanisms have not been investigated and are not fully understood. We focused on coronatine (COR) function, which is one of the well-known pv. DC3000 virulence factors, in pv. infection processes on both dicot and monocot plants. Cabbage and oat plants dip-inoculated with a pv. KB211 COR mutant (Δ) exhibited reduced virulence compared with pv. wild type (WT). Moreover, Δ failed to reopen stomata on both cabbage and oat, suggesting that COR facilitates pv. entry through stomata into both plants. Furthermore, cabbage and oat plants syringe-infiltrated with Δ also showed reduced virulence, suggesting that COR is involved in overcoming not only stomatal-based defense but also apoplastic defense. Indeed, defense-related genes, including and , were highly expressed in plants inoculated with Δ compared with WT, indicating that COR suppresses defense-related genes of both cabbage and oat. Additionally, salicylic acid accumulation increases after Δ inoculation compared with WT. Taken together, COR contributes to causing disease by suppressing stomatal-based defense and apoplastic defense in both dicot and monocot plants. Here, we investigated COR functions in the interaction of pv. and different host plants (dicot and monocot plants), using genetically and biochemically defined COR deletion mutants.[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2021.
Topics: Amino Acids; Indenes; Plant Diseases; Pseudomonas; Pseudomonas syringae; Virulence
PubMed: 33587000
DOI: 10.1094/MPMI-09-20-0261-R -
Microbial Biotechnology Jul 2021Here, we present an improved whole-cell biocatalysis system for the synthesis of heteroaromatic N-oxides based on the production of a soluble di-iron monooxygenase...
Here, we present an improved whole-cell biocatalysis system for the synthesis of heteroaromatic N-oxides based on the production of a soluble di-iron monooxygenase PmlABCDEF in Pseudomonas sp. MIL9 and Pseudomonas putida KT2440. The presented biocatalysis system performs under environmentally benign conditions, features a straightforward and inexpensive procedure and possesses a high substrate conversion and product yield. The capacity of gram-scale production was reached in the simple shake-flask cultivation. The template substrates (pyridine, pyrazine, 2-aminopyrimidine) have been converted into pyridine-1-oxide, pyrazine-1-oxide and 2-aminopyrimidine-1-oxide in product titres of 18.0, 19.1 and 18.3 g l , respectively. To our knowledge, this is the highest reported productivity of aromatic N-oxides using biocatalysis methods. Moreover, comparing to the chemical method of aromatic N-oxides synthesis based on meta-chloroperoxybenzoic acid, the developed approach is applicable for a regioselective oxidation that is an additional advantageous option in the preparation of the anticipated N-oxides.
Topics: Biocatalysis; Iron; Mixed Function Oxygenases; Oxides; Pseudomonas; Pseudomonas putida
PubMed: 34115446
DOI: 10.1111/1751-7915.13849 -
Proceedings of the National Academy of... Nov 2014Pseudomonas aeruginosa infects every type of host that has been examined by deploying multiple virulence factors. Previous studies of virulence regulation have largely...
Pseudomonas aeruginosa infects every type of host that has been examined by deploying multiple virulence factors. Previous studies of virulence regulation have largely focused on chemical cues, but P. aeruginosa may also respond to mechanical cues. Using a rapid imaging-based virulence assay, we demonstrate that P. aeruginosa activates virulence in response to attachment to a range of chemically distinct surfaces, suggesting that this bacterial species responds to mechanical properties of its substrates. Surface-activated virulence requires quorum sensing, but activating quorum sensing does not induce virulence without surface attachment. The activation of virulence by surfaces also requires the surface-exposed protein PilY1, which has a domain homologous to a eukaryotic mechanosensor. Specific mutation of the putative PilY1 mechanosensory domain is sufficient to induce virulence in non-surface-attached cells, suggesting that PilY1 mediates surface mechanotransduction. Triggering virulence only when cells are both at high density and attached to a surface—two host-nonspecific cues—explains how P. aeruginosa precisely regulates virulence while maintaining broad host specificity.
Topics: Bacterial Adhesion; Pseudomonas aeruginosa; Quorum Sensing; Virulence
PubMed: 25385640
DOI: 10.1073/pnas.1415712111