Sonia Mendo
University of Aveiro, Biology, Faculty Member
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The increasing number of multidrug-resistant pathogens, along with the small number of new antimicrobials under development, leads to an increased need for novel alternatives. Class I and class II lanthipeptides (also known as... more
The increasing number of multidrug-resistant pathogens, along with the small number of new antimicrobials under development, leads to an increased need for novel alternatives. Class I and class II lanthipeptides (also known as lantibiotics) have been considered promising alternatives to classical antibiotics. In addition to their relevant medical applications, they are used as probiotics, prophylactics, preservatives, and additives in cosmetics and personal-care products. The genus Bacillus is a prolific source of bioactive compounds including ribosomally and nonribosomally synthesized antibacterial peptides. Accordingly, there is significant interest in the biotechnological potential of members of the genus Bacillus as producers of antimicrobial lanthipeptides. The present review focuses on aspects of the biosynthesis, gene cluster organization, structure, antibacterial spectrum, and bioengineering approaches of lanthipeptides produced by Bacillus strains. Their efficacy and potency against some clinically relevant strains, including MRSA and VRE, are also discussed. Although no lanthipeptides are currently in clinical use, the information herein highlights the potential of these compounds.
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Aeromonas molluscorum Av27 cells were exposed to 0, 5 and 50 μM of TBT and the respective transcriptomes were obtained by pyrosequencing. Gene Ontology revealed that exposure to 5 μM TBT results in a higher number of repressed genes in... more
Aeromonas molluscorum Av27 cells were exposed to 0, 5 and 50 μM of TBT and the respective transcriptomes were obtained by pyrosequencing. Gene Ontology revealed that exposure to 5 μM TBT results in a higher number of repressed genes in contrast with 50 μM of TBT, where the number of over-expressed genes is greater. At both TBT concentrations, higher variations in gene expression were found in the functional categories associated with enzymatic activities, transport/binding and oxidation-reduction. A number of proteins are affected by TBT, such as the acriflavin resistance protein, several transcription-related proteins, several Hsps, ABC transporters, CorA and ZntB and other outer membrane efflux proteins, all of these involved in cellular metabolic processes, important to maintain overall cell viability. Using the STRING tool, several proteins with unknown function were related with others involved in degradation processes, such as the pyoverdine chromophore biosynthetic protein, t...
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Pseudomonas mendocina carrying a novel class 1 integron containing an IMP-8 gene was isolated from an inanimate surface in a female ward sanitary facility of the Hospital Infante D. Pedro, Aveiro, Portugal. Hybridization with the... more
Pseudomonas mendocina carrying a novel class 1 integron containing an IMP-8 gene was isolated from an inanimate surface in a female ward sanitary facility of the Hospital Infante D. Pedro, Aveiro, Portugal. Hybridization with the integrase gene (intI1) and 16S rDNA revealed that the integron is chromosomally located. Here we report for the first time the presence of an IMP-8 metallo-beta-lactamase gene in the Pseudomonas genus.
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Sesquiterpenic compounds are natural chemicals present in organisms from different Phylae or Divisions, which have proved to be important bioactive products, namely in potentiating the action of antibiotics. In the first step, the... more
Sesquiterpenic compounds are natural chemicals present in organisms from different Phylae or Divisions, which have proved to be important bioactive products, namely in potentiating the action of antibiotics. In the first step, the mutagenicity of nine sesquiterpenic compounds (hydrocarbons and alcohols) was screened in a Salmonella typhimurium his(-)-reversion test with strains TA98 and TA100, in the presence or absence of in vitro metabolic activation. Under the test conditions, none of the compounds showed mutagenicity up to a concentration of 222μg/plate. trans-Farnesol, nerolidol, and α-bisabolol displayed cytotoxicity when tested at concentrations ranging from 14 to 222μg/plate. Then, the combined effect of antibiotic-sesquiterpenic compounds was evaluated on two clinically relevant pathogens, Escherichia coli and Staphylococcus aureus, with well-defined resistance-sensitive profiles. The agar-disc diffusion assay revealed that all the combinations of antibiotic-sesquiterpenic compounds increased the antibacterial activity of the antibiotics tested against S. aureus. For E. coli, an antagonistic effect was observed for various combinations on the growth of this bacterium.
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Eisenia andrei was exposed, for 56 days, to a contaminated soil from an abandoned uranium mine and to the natural reference soil LUFA 2.2. The organisms were sampled after 0, 1, 2, 7, 14 and 56 days of exposure, to assess metals... more
Eisenia andrei was exposed, for 56 days, to a contaminated soil from an abandoned uranium mine and to the natural reference soil LUFA 2.2. The organisms were sampled after 0, 1, 2, 7, 14 and 56 days of exposure, to assess metals bioaccumulation, coelomocytes DNA integrity and cytotoxicity. Radionuclides bioaccumulation and growth were also determined at 0 h, 14 and 56 days of exposure. Results have shown the bioaccumulation of metals and radionuclides, as well as, growth reduction, DNA damages and cytotoxicity in earthworms exposed to contaminated soil. The usefulness of the comet assay and flow cytometry, to evaluate the toxicity of contaminants such as metals and radionuclides in earthworms are herein reported. We also demonstrated that DNA strand breakage and immune cells frequency are important endpoints to be employed in the earthworm reproduction assay, for the evaluation of soil geno and cytotoxicity, as part of the risk assessment of contaminated areas. This is the first study that integrates DNA damage and cytotoxicity evaluation, growth and bioaccumulation of metals and radionuclides in a sub lethal assay, for earthworms exposed to soil contaminated with metals and radionuclides.
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Assessment of plastic and heritable components of phenotypic variation is crucial for understanding the evolution of adaptive character traits in heterogeneous environments. We assessed the above in relation to adaptive shell morphology... more
Assessment of plastic and heritable components of phenotypic variation is crucial for understanding the evolution of adaptive character traits in heterogeneous environments. We assessed the above in relation to adaptive shell morphology of the rocky intertidal snail Nucella lapillus by reciprocal transplantation of snails between two shores differing in wave action and rearing snails of the same provenance in a common garden. Results were compared with those reported for similar experiments conducted elsewhere. Microsatellite variation indicated limited gene flow between the populations. Intrinsic growth rate was greater in exposed-site than sheltered-site snails, but the reverse was true of absolute growth rate, suggesting heritable compensation for reduced foraging opportunity at the exposed site. Shell morphology of reciprocal transplants partially converged through plasticity toward that of native snails. Shell morphology of F(2)s in the common garden partially retained characte...
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Earthworms were exposed for 56 days to a contaminated soil from an abandoned uranium mine and to the natural reference soil LUFA 2.2. The exposure occurred in situ: the containers with contaminated soil were placed near the mine pit; the... more
Earthworms were exposed for 56 days to a contaminated soil from an abandoned uranium mine and to the natural reference soil LUFA 2.2. The exposure occurred in situ: the containers with contaminated soil were placed near the mine pit; the containers with reference soil were placed in a reference site. For the assessment of metals bioaccumulation, DNA damages, cell-to-cell variation in DNA content, Median Fluorescence Intensity (MFI), coelomocytes frequency and proliferation, organisms were sampled after 0, 1, 2, 7, 14 and 56 days of exposure. For the assessment of radionuclides bioaccumulation, animals were sampled after 0, 14 and 56 days of exposure. As for growth, organisms were sampled after 0, 14, 28 and 56 days of exposure. The reproduction assay was performed according to the OECD (2004) guideline. DNA damages were assessed by comet assay and flow cytometry was used to determine cell-to-cell variation in DNA content, Median Fluorescence Intensity (MFI), coelomocytes frequency and proliferation. Results have shown a myriad of effects in the organisms exposed to the contaminated soil, namely: the inhibition of reproduction, growth reduction, DNA damages, cytotoxicity, changes in eleocytes fluorescence intensity, coelomocytes proliferation and bioaccumulation of metals and radionuclides. Our results showed that the evaluation of genotoxicity and cytotoxicity endpoints, along with other parameters at an individual level in standard reproduction assays conducted in situ, are important to improve the risk assessment process of areas contaminated with uranium and other radioactive mining wastes.
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Aeromonas molluscorum Av27 is an estuarine bacterium highly resistant to tributyltin (TBT). Also, the strain is able to degrade TBT into the less toxic compounds dibutyltin and monobutyltin. Therefore, this bacterium has potential to be... more
Aeromonas molluscorum Av27 is an estuarine bacterium highly resistant to tributyltin (TBT). Also, the strain is able to degrade TBT into the less toxic compounds dibutyltin and monobutyltin. Therefore, this bacterium has potential to be employed in bioremediation processes. In this context, defining its biological safety is crucial. With that purpose a number of intrinsic characteristics, usually present/associated with virulent strains, were investigated. Few virulence factors were detected in strain Av27. For instance, a DNase gene is present, but it is not apparently expressed in vitro. Motility, adherence factor and phospholipase activity were also detected. Additionally, cytotoxicity to Vero cells was negative. Resistance to penicillin (10 μg ml−1), amoxicillin/clavulanic acid (30 μg ml−1) and cephalothin (30 μg ml−1) and also to the vibriostatic agent O/129 was observed. Five plasmids (4, 7, 10, 100 kb and one greater than 100 kb) were identified. No Class I and II integrons were detected. Study of the optimal growth conditions showed that Av27 easily adapts to different environmental conditions. Overall, the results suggest that A. molluscorum Av27 can be considered safe to use to bioremediate TBT in contaminated environments.
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Microbiology, Environmental microbiology, Bioremediation, Medical Microbiology, Locomotion, and 12 moreCytotoxicity, Cercopithecus aethiops, Animals, Aeromonas, Plasmids, Anti-Bacterial Agents, phospholipases A2, Biotransformation, Virulence Factors, Cell Survival, Vero cells, and Molecular Sequence Data
A potentially new thermotolerant B. licheniformis strain (code name I89), producer of an antibiotic active against Gram-positive bacteria, was genetically characterized and compared with the type strain B. licheniformis ATCC 10716,... more
A potentially new thermotolerant B. licheniformis strain (code name I89), producer of an antibiotic active against Gram-positive bacteria, was genetically characterized and compared with the type strain B. licheniformis ATCC 10716, producer of bacitracin. Studies on DNA base composition (G + C content) and DNA reassociation revealed that the two strains show around 76% homology. Nevertheless, results obtained by rRNA hybridization, with a heterologous probe coding for most of the 16S region of the rRNA operon of Bacillus subtilis, revealed differences in the number of copies for that gene and in the hybridization pattern. Additionally, a different restriction digestion pattern was obtained when DNA was digested with the enzymes NotI, SmaI and analyzed by PFGE. The I89 strain holds a 7.6-kb plasmid not present in the reference strain. The existence of various unique restriction sites and also the stability of this plasmid make it ideal for the future development of a cloning and expression vector.
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Genetics, Microbiology, Medical Microbiology, Heavy metals, Nucleic acid hybridization, and 10 moreBacillus, Microbial genetic and drug resistance, Plasmids, Enzyme, Gram Positive Bacteria, Bacillus subtilis, Current, Pulsed field gel electrophoresis (PFGE), Bacillus licheniformis, and *Hot Temperature
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Environmental microbiology, Mass Spectrometry, International Marine Environmental Law, Portugal, Biological Sciences, and 12 moreHeavy metals, Environmental Sciences, Gas Chromatography, Aeromonas, Gram Positive Bacteria, CHEMICAL SCIENCES, Gram-negative bacteria, Anti-Bacterial Agents, Time Factors, Microbial Sensitivity Tests, Geologic Sediments, and Carbon Source
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Industrial Biotechnology, Porphyrins, Industrial, Escherichia coli, Bacteria, and 16 moreBioluminescence, Real Time, Solar radiation, Antibacterial activity, Anti-Bacterial Agents, Environmental Conditions, Irradiation, Food Sciences, INDUSTRIAL MICROBIOLOGY AND BIOTECHNOLOGY, Antimicrobial photodynamic therapy, Vibrio Fischeri, Microbial Viability, Recombinant Proteins, Solar Irradiation, Aliivibrio fischeri, and Solar Irradiance
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Engineering, Genetics, Physics, Chemistry, Polymorphism, and 58 moreGenetic Drift, Gene Flow, Population Genetics, Fisheries, Crustacea, Biology, Ecology, Invasive Species, Agricultural Biotechnology, Medicine, Multidisciplinary, Genetic Diversity, Portugal, DNA, Phylogeny, Populus, Population structure, Plant Genome Project, Microsatellites, Genetic Structure, Animals, Deoxyribonucleic Acid, Polymerase Chain Reaction, Statistical Significance, Genome Analysis, Genetic Map, Population Size, Fisheries Sciences, Spatial Scale, Phenotype, PLoS one, Genetic linkage analysis, Heterozygosity, Forestry Sciences, Genetic Differentiation, Tree Genetics, Carica papaya, Genotype, Model System, Physical Map, Population Genetic Structure, Linkage Disequilibrium, Arabian Sea, Coastal waters, Genetic variation, Management Strategy, Genome sequence, Indexation, Species Specificity, Carcinus Maenas, Loci, Genotypes, Genetic Markers, DNA marker, DNA probes, DNA polymorphism, ENVIRONMENTAL SCIENCE AND MANAGEMENT, and Simple Sequence Repeat
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Genetics, Microbiology, Medical Microbiology, Heavy metals, Nucleic acid hybridization, and 10 moreBacillus, Microbial genetic and drug resistance, Plasmids, Enzyme, Gram Positive Bacteria, Bacillus subtilis, Current, Pulsed field gel electrophoresis (PFGE), Bacillus licheniformis, and *Hot Temperature
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Tributyltin (TBT) is a toxic compound employed in several industrial processes. Its discharge into the environment has been recognized worldwide as a pollution problem. The importance of bacteria in decontamination processes has been long... more
Tributyltin (TBT) is a toxic compound employed in several industrial processes. Its discharge into the environment has been recognized worldwide as a pollution problem. The importance of bacteria in decontamination processes has been long acknowledged. The aim of this work was to screen TBT resistant/ degrading bacteria in order to investigate the involved mechanisms. Aeromonas molluscorum Av27, isolated from Ria de Aveiro (Portugal), showed high TBT resistance (up to 3 mM). From a genomic library, a TBT resistant clone (5.4 kbp fragment) was selected. In this fragment, ORF P6 was able to confer TBT resistance to E. coli. P6 has homology with a sugE gene, which encodes SugE protein, belonging to small multidrug resistant family, a lipophilic drug transporter. Reverse transcriptase-PCR analysis indicated that increased expression of the sugE gene was found in the original strain (A. molluscorum (Av27) when the cells were grown in the presence of high concentrations of TBT. A. molluscorum Av27 degrades TBT in dibutyltin (DBT) and monobutyltin (MBT) and uses it as carbon source. Microcosm experiments with TBT contaminated sediments revealed that the addition of Av27 strain does not affect the natural bacterial community. Given the interesting characteristics exhibited by Av27, it can potentially be used to develop a bioreporter system to monitor on-site TBT contamination and also be employed as a remediator of TBT polluted