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Microorganisms Oct 2020Natural compounds have had increasing applications in the biotechnological sector, with a large fraction of these substances being channeled to the pharmaceutical...
Natural compounds have had increasing applications in the biotechnological sector, with a large fraction of these substances being channeled to the pharmaceutical industry due to their important pharmacological properties. The discovery of new bioactive molecules with novel mechanisms of action constitutes a promising solution for the design of alternative therapeutic solutions. Actinobacteria are a large group of morphologically and physiologically diverse bacteria well known for their production of biotechnologically relevant compounds. The Portuguese coast is scantly explored in terms of Actinobacteria diversity and respective bioactive potential, offering a good opportunity to find new Actinobacteria taxa and bioactive natural products. In this study, we investigated the Actinobacteria diversity associated with a sediment sample collected from the intertidal zone of a beach in northern Portugal, through a cultivation-dependent approach, and screened its antimicrobial and cytotoxic potential. A total of 52 Actinobacteria strains were recovered from the marine sediment, with the largest fraction of the isolates belonging to the genus . Bioactivity screening assays identified crude extracts of six strains active against , exhibiting minimum inhibition concentration (MIC) values in the range of 3.90-125 μg mL. Twenty-five Actinobacteria crude extracts (obtained from strains of the genera , and ) exhibited significant effects on the viability of at least one tested cancer cell line (breast ductal carcinoma T-47D and liver hepatocellular carcinoma HepG2). The Actinobacteria extracts demonstrating activity in the antimicrobial and/or cytotoxic assays were subjected to metabolomic analysis (Mass spectrometry (MS)-based dereplication and molecular networking analyses), indicating the presence of four clusters that may represent new natural products. The results obtained demonstrate the importance of bioprospecting underexplored environments, like the Portuguese coast, for enhancing the discovery of new natural products, and call attention to the relevance of preserving the natural genetic diversity of coastal environments.
PubMed: 33143202
DOI: 10.3390/microorganisms8111691 -
Organic Letters Aug 2019Two new siderophores, madurastatin D1 and D2, together with (-)-madurastatin C1, the enantiomer of a known compound, were isolated from marine-derived sp. The presence...
Two new siderophores, madurastatin D1 and D2, together with (-)-madurastatin C1, the enantiomer of a known compound, were isolated from marine-derived sp. The presence of an unusual 4-imidazolidinone ring in madurastatins D1 and D2 inspired us to sequence the sp. genome and to identify the biosynthetic gene cluster, knowledge of which enables us to now propose a biosynthetic pathway. Madurastatin D1 and D2 are moderately active in antimicrobial assays with .
Topics: Actinomycetales; Anti-Bacterial Agents; Genome, Bacterial; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Micrococcus luteus; Molecular Structure; Multigene Family; Oligopeptides; Oxazoles; Piperidones; Siderophores; Stereoisomerism
PubMed: 31380646
DOI: 10.1021/acs.orglett.9b02159 -
Frontiers in Plant Science 2022Nitrogen (N) is the first essential nutrient for tea growth. However, the effect of soil acidification on soil N cycle and N forms in tea plantation are unclear. In this...
Nitrogen (N) is the first essential nutrient for tea growth. However, the effect of soil acidification on soil N cycle and N forms in tea plantation are unclear. In this study, the nitrogen contents, soil enzyme activity and N mineralization rate in acidified soil of tea plantation were measured. Moreover, the effects of soil acidification on N cycling functional genes and functional microorganisms were explored by soil metagenomics. The results showed that the NH -N, available N and net N mineralization rate in the acidified tea soil decreased significantly, while the NO -N content increased significantly. The activities of sucrase, protease, catalase and polyphenol oxidase in the acidified tea soil decreased significantly. The abundance of genes related to ammonification, dissimilatory N reduction, nitrification and denitrification pathway in the acidified tea soil increased significantly, but the abundance of functional genes related to glutamate synthesis and assimilatory N reduction pathway were opposite. In addition, the abundance of Proteobacteria, Actinobacteria, Chloroflexi, Nitrospirae, , etc. microorganisms related to nitrification, denitrification and pathogenic effect increased significantly in the acidified tea soil. The correlation results showed that soil pH and N forms were correlated with soil enzyme activity, N cycling function genes and microbial changes. In conclusion, soil acidification results in significant changes in enzyme activity, gene abundance and microorganism involved in various N cycle processes in acidified tea soil, which leads to imbalance of soil N form ratio and is not conducive to N transformation and absorption of tea trees.
PubMed: 36311106
DOI: 10.3389/fpls.2022.998178 -
The Journal of General and Applied... Sep 2019Spirotetronate compounds are polyketide secondary metabolites with diverse biological functions, such as antibacterial, antitumor and antiviral activities. Three pure...
Spirotetronate compounds are polyketide secondary metabolites with diverse biological functions, such as antibacterial, antitumor and antiviral activities. Three pure spirotetronate compounds (2EPS-A, -B, -C) isolated from Actinomadura strain 2EPS showed inhibitory activity against dengue virus serotype 2 (DENV-2). 2EPS-A, -B and -C demonstrated the LC values of 11.6, 27.5 and 12.0 μg/ml, respectively, in a test of cytotoxicity to Vero cells. The least cytotoxic, 2EPS-B, was further analyzed for its impact on viral propagation in a cell-based replication assay. At a concentration of 6.25 μg/ml, it could reduce the DENV-2 infection in Vero cells by about 94% when cells infected with DENV-2 were exposed to 2EPS-B, whereas direct treatment of DENV-2 with 2EPS-B at the same concentration prior to subsequent infection to Vero cell yielded no inhibition. 2EPS-A, -B an -C showed strong DENV-2 NS2B-NS3 protease inhibition in an in vitro assay, with IC values of 1.94 ± 0.18, 1.47 ± 0.15 and 2.51 ± 0.21 μg/ml, respectively. Therefore, the spirotetronate compounds appear to prevent viral replication and viral assembly by inhibition of the viral protease.
Topics: Actinobacteria; Animals; Antiviral Agents; Chlorocebus aethiops; Dengue Virus; Inhibitory Concentration 50; Polyketides; Protease Inhibitors; Serogroup; Vero Cells; Virus Replication
PubMed: 30814437
DOI: 10.2323/jgam.2018.10.001 -
Frontiers in Plant Science 2023() is an economically important forest tree species, often cultivated in continuous monoculture as a coastal protection forest. Continuous planting has gradually...
Metagenomics-based exploration of key soil microorganisms contributing to continuously planted growth inhibition and their interactions with soil nutrient transformation.
() is an economically important forest tree species, often cultivated in continuous monoculture as a coastal protection forest. Continuous planting has gradually affected growth and severely restricted the sustainable development of the industry. In this study, we analyzed the effects of continuous planting on growth and explored the rhizosphere soil microecological mechanism from a metagenomic perspective. The results showed that continuous planting resulted in dwarfing, shorter root length, and reduced seedling root system. Metagenomics analysis showed that 10 key characteristic microorganisms, mainly , , and , were responsible for continuously planted trees. Quantitative analysis showed that the number of microorganisms in these three genera decreased significantly with the increase of continuous planting. Gene function analysis showed that continuous planting led to the weakening of the environmental information processing-signal transduction ability of soil characteristic microorganisms, and the decrease of trees against stress. Reduced capacity for metabolism, genetic information processing-replication and repair resulted in reduced microbial propagation and reduced microbial quantity in the rhizosphere soil of trees. Secondly, amino acid metabolism, carbohydrate metabolism, glycan biosynthesis and metabolism, lipid metabolism, metabolism of cofactors and vitamins were all significantly reduced, resulting in a decrease in the ability of the soil to synthesize and metabolize carbon and nitrogen. These reduced capacities further led to reduced soil microbial quantity, microbial carbon and nitrogen, microbial respiration intensity, reduced soil enzyme nutrient cycling and resistance-related enzyme activities, a significant reduction in available nutrient content of rhizosphere soils, a reduction in the ion exchange capacity, and an impediment to growth. This study provides an important basis for the management of continuously planted plantations.
PubMed: 38126014
DOI: 10.3389/fpls.2023.1324184 -
Marine Drugs Dec 2021The Estremadura Spur pockmarks are a unique and unexplored ecosystem located in the North Atlantic, off the coast of Portugal. A total of 85 marine-derived actinomycetes...
The Estremadura Spur pockmarks are a unique and unexplored ecosystem located in the North Atlantic, off the coast of Portugal. A total of 85 marine-derived actinomycetes were isolated and cultured from sediments collected from this ecosystem at a depth of 200 to 350 m. Nine genera, , , , , , , , , and were identified by 16S rRNA gene sequencing analyses, from which the first two were the most predominant. Non-targeted LC-MS/MS, in combination with molecular networking, revealed high metabolite diversity, including several known metabolites, such as surugamide, antimycin, etamycin, physostigmine, desferrioxamine, ikarugamycin, piericidine, and rakicidin derivatives, as well as numerous unidentified metabolites. Taxonomy was the strongest parameter influencing the metabolite production, highlighting the different biosynthetic potentials of phylogenetically related actinomycetes; the majority of the chemical classes can be used as chemotaxonomic markers, as the metabolite distribution was mostly genera-specific. The EtOAc extracts of the actinomycete isolates demonstrated antimicrobial and antioxidant activity. Altogether, this study demonstrates that the Estremadura Spur is a source of actinomycetes with potential applications for biotechnology. It highlights the importance of investigating actinomycetes from unique ecosystems, such as pockmarks, as the metabolite production reflects their adaptation to this habitat.
Topics: Actinobacteria; Animals; Anti-Bacterial Agents; Antineoplastic Agents; Antioxidants; Aquatic Organisms; Biological Products; Cell Line, Tumor; Ecosystem; HaCaT Cells; Humans; Metabolomics; Phylogeny; Portugal
PubMed: 35049876
DOI: 10.3390/md20010021 -
Frontiers in Microbiology 2019The amendment of crop residues produced under elevated CO (eCO) may alter soil microbial community structure and their functions on residue decomposition and carbon (C)...
The amendment of crop residues produced under elevated CO (eCO) may alter soil microbial community structure and their functions on residue decomposition and carbon (C) cycling in soil. The key to understanding this process is to elucidate the structure of prokaryotic communities that metabolize crop residues derived from eCO. A soil incubation experiment was conducted to explore the response of soil microbial community to the amendment of C-labeled soybean residues produced under ambient CO (aCO) and eCO The residues were applied to a Mollisol, followed by C-DNA stable isotope probing (SIP) and Illumina sequencing on soil prokaryotic community over time. The structure of residue-metabolizing community differed in response to the amendment of eCO- and aCO-derived residues after 28 days of incubation. In particular, genera , , , and were the dominant members of the residue-metabolizing bacteria, which contributed to this difference. The relative abundances of genera , and were 118-144%, 71-113%, and 2-4-fold higher in the Mollisol amended with aCO-derived than eCO-derived residue. In contrast, the relative abundance of was 87-90% greater in the eCO-residue treatment. However, during the incubation period, there was no difference between the two residue treatments in the community structure as a whole without SIP. These results implied that a pioneering prokaryotic community metabolized the residue initially prior to the entire community. Those bacteria genera being inhibited with the amendment of the eCO-derived residue, compared to aCO-derived residue, were likely preferential to metabolize recalcitrant C, which might be associated with changes of chemical composition of the residue under eCO.
PubMed: 31681180
DOI: 10.3389/fmicb.2019.02184 -
Microbial Biotechnology Jul 2020Contaminants such as heavy metals may contribute to the dissemination of antimicrobial resistance (AMR) by enriching resistance gene determinants via co-selection...
Contaminants such as heavy metals may contribute to the dissemination of antimicrobial resistance (AMR) by enriching resistance gene determinants via co-selection mechanisms. In the present study, a survey was performed on soils collected from four areas at the Savannah River Site (SRS), South Carolina, USA, with varying contaminant profiles: relatively pristine (Upper Three Runs), heavy metals (Ash Basins), radionuclides (Pond B) and heavy metal and radionuclides (Tim's Branch). Using 16S rRNA gene amplicon sequencing, we explored the structure and diversity of soil bacterial communities. Sites with legacies of metal and/or radionuclide contamination displayed significantly lower bacterial diversity compared to the reference site. Metagenomic analysis indicated that multidrug and vancomycin antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) including those associated with copper, arsenic, iron, nickel and zinc were prominent in all soils including the reference site. However, significant differences were found in the relative abundance and diversity of certain ARGs and MRGs in soils with metal/radionuclide contaminated soils compared to the reference site. Co-occurrence patterns revealed significant ARG/MRG subtypes in predominant soil taxa including Acidobacteriaceae, Bradyrhizobium, Mycobacterium, Streptomyces, Verrumicrobium, Actinomadura and Solirubacterales. Overall, the study emphasizes the potential risk of human activities on the dissemination of AMR in the environment.
Topics: Anti-Bacterial Agents; Bacteria; Disinfectants; Genes, Bacterial; Humans; Metals, Heavy; RNA, Ribosomal, 16S; Radioisotopes; Soil; Soil Microbiology
PubMed: 32363769
DOI: 10.1111/1751-7915.13578 -
Molecules (Basel, Switzerland) May 2023Novel antitubercular compounds are urgently needed to combat drug-resistant (Mtb). Filamentous actinobacteria have historically been an excellent source of...
Novel antitubercular compounds are urgently needed to combat drug-resistant (Mtb). Filamentous actinobacteria have historically been an excellent source of antitubercular drugs. Despite this, drug discovery from these microorganisms has fallen out of favour due to the continual rediscovery of known compounds. To increase the chance of discovering novel antibiotics, biodiverse and rare strains should be prioritised. Subsequently, active samples need to be dereplicated as early as possible to focus efforts on truly novel compounds. In this study, 42 South African filamentous actinobacteria were screened for antimycobacterial activity using the agar overlay method against the Mtb indicator under six different nutrient growth conditions. Known compounds were subsequently identified through extraction and high-resolution mass spectrometric analysis of the zones of growth inhibition produced by active strains. This allowed the dereplication of 15 hits from six strains that were found to be producing puromycin, actinomycin D and valinomycin. The remaining active strains were grown in liquid cultures, extracted and submitted for screening against Mtb . B60 was the most active sample and was selected for bioassay-guided purification. This resulted in the identification of tetromadurin, a known compound, but which we show for the first time to have potent antitubercular activity, with the MICs within the range of 73.7-151.6 nM against H37Rv under different test conditions. This shows that South African actinobacteria are a good source of novel antitubercular compounds and warrant further screening. It is also revealed that active hits can be dereplicated by HPLC-MS/MS analysis of the zones of growth inhibition produced by the agar overlay technique.
Topics: Humans; Tandem Mass Spectrometry; Actinobacteria; Chromatography, Liquid; South Africa; Agar; Antitubercular Agents; Mycobacterium tuberculosis; Tuberculosis, Multidrug-Resistant; Microbial Sensitivity Tests
PubMed: 37298751
DOI: 10.3390/molecules28114276 -
Organic Letters Feb 2020Forazoline A is a structurally complex PKS-NRPS hybrid produced by marine-derived sp. During the course of studies highlighting the application of IFS analysis as a...
Forazoline A is a structurally complex PKS-NRPS hybrid produced by marine-derived sp. During the course of studies highlighting the application of IFS analysis as a powerful tool for natural products analysis, we were alerted to an earlier misinterpretation with respect to forazoline A structure elucidation. In particular, IFS reveals that forazoline A contains a thioketone moiety rarely seen in secondary metabolites and, thus, constitutes an even more intriguing structure than originally thought.
Topics: Actinomycetales; Biological Products; Isotopes; Mass Spectrometry; Molecular Conformation; Polyketides
PubMed: 32017574
DOI: 10.1021/acs.orglett.9b04535