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Microorganisms May 2024is an emerging human pathogen that has a high rate of incidence in immunocompromised individuals. We have found a putative secondary metabolite pathway within , which...
is an emerging human pathogen that has a high rate of incidence in immunocompromised individuals. We have found a putative secondary metabolite pathway within , which may be a key factor in its pathogenesis. This novel pathway is encoded in a gene cluster spanning MAB_0284c to 0305 and is related to pathways, producing the secondary metabolites streptonigrin and nybomycin. We constructed an in-frame deletion of the MAB_0295 () gene and tested it in our animal model. We have previously shown that tadpoles, which have functional lungs and T cells, can serve as a reliable comparative model for persistent infection and pathogenesis. Here, we report that tadpoles intraperitoneally infected with the ∆ mutant exhibit early decreased bacterial loads and significantly increased survival compared with those infected with WT . ∆ mutant also induced lower transcript levels of several pro-inflammatory cytokines (, , , ) than those of WT in the liver and lungs. In addition, there was impaired macrophage recruitment and decreased macrophage infection in tadpoles infected with the ∆ mutant, by tail wound inoculation, compared to those infected with the WT bacteria, as assayed by intravital confocal microscopy. These data underline the relevance and usefulness of tadpoles as a novel comparative animal model to identify genetic determinants of immunopathogenesis, suggesting a role for this novel and uncharacterized pathway in pathogenesis and macrophage recruitment.
PubMed: 38930501
DOI: 10.3390/microorganisms12061120 -
Biology May 2024This work aimed to study the genome organization and the metabolic potential of strain SCPM-O-B-9993, a promising plant-protecting and plant-stimulating strain isolated...
This work aimed to study the genome organization and the metabolic potential of strain SCPM-O-B-9993, a promising plant-protecting and plant-stimulating strain isolated from brown semi-desert soils with very high salinity. The strain genome contains a linear chromosome 5,968,715 bp long and has no plasmids. The genome contains 5331 coding sequences among which 2139 (40.1%) are functionally annotated. Biosynthetic gene clusters (BGCs) of secondary metabolites exhibiting antimicrobial properties (ohmyungsamycin, pellasoren, naringenin, and ansamycin) were identified in the genome. The most efficient period of SCPM-O-B-9993 strain cultivation was 72 h: during this period, the culture went from the exponential to the stationary growth phase as well as exhibited excellent phytostimulatory properties and antiviral activity against the cucumber mosaic virus in tomatoes under laboratory conditions. The SCPM-OB-9993 strain is a biotechnologically promising producer of secondary metabolites exhibiting antiviral and phytostimulatory properties.
PubMed: 38927268
DOI: 10.3390/biology13060388 -
World Journal of Microbiology &... Jun 2024Thermophilic actinomycetes are commonly found in extreme environments and can thrive and adapt to extreme conditions. These organisms exhibit substantial variation and...
Thermophilic actinomycetes are commonly found in extreme environments and can thrive and adapt to extreme conditions. These organisms exhibit substantial variation and garnered significant interest due to their remarkable enzymatic activities. This study evaluated the potential of Streptomyces griseorubens NBR14 and Nocardiopsis synnemataformans NBRM9 strains to produce thermo-stable amylase via submerged fermentation using wheat and bean straw. The Box-Behnken design was utilized to determine the optimum parameters for amylase biosynthesis. Subsequently, amylase underwent partial purification and characterization. Furthermore, the obtained hydrolysate was applied for ethanol fermentation using Saccharomyces cerevisiae. The optimal parameters for obtaining the highest amylase activity by NBR14 (7.72 U/mL) and NBRM9 (26.54 U/mL) strains were found to be 40 and 30 °C, pH values of 7, incubation time of 7 days, and substrate concentration (3 and 2 g/100 mL), respectively. The NBR14 and NBRM9 amylase were partially purified, resulting in specific activities of 251.15 and 144.84 U/mg, as well as purification factors of 3.91 and 2.69-fold, respectively. After partial purification, the amylase extracted from NBR14 and NBRM9 showed the highest activity level at pH values of 9 and 7 and temperatures of 50 and 60 °C, respectively. The findings also indicated that the maximum velocity (V) for NBR14 and NBRM9 amylase were 57.80 and 59.88 U/mL, respectively, with K constants of 1.39 and 1.479 mM. After 48 h, bioethanol was produced at concentrations of 5.95 mg/mL and 9.29 mg/mL from hydrolyzed wheat and bean straw, respectively, through fermentation with S. cerevisiae. Thermophilic actinomycetes and their α-amylase yield demonstrated promising potential for sustainable bio-ethanol production from agro-byproducts.
Topics: Ethanol; Fermentation; Amylases; Hydrogen-Ion Concentration; Kinetics; Actinobacteria; Temperature; Triticum; Saccharomyces cerevisiae; Hydrolysis; Streptomyces; Enzyme Stability
PubMed: 38926189
DOI: 10.1007/s11274-024-04009-8 -
Chemosphere Jun 2024Polyhydroxyalkanoates (PHAs) are important candidates for replacing petroleum-based plastics. This transition is urgent for the development of a biobased economy and to...
Polyhydroxyalkanoates (PHAs) are important candidates for replacing petroleum-based plastics. This transition is urgent for the development of a biobased economy and to protect human health and natural ecosystems. PHAs are biobased and biodegradable polyesters that when blended with other polymers, such as poly(butylene adipate-co-terephthalate) (PBAT), acquire remarkable improvements in their properties, which allow them to comply with the requirements of packaging applications. However, the biodegradation of such blends should be tested to evaluate the impact of those polymers in the environment. For instance, PBAT is a compostable aliphatic-aromatic copolyester, and its biodegradation in natural environments, such as soil, is poorly studied. In this work, we evaluated the biodegradation of a bilayer film composed of PHB and PBAT, by a soil microbiome. The bilayer film reached 47 ± 1 % mineralization in 180 days and PHB was no longer detected after this period. The increased crystallinity of the PBAT residue was a clear sign of biodegradation, indicating that the amorphous regions were preferentially biodegraded. Seven microorganisms were isolated, from which 4 were closely related to microorganisms already known as PHB degraders, but the other 3 species, closely related to Streptomyces coelicoflavus, Clonostachys rosea and Aspergillus insuetus, were found for the first time as PHB degraders. Most remarkably, two fungi closely related to Purpureocillium lilacinum and Aspergillus pseudodeflectus (99.83 % and 100 % identity by ITS sequencing) were isolated and identified as PBAT degraders. This is very interesting due to the rarity of isolating PBAT-degrading microorganisms. These results show that the bilayer film can be biodegraded in soil, at mesophilic temperatures, showing its potential to replace synthetic plastics in food packaging.
PubMed: 38925517
DOI: 10.1016/j.chemosphere.2024.142696 -
The FEBS Journal Jun 2024Polyketides are natural products synthesized by polyketide synthases (PKSs), where acyltransferase (AT) domains play a crucial role in selection of extender units....
Polyketides are natural products synthesized by polyketide synthases (PKSs), where acyltransferase (AT) domains play a crucial role in selection of extender units. Engineering of AT domains enables the site-specific incorporation of non-natural extender units, leading to generation of novel derivatives. Here, we determined the crystal structures of AT domains from the fifth module of tylosin PKS (TylAT5) derived from Streptomyces fradiae and the eighth module of spinosad PKS (SpnAT8) derived from Saccharopolyspora spinosa, and combined them with molecular dynamics simulations and enzyme kinetic studies to elucidate the molecular basis of substrate selection. The ethylmalonyl-CoA-specific conserved motif TAGH of TylAT5 and the MMCoA-specific conserved motif YASH of SpnAT8 were identified within the substrate-binding pocket, and several key residues close to the substrate acyl moiety were located. Through site-directed mutagenesis of four residues near the active site, we successfully reprogrammed the specificity of these two AT domains toward malonyl-CoA. Mutations in TylAT5 enhanced its catalytic activity 2.6-fold toward malonyl-CoA, and mutations in SpnAT8 eliminated the substrate promiscuity. These results extend our understanding of AT substrate specificity and would benefit the engineering of PKSs.
PubMed: 38922792
DOI: 10.1111/febs.17206 -
Toxins May 2024Zearalenone (ZEN) is a prevalent mycotoxin found in grains and grain-derived products, inducing adverse health effects in both animals and humans. The in-field...
Zearalenone (ZEN) is a prevalent mycotoxin found in grains and grain-derived products, inducing adverse health effects in both animals and humans. The in-field application of microorganisms to degrade and detoxify ZEN is a promising strategy to enhance the safety of food and feed. In this study, we investigated the potential of three actinobacterial strains to degrade and detoxify ZEN in vitro and in planta on wheat ears. The residual ZEN concentration and toxicity in the samples were analysed with UHPLC-MS/MS and a bioluminescence BLYES assay, respectively. subsp. LMG19352 could completely degrade and detoxify 5 mg/L ZEN in LB broth within 24 h, along with significant reductions in ZEN concentration both in a minimal medium (MM) and on wheat ears. Additionally, it was the only strain that showed a significant colonisation of these ears. sp. R25614 exhibited partial but significant degradation in LB broth and MM, whereas sp. LMG16995 degraded and detoxified ZEN in LB broth after 72 h by 39% and 33%, respectively. Although all three actinobacterial strains demonstrated the metabolic capability to degrade and detoxify ZEN in vitro, only subsp. LMG19352 showed promising potential to mitigate ZEN in planta. This distinction underscores the importance of incorporating in planta screening assays for assessing the potential of mycotoxin-biotransforming microorganisms as biocontrol agents.
Topics: Zearalenone; Triticum; Biological Control Agents; Streptomyces; Actinobacteria; Food Contamination; Tandem Mass Spectrometry
PubMed: 38922147
DOI: 10.3390/toxins16060253 -
Marine Drugs Jun 2024Three new cyclic lipopeptides, olenamidonins A-C (-), in addition to two previously reported metabolites ( and ), were accumulated in the Δ deletion mutant of...
Three new cyclic lipopeptides, olenamidonins A-C (-), in addition to two previously reported metabolites ( and ), were accumulated in the Δ deletion mutant of deepsea-derived SCSIO 1071. The structures of these cyclic lipopeptides were determined by a combination of spectroscopic methods and circular dichroism (CD) measurement. The antibacterial assay results showed that compounds displayed different degrees of growth inhibition against multidrug-resistant (MDR) bacterial strains CCARM 5172 and CCARM 5203 with minimum inhibitory concentrations (MICs) of 1.56-6.25 μg/mL.
Topics: Streptomyces; Lipopeptides; Microbial Sensitivity Tests; Anti-Bacterial Agents; Enterococcus faecalis; Peptides, Cyclic; Enterococcus faecium; Drug Resistance, Multiple, Bacterial; Bacterial Proteins
PubMed: 38921573
DOI: 10.3390/md22060262 -
Marine Drugs Jun 2024A new dimeric C-glycoside polyketide chrysomycin F (), along with four new monomeric compounds, chrysomycins G (), H (), I (), J (), as well as three known analogues,...
A new dimeric C-glycoside polyketide chrysomycin F (), along with four new monomeric compounds, chrysomycins G (), H (), I (), J (), as well as three known analogues, chrysomycins A (), B (), and C (), were isolated and characterised from a strain of sp. obtained from a sediment sample collected from the South China Sea. Their structures were determined by detailed spectroscopic analysis. Chrysomycin F contains two diastereomers, whose structures were further elucidated by a biomimetic [2 + 2] photodimerisation of chrysomycin A. Chrysomycins B and C showed potent anti-tuberculosis activity against both wild-type and a number of clinically isolated MDR strains.
Topics: Streptomyces; Mycobacterium tuberculosis; Antitubercular Agents; Polyketides; Microbial Sensitivity Tests; Glycosides; China; Molecular Structure; Anthraquinones
PubMed: 38921570
DOI: 10.3390/md22060259 -
Marine Drugs May 2024Subjecting the Australian marine-derived fungus CMB-M0339 to cultivation profiling using an innovative miniaturized 24-well plate format (MATRIX) enabled access to new...
Subjecting the Australian marine-derived fungus CMB-M0339 to cultivation profiling using an innovative miniaturized 24-well plate format (MATRIX) enabled access to new examples of the rare class of 2,6-diketopiperazines, noonazines A-C (-), along with the known analogue coelomycin (), as well as a new azaphilone, noonaphilone A (). Structures were assigned to - on the basis of a detailed spectroscopic analysis, and in the case of -, an X-ray crystallographic analysis. Plausible biosynthetic pathways are proposed for -, involving oxidative Schiff base coupling/dimerization of a putative Phe precursor. Of note, incorporates a rare -Tyr motif, typically only reported in a limited array of metabolites. Similarly, a plausible biosynthetic pathway is proposed for , highlighting a single point for stereo-divergence that allows for the biosynthesis of alternate antipodes, for example, the 7 noonaphilone A () versus the 7 deflectin 1a ().
Topics: Aspergillus; Australia; Diketopiperazines; Aquatic Organisms; Biosynthetic Pathways; Crystallography, X-Ray; Molecular Structure; Benzopyrans; Pigments, Biological
PubMed: 38921553
DOI: 10.3390/md22060243 -
Organic & Biomolecular Chemistry Jun 2024Synthetic routes to geosmin and its enantiomer are well established, but the enantioselective synthesis of stereoisomers of geosmin is unknown. Here a stereoselective...
Synthetic routes to geosmin and its enantiomer are well established, but the enantioselective synthesis of stereoisomers of geosmin is unknown. Here a stereoselective synthesis of all stereoisomers of geosmin is reported, yielding all compounds in high enantiomeric purity. Furthermore, the stereoselective synthesis of a geosmin derivative isolated from a mangrove associated streptomycete was performed, establishing the absolute configuration of the natural product. Finally, a new side product of the geosmin synthase from was isolated and its structure was elucidated by NMR spectroscopy. The absolute configuration of this new compound was determined through a stereoselective synthesis.
PubMed: 38920404
DOI: 10.1039/d4ob00934g