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Bioinformation 2023Increased amounts of toxicants may cause sever health issues in humans as well as in aquatic life. Scientists are developing new technologies to combat these problems....
Increased amounts of toxicants may cause sever health issues in humans as well as in aquatic life. Scientists are developing new technologies to combat these problems. Biological methods of detoxification are always beneficial for the environment. Pseudomonas fluorescens is known for its detoxification capacity. In this study stains were isolated from different locations of the Ha'il region, Saudia Arabia. The microbial strain AM-1 displayed resistance to heavy metals (Cr6+, Ni2+, Cd2+, Pb2+) and pesticides (BHC, 2,4-D, Mancozeb) at pollutant levels typical of highly contaminated areas. Additionally, AM-1 exhibited substantial detoxification potential, reducing toxicity by 40.67% for heavy metals and 47.4% for pesticides at 3x concentrations. These findings suggest that the AM-1 strain supports environmental remediation and pollution mitigation. Atomic absorption spectrometry (AAS) results exhibited bioremediation efficiency for metals Cr, Ni, and Pb using immobilized cells of AM-1 isolate, estimated to be 60.57%, 68.4%, and 53.93% respectively. These findings show that AM-1 strain has a potential role in bioremediation of water pollutants and may have future implications in wastewater treatment.
PubMed: 37928494
DOI: 10.6026/97320630019901 -
RSC Chemical Biology Nov 2023Obafluorin is a antibacterial natural product that inhibits threonyl-tRNA synthetase (ThrRS). It acts as a broad-spectrum antibiotic against a range of clinically...
Obafluorin is a antibacterial natural product that inhibits threonyl-tRNA synthetase (ThrRS). It acts as a broad-spectrum antibiotic against a range of clinically relevant pathogens and comprises a strained β-lactone ring decorated with catechol and 4-nitro-benzyl moieties. The catechol moiety is widespread in nature and its role in the coordination of ferric iron has been well-characterised in siderophores and Trojan horse antibiotics. Here we use a combination of mutasynthesis, bioassays, enzyme assays and metal binding studies to delineate the role of the catechol moiety in the bioactivity of obafluorin. We use biosynthetic mutants to generate obafluorin analogues with modified catechol moieties. We demonstrate that an intact catechol is required for both antibacterial activity and inhibition of the ThrRS molecular target. Although recent work showed that the obafluorin catechol coordinates Zn in the ThrRS active site, we find that obafluorin is a weak Zn binder , contrasting with a strong, specific 1 : 1 interaction with Fe. We use bioassays with siderophore transporter mutants to probe the role of the obafluorin catechol in Fe-mediated uptake. Surprisingly, obafluorin does not behave as a Trojan horse antibiotic but instead exhibits increased antibacterial activity in the presence of Fe. We further demonstrate that Fe binding prevents the hydrolytic breakdown of the β-lactone ring, revealing a hitherto unreported function for the catechol moiety in natural product bioactivity.
PubMed: 37920400
DOI: 10.1039/d3cb00127j -
Frontiers in Microbiology 2023Bacterial communication is a fundamental process used to synchronize gene expression and collective behavior among the bacterial population. The most studied bacterial...
Bacterial communication is a fundamental process used to synchronize gene expression and collective behavior among the bacterial population. The most studied bacterial communication system is quorum sensing, a cell density system, in which the concentration of inductors increases to a threshold level allowing detection by specific receptors. As a result, bacteria can change their behavior in a coordinated way. While in quorum sensing based on the synthesis of -acyl homoserine lactone molecules is well studied, volatile organic compounds, although considered to be communication signals in the rhizosphere, are understudied. The MFE01 strain has a very active type six secretion system that can kill some competitive bacteria. Furthermore, MFE01 emits numerous volatile organic compounds, including 1-undecene, which contributes to the aerial inhibition of growth. Finally, MFE01 appears to be deprived of -acyl homoserine lactone synthase. The main objective of this study was to explore the role of 1-undecene in the communication of MFE01. We constructed a mutant affected in gene encoding the enzyme responsible for 1-undecene synthesis to provide further insight into the role of 1-undecene in MFE01. First, we studied the impacts of this mutation both on volatile organic compounds emission, using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry and on long-range inhibition. Then, we analyzed influence of 1-undecene on MFE01 coordinated phenotypes, including type six secretion system activity and biofilm formation. Next, to test the ability of MFE01 to synthesize -acyl homoserine lactones in our conditions, we investigated the presence of corresponding genes across the MFE01 genome and we exposed its biofilms to an acyl homoserine lactone-degrading enzyme. Finally, we examined the effects of 1-undecene emission on MFE01 biofilm maturation and aerial communication using an original experimental set-up. This study demonstrated that the Δ mutant is impaired in biofilm maturation. An exposure of the Δ mutant to the volatile compounds emitted by MFE01 during the biofilm development restored the biofilm maturation process. These findings indicate that MFE01 uses 1-undecene emission for aerial communication, reporting for the first time this volatile organic compound as bacterial intraspecific communication signal.
PubMed: 37908545
DOI: 10.3389/fmicb.2023.1264801 -
Plants (Basel, Switzerland) Oct 2023spp. are important pathogens on cereals, capable of causing considerable yield losses and significantly reducing the quality of harvested grains due to contamination...
spp. are important pathogens on cereals, capable of causing considerable yield losses and significantly reducing the quality of harvested grains due to contamination with mycotoxins. The European Union intends to reduce the use of chemical-synthetic plant protection products (csPPP) by up to 50% by the year 2030. To realize this endeavor without significant economic losses for farmers, it is crucial to have both precise early detection of pathogens and effective alternatives for csPPP. To investigate both the early detection of Fusarium head blight (FHB) and the efficacy of selected biological control agents (BCAs), a pot experiment with spring wheat (cv. 'Servus') was conducted under semi-field conditions. Spikes were sprayed with different BCAs prior to inoculation with a mixture of and conidia. While early detection of FHB was investigated by hyperspectral imaging (HSI), the efficiency of the fungal ( sp. T10, T16, T23 and CRP1104) and bacterial ( HG77 and G308) BCAs was assessed by visual monitoring. Evaluation of the hyperspectral images using linear discriminant analysis (LDA) resulted in a pathogen detection nine days post inoculation (dpi) with the pathogen, and thus four days before the first symptoms could be visually detected. Furthermore, support vector machines (SVM) and a combination of LDA and distance classifier (DC) were also able to detect FHB symptoms earlier than manual rating. Scoring the spikes at 13 and 17 dpi with the pathogen showed no significant differences in the FHB incidence among the treatments. Nevertheless, there is a trend suggesting that all BCAs exhibit a diminishing effect against FHB, with fungal isolates demonstrating greater efficacy compared to bacterial ones.
PubMed: 37895997
DOI: 10.3390/plants12203534 -
Microorganisms Oct 2023Plants exposed to abiotic stress such as drought and salinity produce 1-aminocyclopropane-1-carboxylic acid (ACC) that is converted into the stress hormone ethylene....
Plants exposed to abiotic stress such as drought and salinity produce 1-aminocyclopropane-1-carboxylic acid (ACC) that is converted into the stress hormone ethylene. However, plant growth-promoting bacteria (PGPB), which synthesize the enzyme ACC deaminase, may lower the ACC concentration thereby reducing the concentration of ethylene and alleviating the abiotic stress. The PGPB G20-18 (previously named G20-18) harbors the genes and that encode regulation and synthesis of ACC deaminase, respectively. Regulation of the gene has been investigated in several studies, but so far, it has been an open question whether plants can regulate microbial synthesis of ACC deaminase. In this study, small molecules in wheat root exudates were identified using untargeted metabolomics, and compounds belonging to amino acids, organic acids, and sugars were selected for evaluation of their influence on the expression of the and genes in G20-18. and promoters were fused to the fluorescence reporter gene mCherry enabling the study of and promoter activity. In planta studies in wheat seedlings indicated an induced expression of in association with the roots. Exudate molecules such as aspartate, alanine, arginine, and fumarate as well as glucose, fructose, and mannitol actively induced the promoter, whereas the plant hormone indole-3-acetic acid (IAA) inhibited expression. Here, we present a model for how stimulatory and inhibitory root exudate molecules influence promoter activity in G20-18.
PubMed: 37894162
DOI: 10.3390/microorganisms11102504 -
Foods (Basel, Switzerland) Oct 2023Ultra-high temperature sterilized milk (UHT) is a popular dairy product known for its long shelf life and convenience. However, protein gel aging and fat quality defects...
Ultra-high temperature sterilized milk (UHT) is a popular dairy product known for its long shelf life and convenience. However, protein gel aging and fat quality defects like creaming and flavor deterioration may arise during storage. These problems are primarily caused by thermostable enzymes produced by psychrotrophic bacteria. In this study, four representative psychrotrophic bacteria strains which can produce thermostable enzymes were selected to contaminate UHT milk artificially. After 11, 11, 13, and 17 weeks of storage, the milk samples, which were contaminated with , , and , respectively, demonstrated notable whey separation. The investigation included analyzing the protein and fat content in the upper and bottom layers of the milk, as well as examining the particle size, Zeta potential, and pH in four sample groups, indicating that the stability of UHT milk decreases over time. Moreover, the spoiled milk samples exhibited a bitter taste, with the dominant odor being attributed to ketones and acids. The metabolomics analysis revealed that three key metabolic pathways, namely ABC transporters, butanoate metabolism, and alanine, aspartate, and glutamate metabolism, were found to be involved in the production of thermostable enzymes by psychrotrophic bacteria. These enzymes greatly impact the taste and nutrient content of UHT milk. This finding provides a theoretical basis for further investigation into the mechanism of spoilage.
PubMed: 37893644
DOI: 10.3390/foods12203752 -
Antimicrobial Agents and Chemotherapy Nov 2023Type II toxin-antitoxin systems are highly prevalent in bacterial genomes and play crucial roles in the general stress response. Previously, we demonstrated that the...
Type II toxin-antitoxin systems are highly prevalent in bacterial genomes and play crucial roles in the general stress response. Previously, we demonstrated that the type II antitoxin PfMqsA regulates biofilm formation through the global regulator AgtR in . Here, we found that both the C-terminal DNA-binding domain of PfMqsA and AgtR are involved in bacterial antibiotic susceptibility. Electrophoretic mobility shift assay (EMSA) analyses revealed that AgtR, rather than PfMqsA, binds to the intergenic region of , in which encodes an resistance-nodulation-cell division efflux pump and encodes a repressor. Through quantitative real-time reverse-transcription PCR and EMSA analysis, we showed that AgtR directly activates the expression of the by binding to the DNA motif [5´-CTAAGAAATATACTTAC-3´], leading to repression of the . Furthermore, we demonstrated that PfMqsA modulates the expression of EmhABC and EmhR. These findings enhance our understanding of the mechanism by which antitoxin PfMqsA contributes to antibiotic susceptibility.
Topics: Pseudomonas fluorescens; Antitoxins; Anti-Bacterial Agents; Bacterial Proteins
PubMed: 37877694
DOI: 10.1128/aac.00812-23 -
BioRxiv : the Preprint Server For... Oct 2023We present a high-resolution 1D and 2D magic-angle spinning (MAS) solid-state NMR (ssNMR) study to characterize native colony biofilms at natural abundance without...
We present a high-resolution 1D and 2D magic-angle spinning (MAS) solid-state NMR (ssNMR) study to characterize native colony biofilms at natural abundance without isotope-labelling. By using a high-resolution INEPT-based 2D H- C ssNMR spectrum and thorough peak deconvolution approach at the 1D ssNMR spectra, approximately 80/134 (in 1D/2D) distinct biofilm chemical sites were identified. We compared CP and INEPT C ssNMR spectra to different signals originating from the mobile and rigid fractions of the biofilm, and qualitative determined dynamical changes by comparing CP buildup behaviors. Protein and polysaccharide signals were differentiated and identified by utilizing FapC signals as a template, a biofilm forming functional amyloid from . We also attempted to identify biofilm polysaccharide species by using H/ C chemical shifts obtained from the 2D spectrum. This study marks the first demonstration of high-resolution 2D ssNMR spectroscopy for characterizing native bacterial biofilms and expands the scope of ssNMR in studying biofilms. Our experimental pipeline can be readily applied to other in vitro biofilm model systems and natural biofilms and holds the promise of making a substantial impact on biofilm research, fostering new ideas and breakthroughs to aid in the development of strategic approaches to combat infections caused by biofilm-forming bacteria.
PubMed: 37873242
DOI: 10.1101/2023.10.02.560490 -
PLoS Biology Oct 2023The survival of a population during environmental shifts depends on whether the rate of phenotypic adaptation keeps up with the rate of changing conditions. A common way...
The survival of a population during environmental shifts depends on whether the rate of phenotypic adaptation keeps up with the rate of changing conditions. A common way to achieve this is via change to gene regulatory network (GRN) connections-known as rewiring-that facilitate novel interactions and innovation of transcription factors. To understand the success of rapidly adapting organisms, we therefore need to determine the rules that create and constrain opportunities for GRN rewiring. Here, using an experimental microbial model system with the soil bacterium Pseudomonas fluorescens, we reveal a hierarchy among transcription factors that are rewired to rescue lost function, with alternative rewiring pathways only unmasked after the preferred pathway is eliminated. We identify 3 key properties-high activation, high expression, and preexisting low-level affinity for novel target genes-that facilitate transcription factor innovation. Ease of acquiring these properties is constrained by preexisting GRN architecture, which was overcome in our experimental system by both targeted and global network alterations. This work reveals the key properties that determine transcription factor evolvability, and as such, the evolution of GRNs.
Topics: Transcription Factors; Gene Expression Regulation; Gene Regulatory Networks; Models, Theoretical
PubMed: 37871011
DOI: 10.1371/journal.pbio.3002348 -
Frontiers in Microbiology 2023Although the bacterial composition of boar ejaculate has been extensively studied, the bacterial composition of extended boar semen is often overlooked, despite the...
Although the bacterial composition of boar ejaculate has been extensively studied, the bacterial composition of extended boar semen is often overlooked, despite the potential risks these microorganisms may pose to the long-term preservation of extended boar semen at 15-17°C. In this study, we characterized the bacterial community composition of extended semen and discovered that spp. was the dominant flora. The dominant strains were further isolated and identified as a potential new species in the group and named strain, which had adverse effects on sperm quality and was better adapted to growth at 17°C. Antimicrobial susceptibility testing showed that the strain was resistant to all commonly used veterinary antibiotics. Whole-genome sequencing (WGS) and genome annotation revealed the large genetic structure and function [7,253,751 base pairs and 6,790 coding sequences (CDSs)]. Comparative genomic analysis with the closest type strains showed that the strain predicted more diversity of intrinsic and acquired resistance genes to multi-antimicrobial agents. Taken together, our study highlights a problem associated with the long-term storage of extended boar semen caused by a group strain with unique biological characteristics. It is essential to develop a new antibacterial solution for the long-term preservation of boar semen.
PubMed: 37869660
DOI: 10.3389/fmicb.2023.1279630