Fems Microbiology Letters最新文献

Antimicrobial resistance is a global health threat driven by mechanisms like biofilm formation and efflux pumps. This study evaluated the antibacterial activity, antibiotic-modulating potential, and pharmacokinetic properties of 3-methoxycinnamic acid (3MCA) using in vitro and in silico methods. Although 3MCA showed no direct antibacterial effect (MIC > 512 μg/ml), it enhanced the efficacy of gentamicin against multidrug-resistant (MDR) Escherichia coli (60.3% MIC reduction) and ampicillin against MDR Staphylococcus aureus (37% reduction). ADMET analysis revealed good drug-like properties, low intestinal absorption, no interaction with P-glycoprotein, and effective blood-brain barrier penetration, but potential toxicological risks such as hepatotoxicity. Molecular docking showed moderate binding affinities to target proteins through stable hydrogen bonds and aromatic interactions. These results suggest that 3MCA may act as an antibiotic resistance modulator, although further in vivo studies are necessary to confirm its safety and therapeutic potential.

Commensal Neisseria are members of a healthy human oropharyngeal microbiome; however, they also serve as a reservoir of antimicrobial resistance for their pathogenic relatives. Despite their known importance as sources of novel genetic variation for pathogens, we still do not understand the full suite of resistance mutations commensal species can harbor. Here, we use in vitro selection to assess the mutations that emerge in response to ciprofloxacin selection in commensal Neisseria by passaging four replicates of four different species in the presence of a selective antibiotic gradient for 20 days; then categorized derived mutations with whole genome sequencing. Ten out of sixteen selected cells lines across the four species evolved ciprofloxacin resistance (≥1 ug/ml); with resistance-contributing mutations primarily emerging in DNA gyrase subunit A and B (gyrA and gyrB), topoisomerase IV subunits C and E (parC and parE), and the multiple transferable efflux pump repressor (mtrR). Of note, these derived mutations appeared in the same loci responsible for ciprofloxacin-reduced susceptibility in the pathogenic Neisseria, suggesting conserved mechanisms of resistance across the genus. Additionally, we tested for zoliflodacin cross-resistance in evolved strain lines and found 6 lineages with elevated zoliflodacin minimum inhibitory concentrations. Finally, to interrogate the likelihood of experimentally derived mutations emerging and contributing to resistance in natural Neisseria, we used a population-based approach and identified GyrA 91I as a substitution circulating within commensal Neisseria populations and ParC 85C in a single gonococcal isolate. A small cluster of gonococcal isolates shared commensal alleles at parE, suggesting recent cross-species recombination events.

Terminal olefins are important platform chemicals, drop-in compatible hydrocarbons and also play an important role as biocontrol agents of plant pathogens. Currently, 1-alkenes are derived from petroleum, although microbial biosynthetic routes are known. Jeotgalicoccus sp. ATCC 8456 produces 1-alkenes via the fatty acid decarboxylase OleTJE. UndA and UndB are recently identified non-heme iron oxidases converting medium-chain fatty acids into terminal alkenes. Our knowledge about the diversity and natural function of OleTJE, UndA, and UndB homologs is scarce. We applied a combined screening strategy-solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME GC-MS) and polymerase chain reaction (PCR)-based amplification-to survey an environmental strain collection for microbial 1-alkene producers and their corresponding enzymes. Our results reinforce the high level of conservation of UndA and UndB genes across the genus Pseudomonas. In vivo production of defined 1-alkenes (C9-C13; C15; C19) was directed by targeted feeding of fatty acids. Lauric acid feeding enabled 1-undecene production to a concentration of 3.05 mg l-1 in Jeotgalicoccus sp. ATCC 8456 and enhanced its production by 105% in Pseudomonas putida 1T1 (1.10 mg l-1). Besides, whole genome sequencing of Jeotgalicoccus sp. ATCC 8456 enabled reconstruction of the 1-alkene biosynthetic pathway. These results advance our understanding of microbial 1-alkene synthesis and the underlying genetic basis.

This study assesses halophilic archaea's phylogenetic diversity in southern Tunisia's geothermal water. In the arid southern regions, limited surface freshwater resources make geothermal waters a vital source for oases and greenhouse irrigation. Three samples, including water, sediment, and halite soil crust, were collected downstream of two geothermal springs of the Ksar Ghilane (KGH) and Zaouet Al Aness (ZAN) oases, Tunisia. The samples were subjected to 16S rRNA gene sequencing using the Illumina Miseq sequencing approach. Several haloarchaea were identified in the geothermal springs. The average taxonomic composition revealed that 20 out of 33 genera were shared between the two geothermal sources, with uneven distribution, where the Halogranum genus was the most represented genus with an abundance of 18.9% and 11.58% for ZAW and KGH, respectively. Several unique site-specific genera were observed: Halonotius, Halopelagius, Natronorubrum, and Haloarcula in ZAN, and Haloprofundus, Halomarina, Halovivax, Haloplanus, Natrinema, Halobium, Natronoarchaeum, and Haloterrigena in the KGH pool. Most genus members are typically found in low-salinity ecosystems. These findings suggest that haloarchaea can disperse downstream from geothermal sources and may survive temperature and chemical fluctuations in the runoff.

Bacteria that ferment amino acids to ammonia can be categorized as generalists or specialist hyper-ammonia-producing bacteria. In the rumens of ruminant animals, most of the ammonia produced is eventually excreted as urea in urine. This process can be controlled with off-label use of antibiotics, but the practice can lead to antibiotic resistance; therefore, discovery of antibiotic alternatives is pertinent. Plant-derived phenolic compounds have demonstrated antimicrobial efficacy for such purposes. This study investigated the antimicrobial and metabolic suppressive potential of six phenolic compounds on five amino acid fermenting bacteria: Clostridium sporogenes MD1, C. aminophilum F, Acetoanaerobium sticklandii SR, Peptostreptococcus sp. BG1, and Prevotella bryantii B14. Inhibitory action of the compounds was determined using a 10% v/v serial dilution method in basal media. Carvacrol (1 mM), thymol (1 mM), and eugenol (10 mM) demonstrated the greatest antimicrobial potential, where carvacrol and eugenol inhibited growth of all five species and thymol four species except BG1. The cinnamic acids (trans and hydro) demonstrated variable activity against all organisms. Suppression of metabolic activity was determined via colorimetric assay quantifying ammonia in washed stationary phase culture supernatant after 24 h of metabolism on fresh substrate. Carvacrol and eugenol yielded the greatest reduction of ammonia by all organisms except B14, which produced no ammonia under the growth conditions. Thymol greatly reduced ammonia production of four organisms except F. These data demonstrate that eugenol, carvacrol, and thymol may be worthy antimicrobial candidates for the control of ammonia-producing organisms.

Scientific conferences are essential to academic exchange. However, related air travel contributes to greenhouse gas emissions, while expensive registration and travel costs limit the participation of early career researchers and those from low-income countries. Virtual conferences offer promising solutions for reducing emissions and enhancing accessibility and inclusivity but often limit networking and personal interaction. Hybrid multi-hub conferences, which combine virtually connected in-person venues with individual virtual participation, combine the benefits of both conference formats. Thus, we present and discuss MEEhubs2024, a multi-hub conference on microbial ecology and evolution held in January 2024. During this 3-day conference, attendees participated virtually or at one of six hubs in Europe and North America. We analyzed the participants' and organizers' feedback to create a template and provide insights into the scientific community's adoption of this new conference format, which was positively evaluated by most participants. Because technical, logistical, and structural challenges remain, including limited opportunities to interact and network across hubs and participation modes, we provide recommendations for improvement, such as hiring technical hosts and offering virtual-only social activities. Finally, we used the participants' feedback to reflect on conference expectations, highlighting research gaps and the need for organizers to define and communicate goals when organizing conferences.

Efficient screening methods are crucial for developing phage cocktails that can sustainably suppress bacterial growth. We developed a regrowth culture-guided phage screening strategy using Salmonella Enteritidis as a model. The strategy comprises four steps: (1) isolating an initial phage through conventional random screening, (2) generating a regrowth culture from bacteria that survive phage-induced inhibition, (3) enriching a phage pool by coincubating the regrowth culture with environmental samples, and (4) isolating phages that infect the regrowth-adapted bacterial population. Compared to cocktails derived from conventional random or mutant-based screening approaches, those prepared via this strategy demonstrated prolonged inhibitory activity, effectively suppressing S. Enteritidis regrowth for over 24 h in liquid culture. This approach provides a simple, reproducible, and ecologically relevant method for identifying phages with enhanced efficacy against phage-evasive bacterial populations. It may also serve as a valuable screening framework for developing robust phage cocktails against other pathogens.

Two bacterial strains degrading liquefied polypropylene (PP) at a moderately high temperature of 50°C were obtained after enrichment on liquefied PP in surface seawater supplemented with nitrogen, phosphorus, and iron nutrients at 50°C. The strains, designated R1 and R4-2, belonged to Nitratireductor and Oricola, respectively. These genera are phylogenetically close. Nitratireductor R1 or its close relatives were detected as the main bacteria (12% of the total bacteria) and Oricola R4-2 or its close relatives were also significantly detected (5%) in the liquefied PP-enriched seawater, suggesting that these bacteria utilized liquefied PP as a carbon source. Nitratireductor R1 showed liquefied PP-degrading activity at 50°C but not at 28-42°C, while Oricola R4-2 showed the activity at 42-50°C but not at 28°C. At 50°C, these two strains degraded liquefied PP of all lengths detected, isoprenoid-derived branched alkane (pristane), and n-alkane (n-hexadecane) to a similar extent, and also degraded aromatic compounds. Pristane and n-hexadecane appeared not to induce the PP-degrading activity. These results indicate that Nitratireductor and Oricola bacteria could be used in industrial applications for degrading liquefied PP and polyethylene and aromatic structures of liquefied aromatic-containing plastics at 50°C.

Fenclorim is an effective safener that protects rice (Oryza sativa L.) from the phytotoxic effects of certain herbicides. This study investigated its impact on soil bacterial communities, isolated fenclorim-degrading bacteria, assessed environmental contamination by fenclorim and other pesticides, and enhanced their degradation in soil and water under aerobic conditions. Results showed that fenclorim did not adversely affect the bacterial community structure. Acinetobacter sp. F0, capable of using fenclorim as a sole carbon, nitrogen, and energy source, was isolated from soil and degraded 97.1 ± 1.2% of fenclorim (100 µM) within 36 h. Fenclorim was more persistent in soil and water than pretilachlor, butachlor, and pymetrozine. Co-inoculation with target-degrading microorganisms significantly enhanced the degradation of all compounds and reduced the accumulation of intermediate metabolites-4,6-dichloropyrimidine and benzene-via cross-degradation. A packed-bed bioreactor achieved degradation efficiencies of 93.7 ± 4.59% for fenclorim, 94.9 ± 4.09% for pretilachlor, and 90.4 ± 5.52% for butachlor at a 12-h hydraulic retention time. The reactor also effectively removed BOD5, COD, NO3-, NH4+, and PO43- from water. These findings provide valuable insights into fenclorim degradation pathways, pesticide persistence, and the role of microbial augmentation in environmental remediation.