Fems Microbiology Letters最新文献

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.

Chlorhexidine, an antimicrobial with a broad inhibitory spectrum, is commonly used to treat oral infections as an active ingredient in mouthwash. While typically used at high concentrations (1-2 mg/ml), oral bacteria can be exposed to sublethal concentrations due to the bioavailability and protective barrier of biofilms (dental plaques). Sublethal concentrations can cause transcriptional remodelling of bacteria such as Streptococcus mutans, a key player in dental caries. Using an RNA-seq approach, this report provides a compendium on the effect of sublethal concentrations of chlorhexidine on the transcriptome of S. mutans as planktonic cells and in biofilm states. Streptococcus mutans showed major transcriptional remodelling between planktonic and biofilm states. The transcriptional response towards chlorhexidine was more pronounced in planktonic cells compared to sessile cells. However, the response observed for biofilm-associated cells was not specific to chlorhexidine, as the transcriptional response in biofilms exposed to the β-lactam amoxicillin was similar to those observed for chlorhexidine. Furthermore, we found that S. mutans modulates the transcription of a multitude of ABC transporters in both planktonic and biofilm-associated cells upon exposure to these antimicrobials.

Enterohemorrhagic Escherichia coli O157:H7 (E. coli O157) strains do not produce curli and do not form biofilms, but they retain their ability for autoaggregation. In our study, we investigated whether curli expression would impact E. coli O157 autoaggregation. Curli-expressing strain CPM1 was derived from E. coli O157 strain ATCC 43890 as a clone forming red colonies on Congo red (CR)-agar. To quantitatively evaluate autoaggregation we applied a recently developed experimental system based on magnetic levitation. The efficiency of autoaggregation was evaluated by the geometry of macroautoaggregates and by relative amounts of aggregated and free-swimming bacteria. The curli producing CPM1 strain's autoaggregates had a volume 3.4 times smaller than that of ATCC 43890, despite the number of autoaggregated CPM1 bacteria being higher. Curli proteins were incorporated into matrix, making CPM1 autoaggregate more compact. Curliated CPM1 bacteria adhered better to vertical surfaces reducing the number of free swimmers. The Ser206Phe substitution in the transcriptional regulator RcsB was responsible for CPM1 curli-expressing phenotype. The mutation affected RcsB interactions with the accessory protein RscA. RcsA hyperexpression inhibited curli production and decreased efficiency of autoaggregation. Taken together, the obtained results demonstrated that removal of RcsB/RcsA-dependent inhibition of curli expression improves autoaggregation in the E. coli O157.

A practical storytelling approach can help scientists transform their complex research into engaging narratives. This commentary discusses a practical workshop setup through which scientists can focus on leveraging emotions, character development, logical connections and active language to enhance science communication with both expert and nonexpert audiences.

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.

The rapid dissemination of antibiotic resistance genes (ARGs) represents a significant global threat, with wastewater treatment plants (WWTPs) playing an important role as reservoirs and propagation hubs. In this study, we performed whole-genome sequencing and bioinformatic analyses on eight multidrug-resistant Escherichia coli isolates previously obtained from domestic WWTPs in Costa Rica. We identified 61 ARGs (23 unique), with 40 located on plasmids, and 21 on chromosomal sequences, seven of which were within integrons. Several ARGs were associated with resistance to clinically and veterinary important antibiotics, including sulfamethoxazole/trimethoprim, beta-lactams, and tetracyclines. One hundred twenty-one virulence-associated genes (29 unique) were detected, with 16 located on plasmids. Notably, the presence of virulence factors such as ompT and hlyF genes alongside ARGs on plasmids underscores the transmissible pathogenic potential of WWTP-associated E. coli strains. These findings highlight the role of small domestic WWTPs in disseminating pathogenic and multidrug-resistant bacteria and their mobile genetic elements, emphasizing the need for further research to understand how these discharges impact aquatic environments.

Pseudomonas aeruginosa has increasing clinical relevance and commonly occupies the cystic fibrosis (CF) airways. Its ability to colonize and persist in diverse niches is attributed to its large accessory genome, where prophages represent a common feature and may contribute to its fitness and persistence. We focused on the CF airways niche and used 197 longitudinal isolates from 12 patients persistently infected by P. aeruginosa. We computationally predicted intact prophages for each longitudinal group and scored their long-term persistence. We then confirmed prophage inducibility and mapped their location in the host chromosome with lysate sequencing. Using comparative genomics, we evaluated prophage genomic diversity, long-term persistence, and level of genomic maintenance. Our findings support previous findings that most P. aeruginosa genomes harbour prophages some of which can self-induce, and that a common CF-treating antibiotic, ciprofloxacin, can induce prophages. Induced prophage genomes displayed high diversity and even genomic novelty. Finally, all induced prophages persisted long-term with their genomes avoiding gene loss and degradation over 4 years of host replication in the stressful CF airways niche. This and our detection of phage genes, which contribute to host competitiveness and adaptation, lends support to our hypothesis that the vast majority of prophages detected as intact and inducible in this study facilitated their host fitness and persistence.

Akanthomyces lecanii is an entomopathogenic fungus, and spores of this fungus could be incorporated into films generated using cast film extrusion for biocontrol applications. However, the extrusion process involves high temperature processing (150°C) although this only lasts for a few minutes. The elevated temperature destroys spores, thereby eliminating functionality, unless the spores are protected from this heat. Initial experiments revealed that the heat tolerance of free A. lecanii spores to be 60°C. The spores were therefore encapsulated into beads prepared using a combination of Gelrite, cellulose, and Cel-fine at different concentrations. The beads were freeze-dried and then immersed in hot glycerol for 2 min at a selected temperature within the range of 50°C-100°C. The results indicated that some combinations of encapsulating agents resulted in the spores retaining viability (plate counting) after heat treatment at 100°C. Beads stored at room temperature for 1 week showed a reduction in the upper temperature tolerance. This study revealed that the temperature tolerance of A. lecanii spores could be improved by 40°C by encapsulation in freeze-dried beads containing 2% Gelrite (purified gellum gum), 0.4% cellulose, and 0.4% Cel-fine.