FEMS Microbes

Abstract Biofilm formation is a critical step in the pathogenesis of difficult-to-treat Gram-positive bacterial infections. We identified that YajC, a conserved membrane protein in bacteria, plays a role in biofilm formation of the clinically relevant Enterococcus faecium strain E1162. Deletion of yajC conferred significantly impaired biofilm formation in vitro and was attenuated in a rat endocarditis model. Mass spectrometry analysis of supernatants of washed ΔyajC cells revealed increased amounts in cytoplasmic and cell-surface-located proteins, including biofilm-associated proteins, suggesting that proteins on the surface of the yajC mutant are only loosely attached. In Streptococcus mutans YajC has been identified in complex with proteins of two cotranslational membrane protein-insertion pathways; the signal recognition particle (SRP)-SecYEG-YajC-YidC1 and the SRP-YajC-YidC2 pathway, but its function is unknown. In S. mutans mutation of yidC1 and yidC2 resulted in impaired protein insertion in the cell membrane and secretion in the supernatant. The E. faecium genome contains all homologous genes encoding for the cotranslational membrane protein-insertion pathways. By combining the studies in S. mutans and E. faecium, we propose that YajC is involved in the stabilization of the SRP-SecYEG-YajC-YidC1 and SRP-YajC-Yid2 pathway or plays a role in retaining proteins for proper docking to the YidC insertases for translocation in and over the membrane.

Janetta Top

Xinglin Zhang

Antoni P A Hendrickx

Sjef Boeren

Willem van Schaik

Johannes Huebner

Rob J L Willems

Helen L Leavis

Fernanda L Paganelli

YajC, a predicted membrane protein, promotes Enterococcus faecium biofilm Formation in vitro and in a rat endocarditis model

预测的膜蛋白YajC促进粪肠球菌生物膜在体外及大鼠心内膜炎模型中的形成

Haloalkaliphilic chemolithoautotrophic sulfur-oxidizing bacteria belonging to the genus Thioalkalivibrio are highly abundant in microbial communities found in soda lakes and dominant in full-scale bioreactors removing sulfide from industrial waste gases. Despite certain soda lakes being remote and unaffected by anthropogenic activities, haloalkaliphilic microorganisms, including Thioalkalivibrio strains, possess various antibiotic resistance genes. In this study, we investigated the impact of the antibiotic ampicillin on a co-culture of two Thioalkalivibrio species, Tv. thiocyanoxidans ARh2T and Tv. versutus AL2T, both experimentally and through in silico analysis of antibiotic resistance. Cell growth dynamics were monitored over time at increasing ampicillin concentrations using rep- and qPCR. Within ten days after the addition of ampicillin, the co-culture transitioned from a Tv. thiocyanoxidans ARh2T-dominated to a stable Tv. versutus AL2T-dominated culture. This shift was attributed to Tv. versutus AL2T displaying a lower susceptibility to ampicillin, making it more competitive. These results emphasize the potential implications of antibiotic pressure on microbial communities, where a resistant species can outcompete a stable co-culture. This study presents the first evidence of such dynamics in haloalkaliphilic chemolithoautotrophs. By understanding the antibiotic resistance and the competitive dynamics of haloalkaliphilic bacteria like Thioalkalivibrio, we can gain insights into their behaviour and stress response.

Anne-Catherine Ahn

J Merijn Schuurmans

Dimitry Sorokin

Gerard Muyzer

Dynamics of Thioalkalivibrio species in a co-culture under selective pressure of ampicillin

氨苄西林选择压力下共培养中Thioalkalivibrio物种的动态变化

Abstract Anaerobic gut fungi (AGF, Neocallimastigomycota), inhabit the alimentary tract of herbivores. Although strict anaerobes, studies have suggested their capacity to retain viability after various durations of air exposure. It is currently unclear whether AGF can actively grow, and not merely survive, in redox potentials (Eh) higher than those encountered in the herbivorous gut. We evaluated the growth of two AGF strains (Orpinomyces joyonii and Testudinimyces gracilis) at various Eh levels, achieved by manipulating the concentrations of reductant (cysteine hydrochloride) in culture media. Both strains exhibited robust and sustainable growth at negative Eh (-50 mV or below). However, growth in the absence of cysteine hydrochloride (Eh value around +50 mV) was possible only for O. joyonii and only for one subcultivation. The capacity to grow at +50 mV was further confirmed in four additional taxa (Pecoramyces ruminatium, Anaeromyces mucronatus, Aklioshbmyces papillarum, and Piromyces communis), while two (Aestipascuomyces dupliciliberans and Capellomyces foraminis) failed to grow under these conditions. Our results establish the ability of AGF to grow at redox potential values higher than those encountered in their natural habitats. Such capability could contribute to efficient AGF dispersal and horizontal transmission between hosts, and could have important implications for industrial applications of AGF.

Emma E England

Carrie J Pratt

Mostafa S Elshahed

Noha H Youssef

Evaluating the impact of redox potential on the growth capacity of anaerobic gut fungi

评估氧化还原电位对厌氧肠道真菌生长能力的影响

Abstract Background Important questions remain about the sources of transmission of pneumococcus to older adults in the community. This is critical for understanding the potential effects of using pneumococcal conjugate vaccines (PCVs) in children and older adults. For non-institutionalized individuals, we hypothesized that the most likely source of adult-to-adult transmission is within the household. Methods We designed a longitudinal study to sample adults ≥60 years of age living in the same household (New Haven, CT, USA), without younger residents in the household. Saliva samples and social and health questionnaires were obtained every 2 weeks for a period of 10 weeks. DNA extracted from culture-enriched saliva was tested using qPCR for pneumococcus genes piaB, lytA, and serotype. Results Across two study seasons (November 2020-August 2021, November 2021-September 2022), 121 individuals from 61 households completed all 6 visits; 62 individuals were enrolled in both seasons. Overall, 52/1088 (4.8%) samples tested positive for pneumococcus, with 27/121 (22.3%) individuals colonized at least once. Several individuals were colonized at multiple timepoints; two individuals were colonized at 5/6 time points and two at all six. In 5 instances, both household members were carriers in the same season, though not necessarily at the same time. Pneumococcal carriage was substantially higher among individuals who had contact with children (10.0% vs 1.6%). Conclusions Contact with young children was the most important factor that influenced pneumococcal acquisition rates. While there were several instances where both adult household members were colonized at the same time or at sequential visits, these individuals typically had contact with children. As such, PCV immunization can directly protect older adults who have contact with children.

Anne L Wyllie

Devyn Yolda-Carr

Maikel S Hislop

Sidiya Mbodj

Loren Wurst

Pari Waghela

Ronika Alexander-Parrish

Lindsay R Grant

Adriano Arguedas

Bradford D Gessner

Daniel M Weinberger

Contact with young children is a major risk factor for pneumococcal colonization in older adults

与幼儿接触是老年人肺炎球菌定植的主要风险因素

Abstract The inebriation of wild African elephants from eating the ripened and rotting fruit of the marula tree is a persistent myth in Southern Africa. However, the yeasts responsible for alcoholic fermentation to intoxicate the elephants remain poorly documented. In this study, we considered Botswana, a country with the world's largest population of wild elephants, and where the marula tree is indigenous, abundant and protected, to assess the occurrence and biodiversity of yeasts with a potential to ferment and subsequently inebriate the wild elephants. We collected marula fruits from over a stretch of 800 km in Botswana and isolated 106 yeast strains representing 24 yeast species. Over 93% of these isolates, typically known to ferment simple sugars and produce ethanol comprising of high ethanol producers belonging to Saccharomyces, Brettanomyces, and Pichia, and intermediate ethanol producers Wickerhamomyces, Zygotorulaspora, Candida, Hanseniaspora, and Kluyveromyces. Fermentation of marula juice revealed convincing fermentative and aromatic bouquet credentials to suggest the potential to influence foraging behaviour and inebriate elephants in nature. There is insufficient evidence to refute the aforementioned myth. This work serves as the first work towards understanding the biodiversity marula associated yeasts to debunk the myth or approve the facts.

Tawanda Proceed Makopa

Gorata Modikwe

Urska Vrhovsek

Cesare Lotti

José Paulo Sampaio

Nerve Zhou

The marula and elephant intoxication myth: assessing the biodiversity of fermenting yeasts associated with marula fruits (Sclerocarya birrea)

马鲁拉与大象醉酒的神话：评估与马鲁拉果实（Sclerocarya birrea）相关的发酵酵母的生物多样性

Abstract Enterococcus faecalis is ranked among the top five bacterial pathogens responsible for catheter-associated urinary tract infections, wound infections, secondary root canal infections, and infective endocarditis. Previously, we showed that inactivation of either the manganese- and iron-binding (EfaA) or zinc-binding (AdcA and AdcAII) lipoproteins significantly reduced E. faecalis virulence. Here, we explored whether immunization using a multi-valent approach induce protective immunity against systemic enterococcal infections. We found that multi-antigen antisera raised against EfaA, AdcA, and AdcAII displayed similar capacities to initiate neutrophil-mediated opsonization, like their single-antigen counterparts. Further, these antigen-specific antibodies worked synergistically with calprotectin, a divalent host metal chelator, to inhibit the growth of E. faecalis in laboratory media as well as in human sera. Using the Galleria mellonella invertebrate model and mouse peritonitis model, we showed that passive immunization with multi-antigen antisera conferred robust protection against E. faecalis infection while the protective effects of single antigen antisera was negligible in G. mellonella, and negligible-to-moderate in the mouse model. Lastly, active immunization with the 3-antigen (trivalent) cocktail significantly protected mice against either lethal or non-lethal E. faecalis infections, with this protection appearing to be far-reaching based on immunization results obtained with contemporary strains of E. faecalis and closely-related Enterococcus faecium.

Ling Ning Lam

Angie Sedra

Jessica Kajfasz

Aym Berges

Irene S Saengpet

Grace Adams

Jeffery Fairman

José A Lemos

Trivalent immunization with metal-binding proteins confers protection against enterococci in a mouse infection model

三价免疫接种金属结合蛋白在鼠感染模型中对肠球菌提供保护

Abstract Enterococcus faecalis is a commensal bacterium in the gastrointestinal tract (GIT) of humans and other organisms. E. faecalis also causes infections in root canals, wounds, the urinary tract, and on heart valves. E. faecalis metabolizes arginine through the arginine deiminase (ADI) pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO2. E. faecalis arginine metabolism also affects virulence of other pathogens during co-culture. E. faecalis may encounter elevated levels of arginine in the GIT or the oral cavity, where arginine is used as a dental therapeutic. Little is known about how E. faecalis responds to growth in arginine in the absence of other bacteria. To address this, we used RNAseq and additional assays to measure growth, gene expression, and biofilm formation in E. faecalis OG1RF grown in arginine. We demonstrate that arginine decreases E. faecalis biofilm production and causes widespread differential expression of genes related to metabolism, quorum sensing, and polysaccharide synthesis. Growth in arginine also increases aggregation of E. faecalis and promotes decreased susceptibility to the antibiotics ampicillin and ceftriaxone. This work provides a platform for understanding of how the presence of arginine in biological niches affects E. faecalis physiology and virulence of surrounding microbes.

Alex Snell

Dawn A Manias

Reham R Elbehery

Gary M Dunny

Julia L E Willett

Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility in Enterococcus faecalis

精氨酸影响粪肠球菌的聚集、生物膜形成及抗生素敏感性

Abstract Student engagement is one of the critical issues in science classes. This commentary explores the value of storytelling in microbiology education and student engagement. It is a result of an undergraduate exercise, where students were asked to draft short stories on pandemics before the COVID-19 pandemic (i.e., conducted in 2016–2019). The analysis of student writings (total of 244 short stories) aimed to understand the students' perception of pandemics, the diseases they chose to write about, and their level of knowledge of pandemics. Interestingly, 56.6% of students chose viruses to be the cause of their pandemics, 35.7% chose bacteria, 4.5% chose parasites, and a single student chose a fungus. Respiratory mode of transmission was the top pick in the stories (30%), followed by fecal-oral route, sexually transmitted, and skin-to-skin contact. Therefore, their choice of respiratory diseases as the focus of their short story may suggest their limited understanding of pandemics beyond such diseases. The varying levels of detail in the stories suggested that storytelling could be insightful in identifying knowledge gaps and engaging students. Two exciting questions remain: (1) For the students who wrote those short stories before the COVID-19 pandemic, how did they feel when it hit? (2) If the students are asked again to write a pandemic short story, what would it look like nowadays? A deeper understanding of epidemiology and the social impact of pandemics is crucial for developing effective pandemic preparedness and response plans, and undergraduate courses can play a vital role in this endeavor. Overall, this commentary highlights the value of storytelling in engaging students to assess their knowledge of specific subject matters.

Moamen M Elmassry

Pandemic storytelling and student engagement: How students imagined pandemics before COVID-19 pandemic

大流行叙事与学生参与：学生在COVID-19大流行前如何想象大流行

Publication Information	Publisher: Oxford University Press，Publishing cycle: ，Journal Type: journal，Open Access Journals: Yes
Basic data	Year of publication: 2020，Proportion of original research papers: 0.00%，Self Citation Rate:N.A.， Gold OA Rate: 0.00%
Journal Fees	$Details
Average review cycle	网友分享经验：15 Weeks

FEMS Microbes

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YajC, a predicted membrane protein, promotes Enterococcus faecium biofilm Formation in vitro and in a rat endocarditis model

Dynamics of Thioalkalivibrio species in a co-culture under selective pressure of ampicillin

Evaluating the impact of redox potential on the growth capacity of anaerobic gut fungi

Contact with young children is a major risk factor for pneumococcal colonization in older adults

The marula and elephant intoxication myth: assessing the biodiversity of fermenting yeasts associated with marula fruits (Sclerocarya birrea)

Evaluating the impact of redox potential on the growth capacity of anaerobic gut fungi

Contact with young children is a major risk factor for pneumococcal colonization in older adults

Trivalent immunization with metal-binding proteins confers protection against enterococci in a mouse infection model

Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility in Enterococcus faecalis

Pandemic storytelling and student engagement: How students imagined pandemics before COVID-19 pandemic

ISSN	2633-6685
h-index	8