Applied and Environmental Microbiology最新文献

{"title":"Phylogenetic analysis of plant-pathogenic and non-pathogenic <i>Trichoderma</i> isolates on maize from plants, soil, and commercial bio-products.","authors":"Annette Pfordt, Clovis Douanla-Meli, Bernhard C Schäfer, Gritta Schrader, Eike Tannen, Madhav Jatin Chandarana, Andreas von Tiedemann","doi":"10.1128/aem.01931-24","DOIUrl":"https://doi.org/10.1128/aem.01931-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Fungi of the genus &lt;i&gt;Trichoderma&lt;/i&gt; are primarily associated with the mycobiome of dead wood but can also be occasionally found in soil and plant rhizospheres. Several &lt;i&gt;Trichoderma&lt;/i&gt; spp. are used in crop health management to promote growth and control plant diseases. Although widely considered beneficial to plants, some members have been reported to be pathogenic to maize, causing a disease called &lt;i&gt;Trichoderma&lt;/i&gt; ear rot. Since 2018, &lt;i&gt;Trichoderma afroharzianum&lt;/i&gt; has caused significant infections of maize cobs in Germany, France, and Italy. This study aimed to investigate the pathogenicity and phylogenetic relationships among different &lt;i&gt;Trichoderma&lt;/i&gt; strains from diverse sources and geographical origins. While previous studies primarily identified &lt;i&gt;T. afroharzianum&lt;/i&gt; as the main species causing &lt;i&gt;Trichoderma&lt;/i&gt; ear rot, this study found that isolates of &lt;i&gt;T. asperellum&lt;/i&gt;, &lt;i&gt;T. atroviride,&lt;/i&gt; and &lt;i&gt;T. guizhouense&lt;/i&gt; may also exhibit pathogenicity on maize cobs. Additionally, &lt;i&gt;Trichoderma&lt;/i&gt; strains from commercial biocontrol products displayed unexpected pathogenicity inducing up to 92% disease severity on maize cobs. Most &lt;i&gt;T. afroharzianum&lt;/i&gt; strains induced high levels of disease severity, although some isolates of the same species did not cause any disease, indicating a large heterogeneity in pathogenicity within the species. Notably, phylogeny reconstruction based on the &lt;i&gt;tef1-α&lt;/i&gt; and &lt;i&gt;rpb2&lt;/i&gt; genes did not result in any discernible clustering between pathogenic and non-pathogenic isolates. A further novel finding is the isolation of pathogenic &lt;i&gt;Trichoderma&lt;/i&gt; isolates from agricultural soil, demonstrating that soil can serve as a reservoir for pathogenic species. This study highlights the need for biosecurity assessment and monitoring of &lt;i&gt;Trichoderma&lt;/i&gt; strains for agricultural use, considering their beneficial and pathogenic potential.IMPORTANCEIn this study, we explored the ability of different &lt;i&gt;Trichoderma&lt;/i&gt; species to infect maize plants. &lt;i&gt;Trichoderma&lt;/i&gt; is a group of fungi known for its beneficial role in agriculture, often used as a biological pesticide to control fungal plant diseases. However, some species within this genus can also act as pathogens, causing infections in crops like maize. We found that one species, &lt;i&gt;T. afroharzianum&lt;/i&gt;, is particularly aggressive, capable of infecting maize without the plant being wounded first. This makes it a potentially serious threat to crop health. In contrast, other species, such as &lt;i&gt;T. atroviride&lt;/i&gt; and &lt;i&gt;T. asperellum&lt;/i&gt;, only caused infections when maize plants were injured before. Our research suggests that pathogenic &lt;i&gt;Trichoderma&lt;/i&gt; species not only effectively infect plants but can also survive well in soil, making their control difficult. These findings highlight the need for better understanding of how these fungi operate in order to manage the risks they pose to important crops like maize, while still taking advan","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0193124"},"PeriodicalIF":3.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The production of esters by specific sourdough lactic acid bacteria species is limited by the precursor concentrations.","authors":"Inés Pradal, Stefan Weckx, Luc De Vuyst","doi":"10.1128/aem.02216-24","DOIUrl":"https://doi.org/10.1128/aem.02216-24","url":null,"abstract":"<p><p>The production of fruity esters by sourdough lactic acid bacteria (LAB) and yeasts has not been explored in detail. Moreover, the biosynthesis of esters by LAB species under conditions similar to those occurring during sourdough production is still questionable. Concerning yeasts, a genome mining of 75 genomes revealed a strain dependency of the presence of seven specific ester biosynthesis genes. Accordingly, PCR assays to detect these acetate (<i>ATF1</i> and <i>ATF2</i>) and ethyl ester (<i>EHT1</i> and <i>EEB1</i>) biosynthesis genes were developed and used to screen 91 strains of yeast species. Concerning LAB, a genome mining of 401 genomes revealed a species dependency of the presence of three esterase-encoding genes (<i>estA</i>, <i>estB</i>, and <i>estC</i>). A phenotypic analysis carried out with a selection of 10 strains of the LAB species <i>Companilactobacillus crustorum</i>, <i>Companilactobacillus nantensis</i>, <i>Companilactobacillus paralimentarius, Fructilactobacillus sanfranciscensis</i>, <i>Lactiplantibacillus xiangfangensis</i>, <i>Levilactobacillus zymae</i>, and <i>Limosilactobacillus fermentum</i> in a wheat sourdough simulation medium (WSSM) supplemented with ester precursor molecules ([higher] alcohols and fatty acids) revealed that their ester biosynthesis capacity was limited by the precursor concentrations. Ethyl acetate and ethyl lactate were produced by all strains, except for those of <i>Frul. sanfranciscensis</i>. These results suggested that one of the esterase-encoding genes considered could be implicated in the ethyl acetate and/or ethyl lactate biosynthesis. Overall, the ester biosynthesis capacity by LAB is of great interest in view of fruity flavor formation during sourdough and sourdough bread productions.</p><p><strong>Importance: </strong>The present study gave insights into the production of esters, which impart fruity flavors to fermented foods, by not only sourdough yeasts but also lactic acid bacteria. It showed that some lactic acid bacteria species can synthesize the esters ethyl acetate (sweet notes) and ethyl lactate (creamy notes) under specific conditions. The information gathered during the present study will enable sourdough bakers and companies from the bakery sector to get more information on how to produce sourdoughs that can add fruity notes to the final products after a rational screening and selection of potential starter culture strains.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0221624"},"PeriodicalIF":3.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A call for healing and unity.","authors":"Patrick D Schloss","doi":"10.1128/aem.00448-25","DOIUrl":"https://doi.org/10.1128/aem.00448-25","url":null,"abstract":"","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0044825"},"PeriodicalIF":3.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification and functional characterization of major gene <i>pcmfs</i>, controlling cap color formation in <i>Pleurotus cornucopiae</i>.","authors":"Yan Zhang, Siyu Xu, Yuting Li, QianQian Zhang, Wei Wang, Zhuang Li","doi":"10.1128/aem.01894-24","DOIUrl":"https://doi.org/10.1128/aem.01894-24","url":null,"abstract":"<p><p>Oyster mushrooms are grown commercially worldwide, especially in many developing countries, for their easy cultivation and high biological efficiency. Cap color is an important commercial trait for oyster mushrooms. Little is known about the genetic mechanism of the cap color trait in oyster mushrooms, which limits molecular breeding for the improvement of cap color-type cultivars. In this study, an important candidate gene, <i>pcmfs</i>, for cap color in the oyster mushroom <i>Pleurotus cornucopiae</i> was identified based on the results of QTL (quantitative trait loci) mapping and comparative transcriptome analysis of our previous research. The <i>pcmfs</i> gene belonged to major facilitator superfamily (MFS) and was localized to the cell membrane. Expression pattern analysis and overexpression experiment demonstrated that <i>pcmfs</i> played an important positive role in cap color formation, with high expression levels leading to dark cap color. To our knowledge, this is the first reported gene that may be involved in the melanin transport in edible fungi. The results will enhance our understanding of the genetic basis for cap color formation in oyster mushrooms, ultimately facilitating the targeted molecular breeding of this phenotypic trait.IMPORTANCEOyster mushrooms are widely cultivated worldwide, particularly in developing countries, owing to their straightforward cultivation requirements and high biological efficiency. Cap color represents a significant commercial trait of oyster mushrooms. Despite its significance, the genetic basis of this trait remains poorly understood, limiting progress in molecular breeding to diversify cap color variants. Bridging this knowledge gap could improve the market appeal and consumer satisfaction of these cultivars by facilitating targeted breeding strategies. In our previous research, a major QTL of cap color in oyster mushroom <i>P. cornucopiae</i> was mapped and DEGs (differentially expressed genes) between the dark strains and white strains were identified. Based on this, the candidate gene for cap color <i>pcmfs</i> was further mined. The <i>pcmfs</i> gene, belonging to the major facilitator superfamily (MFS), is localized to the cell membrane. Expression pattern analysis and overexpression experiments have shown that <i>pcmfs</i> plays a significant role in cap color formation. To our knowledge, this is the first reported gene that may be involved in the melanin transport in edible fungi. The results contribute to elucidate the genetic mechanisms governing cap color formation in mushrooms, advancing targeted molecular breeding for this trait.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0189424"},"PeriodicalIF":3.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular piracy in deep-sea hydrothermal vent: phage-plasmid interactions revealed by phage-FISH in <i>Marinitoga piezophila</i>.","authors":"Min Jin, Ouafae Rouxel, Nadège Quintin, Claire Geslin","doi":"10.1128/aem.02306-24","DOIUrl":"https://doi.org/10.1128/aem.02306-24","url":null,"abstract":"<p><p>Prokaryotes and mobile genetic elements (MGEs, such as viruses and plasmids) interact extensively, leading to horizontal gene transfer (HGT) and consequent microbial evolution and diversity. However, our knowledge of the interactions between MGEs in deep-sea hydrothermal ecosystems is limited. In this study, we adapted a phage-fluorescence <i>in situ</i> hybridization (phage-FISH) approach to visualize and quantify the dynamics of phage-plasmid interactions in an anaerobic, thermophilic deep-sea bacterium, <i>Marinitoga piezophila</i>. Notably, our results revealed that plasmid signals were detected in viral particles released from lysed cells, indicating that mitomycin C not only induced plasmid replication but also its packaging into phage particles. Further analysis of the DNA content in purified virions showed that the phage capsids incorporated plasmid DNA even without induction, and the majority of capsids (up to 70%) preferentially packaged plasmid DNA rather than viral DNA after induction. Therefore, this study provided direct evidence of molecular piracy in the deep-sea hydrothermal ecosystem, highlighting the important roles of selfish MGEs in virus-host interactions and HGT in extreme marine environments.</p><p><strong>Importance: </strong>Deep-sea hydrothermal vents are hotspots for microbes. Several studies revealed that virus-mediated horizontal gene transfer (HGT) in deep-sea hydrothermal vent ecosystems may be crucial to the survival and stability of prokaryotes in these extreme environments. However, little is known about the interaction between viruses and other mobile genetic elements (MGEs, such as plasmids), and how their interactions influence virus-mediated HGT in these ecosystems. In this study, we adapted a phage-fluorescence <i>in situ</i> hybridization approach to directly monitor the dynamics of phage-plasmid-host interactions at the single-cell level in the <i>Marinitoga piezophila</i> model. Interestingly, our results indicate that plasmid DNA could not only be induced by mitomycin C to a great extent but also hijacked viral assembly machinery to facilitate its propagation and spread. Therefore, the data presented here imply that the interaction between the viruses and other MGEs could play profound roles in virus-host interaction and virus-mediated HGT in the deep-sea hydrothermal ecosystem.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0230624"},"PeriodicalIF":3.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into the mechanism of substrate specificity in a novel PL15_3 subfamily oligo-alginate lyase VBAly15A.","authors":"Yongqi Tang, Ziyan Song, Xiaodong Xu, Yingjie Li, Lushan Wang","doi":"10.1128/aem.02351-24","DOIUrl":"https://doi.org/10.1128/aem.02351-24","url":null,"abstract":"<p><p>Alginate is a major component of brown algae cell walls and can be degraded via β-elimination by alginate lyases. These enzymes are classified into polysaccharide lyases and oligo-alginate lyases (Oals), with Oals mainly represented by the PL15 and PL17 families. Unlike PL17 Oals, which are widely present in alginate-degrading microorganisms, PL15 enzymes are only identified in a limited number of microorganisms, and their biochemical characteristics remain poorly understood. In this research, a novel PL15 alginate lyase, VBAly15A, from the marine bacterium, <i>Vibrio</i> sp. B1Z05, was identified and characterized. It belongs to a new PL15_3 subfamily and exhibits high activity toward polyM substrates. VBAly15A is thermostable in medium temperatures, tolerant to alkaline up to 11.0, and polyM-specific Oal, and it can first degrade alginate polymers into disaccharides and subsequently catalyze disaccharides into monomers via an exolytic mode. Site-directed mutagenesis showed that Arg¹¹⁴, Tyr⁴⁷⁰, and Arg¹¹⁰ in the active groove are essential for the stable binding of the substrate. In addition, the amino acid His²²⁶ in VBAly15A, previously suggested to act as a catalytic base, is not essential for catalysis, whereas Tyr²⁸⁰, previously proposed to act as a catalytic acid, is required for enzyme activity. Structural bioinformatic and biochemical analyses revealed that His²²⁶ functions as a catalytic base, specifically abstracting protons from G-type substrates, while Tyr²⁸⁰ acts as both a catalytic acid and a base. This catalytic mechanism is likely conserved in PL15 family alginate lyases.IMPORTANCEAlginate, as a renewable resource for sustainability, has great application prospects. In addition to polysaccharide lyases, Oals are critical for the full degradation of alginate, a key prerequisite for biorefinery. So far, most identified and well-characterized Oals belong to the PL17 family. However, the catalytic mechanism of PL15 Oals is limited, and even the catalytic base and acid are not fully elucidated. The significance of this study lies in discovering and characterizing a novel Oal VBAly15A that divides into a new PL15 subfamily, PL15_3. Not only are key amino acid residues involved in enzyme activity identified, but residues acting as the catalytic base and acid are also demonstrated. The distance of the catalytic residues His and Tyr to the C5 proton of the sugar ring determines the substrate specificity. Therefore, this work provides new insights into the mechanism of substrate specificity in alginate lyases.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0235124"},"PeriodicalIF":3.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inhibition of pneumococcal growth and biofilm formation by human isolates of <i>Streptococcus mitis</i> and <i>Streptococcus oralis</i>.","authors":"João Borralho, Sara Handem, João Lança, Bárbara Ferreira, Catarina Candeias, Adriano O Henriques, N Luisa Hiller, Carina Valente, Raquel Sá-Leão","doi":"10.1128/aem.01336-24","DOIUrl":"https://doi.org/10.1128/aem.01336-24","url":null,"abstract":"<p><p>In a world facing the unprecedented threat of antibiotic-resistant bacteria, targeted approaches to control colonization and prevent disease caused by common pathobionts offer a promising solution. <i>Streptococcus pneumoniae</i> (pneumococcus) is a leading cause of infections worldwide, affecting both children and adults despite available antimicrobials and vaccines. Colonization, which occurs in the form of a biofilm in the upper respiratory tract, is frequent and a prerequisite for disease and transmission. The use of live bacterial strains as biotherapeutics for infectious diseases is actively being explored. Here, we investigated the potential of commensal streptococci to control <i>S. pneumoniae</i>. Screening of over 300 human isolates led to the identification of seven strains (one <i>Streptococcus oralis</i> and six <i>Streptococcus mitis</i>, designated A22 to G22) with inhibitory activity against <i>S. pneumoniae</i> of multiple serotypes and genotypes. Characterization of A22 to G22 cell-free supernatants indicated the involvement of secreted proteins or peptides in the inhibitory effect of all <i>S. mitis</i> isolates. Genome analyses revealed the presence of 64 bacteriocin loci, encoding 70 putative bacteriocins, several of which are novel and absent or rare in over 7,000 publicly available pneumococcal genomes. Deletion mutants indicated that bacteriocins partially or completely explained the anti-pneumococcal activity of the commensal strains. Importantly, strains A22 to G22 were further able to prevent and disrupt pneumococcal biofilms, a proxy for nasopharyngeal colonization. These results highlight the intricacy of the interactions among nasopharyngeal colonizers and support the potential of strains A22 to G22 to be used as live biotherapeutics, alone or in combination, to control <i>S. pneumoniae</i> colonization.</p><p><strong>Importance: </strong><i>Streptococcus pneumoniae</i> (pneumococcus) infections remain a major public health issue despite the use of vaccines and antibiotics. Pneumococci asymptomatically colonize the human upper respiratory tract, a niche shared with several commensal <i>Streptococcus</i> species. Competition for space and nutrients among species sharing the same niche is well documented and tends to be more intense among closely related species. Based on this rationale, a screening of several commensal streptococci isolated from the human upper respiratory tract led to the identification of strains of <i>Streptococcus mitis</i> and <i>Streptococcus oralis</i> capable of inhibiting most pneumococcal strains, across diverse serotypes and genotypes. This inhibition was partially or wholly linked to the expression of novel bacteriocins. The selected <i>S. mitis</i> and <i>S. oralis</i> strains significantly disrupted pneumococcal biofilms, indicating a potential for using commensals as biotherapeutics to control pneumococcal colonization, a key step in preventing disease and transmission.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0133624"},"PeriodicalIF":3.9,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143498060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shifts in surface microbiota after cleaning and disinfection in broiler processing plants: incomplete biofilm eradication revealed by robotic high-throughput screening.","authors":"Thorben Reiche, Gunhild Hageskal, Mihai Mares, Sunniva Hoel, Anne Tøndervik, Tonje Marita Bjerkan Heggeset, Tone Haugen, Sigri Bakken Sperstad, Hanne Hein Trøen, Solfrid Bjørkøy, Anita Nordeng Jakobsen","doi":"10.1128/aem.02401-24","DOIUrl":"https://doi.org/10.1128/aem.02401-24","url":null,"abstract":"<p><p>Broiler processing environments are a source of spoilage bacteria and potential pathogens. The aim of this study was to investigate the impact of cleaning and disinfection (C&D) on bacterial load and diversity in two broiler processing plants and to determine the efficacy of industry-standard disinfectants (DIs). C&D significantly reduced average bacterial loads on surfaces from 3.7 to 1.8 log CFU/cm² in Plant A and from 7.0 to 3.8 log CFU/cm² in Plant B (<i>P</i> < 0.001). Metataxonomics revealed that <i>Acinetobacter</i> and an unknown Enterobacteriaceae genus dominated before C&D in Plants A and B, respectively, while <i>Pseudomonas</i> was predominant after C&D in both plants. Bacterial diversity only declined significantly after C&D in Plant B. Bacterial loads also declined across hygienic zones along the broiler processing line in Plant A. During slaughter, <i>Staphylococcus</i>, <i>Lactobacillus</i>, and <i>Anoxybacillus</i> dominated, and bacterial loads were significantly higher compared with post-slaughter zones, which were dominated by <i>Pseudomonas</i>. Culture-dependent analyses confirmed the presence of <i>Pseudomonas</i> spp. and also bacteria affecting food safety, including <i>Listeria monocytogenes</i>, <i>Escherichia coli</i>, <i>Yersinia enterocolitica</i>, <i>Acinetobacter baumannii</i>, and <i>Pseudomonas aeruginosa</i>. A selection of these was tested against DIs using robotic high-throughput screening. At the recommended user concentrations, DIs effectively inhibited planktonic bacteria and significantly reduced mono-species biofilms. However, none of the DIs completely eradicated all biofilms at these concentrations, with survival rates ranging from 7% to 53%, depending on the DI. In conclusion, C&D effectively reduces the bacterial burden and reshapes the bacterial microbiota with incomplete biofilm eradication by commercial DIs.IMPORTANCEBroiler meat continues to be involved in bacterial disease outbreaks. The surface microbiota in broiler processing environments can be a source of contaminating bacteria. Our study highlights the importance of effective C&D routines since potential pathogens and spoilage bacteria are found in these environments. Furthermore, the study provides evidence of biofilms surviving high concentrations of industry-standard DIs. This emphasizes the importance of additional measures to facilitate biofilm removal, such as mechanical cleaning, but also suggests that there is a need for DIs with stronger biofilm eradication capabilities. Ultimately, it is important to understand and continuously improve the state of hygiene in broiler processing plants to mitigate the risk of foodborne disease outbreaks.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0240124"},"PeriodicalIF":3.9,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143498024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A strain of <i>Streptococcus mitis</i> inhibits biofilm formation of caries pathogens via abundant hydrogen peroxide production.","authors":"Isabella Williams, Jacob S Tuckerman, Daniel I Peters, Madisen Bangs, Emily Williams, Iris J Shin, Justin R Kaspar","doi":"10.1128/aem.02192-24","DOIUrl":"10.1128/aem.02192-24","url":null,"abstract":"<p><p>Commensal oral streptococci that colonize supragingival biofilms deploy mechanisms to combat competitors within their niche. Here, we determined that <i>Streptococcus mitis</i> more effectively inhibited biofilm formation of <i>Streptococcus mutans</i> compared to other oral streptococci. This phenotype was common among all isolates of <i>S. mutans</i>, but was specific to a single strain of <i>S. mitis</i>, ATCC 49456. We documented ATCC 49456 to accumulate four to five times more hydrogen peroxide (H₂O₂) than other <i>Streptococcus</i> species tested, and 5-18 times more than other <i>S. mitis</i> strains assayed. <i>S. mutans</i> biofilm formation inhibition was dependent on cell contact/proximity and reduced when grown in media containing catalase or with a <i>S. mitis</i> mutant of pyruvate oxidase (<i>spxB; pox</i>), confirming that SpxB-dependent H₂O₂ production was a major antagonistic factor. Addition of <i>S. mitis</i> within hours after <i>S. mutans</i> inoculation was effective at reducing biofilm biomass, but not for 24 h pre-formed biofilms in an SpxB-dependent manner. Transcriptome analysis revealed responses for both <i>S. mitis</i> and <i>S. mutans</i>, with several <i>S. mutans</i> differentially expressed genes following a gene expression pattern we have previously described, while others being unique to the interaction with <i>S. mitis</i>. Finally, we show that <i>S. mitis</i> also affected coculture biofilm formation of several other commensal streptococci as well as cariogenic <i>Streptococcus sobrinus</i>. Our study shows that strains with abundant H₂O₂ production are effective at inhibiting initial growth of caries pathogens like <i>S. mutans</i>, but are less effective at disrupting pre-formed biofilms and have the potential to influence the stability of other oral commensal strains.IMPORTANCEAntagonistic properties displayed by oral bacteria have been sought as therapeutic approaches against dental caries pathogens like <i>Streptococcus mutans</i>. An emergent theme has been the ability of select strains that produce high amounts of hydrogen peroxide to effectively inhibit the growth of <i>S. mutans</i> within <i>in vitro</i> and <i>in vivo</i> models. Our study builds on these previous findings by determining that <i>Streptococcus mitis</i> ATCC 49456 is a high hydrogen peroxide producer, compared to other <i>Streptococcus</i> species as well as additional strains of <i>S. mitis</i>. In addition to <i>S. mutans</i>, we show that ATCC 49456 also affects biofilm formation of other oral streptococci, a non-desirable trait that should be weighed heavily for strains under consideration as probiotics. Further phenotypic characterization of strains like <i>S. mitis</i> ATCC 49456 in mixed-species settings will allow us to hone in on qualities that are optimal for probiotic strains that are intended to prevent the emergence of odontopathogens.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0219224"},"PeriodicalIF":3.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143490483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Current prevalence and therapeutic strategies for porcine <i>Streptococcus suis</i> in China.","authors":"Ruoyi Lv, Wenjing Zhang, Zhigang Sun, Xiaohui Si, Hong Dong, Xiaoye Liu","doi":"10.1128/aem.02160-24","DOIUrl":"https://doi.org/10.1128/aem.02160-24","url":null,"abstract":"<p><p>Porcine <i>Streptococcus suis</i> is a zoonotic bacterial pathogen that poses serious threats to both human and animal health. <i>S. suis</i> is ubiquitously transmitted from the swine industry to the environments and human communities. However, the ambiguous epidemiological patterns and the escalating risk of antimicrobial resistance render <i>S. suis</i> infections a considerable challenge. Here, we review the current prevalence of <i>S. suis</i> infection worldwide, including identified bacterial strains, routes of infection, and transformation of resistance genes. This comprehensive overview of the prevalent patterns in <i>S. suis</i> offers detailed insights into therapeutic approaches for porcine infections and alternative strategies to address emerging resistant strains, highlighting potential multitarget prevention and treatment options to combat <i>S. suis</i> infection.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0216024"},"PeriodicalIF":3.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143490486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}