Applied and Environmental Microbiology最新文献

{"title":"Hijacking anaerobic metabolism to restore antibiotic efficacy in <i>Pseudomonas aeruginosa</i>.","authors":"Zealon Gentry-Lear, Celine Lopez Padilla, Melanie A Spero","doi":"10.1128/aem.01425-25","DOIUrl":"https://doi.org/10.1128/aem.01425-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Bacterial pathogens regularly encounter oxygen (O&lt;sub&gt;2&lt;/sub&gt;) limitation at sites of infection in the human body. Many pathogens exhibit antibiotic recalcitrance under low O&lt;sub&gt;2&lt;/sub&gt; conditions, spotlighting the need for new therapeutics that are effective in O&lt;sub&gt;2&lt;/sub&gt;-limited environments. We demonstrate that several classes of antibiotics display limited toxicity against hypoxic cultures of the opportunistic pathogen, &lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt;, where the pathogen exhibits antibiotic tolerance. In O&lt;sub&gt;2&lt;/sub&gt;-limited host environments, many pathogens employ nitrate respiration, marking this anaerobic bacterial metabolism as an excellent drug target. Chlorate is a nitrate analog that hijacks nitrate respiration to kill &lt;i&gt;P. aeruginosa&lt;/i&gt;. Chlorate acts as a prodrug: nitrate reductase reduces chlorate, thereby forming the toxic oxidizing agent, chlorite. Chlorate treatment is most toxic to &lt;i&gt;P. aeruginosa&lt;/i&gt; under anoxia and displays limited-to-no toxicity under hypoxic or oxic conditions. Thus, neither chlorate nor antibiotics alone efficiently kill O&lt;sub&gt;2&lt;/sub&gt;-limited &lt;i&gt;P. aeruginosa&lt;/i&gt;. Excitingly, combined chlorate-antibiotic treatment showed that chlorate addition potentiates all tested classes of antibiotics, often eradicating hypoxic &lt;i&gt;P. aeruginosa&lt;/i&gt; populations to below detection. Chlorate addition reduced the lethal dose of ceftazidime by &gt;100-fold, further highlighting chlorate's capacity to potentiate antibiotic treatment. Unlike chlorate, we found that most antibiotics do not synergize with different classes of drugs, except for colistin. Given that combination therapy is a promising strategy for combating antibiotic treatment failure, future studies should continue exploring chlorate's therapeutic potential, including examining the mechanisms of chlorate-antibiotic synergy. Our work points to the critical relationship between bacterial physiology and drug efficacy and highlights anaerobic metabolism as a promising drug target.IMPORTANCEMany antibiotics are less effective at killing pathogens under oxygen (O&lt;sub&gt;2&lt;/sub&gt;)-limited conditions. Pathogens frequently encounter O&lt;sub&gt;2&lt;/sub&gt; limitation within host environments, which helps explain why antibiotic therapies often fail to resolve chronic infections. We are investigating the relationship between O&lt;sub&gt;2&lt;/sub&gt; availability and drug efficacy in the opportunistic pathogen, &lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt;. In agreement with prior work, we demonstrate that &lt;i&gt;P. aeruginosa&lt;/i&gt; exhibits antibiotic recalcitrance under hypoxic conditions. We also explore the use of a novel therapeutic, chlorate, which kills &lt;i&gt;P. aeruginosa&lt;/i&gt; under O&lt;sub&gt;2&lt;/sub&gt;-limited conditions when the pathogen utilizes anaerobic metabolism (nitrate respiration). Excitingly, we find that chlorate-antibiotic combinations are highly lethal to &lt;i&gt;P. aeruginosa&lt;/i&gt; across a wide range of O&lt;sub&gt;2&lt;/sub&gt; availabilities similar to those the pathogen encounters during infection. Our work demons","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0142525"},"PeriodicalIF":3.7,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145184620","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":"Detergent-based separation of microbes from marine particles.","authors":"Jordan T Coelho, Lauren Teubner, J Cameron Thrash","doi":"10.1128/aem.01426-25","DOIUrl":"https://doi.org/10.1128/aem.01426-25","url":null,"abstract":"<p><p>Marine particles, typically composed of organic detritus and cellular debris, harbor microbial communities that are distinct from the planktonic, or free-living, communities in the pelagic ocean. However, without being first separated from the particle and microbial consortia, these microbes are inaccessible to further investigation via single-cell microbiology methods like flow cytometry, cell sorting, and dilution-based isolation. To confront this obstacle, we compared the dissociative effects of two commonly used detergents, Tween 20 and Tween 80, on particle-associated marine microbial communities. The ability of Tween treatments to liberate cells from particles and to maintain cell integrity was quantified by flow cytometry from multiple communities across seasons and locations. Both Tween 20 and Tween 80, at 185 RPM shaking, gently dissociated microbes from their particles, causing very little cell mortality. Additionally, Tween 80 liberated a greater number of particle-associated cells into the free-living fraction. We also analyzed the effects of Tween treatments on the microbial community composition for one of these collections via 16S rRNA gene amplicon sequencing of the particle-associated and free-living fractions relative to unamended controls. Tween 20 and Tween 80 were both effective for microbial detachment from particles; however, Tween 80 treatments displayed greater uniformity in the dissociated communities and significantly enriched for the most abundant particle-associated members. Together, these data indicate that Tween 80 was most effective at gently dissociating particle-associated cells.IMPORTANCEMicrobes that reside on marine particulate organic matter are vital facets of marine biogeochemistry. As they degrade the particle on which they reside, the resulting concentrated region of activity influences surrounding biogeochemistry and redox gradients, making particle-associated microbes significant to overall marine ecology. To understand single-cell activities amidst the microbial assemblage on the particle, cells must first be removed from the substrate for downstream analyses. Methods for microbial dissociation from solid surfaces or sediment communities have been described; however, analogous methods for more ephemeral particles that also maintain cell viability and preserve DNA for next-generation sequencing are understudied. Here, we optimized a method that leveraged detergents to dissociate microbes from marine particles. We evaluated effectiveness through filter size fractionation, flow cytometry, and community composition analyses and provided recommendations to gently and effectively remove microbes from marine particles.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0142625"},"PeriodicalIF":3.7,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145136383","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":"Is it time to assign <i>Lactiplantibacillus plantarum</i> as a keystone species in the <i>Drosophila melanogaster</i> microbiota?","authors":"John M Chaston","doi":"10.1128/aem.01491-25","DOIUrl":"https://doi.org/10.1128/aem.01491-25","url":null,"abstract":"<p><p>Recent work by Yang et al. published in <i>Applied and Environmental Microbiology</i> (91:e00707-25, 2025, https://doi.org/10.1128/aem.00707-25) offers fresh insights into the important roles played by <i>Lactiplantibacillus plantarum</i> within the microbial community of the fruit fly <i>Drosophila melanogaster</i>. This commentary summarizes their findings in the context of earlier studies, highlighting the unique and influential position of <i>L. plantarum</i> in shaping the biology and microbial dynamics of <i>D. melanogaster</i>.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0149125"},"PeriodicalIF":3.7,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145136306","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":"Boundary conditions for exploiting the cooperation of <i>Aminobacter niigataensis</i> MSH1 with <i>Piscinibacter</i> sp. K169 to support 2,6-dichlorobenzamide biodegradation in sand filters for drinking water treatment: role of cell density and organic carbon.","authors":"Siyao Du, Aura Wouters, Manon Glorieux, Laurien van Lieshout, Benjamin Horemans, Dirk Springael","doi":"10.1128/aem.01149-25","DOIUrl":"https://doi.org/10.1128/aem.01149-25","url":null,"abstract":"<p><p><i>Aminobacter niigataensis</i> MSH1 mineralizes the groundwater micropollutant 2,6-dichlorobenzamide (BAM) and is a candidate for bioaugmentation of sand filters in drinking water treatment plants (DWTP) to avert BAM-contamination. <i>Piscinibacter</i> sp. K169 is a sand filter isolate that improves MSH1-mediated BAM mineralization through a cooperative interaction, and co-inoculation of MSH1 with K169 is proposed as a strategy to support bioaugmentation with MSH1. In this study, boundaries regarding the initial population size and the supply of organic carbon resources determining the interaction between MSH1 and K169 in sand filter microcosms were explored. The cooperative interaction was only disturbed when initial cell densities of one of the two partners were 10⁴ cells/mL or lower. Supplying acetate as a carbon source appeared redundant for supporting BAM mineralization. Instead, the organic carbon present on the sand drove the cooperative interaction between K169 and MSH1 as the effect of K169 on BAM mineralization disappeared, and none of the two strains showed growth in sand devoid from organic carbon. These findings highlight the feasibility of K169-assisted bioaugmentation with MSH1 under realistic field conditions, as it requires no supplementary organic carbon and remains effective, even at relatively low inoculum densities, thereby addressing key challenges in bioaugmentation strategies.IMPORTANCEBioaugmentation of sand filters exploited in drinking water treatment, with the BAM catabolic strain <i>Aminobacter niigataensis</i> MSH1, has previously been successful during the first 1-2 weeks, where after BAM degradation deteriorated together with the loss of MSH1 cell density and cell activity. Bacterial isolates obtained from sand filters can support BAM degradation activity by MSH1 involving mutualistic interactions which resulted in the proposition of a novel bioaugmentation approach involving the co-inoculation of \"support\" bacteria that are adapted to the target environment. This paper focuses on understanding the boundary conditions required for sustaining the mutualistic interaction between MSH1 and such a \"supportive\" sand filter isolate in sand microcosm, showing that the interaction could be maintained when using relatively low cell densities and with no additional carbon supplemented. To the best of our knowledge, this paper is the first study to examine the boundary conditions of a bacterial mutualistic interaction, particularly in a bioaugmentation context of water treatment.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0114925"},"PeriodicalIF":3.7,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145136337","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":"Environment and diet shape the geography-specific <i>Drosophila melanogaster</i> microbiota composition.","authors":"Joseph T Gale, Rebecca Kreutz, Sarah J Gottfredson Morgan, Emma K Davis, Connor Hough, Wendy A Cisneros Cancino, Brittany Burnside, Ryan Barney, Reese Hunsaker, Ashton Tanner Hoyt, Aubrey Cluff, Maggie Nosker, Chandler Sefcik, Eliza Beales, Jack K Beltz, Paul B Frandsen, Paul Schmidt, John M Chaston","doi":"10.1128/aem.00883-25","DOIUrl":"10.1128/aem.00883-25","url":null,"abstract":"<p><p>Geographic and environmental variation in the animal microbiota can be directly linked to the evolution and wild fitness of their hosts, but it can be difficult to explain the underlying patterns. Here, we sought to better understand wild variation in the microbiota composition of <i>Drosophila melanogaster</i>. First, environmental temperature predicted geographic variation in fly microbial communities more consistently than latitude did. The microbiota also differed between wild flies and their diets, supporting previous conclusions that the fly microbiota is not merely a reflection of diet. Flies feeding on different diets varied significantly in their microbiota composition, and flies sampled from individual apples were exceptionally depauperate for the lactic acid bacteria (LAB), a major bacterial group in wild and laboratory flies. However, flies bore significantly more LAB when sampled from other fruits or compost piles. Follow-up analyses revealed that LAB abundance in the flies uniquely responds to fruit decomposition, whereas other microbiota members better indicate temporal seasonal progression. Finally, we show that diet-dependent variation in the fly microbiota is associated with phenotypic differentiation of fly lines collected in a single orchard. These last findings link covariation between the flies' dietary history, microbiota composition, and genetic variation across relatively small (single-orchard) landscapes, reinforcing the critical role that environment-dependent variation in microbiota composition can play in local adaptation and genomic differentiation of a model animal host.IMPORTANCEThe microbial communities of animals influence their hosts' evolution and wild fitness, but it is hard to predict and explain how the microbiota varies in wild animals. Here, we describe that the microbiota composition of wild <i>Drosophila melanogaster</i> can be determined by temperature, humidity, geographic distance, diet decomposition, and diet type. We show how these determinants of microbiota variation can help explain lactic acid bacteria (LAB) abundance in the flies, including the rarity of LAB in some previous studies. Finally, we show that wild fly phenotypes segregate with the flies' diet and microbiota composition, illuminating links between the microbiota and host evolution. Together, these findings help explain how variation in microbiota compositions can shape an animal's life history.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0088325"},"PeriodicalIF":3.7,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145136301","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 production of erythritol by strains of <i>Limosilactobacillus fermentum</i> of sourdough origin.","authors":"Víctor González-Alonso, Marko Verce, Inés Pradal, Frédéric Leroy, Luc De Vuyst","doi":"10.1128/aem.01565-25","DOIUrl":"https://doi.org/10.1128/aem.01565-25","url":null,"abstract":"<p><p>Erythritol is a sugar alcohol that is occasionally produced by heterofermentative lactic acid bacteria (LAB). Although such biosynthesis has rarely been reported during sourdough production, the potential of the sourdough strains <i>Limosilactobacillus fermentum</i> IMDO 130101 and IMDO TC9L10 to produce erythritol was demonstrated in the context of their broader metabolic capacity both during wheat sourdough productions and in a wheat sourdough simulation medium (WSSM). Indeed, both strains produced up to 0.4 mM of erythritol during starter culture-initiated wheat sourdough productions. The strain <i>L. fermentum</i> IMDO 130101 was further used to carry out controlled fermentation processes in WSSM and was able to synthesize 0.53 ± 0.03 mM of erythritol. During both the wheat sourdough productions and WSSM fermentation processes, acetate was co-produced with erythritol and/or glycerol. The primary role of erythritol was likely its involvement in redox balancing. Besides, the pathways for erythritol production were probed <i>in silico</i>, but no genes corresponding with erythrose-producing or erythrose-converting enzymes could be identified. Therefore, it was suggested that the enzymes responsible for the production of erythritol in <i>L. fermentum</i> IMDO 130101, and other heterofermentative LAB species, are the same as those producing mannitol or glycerol.</p><p><strong>Importance: </strong>Lactic acid bacteria have a limited biosynthesis capacity. Their main carbohydrate breakdown pathways enable them to produce energy and to maintain their redox balance. The latter is accomplished through the production of lactic acid in the case of homofermentative lactic acid bacteria and ethanol or acetic acid in the case of heterofermentative ones. However, under certain conditions, other branches of this pathway become active, which lead to end-metabolites that are produced seldomly. An example of such an end-metabolite is erythritol, which was already detected during sourdough production but never investigated in detail. The present study showed the production of erythritol by <i>Limosilactobacillus fermentum</i> inhabiting sourdough environments and its involvement in redox balancing.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0156525"},"PeriodicalIF":3.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145129898","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":"Mechanism of <i>Lysobacter enzymogenes</i> resistance toward fungi induced by fungal-derived signal α-terpinene.","authors":"Meixue Zhu, Yuying Li, Fang Nan, Jia Wang, Benfeng Gao, Huihui Song, Zeran Bian, Xuejie Wang, Yuxiang Zhu, Yan Wang","doi":"10.1128/aem.01471-25","DOIUrl":"https://doi.org/10.1128/aem.01471-25","url":null,"abstract":"<p><p>Bacterial-fungal interactions (BFI) are critical drivers of ecosystem functions, and their molecular mechanisms remain incompletely understood. Chemical signals are crucial mediators of microbial communication, but the signaling mechanisms of terpene compounds secreted by fungi are not fully elucidated. In this study, the environmental bacterium <i>Lysobacter enzymogenes</i> YC36 (<i>Le</i>YC36) was employed to systematically investigate the regulatory mechanism of α-terpinene, a fungal-derived terpene, on biofilm formation and antifungal activity. Our results indicate that α-terpinene enhances the competitiveness of <i>Le</i>YC36 in BFI by promoting the biosynthesis of antifungal effectors, heat-stable antifungal factor (HSAF), and fungal cell wall hydrolase GluB, as well as biofilm formation. Furthermore, we reveal the α-terpinene-mediated signaling pathway in <i>Le</i>YC36. <i>Le</i>YC36 detects the fungal signal α-terpinene through <i>Le</i>CzcS, the sensor histidine kinase of the two-component system <i>Le</i>CzcS/<i>Le</i>CzcR, which then transmits the information to the regulator <i>Le</i>CzcR. The phosphorylated <i>Le</i>CzcR directly stimulates the expression of downstream functional genes <i>Lepks/nrps</i>_HSAF (<i>Lehsaf</i>), <i>LegluB</i>, and <i>Lepsl</i>, which enhance the production of antifungal effectors (HSAF and GluB), improve biofilm formation, and ultimately boost the competitiveness of <i>Le</i>YC36 against fungi. This study elucidates the role of α-terpinene in BFI and its regulatory mechanisms, which provides a novel perspective on communication and cooperative adaptation among microorganisms.</p><p><strong>Importance: </strong>The complex interactions between bacteria and fungi play a crucial role in maintaining ecosystem balance and biodiversity. This study elucidates the molecular mechanism by which α-terpinene, as a fungal-derived signaling molecule, regulates biofilm formation and antifungal activity in <i>Lysobacter enzymogenes</i> YC36 (<i>Le</i>YC36) and preliminarily establishes the signaling regulatory pathway of α-terpinene. These findings advance our understanding of interkingdom signals between bacteria and fungi and provide a theoretical framework for developing biocontrol technologies using microbial signaling molecules.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0147125"},"PeriodicalIF":3.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145129940","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":"Cystathionine β-synthase TtCbs1 from <i>Tetrahymena thermophila</i> catalyzes the synthesis of CdS quantum dots for methyl orange decolorization.","authors":"Wenliang Lei, Juan Liu, Jing Xu, Wei Wang","doi":"10.1128/aem.01255-25","DOIUrl":"https://doi.org/10.1128/aem.01255-25","url":null,"abstract":"<p><p>Cystathionine β-synthase (CBS) is a pivotal enzyme in the transsulfuration metabolic pathway, catalyzing the synthesis of H₂S and cystathionine. These metabolites mediate stress responses and maintain cellular redox homeostasis. In <i>Tetrahymena thermophila</i>, <i>TtCBS1</i> expression was upregulated under cadmium stress, with cysteine further enhancing its transcription. The recombinant His-TtCbs1 protein was expressed in <i>Escherichia coli</i> and purified by affinity chromatography. The His-TtCbs1 catalyzed the synthesis of monodisperse cadmium sulfide quantum dots (CdS QDs) in cysteine and Cd²⁺ solutions. The QDs exhibited an average diameter of 3.51 nm, with size increasing over reaction time. Fourier-transform infrared spectroscopy revealed characteristic amide I (1,640 cm⁻¹) and amide II (1,520 cm⁻¹) peaks, confirming interactions of CdS and the protein. Cysteine and glutathione stabilized the CdS QDs in the solution. Under UV light irradiation, the CdS QDs decolorized 91% of methyl orange. This study shows that CBS from protists mitigates cadmium toxicity by synthesizing CdS QDs. The biosynthesized CdS QDs also function as effective biocatalysts for the decolorization of organic dyes.</p><p><strong>Importance: </strong>The significant upregulation of <i>TtCBS</i>1 in <i>Tetrahymena thermophila</i> under cadmium stress indicates that this enzyme is a key player in the organism's defense mechanism against cadmium toxicity. Cadmium sulfide (CdS) nanoparticles were synthesized using the TtCbs1 single-enzyme system <i>in vitro</i>. Cysteine and glutathione play a critical role in controlling the growth of biosynthetic CdS particle size. Understanding the precise mechanisms by which cysteine and glutathione control particle size could lead to the development of more precise and efficient biomineralization processes. The synthesized CdS quantum dots exhibited significant photocatalytic activity. This work highlights the potential of cystathionine β-synthase from protists in metal detoxification and environmental remediation.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0125525"},"PeriodicalIF":3.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145129942","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 novel homoarginine-containing cyclic peptide pioamide with selective antipseudomonal activity isolated from the nematode symbiont <i>Photorhabdus khanii</i>.","authors":"Yu Imai, Sangkeun Son, Miho Sasaki, Libang Liang, Michael F Gates, Meghan Ghiglieri, Takeshi Shimosato, Chandrashekhar Honrao, Xiaoyu Ma, Jason J Guo, Kim Lewis","doi":"10.1128/aem.01123-25","DOIUrl":"https://doi.org/10.1128/aem.01123-25","url":null,"abstract":"<p><p>Gram-negative bacteria harbor an outer membrane that physically protects them from the penetration of antibiotics into the cells. This barrier makes it challenging to develop antibiotics that effectively kill Gram-negative pathogens. The entomopathogenic bacterium <i>Photorhabdus</i> species produces various bioactive molecules and is receiving attention as an attractive source of novel antibiotics. We identified a novel antipseudomonal antibiotic, pioamide, from the culture supernatant of <i>Photorhabdus khanii</i> HGB1456, a strain that produces darobactin, which selectively kills Gram-negative bacteria. Pioamide, a pentapeptide antibiotic with a molecular weight of 704, exhibits selective activity against <i>Pseudomonas aeruginosa</i> but does not exhibit any activity against other bacteria or human cell lines. Whole-genome sequencing of spontaneous pioamide-resistant mutants of <i>P. aeruginosa</i> revealed mutations in <i>pmrB</i>, which encodes a two-component regulatory system response regulator that modifies the lipopolysaccharide composition in Gram-negative bacteria, conferring pioamide resistance to <i>P. aeruginosa</i>. Furthermore, the susceptibility of both <i>P. aeruginosa</i> PAO1 and the mutant strain PΔ6-Pore, which overexpresses porins and lacks six efflux pumps, to pioamide was identical, indicating that porins and the efflux pump exert no significant effect on the activity of pioamide. These results suggest that pioamide either targets the cell surface of <i>P. aeruginosa</i> or is incorporated via a species-specific uptake mechanism. Our findings highlight the potential of <i>Photorhabdus</i> strains as an attractive source for the discovery of antibiotics active against Gram-negative pathogens.</p><p><strong>Importance: </strong>The rise of multidrug-resistant Gram-negative bacteria is a growing threat to global public health. Narrow-spectrum antibiotics minimize disruption of the host microbiota and reduce the risk of resistance development in off-target bacteria. In the field of antibacterial discovery, developing compounds effective against <i>Pseudomonas aeruginosa</i> remains particularly challenging. Although <i>Photorhabdus</i> species are known to produce various antibiotics, their potential remains largely underexplored. In this study, we applied differential screening to a highly concentrated culture extract of <i>Photorhabdus khanii</i> HGB1456 and discovered pioamide, a novel cyclic peptide with unusual selective activity against <i>P. aeruginosa</i>. Mutations in pmrB confer pioamide resistance to <i>P. aeruginosa</i>. However, the mechanism of action is distinct from that of colistin, which also involves resistance conferred by <i>pmrB</i> mutations. These findings underscore the untapped potential of <i>Photorhabdus</i> species as an attractive source of species-specific antibiotics and highlight the utility of differential screening for discovering compounds with targeted antibacterial activity.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0112325"},"PeriodicalIF":3.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145129958","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":"Fecal microbiota transplantation alleviated heat-induced colonic tissue damage, epithelial apoptosis, and oxidative stress.","authors":"Xiyu Liu, Chuchu Liu, Xiaoli Qian, Shiqing Zhang, Zhenghong Yao, Yanxi Chai, Qianhan Shi, Wenwen Yang, Qingxian Wang, Lina Zhang, Xiang Zeng, Cuiqing Liu, Yue Wu, Qinghua Sun","doi":"10.1128/aem.00976-25","DOIUrl":"https://doi.org/10.1128/aem.00976-25","url":null,"abstract":"<p><p>Exposure to high ambient temperatures can cause significant damage to the gastrointestinal tract; however, the therapeutic potential of fecal microbiota transplantation (FMT) in this context remains largely unexplored. We investigated whether FMT could alleviate heat-induced colonic injury in C57BL/6J mice. Mice were randomly divided into four groups: normal control (22°C only), normal-FMT (NF, 22 °C+ FMT), heat exposure (HE, 39°C only), and HE-FMT (HF, 39°C + FMT). The HE and HF groups were exposed to 39°C for 2 hours daily over 15 consecutive days. FMT (100 µL/day) was administered by oral gavage to the NF and HF groups for 15 days, starting after the first HE. Our results showed that FMT significantly modulated gut microbiota composition, increasing the relative abundance of <i>Alistipes</i>, <i>Citrobacter</i>, <i>Parasutterella</i>, <i>Bifidobacterium, Lachnospiraceae_UCG-001</i>, <i>Raoultella</i>, <i>Woeseia</i>, <i>Prevotellaceae_UCG-001,</i> and <i>Christensenellaceae,</i> while decreasing <i>Clostridium_sensu_stricto_1</i>, <i>Eubacterium_xylanophilum_group</i>, <i>Clostridioides</i>, <i>Bilophila</i>, <i>GCA-900066575,</i> and <i>Peptococcus</i>. Notably, FMT markedly restored epithelial integrity and enhanced mucus production, as shown by hematoxylin-eosin and periodic acid-Schiff staining. Moreover, FMT attenuated heat-induced epithelial cell apoptosis, evidenced by reduced apoptotic cells and downregulation of mitochondrial apoptotic markers, including Bax, Bak, cleaved Caspase-3, cleaved Caspase-9, and the phospho-P53/P53 ratio. In addition, FMT mitigated oxidative stress induced by HE, indicated by decreased 3-nitrotyrosine levels and normalization of antioxidant-related proteins, such as <i>Nrf2</i>, <i>Sod1</i>, <i>Cat</i>, and <i>Gpx4</i>. Collectively, these findings demonstrate that FMT alleviates heat-induced colonic injury by restoring mucosal barrier integrity, inhibiting apoptosis, and reducing oxidative stress, highlighting its potential as a promising therapeutic strategy for heat-related gastrointestinal disorders.</p><p><strong>Importance: </strong>This study is the first to demonstrate the protective role of fecal microbiota transplantation (FMT) against heat-induced colonic injury in a mouse model. We show that FMT mitigates colonic damage by restoring gut microbiota balance, preserving mucosal barrier integrity, inhibiting epithelial cell apoptosis, and reducing oxidative stress. These findings underscore the essential role of the gut microbiota in maintaining intestinal homeostasis under heat stress and highlight the therapeutic potential of microbiota-targeted strategies, such as FMT, in preventing or treating heat-related intestinal injury.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0097625"},"PeriodicalIF":3.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145129879","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}