Applied and Environmental Microbiology最新文献

{"title":"Genomics and physiological characterizations of an acidotolerant nitrite-oxidizing <i>Nitrospira</i> enriched from freshwater pond.","authors":"Minji Kim, Yoichi Kamagata, Soo-Je Park","doi":"10.1128/aem.01522-25","DOIUrl":"https://doi.org/10.1128/aem.01522-25","url":null,"abstract":"<p><p>Nitrite-oxidizing bacteria (NOB) play a crucial role in global nitrogen cycling, yet their presence and adaptations in acidic environments remain poorly understood. This study unveils the cultivation and characterization of a novel acid-tolerant NOB, NS4 culture, affiliated with lineage II (<i>Nitrospira</i>_<i>D</i>) within the genus <i>Nitrospira</i>. Enriched and isolated from a freshwater pond sediment, NS4 culture exhibits remarkable physiological and genomic traits that shed light on NOB survival strategies in low pH conditions. NS4 culture demonstrates the optimal growth at pH 6 and 0.5 mM nitrite concentration, with a maximum growth rate of 0.62 day⁻¹. Kinetic analyses reveal a high affinity for nitrite (<i>K_m</i>_(app) = 4.02 µM), suggesting adaptation to oligotrophic environments. Phylogenomic and genomic-relatedness analyses position NS4 culture as a novel member within the genus <i>Nitrospira</i>, for which we propose as \"<i>Candidatus</i> Nitrospira acidotolerans.\" Genomic investigations indicate the presence of a complete reductive tricarboxylic acid cycle and genes for nitrite oxidation, confirming its chemolithoautotrophic lifestyle. Intriguingly, NS4 genome lacks complete pathways for cobalamin biosynthesis, implying a potential dependence on symbiotic partners for this essential cofactor. The NS4 genome harbors genes associated with acid resistance, including chaperones, transporters, and amino acid metabolism, suggesting a genetic potential for adaptation or resistance to low pH conditions. This discovery expands our understanding of NOB diversity and adaptability, offering insights into nitrogen cycling in acid-impacted ecosystems. The physiological and genomic traits of this acid-tolerant NOB open new insights for exploring the ecological significance of NOB in previously overlooked acidic habitats.IMPORTANCENitrite-oxidizing bacteria (NOB) are integral to the global nitrogen cycle, yet their adaptations to acidic environments remain poorly understood. This study introduces <i>Candidatus</i> Nitrospira acidotolerans, an acid-tolerant NOB highly enriched from freshwater pond sediment. By combining physiological and genomic analyses, this work reveals unique adaptations that enable survival and nitrite oxidation under low pH conditions. Notably, the NS4 culture demonstrates high nitrite affinity and resistance to acidic stress, suggesting its ecological significance in acid-impacted ecosystems. Additionally, NS4 genomic traits reveal genetic potential of metabolic dependencies, including reliance on symbiotic partners for cobalamin synthesis. These findings expand our understanding of NOB diversity and their role in nitrogen cycling under extreme conditions, offering novel insights into microbial ecology and potential applications in managing nitrogen processes in acidic environments.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0152225"},"PeriodicalIF":3.7,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145079544","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":"Correction for Thompson et al., \"High-Resolution Identification of Multiple <i>Salmonella</i> Serovars in a Single Sample by Using CRISPR-SeroSeq\".","authors":"Cameron P Thompson, Alexandra N Doak, Naufa Amirani, Erin A Schroeder, Justin Wright, Subhashinie Kariyawasam, Regina Lamendella, Nikki W Shariat","doi":"10.1128/aem.01226-25","DOIUrl":"https://doi.org/10.1128/aem.01226-25","url":null,"abstract":"","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0122625"},"PeriodicalIF":3.7,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145079492","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":"Correction for Deaven et al., \"<i>Salmonella</i> Genomics and Population Analyses Reveal High Inter- and Intraserovar Diversity in Freshwater\".","authors":"Abigail M Deaven, Christina M Ferreira, Elizabeth A Reed, Jeremy R Chen See, Nora A Lee, Eduardo Almaraz, Paula C Rios, Jacob G Marogi, Regina Lamendella, Jie Zheng, Rebecca L Bell, Nikki W Shariat","doi":"10.1128/aem.01227-25","DOIUrl":"https://doi.org/10.1128/aem.01227-25","url":null,"abstract":"","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0122725"},"PeriodicalIF":3.7,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145079555","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":"Copper-induced stress mechanisms in <i>Erwinia amylovora</i>: a comparative phenotypic and transcriptomic study using copper-sensitive and -tolerant strains.","authors":"Ricardo Delgado Santander, Srđan G Aćimović","doi":"10.1128/aem.00334-25","DOIUrl":"https://doi.org/10.1128/aem.00334-25","url":null,"abstract":"<p><p><i>Erwinia amylovora</i> causes fire blight of apple and pear. Among the management strategies, copper-based treatments are widely used to control the disease. However, the impact of copper on the pathogen is not uniform, and different strains show different tolerance levels to the heavy metal. Upon identifying <i>E. amylovora</i> strains with unusually high (EaR2 and Ea17) and intermediate (Ea19) copper sensitivity, we conducted phenotypic and transcriptomic analyses to understand the basis of these differences. The highly copper-sensitive strains EaR2 and Ea17 grew slower, showed increased sensitivity to paraquat and cadmium, and developed a characteristic copper-dependent overproduction of amylovoran and levan, with patterns not observed in strain Ea273, with regular copper tolerance. Copper sensitivity was also associated with higher copper-shock death rates after copper pre-exposure during growth. Transcriptomic analysis via RNA-Seq revealed similar responses to copper shock in EaR2 and Ea273 but very different transcriptomic responses during copper adaptation (prolonged growth with copper). EaR2 responded to copper adaptation with earlier activation of stress responses, exopolysaccharide biosynthesis pathways, and protein quality control systems, while reducing the expression of genes linked to iron uptake. Ea273 mostly displayed an activation of copper homeostasis-related genes, with a characteristic downregulation of histidine catabolism.IMPORTANCEThis study identified and characterized, for the first time, copper hypersensitive <i>E. amylovora</i> strains, providing critical insights into the mechanisms of copper homeostasis and detoxification in the fire blight pathogen. Our study contributes to a broader understanding of bacterial adaptation to copper as well as the connection between phenotypic traits and transcriptomic responses to copper. Furthermore, our findings set the basis for future optimization of copper-based treatments and future development of more effective disease control methods.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0033425"},"PeriodicalIF":3.7,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145079466","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":"Influence of a 7 T magnetic field on growth, biomineralization, and denitrification metabolism in <i>Magnetospirillum gryphiswaldense</i> MSR-1.","authors":"Jing Zhang, Juan Wan, Chengyin Shen, Yaoyao Zhang, Jiarong Wang, Hengjia Wan, Tongwei Zhang, Kun Ma, Wei Lin, Junfeng Wang, Yongxin Pan","doi":"10.1128/aem.01069-25","DOIUrl":"https://doi.org/10.1128/aem.01069-25","url":null,"abstract":"<p><p>High magnetic fields represent an extreme physical condition with growing applications in advanced materials and magnetic resonance technologies. However, the physiological and molecular responses of organisms under such conditions remain poorly characterized. Understanding these responses is essential for elucidating magnetobiological mechanisms and enabling biomedical and engineering innovations. Owing to their intrinsic magnetic sensitivity and well-characterized metabolic pathways, magnetotactic bacteria (MTB) offer an ideal model for investigating biological responses to high magnetic fields. Here, we systematically investigated the impact of a steady-state 7 Tesla (7 T) magnetic field on the growth, magnetosome biomineralization, and nitrogen metabolism of the MTB strain <i>Magnetospirillum gryphiswaldense</i> strain MSR-1 (MSR-1). Exposure to the 7 T magnetic field significantly enhanced bacterial proliferation and increased magnetosome number, without altering the average size of individual magnetosome crystals. Transcriptomic analysis demonstrated upregulation of genes encoding the key denitrification enzymes, indicating a pivotal role for nitrogen metabolism in MSR-1 adaptation to the 7 T high magnetic field stress. These transcriptomic results were further supported by proton transfer reaction-mass spectrometry, which confirmed the enhanced denitrification activity under 7 T magnetic field by measuring the intermediate NO and N₂O gas production. Collectively, our findings provide new insights into the biological effects of high magnetic field on MTB and identify nitrogen metabolism as a key mechanism for MTB adaptation to extreme magnetic environments. These work advances our understanding of microbial magnetic responses and expands the knowledge of magnetobiology.</p><p><strong>Importance: </strong>The physiological impacts of high magnetic fields on microorganisms remain poorly understood. Here, we establish a stable 7 Tesla static magnetic field platform to investigate how <i>Magnetospirillum gryphiswaldense</i> MSR-1 responds to extreme magnetic environments. We show that high-field exposure accelerates bacterial growth and increases magnetosome production, coinciding with transcriptional upregulation of key denitrification genes. Using transcriptomics and proton transfer reaction-mass spectrometry, we uncover a metabolic shift toward enhanced redox regulation, suggesting that denitrification plays a central role in magnetic field adaptation. These findings uncover a previously underappreciated connection between magnetic field sensing and metabolic control, providing new insights into how prokaryotes modulate redox homeostasis in extreme environments.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0106925"},"PeriodicalIF":3.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145074310","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":"An organotrophic <i>Sideroxydans</i> reveals potential iron oxidation marker genes.","authors":"Rene L Hoover, Kirsten Küsel, Clara S Chan","doi":"10.1128/aem.00395-25","DOIUrl":"10.1128/aem.00395-25","url":null,"abstract":"<p><p>To understand the ecophysiology and the role of iron-oxidizing bacteria (FeOB) in various ecosystems, we need to identify marker genes of the iron oxidation pathway to track activity <i>in situ</i>. The Gallionellaceae <i>Sideroxydans</i> sp. CL21, an autotrophic iron-oxidizing bacterium isolated from a peatland, is unusual among FeOB isolates in its genomic potential to utilize organic compounds as energy sources. Therefore, it offers the unique opportunity to determine genes expressed under litho- vs organotrophic conditions. We demonstrated the growth of <i>Sideroxydans</i> sp. CL21 on organic substrates (lactate and pyruvate) and inorganic substrates [Fe(II), magnetite, thiosulfate, and S(0)]. Thus, cells were capable of lithoautotrophic, organotrophic, and potentially organoheterotrophic growth. Surprisingly, when lactate-grown cells were given Fe(II), mid-log phase cells were unable to oxidize iron, while late-log phase cells oxidized iron. To elucidate iron oxidation pathways, we compared gene expression between mid-log (non-iron-oxidizing) and late-log (iron-oxidizing) lactate-grown cells. Genes for iron oxidases (<i>cyc2</i>, <i>mtoA</i>) were highly expressed at both time points but did not correspond to iron oxidation capability, making them unsuitable marker genes of iron oxidation activity by themselves. However, genes encoding periplasmic and inner membrane cytochromes were significantly upregulated in cells capable of iron oxidation. These genes include <i>mtoD</i>, <i>cymA/imoA</i>, and a cluster of Fe(II)-responsive genes (<i>ircABCD</i>). These findings suggest that Gallionellaceae regulate their iron oxidation pathways in multiple stages, with iron oxidase-encoding genes proactively expressed. Other genes encoding electron carriers are upregulated only when iron oxidation is needed, which makes these genes (i.e., <i>ircABCD</i>) good prospective indicators of iron oxidation ability.IMPORTANCEIron-oxidizing bacteria (FeOB) are widespread in the environment, and we suspect that they play key roles in nutrient and other elemental cycles. However, with no isotopic marker, we lack the ability to monitor FeOB activity, prompting us to search for genetic markers. Previous work suggests that expression of iron oxidase genes does not directly correspond to iron oxidation activity in Gallionellaceae, and little was known about the other genes in the pathway. Here, we study a unique FeOB isolate that possesses organotrophic capabilities and demonstrate its potential for mixotrophic growth on lactate and Fe(II). Its ability to oxidize iron is regulated, allowing us to discover potential iron oxidation pathway genes with expression that corresponds to iron oxidation activity. If these genes can be further validated as iron oxidation marker genes, they will enable us to delineate autotrophic and organoheterotrophic FeOB impacts on carbon cycling in wetlands and other natural and engineered environments.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":"91 9","pages":"e0039525"},"PeriodicalIF":3.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12442390/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145074470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The HOG signal pathway contributes to survival strategies of the piezo-tolerant fungus <i>Aspergillus sydowii</i> DM1 in hadal sediments.","authors":"Guangzhao Hu, Maosheng Zhong, Changhao Zhang, Hongfu Lai, Eva Breyer, Jiasong Fang, Xi Yu","doi":"10.1128/aem.00921-25","DOIUrl":"10.1128/aem.00921-25","url":null,"abstract":"<p><p>The hadal zone, one of Earth's most extreme ecosystems, harbors diverse and unique microbial communities adapted to its harsh environmental conditions, including high hydrostatic pressure (HHP) and low temperatures. Within these communities, deep-sea fungi play a critical role in geochemical cycling and marine ecosystem functioning; however, research on their cultivable strains and adaptation mechanism remains scarce. In this study, the piezo-tolerant fungus <i>Aspergillus sydowii</i> DM1, isolated from the Mariana Trench sediments (10,898 m), was selected as a representative strain. A comprehensive genome analysis using high-throughput sequencing revealed a genome size of 34.5 Mb, with 12,241 predicted genes. Functional annotations across multiple databases identified a substantial number of pathways associated with environmental adaptations, including extensive carbohydrate, amino acid, sulfur, and nitrogen metabolic pathways. Among them, the HOG (high-osmolarity glycerol) signal pathway, which responds to external stimuli, was indicated to play a crucial role. To study the HOG signal pathways in more detail, we developed a knockout technique for <i>A. sydowii</i> and constructed a <i>hog1</i> mutant strain (Δ<i>Ashog1</i>). The Δ<i>Ashog1</i> strain displayed notable differences in colony phenotype, spore production, secondary metabolites, and oxidative stress tolerance compared to the wild type. Furthermore, the <i>Ashog1</i> gene was found to regulate reactive oxygen species (ROS) and ATP levels in response to osmotic pressure and HHP, suggesting a role of <i>hog1</i> in the fungal adaptation to this extreme environment. Our study serves as an ideal candidate for exploring gene functions in extreme microorganisms and carries significant implications for understanding the adaptive mechanisms of hadal microorganisms.</p><p><strong>Importance: </strong>Research on the genomes and gene functions of hadal zone fungi is crucial for understanding life's adaptation to extreme environments. However, current studies on constructing genetic operation systems for marine-derived filamentous fungi are scarce, and research on HHP environments in related fields is virtually non-existent. Our study highlights the critical role of the HOG-mediated pathway in regulating stress responses and metabolic processes in extremophiles, a regulatory mechanism that had not been previously investigated under HHP conditions. Notably, the whole-genome annotation of the hadal fungus <i>Aspergillus sydowii</i> DM1 advances our understanding of the life processes of hadal fungi. The development of gene knockout technology, combined with insights into stress adaptation and metabolic regulation in <i>A. sydowii</i> strain DM1, provides a strong foundation for future research and biotechnological applications.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0092125"},"PeriodicalIF":3.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12442359/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144820419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping <i>Histoplasma</i> spp. in bats and cave ecosystems: evidence from midwestern Brazil.","authors":"João Paulo Romualdo Alarcão Bernardes, Bernardo Guerra Tenório, Joaquim Lucas, Carlos Emilio Molano Paternina, Regianne Kelly Moreira da Silva, Fabián Andrés Hurtado Erazo, Ildinete Silva Pereira, Lucas Gomes de Brito Alves, Paulo Henrique Rosado Arenas, Igor Daniel Bueno-Rocha, Lucas Silva de Oliveira, Edvard Dias Magalhães, Herdson Renney de Sousa, Hugo Costa Paes, Rosely Maria Zancopé-Oliveira, Daniel Ricardo Matute, Maria Sueli Soares Felipe, Ludmilla Moura de Souza Aguiar, Sébastien Charneau, André Moraes Nicola, Marcus de Melo Teixeira","doi":"10.1128/aem.00335-25","DOIUrl":"10.1128/aem.00335-25","url":null,"abstract":"<p><p>Caves serve as natural reservoirs for diverse microbial species due to their unique biotic and abiotic conditions. <i>Histoplasma</i> spp. is frequently associated with guano-enriched soil, low luminosity, and high humidity, particularly in Latin America, a region highly endemic for histoplasmosis. Despite the continent's diverse biomes, local environmental and host distributions of <i>Histoplasma</i> remain poorly understood. To address this knowledge gap, we conducted a <i>Histoplasma</i>-specific quantitative PCR assay targeting the <i>hc100</i> gene on guano samples from seven bat-inhabited caves and tissue samples from 74 bats of nine species in the Federal District of Brazil and surrounding regions. We detected <i>Histoplasma</i> DNA in 16 of 80 soil samples (20%) and in 33 bats representing seven species. Among 222 tissue samples (74 lung, 74 spleen, and 74 brain samples), 39 tested positive: 22 lung, 10 spleen, and 7 brain samples. Four bats had <i>Histoplasma</i> DNA in both lungs and brain, and two in both lungs and spleen. By mapping the presence of <i>Histoplasma</i> spp. across sampled caves, we identified environmental hotspots of fungal prevalence, emphasizing the need for targeted surveillance.</p><p><strong>Importance: </strong>Our study provides critical insights into the environmental and host distribution of <i>Histoplasma</i> spp. in Brazil, identifying caves with high fungal prevalence and demonstrating its presence in multiple bat species. These findings underscore the necessity of public health interventions to mitigate the risk of histoplasmosis among cave visitors in the region. Additionally, we highlight the utility of quantitative PCR for detecting <i>Histoplasma</i> spp. in environmental and biological samples, supporting future epidemiological research in Latin America.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0033525"},"PeriodicalIF":3.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12442369/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144820414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly efficient degradation of polybutylene succinate (PBS) and polycaprolactone (PCL) by a recombinant marine fungal cutinase.","authors":"Fengjuan Lang, Fan Fei, Chaomin Sun, Shimei Wu","doi":"10.1128/aem.00833-25","DOIUrl":"10.1128/aem.00833-25","url":null,"abstract":"<p><p>Biodegradable plastics, such as polybutylene succinate (PBS) and polycaprolactone (PCL), pose potential ecological risks due to their slow degradation rates in natural environments. Therefore, there is an urgent need to develop efficient enzymatic degradation technologies for the end-of-life management of PBS and PCL. In this study, we identified a marine fungal cutinase, <i>Aa</i>Cut10, which exhibits significant degradation activity on PBS and PCL films under mild conditions. <i>Aa</i>Cut10 can achieve degradation rates of 26.33% for PBS and 85.67% for PCL films within 20 min at 37°C, corresponding to degradation efficiencies of 315.96  kg PBS·(mol <i>Aa</i>Cut10·h)⁻¹ and 1028.04  kg PCL·(mol <i>Aa</i>Cut10·h)⁻¹, respectively. Notably, <i>Aa</i>Cut10 showed even higher degradation efficiency on PBS and PCL emulsions, achieving degradation rates of 81.88% for PBS and 99.45% for PCL after just 1 min at room temperature. Product analysis showed that <i>Aa</i>Cut10 degrades PBS into monomers and dimers and completely degrades PCL into monomers. The optimal degradation temperature for <i>Aa</i>Cut10 was 23°C for both PBS and PCL. Even at 4°C, <i>Aa</i>Cut10 retained high degradation activity, with relative activities of 60.58% for PBS emulsion and 81.41% for PCL emulsion. Additionally, Ca²⁺, Mg²⁺, and Mn²⁺ significantly enhanced the degradation activity of <i>Aa</i>Cut10, and the enzyme remained stable in the presence of chemicals such as methanol, ethanol, and glycerol. Finally, we identified that the amino acids Leu209 and Leu216 in <i>Aa</i>Cut10 play key roles in its degradation functions toward both PBS and PCL.IMPORTANCEAlthough biodegradable plastics can be degraded, their degradation rates in natural environments are slower than expected. To address this issue, we identified a marine fungal cutinase, <i>Aa</i>Cut10, which efficiently degrades various polyesters, including PBS and PCL, into their corresponding monomers, thereby facilitating subsequent recycling and remanufacturing. Notably, <i>Aa</i>Cut10 achieves maximum degradation efficiency at ambient temperature (23°C) and retains high activity even at 4°C, meeting the energy efficiency requirements of industrial applications. Furthermore, <i>Aa</i>Cut10 exhibits high stability in the presence of chemicals, making it suitable for multiphase catalytic systems while the enhancing effects of metal ions on its activity provide tunable targets for process optimization. The catalytic properties of <i>Aa</i>Cut10 not only establish a theoretical framework for designing high-performance degrading enzymes but also offer essential support for developing eco-friendly plastic recycling systems.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0083325"},"PeriodicalIF":3.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12442398/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144854274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional interplay between RND efflux pumps and GacS in <i>Pseudomonas aeruginosa</i>.","authors":"Justyna W Adamiak, Charles Bergen, Laiba Ajmal, Sidhvi Reddy, Paolla Gruber Anderson, Valentin V Rybenkov, Helen I Zgurskaya","doi":"10.1128/aem.01223-25","DOIUrl":"10.1128/aem.01223-25","url":null,"abstract":"<p><p><i>Pseudomonas aeruginosa</i> is an opportunistic human pathogen that is ubiquitous in the environment. The environmental versatility of <i>P. aeruginosa</i> is often attributed to a large arsenal of active efflux pumps, low permeability of the outer membrane, and extensive regulatory networks. In this study, we analyzed putative functional interplay between polyspecific drug efflux pumps of the Resistance-Nodulation-Division (RND) superfamily of proteins and the GacSA two-component regulatory system. RND transporters are the major contributors to antibiotic resistance and survival under various environmental stresses, whereas GacSA is a global regulator and governs critical lifestyles during human colonization. We found that the inactivation of either RND pumps or <i>gacS</i> induces broad, partially overlapping responses in lifestyle (e.g., rhamnolipid biosynthesis, heat shock response, and quorum sensing), virulence (e.g., proteases, toxins, and phenazines secretion systems), and metabolic programs (e.g., electron, iron capture, synthesis/degradation of ketone bodies, and cyanoamino acid metabolism) that are more pronounced during the exponential than the stationary phase. GacSA and RND efflux pumps induced opposite responses in the gene expression of <i>P. aeruginosa</i>, whereas the overexpression of GacS was additive with the deletion of efflux pumps in gene expression and under growth conditions typically associated with human infections such as elevated temperature and iron deprivation. We conclude that RND efflux and GacSA networks partially overlap with each other.IMPORTANCERND efflux pumps are the major contributors to intrinsic and clinical levels of antibiotic resistance of <i>P. aeruginosa,</i> and their expression is regulated by various environmental factors. However, functional relationships between active efflux pumps and regulatory networks involved in virulence and pathogenesis of <i>P. aeruginosa</i> remain unclear. This study showed that the loss of RND-dependent efflux functions or the inactivation of the <i>gacS</i> pathway induces partially overlapping transcriptional and physiological responses, suggesting that these pathways could be complementary to each other in hostile environments.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0122325"},"PeriodicalIF":3.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12442375/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144871068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}