Applied and Environmental Microbiology最新文献

{"title":"Long-term culturing of <i>Pseudomonas aeruginosa</i> in static, minimal nutrient medium results in increased pyocyanin production, reduced biofilm production, and loss of motility.","authors":"Rhiannon E Cecil, Elana Ornelas, Anh Phan, Nahui Olin Medina-Chavez, Michael Travisano, Deborah R Yoder-Himes","doi":"10.1128/aem.00975-25","DOIUrl":"https://doi.org/10.1128/aem.00975-25","url":null,"abstract":"<p><p><i>Pseudomonas aeruginosa</i> is a multidrug-resistant opportunistic human pathogen that can survive in many natural and anthropogenic environments. It is a leading cause of morbidity in individuals with cystic fibrosis and is one of the most prevalent pathogens associated with nosocomial infections in the United States. It has been shown that this organism can survive and persist in low-nutrient environments, such as sink drains. How adaptation to these types of environments influences the phenotypic traits of this organism has not been well studied. Here, we implemented an experimental evolution system in which six strains of <i>P. aeruginosa</i> were subjected to low-nutrient conditions over the course of 12 weeks and assessed phenotypic and genotypic changes that occurred as a result of adaptation to such environments. We observed that adaptation to low-nutrient environments resulted in decreased generation time, reduced cell size, reduced biofilm formation, increased pyocyanin production, and decreased motility for some of the strains. Furthermore, some of the evolved isolates were significantly more virulent/competitive against a phagocytic predator. This study is significant as it allows us to predict how this organism will evolve in hospital and domestic environments and can help us improve treatment options for patients.IMPORTANCEHuman commensal and pathogenic organisms undergo dynamic cycles across human and non-human environments. Despite the crucial implications for human health, the understanding of bacterial adaptations to these diverse environments and their subsequent impact on human-bacterial interactions remains underexplored. This study shows how <i>Pseudomonas aeruginosa</i>, an opportunistic human pathogen, adapts phenotypically in response to a shift from high nutrients (like those found in the human body) to low nutrients (like those found in many other environments, like sink drains). This work also shows that, in some cases, resistance to predatory forces can evolve in the absence of a predator. This work is important as it contributes to the growing body of knowledge concerning how external, non-host-related abiotic conditions influence host-pathogen interactions.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0097525"},"PeriodicalIF":3.7,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145273510","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":"Habitat transformation reshapes protistan community composition and assembly processes in coastal wetlands of southeastern China.","authors":"Anqi Wang, Ping Yang, Guiping Ye, Chuan Tong, Luyuan Sun, Mengmeng Feng, Zi-Yang He, Ji-Zheng He, Yongxin Lin","doi":"10.1128/aem.01661-25","DOIUrl":"https://doi.org/10.1128/aem.01661-25","url":null,"abstract":"<p><p>Coastal wetlands along southeastern China have undergone extensive habitat transformations, notably from natural mudflats (MFs) to <i>Spartina alterniflora</i> marshes (SAs) and aquaculture ponds (APs), yet the ecological consequences for sediment protistan communities remain largely unknown. Here, we systematically examined protistan diversity, community composition, functional groups, and assembly processes across 21 wetlands spanning five provinces using amplicon sequencing. Although alpha diversity remained stable across habitat types, community composition and functional group distributions were significantly altered. In particular, phototrophic protists declined markedly following <i>S. alterniflora</i> invasion and then increased after aquaculture pond reclamation. Meanwhile, consumer and phototroph assemblages were strongly influenced by sediment grain size. Salinity emerged as the key environmental driver of protistan diversity and community structure. Distance-decay relationships indicated elevated spatial turnover in SAs, suggesting increased environmental filtering after plant invasion. Assembly process analysis revealed a dominance of deterministic mechanisms in shaping community structure across all habitats, with the strongest signal observed in SAs. These findings demonstrate that land-use change reshapes protistan communities through altered environmental constraints, highlighting the ecological sensitivity of microbial eukaryotes to anthropogenic disturbance in coastal wetland ecosystems.</p><p><strong>Importance: </strong>Protists play essential roles in nutrient cycling, energy transfer, and microbial food web dynamics, yet their responses to anthropogenic habitat transformation in coastal wetlands remain underexplored. This study offers the first large-scale biogeographic assessment of sediment protistan communities across three contrasting coastal habitat types in southeastern China. We show that while alpha diversity remains resilient, profound shifts in community composition, functional group structure, and spatial turnover occur following <i>Spartina alterniflora</i> invasion and aquaculture conversion. Our findings underscore the primacy of environmental filtering, driven by salinity and sediment texture, in mediating these patterns and shaping community assembly. These insights not only expand our understanding of protistan ecology under coastal land-use change but also highlight their potential as sensitive bioindicators for monitoring ecological integrity and resilience in dynamic coastal systems.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0166125"},"PeriodicalIF":3.7,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145249421","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 regulation of an alternative PTS for disaccharide utilization in <i>Clostridium acetobutylicum</i>.","authors":"Zhenxing Ren, Zili Qiu, Yali Tian, Mengcheng You, Chenggang Xu","doi":"10.1128/aem.00709-25","DOIUrl":"https://doi.org/10.1128/aem.00709-25","url":null,"abstract":"<p><p><i>Clostridium acetobutylicum</i> is an important solventogenic bacterium capable of acetone-butanol-ethanol fermentation by utilizing a variety of carbon sources. It employs the transport systems of the phosphoenolpyruvate:sugar phosphotransferase systems (PTSs) to assimilate various saccharides. Here, we investigated a β-glucoside PTS (<i>bglT</i>) encoded by the <i>bgl</i> operon (<i>bglGTH</i>) in <i>C. acetobutylicum</i>, which showed significant expression in response to cellobiose and sucrose. Interestingly, <i>bglT</i> is not essential for the transport of these sugars, as <i>C. acetobutylicum</i> possesses dedicated PTSs for the uptake of each individual sugar. We further elucidated the regulatory mechanism of <i>bglT</i>, which is governed by an upstream anti-transcriptional termination factor (<i>bglG</i>). A putative ribonucleic antiterminator (RAT) was identified upstream of <i>bglG</i> and <i>bglT</i>. Inactivation of <i>bglG</i> led to consistent read-through frequencies of the genes downstream of the RAT, irrespective of the sugar present. Conversely, complete removal of RAT elevated the transcriptional levels of downstream genes, while partial deletion of RAT, causing a long stem-loop structure (terminator), resulted in transcription termination. These findings provide novel insights into the regulatory mechanisms controlling sugar utilization in <i>C. acetobutylicum</i>.</p><p><strong>Importance: </strong>Cellulose, the most abundant organic compound on Earth, is primarily found in plant cell walls and can be broken down into sugars such as cellobiose. These sugars are crucial for microbial fermentation, especially in biofuel production. <i>Clostridium acetobutylicum</i>, a promising microorganism for producing short-chain alcohol chemicals, can utilize cellulose degradation products as a carbon source for fermentation. This study identifies the transport systems involved in the utilization of cellobiose and other disaccharides in <i>C. acetobutylicum</i> and analyzes their regulatory mechanisms. Understanding these pathways is essential for enhancing biofuel production from plant biomass.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0070925"},"PeriodicalIF":3.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145249484","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":"Analyses of 37 composts revealed microbial taxa associated with disease suppressiveness.","authors":"Anja Logo, Benedikt Boppré, Jacques Fuchs, Monika Maurhofer, Thomas Oberhänsli, Barbara Thürig, Franco Widmer, Johanna Mayerhofer, Pascale Flury","doi":"10.1128/aem.01100-25","DOIUrl":"https://doi.org/10.1128/aem.01100-25","url":null,"abstract":"<p><p>Compost is a valuable amendment for soil and potting substrate when it comes to suppressing soilborne pathogens. However, the effectiveness of different composts varies and cannot yet be predicted. Microbial communities in compost play a key role in disease suppression, and therefore their composition or specific taxa may serve as indicators of suppressive composts. In this study, we investigated 37 composts from 7 commercial compost producers to analyze the association of their bacterial and fungal communities with suppressive activity in three plant-pathogen systems: cress-<i>Globisporangium ultimum</i>, cucumber-<i>G</i>. <i>ultimum</i>, and cucumber-<i>Rhizoctonia solani</i>. Our results underscore that compost suppressiveness is primarily pathogen-specific and, to a lesser extent, host-plant-specific. Suppressiveness was not correlated with physicochemical properties, microbial activity, or the alpha- and beta-diversity of composts' bacterial and fungal communities. Instead, microbial composition was largely shaped by producer-specific composting conditions and maturation processes, which were not necessarily linked to suppressive activity. A more nuanced comparison between the most and least suppressive composts revealed bacterial and a few fungal taxa as potential indicators of suppressiveness for each plant-pathogen system. Notably, for <i>G. ultimum</i>-suppression, bacteria from the genera <i>Luteimonas</i>, <i>Sphingopyxis</i>, and <i>Algoriphagus,</i> and for <i>R. solani,</i> bacteria belonging to the phylum <i>Actinomycetota</i> emerged as promising candidates.</p><p><strong>Importance: </strong>Soilborne diseases are a major yield-limiting factor in agricultural crop production worldwide, particularly in seedling cultivation. Their control remains a significant challenge and still largely relies on chemical fumigation of soils and steam sterilization of potting substrates. While chemical fumigants are increasingly criticized for their negative environmental impact, sterilization practices, in general, disrupt beneficial microbial communities, making substrates more susceptible to pathogen (re)-infestation. Amending soil or potting substrate with disease-suppressive compost offers a promising alternative. However, the targeted use of compost for plant protection is hindered by variable effectiveness and the lack of reliable tools to identify effective composts. This study provides a comprehensive abiotic and biotic characterization of compost, enabling a detailed analysis of the properties associated with suppressiveness. The identification of bacterial and fungal taxa indicative of disease-suppressive composts lays the groundwork for targeted isolation of microorganisms and functional studies, with the ultimate aim of predicting and optimizing compost-mediated disease suppression.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0110025"},"PeriodicalIF":3.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145249376","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 center of wheat domestication drives diversity of <i>Clavibacter</i> pathogens.","authors":"Asma Rahmanzadeh, S Mohsen Taghavi, Sadegh Zarei, Hamid Abachi, Nastaran Zamani, Mozhde Hamidizade, Ardavan Soleimani, Xiang Li, Jiacheng Chuan, Nemanja Kuzmanović, Marie-Agnès Jacques, Perrine Portier, Ebrahim Osdaghi","doi":"10.1128/aem.01245-25","DOIUrl":"https://doi.org/10.1128/aem.01245-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Microbial plant pathogens possess higher diversity in the center of domestication of their host plants than in the introduced geographic area of the corresponding crops. In this study, the center of wheat, barley, and oat domestication in the Iranian Plateau was surveyed to shed light on the population structure, taxonomic diversity, and biology of &lt;i&gt;Clavibacter&lt;/i&gt; species associated with these crops. Comprehensive field surveys completed with pathological assays and molecular-phylogenetic analyses showed that phylogenetically diverse groups of &lt;i&gt;Clavibacter&lt;/i&gt; strains were associated with bacterial mosaic symptoms on small grain cereals in this domestication center. Besides the two previously described species, &lt;i&gt;Clavibacter tessellarius&lt;/i&gt; and &lt;i&gt;Clavibacter zhangzhiyongii&lt;/i&gt;, three clades of atypical &lt;i&gt;Clavibacter&lt;/i&gt; strains, phylogenetically distinct from all described &lt;i&gt;Clavibacter&lt;/i&gt; species, were isolated from wheat, barley, and oat in this study. Thus, &lt;i&gt;Clavibacter&lt;/i&gt; strains associated with small grain cereals in the center of domestication of these crops belong to at least five taxonomically distinct clades, whereas simultaneous occurrence of multitaxa &lt;i&gt;Clavibacter&lt;/i&gt; strains on small grain cereals has never been reported outside the Iranian Plateau. All five phylogenetic &lt;i&gt;Clavibacter&lt;/i&gt; clades were capable of inducing mosaic and chlorosis on their host of isolation. Whole genome sequence-based comparative investigations showed that most virulence-associated genomic contents of the five &lt;i&gt;Clavibacter&lt;/i&gt; clades isolated in this study were somewhat similar. Data obtained in this study suggest a correlation between the center of wheat, barley, and oat domestication and the high taxonomic diversity of the accompanying &lt;i&gt;Clavibacter&lt;/i&gt; pathogens. Additional phylogeographic investigations in the area would strengthen this co-evolutionary hypothesis.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Members of the gram-positive corynebacterial genus &lt;i&gt;Clavibacter&lt;/i&gt; sp. (family &lt;i&gt;Microbacteriaceae&lt;/i&gt;) are seed-borne plant pathogens causing economically important plant diseases on annual crops and vegetables. While comprehensive global-scale studies have been conducted to study the population structure of &lt;i&gt;Clavibacter&lt;/i&gt; species infecting tomato, potato, and pepper, phylogenomics investigations have not yet been conducted to monitor the taxonomic diversity, pathogenicity, and origin of &lt;i&gt;Clavibacter&lt;/i&gt; strains pathogenic to small grain cereals. Archaeobotanical investigations suggested that human agriculture was established ≈11,000 years ago in the foothills of the Zagros Mountains in Northwestern Iran, while wheat and barley were among the very first crops domesticated in these areas. Thus, the analyses of taxonomic diversity and population structure of &lt;i&gt;Clavibacter&lt;/i&gt; strains in the Iranian Plateau would shed light on the correlation between the center of domestication of these crops and the center of diversity of a","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0124525"},"PeriodicalIF":3.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145249439","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 river in crisis: water quality, microbial burden, and public health implications of a South African urban river.","authors":"Sanelisiwe Thinasonke Duze, Luyanda Mkhize, Musa Marimani, Mrudula Patel","doi":"10.1128/aem.01566-25","DOIUrl":"https://doi.org/10.1128/aem.01566-25","url":null,"abstract":"<p><p>This study evaluated water quality, microbial contamination, and public health implications of a South African urban river. Water samples were collected monthly over 12 months from five sites and analyzed for physico-chemical parameters and microbial indicators (total coliforms and <i>Escherichia coli</i>). <i>Salmonella</i>, <i>Shigella,</i> and <i>Vibrio cholerae</i> were enumerated using culture-based methods and confirmed with real-time PCR targeting the <i>invA</i>, <i>ipaH</i>, and <i>toxR</i> genes. The β-Poisson dose-response model estimated the probability of infection (<i>Pi</i>) following ingestion of 1 mL, 16 mL, and 37 mL of river water during baptism, swimming by adults and non-adults, respectively. Average values for pH, temperature, and total dissolved solids were 7.29, 18˚C, and 160 mg/L, respectively. The total coliform and <i>E. coli</i> counts exceeded 2,000 and 400 CFU/100 mL at most sites. Mean bacterial counts (Log CFU/100 mL) in dry and rainy seasons were 3.22 ± 0.88; 3.28 ± 0.97 for <i>Salmonella</i>, 4.60 ± 0.53; 4.45 ± 0.79 for <i>Shigella,</i> and 0.73 ± 1.97; 3.27 ± 2.24 for <i>Vibrio cholerae</i>. Estimated <i>Pi</i> from ingesting 1 mL of water ranged from 2.57% to 24.73, 4.91%-15.99%, and 1.44%-19.5% for <i>Salmonella</i>, <i>Shigella,</i> and <i>V. cholerae</i>, respectively, increasing with the volume ingested and frequency of exposure. Site C, located within a densely populated urban informal settlement, posed the highest infection risk. Our findings highlight the substantial public health risk from this urban river and reinforce the urgent need for improved water quality management and public health interventions to protect vulnerable communities. In addition, results from this study underscore the need for a One Health Approach for enteric pathogen surveillance in South Africa.</p><p><strong>Importance: </strong>Urban rivers in low- and middle-income countries are essential for domestic, religious, and recreational use but often pose significant public health risks. This study quantified microbial contamination and assessed the infection risk from accidental ingestion of water from a South African urban river. Total coliform and <i>Escherichia coli</i> counts consistently exceeded safe limits, with high levels of <i>Salmonella</i>, <i>Shigella</i>, and <i>Vibrio cholerae</i>. Infection probabilities of up to 25% for a single exposure, ingesting 1 mL of river water, were noted, which increased with ingested volume and multiple exposures. Risk of infection was higher at sites alongside informal settlements, highlighting the impact of socioeconomic inequities and poor sanitation infrastructure. These findings underscore the urgent need for improved water quality management and integrated One Health surveillance of enteric pathogens to mitigate exposure risks and safeguard vulnerable populations.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0156625"},"PeriodicalIF":3.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145249316","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":"Genomic adaptation of an autochthonous cider yeast strain to buckwheat and barley wort under stressful brewing conditions.","authors":"Martina Podgoršek, Katja Doberšek, Maja Paš, Miha Tome, Miha Ocvirk, Uroš Petrovič, Iztok Jože Košir, Neža Čadež","doi":"10.1128/aem.01015-25","DOIUrl":"https://doi.org/10.1128/aem.01015-25","url":null,"abstract":"<p><p>Growing consumer demand for specialty beers with unique flavors and enhanced nutritional properties is driving the development of novel, high-performance industrial yeasts. However, the genetic diversity of beer yeast strains is limited. Traditional spontaneous fermentations are a rich source of new strains that are well adapted to fermentative environments but lack the ability to efficiently convert maltose-based substrates that are rich in polyphenols (e.g., buckwheat wort) or maltotriose-rich substrates (e.g., barley wort). To simulate the selection pressure exerted on beer yeasts during domestication, we used adaptive laboratory evolution to yield cider yeast <i>Saccharomyces cerevisiae</i> that can efficiently convert buckwheat and barley wort into beer. To this end, 30 serial transfers of yeast biomass were conducted in high-pressure fermenters simulating industrial-scale stress conditions. This approach resulted in efficient maltose conversion in buckwheat wort and improved maltotriose conversion in barley wort. Three evolved clones from each evolutionary experiment were sequenced using short-read technology and aligned to the chromosome-level assembly of the ancestral cider strain. We observed pronounced genomic changes, including near-complete loss of heterozygosity, novel single-nucleotide mutations, and chromosomal aberrations resulting in altered chromosome copy numbers or segmental duplications. Additionally, the clones adapted to buckwheat wort were respiratory-deficient, either lacking or having impaired mitochondrial DNA, whereas clones adapted to barley wort retained a truncated mitochondrial genome. These genetic changes mirror hallmarks of beer yeast domestication and were also reflected phenotypically, including loss of sporulation capacity, decreased fitness under non-brewing conditions, and altered production of aromatic compounds.IMPORTANCEConsumer demand for specialty beers with distinctive flavors and nutritional value is growing and highlights the need for novel, high-performance beer yeasts adapted to stressful industrial conditions. This study demonstrates how adaptive laboratory evolution can be used to domesticate non-traditional yeasts, enabling efficient fermentation of alternative substrates, such as buckwheat and barley worts. The evolved strains not only improved sugar utilization under industrial conditions but also acquired genomic and phenotypic traits characteristic of domesticated beer yeasts. These findings demonstrate a viable strategy for expanding the functional diversity of brewing yeasts and support innovation in craft beer production.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0101525"},"PeriodicalIF":3.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145249398","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":"Enhancing <i>Escherichia coli</i> production of material proteins using circular mRNAs.","authors":"Alden Filko, Fuzhong Zhang","doi":"10.1128/aem.01579-25","DOIUrl":"https://doi.org/10.1128/aem.01579-25","url":null,"abstract":"<p><p>Industrial bioproduction of proteins, particularly protein-based materials (PBMs) like spider silk and elastin proteins, is rapidly expanding. PBMs often have high molecular weights and are highly repetitive, transcribed from long and repetitive mRNAs that are prone to degradation in microbial hosts. As a result, recombinant expression of PBMs often has low protein yields. In this study, we engineered a circular mRNA expression system to enhance mRNA stability and protein expression. The system uses self-cleaving ribozymes to form circular mRNA structures and a pair of insulation RNA loops to improve protein translation. When tested using a green fluorescent protein (GFP) reporter, the engineered circular mRNA enhanced GFP expression by 1.5-fold compared to expression from a linear construct. mRNA circularization was further confirmed using reverse transcription followed by DNA amplification and sequencing. We also demonstrate the effectiveness of circular mRNA in enhancing the expression of various material proteins, including a 96-mer repeat of <i>Nephila clavipes</i> dragline silk, a titin repeat, a mussel foot protein oligomer, and an silk-amyloid repeat, resulting in up to 2.5-fold increase in protein yield. Additionally, the circular mRNA system also improved the stability of the PBM-encoding plasmid. Overall, the circular RNA expression system enhances both the expression level and plasmid stability and is suitable for various protein production applications.IMPORTANCEIndustrial bioproduction of complex proteins is limited by unstable expression. Long and repetitive proteins have unstable expression and often yield truncated products that will change the properties of the final materials. We show that by using a self-circularizing mRNA system, the expression is stabilized to not only increase yields but also prevent truncated products. The ability to produce full-length proteins consistently and control their size offers precise control over protein properties, making it highly relevant for products with specific mechanical properties. The study showcases the potential for scaling up protein production in industrial bioreactors under challenging conditions. The findings contribute to synthetic biology tools and offer new avenues for manufacturing bioproducts at an industrial scale.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0157925"},"PeriodicalIF":3.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237609","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":"Endospore appendages enhance adhesion of <i>Bacillus cereus sensu lato</i> spores to industrial surfaces, modulated by physicochemical factors.","authors":"Unni Lise Albertsdottir Jonsmoen, Jennie Ann Allred, Dmitry Malyshev, Jonas Segervald, Magnus Andersson, Marina Elisabeth Aspholm","doi":"10.1128/aem.00944-25","DOIUrl":"https://doi.org/10.1128/aem.00944-25","url":null,"abstract":"<p><p>Spores of species belonging to the <i>Bacillus cereus sensu lato</i> (s.l.) group are common contaminants in food processing environments due to their ability to adhere to surfaces and resist cleaning procedures. These spores are equipped with pilus-like endospore appendages (ENAs), which are believed to promote surface adhesion. We investigated the role of ENAs in spore adhesion to abiotic surfaces using a wild-type (WT) <i>Bacillus paranthracis</i> strain and isogenic mutants lacking ENAs or an intact exosporium. WT spores expressing both short and long ENAs (S+L+) adhered significantly more to stainless steel (SS) and polypropylene (PP) compared to bald spores (S-L-) and spores of an exosporium-deficient mutant (Δ<i>exsY</i>), whereas adhesion to polystyrene (PS) and glass was not significantly affected by the presence of ENAs. The Δ<i>exsY</i> mutant also showed the lowest adhesion across all tested surfaces, a pattern similarly observed for vegetative cells. The strongest adhesion to PP was observed when both fiber types were present. A clear trend also emerged: on PP, WT remained adhered for at least an hour, while bald spores tended to detach within that time. Under saline conditions and at different pH levels, bald spores adhered strongly to SS. However, in the presence of a non-ionic surfactant or a concentrated protein solution, WT spores adhered more. Our results highlight the crucial role of ENAs in <i>B. cereus</i> spp. spore adhesion to industrially relevant surfaces, providing mechanistic insight into spore persistence. These insights support the design of surface treatments to prevent contamination, spoilage, and foodborne illnesses.IMPORTANCEBacteria belonging to the <i>Bacillus cereus sensu lato</i> group represent a persistent challenge in food production due to their highly resilient endospores (spores), which withstand cleaning, disinfection, and food processing. Understanding spore adhesion is essential for designing effective surface treatments that reduce chemical use, enhance food safety and quality, and minimize environmental impact. This study underscores the important role of endospore appendages (ENAs) in spore adhesion to common materials in food processing and laboratory environments. Wild-type spores expressing both S-ENA and L-ENA adhered significantly more than mutants lacking ENAs or the exosporium, highlighting ENAs as potential targets for disrupting spore adhesion. Time-dependent adhesion assays on polypropylene revealed strong, sustained attachment by wild-type spores, contrasting with weaker, transient adhesion by ENA-depleted mutants. These findings offer valuable insights into <i>B. paranthracis</i> spore adhesion dynamics, guiding the development of tailored cleaning protocols to improve contamination control and sustainability.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0094425"},"PeriodicalIF":3.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237890","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":"<i>Legionella</i> detection and enumeration in water samples by ISO 11731-2017: which method is the most sensitive?","authors":"Bruno Grandbastien, Florian Mauffrey, Gilbert Greub, Dominique S Blanc","doi":"10.1128/aem.01147-25","DOIUrl":"https://doi.org/10.1128/aem.01147-25","url":null,"abstract":"<p><p>Legionnaires' disease is a severe pneumonia caused by inhalation of <i>Legionella</i>-contaminated aerosols. The prevention of <i>Legionella</i> relies on water disinfection and on accurate water testing to assess the effectiveness of these interventions. The norm ISO 11731:2017 provides multiple culture-based methods for detecting <i>Legionella</i> in water and recommends taking into account the most unfavorable result. This study evaluated six ISO-standardized techniques, including variations in media, concentration, and pre-treatments (heat or acid), applied to 276 hospital hot water samples. <i>Legionella</i> was detected in 120 samples, with substantial variability across methods. The most sensitive single technique (76%) was concentration and elution with membrane filter on GVPC medium after heat treatment. Combinations of three techniques yielded a higher detection rate (98%), while using all six techniques detected all positive samples. Techniques involving concentration and elution proved superior to direct plating or simple filtration. Heat treatment enhanced detection more effectively than acid treatment, especially in samples with interfering flora. GVPC medium consistently outperformed BCYE. The study supports using a strategic combination of methods, particularly those involving membrane filtration and GVPC medium with heat treatment, to optimize <i>Legionella</i> detection in healthcare water systems.</p><p><strong>Importance: </strong>This study is of critical importance as it provides a comprehensive evaluation of the sensitivity of various ISO 11731:2017-standardized methods for detecting Legionella in hospital water systems-a key concern in infection prevention. Given the high variability in recovery rates across different techniques and the limitations posed by adjacent flora, the study offers valuable insights into optimizing laboratory protocols. By analyzing 276 water samples using six techniques and their combinations, the researchers highlight the superiority of methods involving concentration, membrane filtration, and heat treatment-particularly those using GVPC medium. These findings not only support evidence-based recommendations for routine environmental surveillance in healthcare settings but also help laboratories balance accuracy, cost, and resource allocation. The study's implications are especially relevant for institutions housing vulnerable populations, where early and reliable Legionella detection is essential to prevent potentially fatal outbreaks of Legionnaires' disease.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0114725"},"PeriodicalIF":3.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237809","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}