Applied and Environmental Microbiology最新文献

{"title":"Anaerobic degradation of polycyclic aromatic hydrocarbons.","authors":"Isabelle Heker, Nadia A Samak, Yachao Kong, Rainer U Meckenstock","doi":"10.1128/aem.02268-24","DOIUrl":"https://doi.org/10.1128/aem.02268-24","url":null,"abstract":"<p><p>Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and toxic pollutants in the environment that are mostly introduced through anthropogenic activities. They are very stable with low bioavailability and, because aerobic degradation is mostly limited in aquifers and sediments, often persist in anoxic systems. In this review, we elucidate the recent advances in PAH degradation by anaerobic, mostly sulfate-reducing cultures. The best-studied compound is naphthalene, the smallest and simplest PAH, which often serves as a model compound for anaerobic PAH degradation. In recent years, three-ring PAHs have also shifted into focus, using phenanthrene as a representative compound. Anaerobic degradation of PAHs has to overcome several biochemical problems. First, non-substituted PAHs have to be activated by carboxylation, which is chemically challenging and proposed to involve a 1,3-cycloaddition with a UbiD-like carboxylase and a prenylated flavin cofactor. The second key reaction is to overcome the resonance energy of the ring system, which is performed by consecutive two-electron reduction steps involving novel type III aryl-CoA reductases belonging to the old-yellow enzyme family. In naphthalene degradation, a type I aryl-CoA reductase is also involved in reducing a benzene ring structure. The third key reaction is the ring cleavage, involving β-oxidation-like reactions in cleaving ring I of naphthalene. Ring II, however, is opened by a novel lyase reaction at a tertiary, hydroxylated carbon atom. These principles are explained using examples of anaerobic naphthalene and phenanthrene degradation to give an overview of recent advances, from the initial activation of the molecules to the complete degradation to CO₂.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0226824"},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143762875","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":"Discovery of two novel cutinases from a gut yeast of plastic-eating mealworm for polyester depolymerization.","authors":"Tong Huang, Jingya Zhang, Xuena Dong, Yu Yang","doi":"10.1128/aem.02562-24","DOIUrl":"https://doi.org/10.1128/aem.02562-24","url":null,"abstract":"<p><p>Identification of novel plastic-degrading enzymes is crucial for developing enzymatic degradation and recycling strategies for plastic waste. Here, we report the discovery of two novel cutinases, SiCut1 and SiCut2, from a yeast strain <i>Sakaguchia</i> sp. BIT-D3 was isolated from the gut of plastic-eating mealworms. Their amino acid sequences share less than 25% identity with all previously described cutinases and reveal a conserved S-D-H catalytic triad with a unique GYSKG motif. Their recombinant proteins were successfully overexpressed in <i>Pichia pastoris</i>. The pH range for both enzymes was 4.0 to 11.0 and the temperature range for SiCut1 and SiCut2 was 10°C to 50°C and 10°C to 70°C, respectively. Both enzymes showed strong activity against apple cutin and short-chain fatty acid esters of <i>p</i>-nitrophenol and glycerol, substantiating their classification as true cutinases. SiCut1 and SiCut2 have been demonstrated to exhibit efficient degradation of polycaprolactone (PCL) film, polybutylene succinate (PBS) film, and polyester-polyurethane (PUR) foam. Molecular docking and molecular dynamics simulations were used to elucidate the underlying mechanisms of the observed catalytic activity and thermal stability. This study shows that SiCut1 and SiCut2 are novel yeast-derived cutinases with the potential for depolymerization and recycling of plastic waste.IMPORTANCEThe identification of novel plastic-degrading enzymes is critical in addressing the pervasive problem of plastic pollution. This study presents two unique cutinases, SiCut1 and SiCut2, derived from the yeast <i>Sakaguchia</i> sp. BIT-D3 isolated from the gut of plastic-feeding mealworms. Despite sharing less than 25% sequence identity with known cutinases, both enzymes exhibit remarkable degradation capabilities against various polyester plastics, including polycaprolactone (PCL) film, polybutylene succinate (PBS) film, and polyester-polyurethane (PUR) foam. Our results elucidate the catalytic mechanisms of SiCut1 and SiCut2 and provide insights into their potential applications in enzymatic degradation and recycling strategies. By harnessing the gut microbiota of plastic-degrading organisms, this research lays the foundation for innovative enzyme-based solutions to reduce plastic waste and promote sustainable practices in waste management.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0256224"},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143762513","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 suite of ddPCR assays targeting microbial pathogens for improved management of shellfish aquaculture.","authors":"Mark Ciesielski, Thomas Clerkin, Nicholas Funnell, Tal Ben-Horin, Rachel T Noble","doi":"10.1128/aem.02149-24","DOIUrl":"https://doi.org/10.1128/aem.02149-24","url":null,"abstract":"<p><p>The shellfish aquaculture industry is one of the fastest-growing sectors of global food production, but it is currently facing major challenges stemming from microbial pathogens. This study presents an optimized and validated suite of droplet digital PCR (ddPCR) assays using water samples proximal to oyster farms in North Carolina to quantify pathogens relevant to the aquaculture industry. Two of the molecular assays enable the quantification of the pathogens, <i>Vibrio parahaemolyticus</i> and <i>Perkinsus marinus</i>, that threaten human health and oyster performance, respectively. This work also introduces two ddPCR assays that enable the simultaneous quantification of at least nine ecologically relevant <i>Vibrio spp</i>. using only two sets of primers and probes targeting the glycosyl hydrolase family 18 (GH18) domain of the <i>chiA</i> gene in <i>Vibrio</i> bacteria. The entire suite of assays was applied to single assessments at 12 sites, revealing heterogeneity in microbial pathogen concentrations across the coastal landscape and variability of abundances within individual estuarine river systems. Additionally, a longitudinal study conducted at a demonstration lease elucidated unique temporal trends for all microbial targets. Notably, when concentrations of <i>Vibrio spp</i>. quantified using the two assays targeting the <i>chiA</i> gene reached their maximum, the daily probability of mortality increased, suggesting a role for other ecologically pertinent <i>Vibrio spp</i>. in the progression of mortality that would otherwise be missed. This study highlights the utility of ddPCR for the advancement of shellfish management by offering insights into the spaciotemporal dynamics of microbial pathogens.</p><p><strong>Importance: </strong>Climate change is drastically altering the environment and changing the abundance and geographical distribution of marine pathogens. These microbial species put additional pressure on the aquaculture industry by acting as sources of disease for animals important to the food industry as well as for humans upon consumption of contaminated food. To address growing concerns, high-resolution monitoring of pathogens can offer insights for effective management in a critical industry. Validated in the field, the suite of molecular droplet digital PCR assays presented here improves upon current methods, enabling the simultaneous quantification of several targets. This technology makes it possible to track pathogens as they move through the environment and reveals changes in abundance that may inform adjustments to farming practices aimed at mitigating negative outcomes. Additionally, this work presents a unique approach to molecular assay design that unveils potential drivers of ecological shifts and emerging etiologies of disease more efficiently.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0214924"},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143762869","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>Clostridioides difficile</i> in feral horse populations in Australia.","authors":"Natasza M R Hain-Saunders, Daniel R Knight, Andrea Harvey, Mieghan Bruce, Brian A Hampson, Thomas V Riley","doi":"10.1128/aem.02114-24","DOIUrl":"https://doi.org/10.1128/aem.02114-24","url":null,"abstract":"<p><p><i>Clostridioides difficile</i> is a known cause of diarrhea and colitis in human and non-human animals. While <i>C. difficile</i> is regularly isolated from domesticated horses, little is known about its prevalence in wild or feral populations. In Australia, the horse population encompasses a mix of both domesticated and feral animals, with the feral population of 400,000 estimated to be the largest in the world. This study investigated the presence and characteristics of <i>C. difficile</i> in Australian feral horses and evaluated their potential as a source or reservoir of <i>C. difficile</i> in the wider community. Fecal samples (<i>n</i> = 380) were collected from free-roaming feral horses from five Australian jurisdictions and cultured for <i>C. difficile</i>. Isolates were characterized by PCR ribotyping and toxin profiling. Antimicrobial susceptibility testing was performed for fidaxomicin, vancomycin, metronidazole, rifaximin, clindamycin, erythromycin, amoxicillin-clavulanate, moxifloxacin, meropenem, and tetracycline. <i>C. difficile</i> was isolated from 45 of the 380 samples (11.8%)-one-third of that seen in recent studies on Australian domesticated horses but consistent with wild animal species worldwide. Forty ribotypes (RTs) were identified, 28 of which (70%) were novel; other RTs had been previously reported in humans, livestock, and soils. Eighteen toxigenic <i>C. difficile</i> strains were isolated, of which eight contain binary toxin genes. Strains were largely susceptible to the antimicrobial agents tested. This investigation provides preliminary information on <i>C. difficile</i> in feral horses in Australia and allows a comparison with their domestic counterparts. The findings support the hypothesis that all horse feces represent a potential source of <i>C. difficile</i> in the community.</p><p><strong>Importance: </strong><i>Clostridioides difficile</i> poses an ongoing threat to healthcare in the community, with increasing evidence of transmission outside the hospital setting. In keeping with a One Health model of dispersion, investigations into this microorganism within the wider environment are vital to understanding this evolving epidemiology. Australia has the biggest population of feral horses in the world, and this study of <i>C. difficile</i> in feral horses provides insight into the role of non-domesticated animals in the dissemination of <i>C. difficile</i>. Examination of prevalence and characterization of isolates provides a baseline for evaluating the effect of antimicrobials and other factors associated with domestication on equine <i>C. difficile</i> infection.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0211424"},"PeriodicalIF":3.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143762852","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":"Novel and diverse features identified in the genomes of bacteria isolated from a hydrothermal vent plume.","authors":"S R Major, J M Polinski, K Penn, M Rodrigue, M J Harke","doi":"10.1128/aem.02593-24","DOIUrl":"https://doi.org/10.1128/aem.02593-24","url":null,"abstract":"<p><p>Hydrothermal vent plumes (HVPs), formed by high-temperature vent emissions, are rich in compounds that support chemosynthesis and serve as reservoirs of microbial diversity and genetic innovation. Through turbulence, mixing, and interaction with subsea currents, vent communities are thought to disperse across ocean basins. In this study, we focused on the plume of the Moytirra hydrothermal vent field, a relatively unexplored site, to investigate its microbial inhabitants. We cultured bacteria from the Moytirra HVP using 11 different media types and performed complete genome sequencing on 12 isolates. Our analyses revealed four putatively novel species from the <i>Thalassobaculum</i>, <i>Sulfitobacter</i>, <i>Idiomarina</i>, and <i>Christiangramia</i> genera. Comparative genomics identified unique genomic islands containing biosynthetic gene clusters, including a novel Non-Ribosomal Peptide Synthetase/Polyketide Synthase cluster, toxin-antitoxin systems, and evidence of horizontal gene transfer facilitated by prophages. These findings underscore the potential of HVPs as a source of novel microbial species and biotechnologically relevant genes, contributing to our understanding of the biodiversity and genetic complexity of these extreme environments.IMPORTANCEHydrothermal vents are dynamic environments that offer unique nutrients for chemosynthetic organisms to drive biology in the deep-sea. The dynamics of these ecosystems are thought to drive genomic innovation in resident populations. Hydrothermal vent plumes (HVPs) mix with surrounding water, carrying local microbiota with them and dispersing for hundreds of kilometers. This study isolated bacteria from a HVP to capture a genomic snapshot of the microbial community, revealing four putatively novel species of bacteria within three taxonomic classes. The addition of these genomes to public databases provides valuable insights into the genomic function, architecture, and novel biosynthetic gene clusters of bacteria found in these extreme environments.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0259324"},"PeriodicalIF":3.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143750791","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":"Adaptive evolution and reverse engineering to explore the low pH tolerance mechanisms of <i>Streptomyces albulus</i>.","authors":"Yuxi Liu, Tianyi Liu, Yulin Zhang, Liang Wang, Hongjian Zhang, Jianhua Zhang, Xusheng Chen","doi":"10.1128/aem.00036-25","DOIUrl":"https://doi.org/10.1128/aem.00036-25","url":null,"abstract":"<p><p><i>Streptomyces albulus</i> is well-known as a cell factory for producing ε-poly-L-lysine (ε-PL), but its ability to produce effectively requires an environment with a pH of about 4.0. Unfortunately, prolonged exposure to low pH environment compromises the cellular integrity of <i>S. albulus</i>, leading to a decrease in the efficiency of ε-PL biosynthesis. To enhance the low pH tolerance of <i>S. albulus</i> and investigate its low pH tolerance mechanisms, we employed adaptive laboratory evolution (ALE) technology to evolve the <i>S. albulus</i> GS114 strain by progressively lowering the environmental pH. This process ultimately yielded the mutant strain ALE3.6, which exhibited significantly improved low pH tolerance at pH 3.6 and achieved a 37.9% increase in ε-PL production compared to the parental GS114 strain under the optimal fermentation condition. The physiological evaluation of the mutant strain ALE3.6 indicated a pronounced enhancement in the integrity of its cell membrane and cell wall under low pH conditions. To identify the key genes involved in low pH tolerance, we employed whole-genome resequencing and quantitative real-time PCR, which pinpointed <i>desA</i>, <i>gatD</i>, and <i>mamU</i> as critical contributors. We further validated the roles of these genes through reverse engineering, which improved both low pH tolerance and ε-PL production efficiency. Finally, we elucidated the response mechanisms of the <i>S. albulus</i> cell membrane and cell wall under low pH stress. This study enhances the understanding of low pH tolerance in the <i>Streptomyces</i> species, particularly regarding the production of valuable biochemical products under challenging environmental conditions.IMPORTANCEIn this study, we improved the viability and ε-poly-L-lysine production efficiency of <i>Streptomyces albulus</i> at low pH by staged adaptive laboratory evolution while simplifying the previously studied fed-batch fermentation strategy. We identified key genes associated with the mutant strains' cell membrane and cell wall phenotypes by utilizing whole-genome resequencing and reverse engineering. Subsequently, we validated the cell membrane and cell wall response mechanisms in <i>S. albulus</i> under low pH conditions.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0003625"},"PeriodicalIF":3.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143750787","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":"Multiple extracellular polymeric substance pathways transcribed by <i>Accumulibacter</i> and the flanking community during aerobic granule formation and after influent modification.","authors":"Laëtitia Cardona, Jaspreet Singh Saini, Pilar Natalia Rodilla Ramírez, Aline Adler, Christof Holliger","doi":"10.1128/aem.01769-24","DOIUrl":"https://doi.org/10.1128/aem.01769-24","url":null,"abstract":"<p><p>Aerobic granular sludge is a biological wastewater treatment process in which a microbial community forms a granular biofilm. The role of <i>Candidatus</i> Accumulibacter in the production of a biofilm matrix composed of extracellular polymeric substances was studied in a sequencing batch reactor enriched with polyphosphate-accumulating organisms. The metabolisms of the microbial populations were investigated using <i>de novo</i> metatranscriptomics analysis. Finally, the effect of decreasing the influent phosphate concentration on the granule stability and microbial activity was investigated. A few weeks after the reactor start-up, the microbial community was dominated by <i>Accumulibacter</i> with up to nine species active in parallel. However, the most active species differed according to sampling time. Decreasing drastically the influent phosphate concentration led to a dominance of the glycogen-accumulating organism <i>Propionivibrio</i>, with some <i>Accumulibacter</i> species still abundant. <i>De novo</i> metatranscriptomics analysis indicated a high diversity of potential extracellular substances produced mainly by <i>Accumulibacter</i>, <i>Azonexus</i>, <i>Candidatus</i> Contendobacter, and <i>Propionivibrio</i>. Moreover, the results suggest that <i>Azonexus</i>, <i>Contendobacter,</i> and <i>Propionivibrio</i> recycle the neuraminic acids produced by <i>Accumulibacter</i>. Changes in the microbial community did not cause the granules to disintegrate, indicating that a <i>Propionivibrio</i>-dominated community can maintain stable granules.IMPORTANCEOne of the main advantages of the aerobic granular sludge wastewater treatment process is the higher settling velocities compared to the conventional activated sludge-based process. In aerobic granular sludge, the biomass is concentrated into a biofilm matrix composed of biopolymers, providing micro-niches to different types of microbial populations. We demonstrate with the help of <i>de novo</i> metatranscriptomics analysis that the formation of granules is a highly dynamic microbial process, even when enriching for a microbial guild, such as phosphate-accumulating organisms. Often underestimated, the flanking community of the main phosphate-accumulating organisms population enriched in the reactor is nonetheless active and transcribing genes related to different extracellular polymeric substance pathways. The multiplicity of the extracellular polymeric substances produced probably helped the matrix to remain stable, thanks to their specific properties. Moreover, the results suggest microbial interactions in extracellular polymeric substance recycling between different microbial populations that can be helpful to prevent a disruption of the granules while stressing out the microbial community.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0176924"},"PeriodicalIF":3.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143750790","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":"Inoculum growth impacts <i>Salmonella</i> and Shiga-toxin producing <i>Escherichia coli</i> resilience on wheat grain.","authors":"Yawei Lin, Carolyn Peterson, Bradley P Marks, Teresa M Bergholz","doi":"10.1128/aem.00177-25","DOIUrl":"https://doi.org/10.1128/aem.00177-25","url":null,"abstract":"<p><p>Previous studies have shown that using a surface growth method for preparing inoculum impacted pathogen population stability and inactivation kinetics. Here, we quantified the desiccation survival and responses to tempering treatment of <i>Salmonella</i> and Shiga-toxin producing <i>Escherichia coli</i> (STEC) on wheat grain when grown using five different methods: broth, lawn-aerobic, lawn-anaerobic, lawn-acid-adapted, and lawn-low inoculum. Three strains of <i>Salmonella</i> and STEC each were individually inoculated onto wheat grain, conditioned to 0.45 <i>a</i>_w and stored up to 24 weeks. Pathogen survival curves on grain were different when inoculated with a lawn-grown culture compared to broth-grown. Acid adaptation of STEC led to increased (<i>P</i> < 0.001) tolerance to desiccation, while no change in <i>Salmonella</i> desiccation tolerance was observed. While most survival curves were better described by the log-linear model, survival of pathogens from broth-grown inoculum was better characterized by the Weibull model. Five-strain cocktails of each species were inoculated onto wheat, stored for 1, 2, 7, 28, and 84 days, followed by tempering for 18 h with three chemical interventions: water (control), 800 ppm chlorine, 5% lactic acid (LA) + 26.6% NaCl and 5% sodium bisulfate (SBS). These treatments led to different (<i>P</i> < 0.001) average reductions of 0.52, 1.04, 1.43, and 1.96 log CFU/g, respectively. The length of storage and inoculum growth method affected (<i>P</i> < 0.001) pathogen survival during tempering. In general, pathogens inoculated on grain survived better during tempering when inoculum was prepared by acid-adapted ≥ lawn-aerobic ≥ low inoculum > lawn-anaerobic = broth.IMPORTANCEOutbreaks linked to wheat flour increased interest in evaluating pathogen survival kinetics. With minimal information on how foodborne pathogens contaminate wheat grain, the \"worst-case scenario\" should be identified to characterize pathogen survival kinetics on grain and be used to assess the effectiveness of food safety interventions. Using an antimicrobial solution during wheat tempering, an existing unit operation where grain is exposed to water prior to milling into flour can be a cost-effective way to mitigate the risk of foodborne pathogens. The lack of consistent inoculum preparation methods makes it difficult to compare results across studies evaluating tempering treatments. We assessed five different inoculum growth methods to quantify pathogen survival during desiccation and long-term storage and pathogen inactivation efficacy of several existing tempering solutions. In addition, these data provide insights on statistically important parameters to consider for low-moisture food challenge study experimental design, such as inoculum growth, inoculation level, and pathogen adaptation.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0017725"},"PeriodicalIF":3.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143750789","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":"Zooplankton protect viruses from sunlight disinfection.","authors":"J A Wang, O Aryal, L N Brownstein, H Shwwa, A L Rickard, A E Stephens, M Lanzarini-Lopes, N S Ismail","doi":"10.1128/aem.02540-24","DOIUrl":"https://doi.org/10.1128/aem.02540-24","url":null,"abstract":"<p><p>Sunlight disinfection is an important inactivation process for enteric viruses in water. Understanding how dark biotic processes, such as zooplankton filter feeding, impact sunlight disinfection for viruses has important implications for public health. This research quantifies the uptake of MS2, a model for enteric viruses, by the filter feeder <i>Branchionus plicatilis</i> (rotifer) and the effects of such uptake on subsequent sunlight inactivation of MS2. Experiments co-incubating MS2 with rotifers showed 2.6 log viral removal over 120 hours. Viable virus was recovered from rotifer bodies after co-incubation, indicating incomplete viral inactivation via ingestion. When live rotifers were co-incubated with MS2 and the system was treated with sunlight, experimental treatments with rotifers showed that the virus was protected with 2-3 log viral inactivation compared to 4.5 log inactivation for sunlight controls without rotifers. Dead rotifers placed in the system did not show the same magnitude of protection effects, indicating that active filter feeding of rotifers is associated with protection from sunlight. Data from this study show that zooplankton may serve as a vector for viruses and reduce the efficiency of sunlight inactivation.IMPORTANCEEnteric viral contamination in water is a leading global cause of waterborne disease outbreaks. Sunlight inactivation is an important disinfection mechanism in natural waters, but accurately modeling inactivation is challenging due to the complex nature of aquatic systems. Zooplankton play a critical role in natural systems and are known to inactivate bacteria, but their interaction with viruses is not well understood. Our research examines the impact of a model zooplankton species on the sunlight disinfection of viruses. The results from this study address knowledge gaps in the importance of dark processes such as zooplankton filter feeding and their impact on viral fate.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0254024"},"PeriodicalIF":3.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143750792","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":"Identity and timing of protist inoculation affect plant performance largely irrespective of changes in the rhizosphere microbial community.","authors":"Nathalie Amacker, Zhilei Gao, Alexandre L C Jousset, Stefan Geisen, George A Kowalchuk","doi":"10.1128/aem.00240-25","DOIUrl":"https://doi.org/10.1128/aem.00240-25","url":null,"abstract":"<p><p>Bacterivorous soil protists can have positive impacts on plant performance, making them attractive targets for novel strategies to improve crop production. However, we generally lack the knowledge required to make informed choices regarding the protist species to be used or the optimal conditions for such amendments. Here, we examined how identity, diversity, and timing of inoculation of well-described protists impacted plant development and rhizosphere microbiome assembly. We first studied the impact of individual inoculation of six well-characterized protists on lettuce growth, with <i>Cercomonas</i> sp. S24D2 emerging as the strain with the largest impact on plant growth. In a second step, we created a three-protist species mixture inoculant by adding two protist species (<i>Acanthamoeba</i> sp. C13D2 and a heterolobosean isolate S18D10), based on differences in their feeding patterns. We then inoculated <i>Cercomonas</i> sp. either individually or in the protist mixture to lettuce plants 1 week before, simultaneously with, or 1 week after seedling transfer. We monitored plant growth and nutrient content, as well as impacts on the resident soil and rhizosphere microbiome composition. We found that early protist inoculation provided the greatest increase in aboveground biomass compared to the non-inoculated control. Single- and mixed-species inoculations had similar impacts on plant development and only minor impacts on prokaryotic community composition. While early inoculation seems to be the most promising timing for eliciting the positive effects of protist amendments, further, more systematic studies will be necessary to determine the conditions and ecological interactions that yield consistent and predictable improvements in plant performance.</p><p><strong>Importance: </strong>The application of microorganisms, including bacterivorous soil protists, has been increasingly suggested as a sustainable agricultural approach. While positive impacts of the presence of predatory protists have been generally reported, the effects of the selected species and amendment conditions are largely unknown. Here, we examined how identity, diversity, and timing of inoculation of well-described protists impacted plant development and rhizosphere microbiome assembly. One species emerged as the one having the strongest impact in our specific system. This result highlights the importance of species selection for optimal outcome, but also suggests a huge potential in the barely investigated protist diversity for targeted application. Furthermore, the application of the inoculants before plant transfer showed the strongest effects on plants, providing some useful and new insights on the optimal time for such amendments.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":" ","pages":"e0024025"},"PeriodicalIF":3.9,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143750788","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}