International Microbiology最新文献

{"title":"Nematicidal and plant growth-promoting rhizobacteria: a sustainable strategy for controlling Tylenchulus semipenetrans and enhancing citrus growth.","authors":"Btissam Zoubi, Mohamed Hijri, Fouad Mokrini, Abdelilah Iraqi Housseini, Ahmed Qaddoury","doi":"10.1007/s10123-025-00652-9","DOIUrl":"https://doi.org/10.1007/s10123-025-00652-9","url":null,"abstract":"<p><p>Tylenchulus semipenetrans is a soil-borne pathogen that causes substantial damage and economic losses to citrus crops worldwide. Due to the high toxicity of chemical nematicides to humans and the environment, biocontrol bacteria have emerged as a promising alternative for managing citrus nematodes. This study aimed to screen bacterial strains for their efficacy to control T. semipenetrans and assess their impact on citrus plant growth. A total of 107 bacterial strains were isolated from the soil and roots of infested citrus trees. Among these, five strains exhibited significant nematicidal activity against T. semipenetrans. Four bacterial densities were tested for each strain: 3.6 × 10⁵, 2.5 × 10⁴, 3.6 × 10³, and 1.2 × 10³ cells/ml. These strains were tested both individually and in combination to evaluate their efficacy. The five strains were identified as Variovorax paradoxus, Bacillus pseudomycoides, Bacillus simplex, Bacillus cereus, and Paracoccus speluncae based on physiological, biochemical, and molecular (16S rRNA gene sequences) analyses. Juvenile mortality (J2s) and egg hatching inhibition were positively correlated with bacterial concentration and exposure duration. The highest juvenile mortality (100%) was observed with a combination of all five bacteria (3.6 × 10⁵ cells/ml) after 96 h, while B. cereus alone achieved 98.98% mortality. The maximum nematicidal activities of the bacterial filtrates were generally observed between the 4th and 6th days of incubation, coinciding with peak bacterial growth and biomass production. The selected isolates also demonstrated the ability to produce indole acetic acid and solubilize phosphorus. In greenhouse experiments, the five isolates reduced T. semipenetrans populations by up to 62.96% compared to the control. Additionally, all rhizosphere bacteria and their combination significantly enhanced plant growth parameters (p < 0.0001). Notably, P. speluncae BR21 has not previously been tested for nematicidal effects on any nematode, making this the first documented report of its nematicidal potential.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143541077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methanotroph Methylotuvimicrobium alcaliphilum 20Z-3E as a fumarate producer: transcriptomic analysis and the role of malic enzyme.","authors":"O N Rozova, S Y But, O I Melnikov, K S Shavkunov, G A Ekimova, V N Khmelenina, I I Mustakhimov","doi":"10.1007/s10123-025-00647-6","DOIUrl":"https://doi.org/10.1007/s10123-025-00647-6","url":null,"abstract":"<p><p>The halotolerant obligate methanotroph Methylotuvimicrobium alcaliphilum 20Z is a promising biotechnological strain that has been repeatedly tested as a producer of high-added-value polycarbon compounds. The mutant M. alcaliphilum 20Z-3E lacking two fumarases and a malic enzyme is a potential fumarate producer. The analysis of strand-specific 3'-end sequencing of mRNA did not reveal any effects of the mutations on the central metabolism of the methanotroph; however, it showed a dramatic change in the expression of putative iron transport genes, as well as some genes associated with stress response. When the strain 20Z-3E grows at low salinity under methane, some part of fumarate is formed from aspartate, since the increase in salinity results in the biosynthesis of ectoine and the decrease in fumarate concentration. However, when the strain grows on methanol, the fumarate pool is lower and does not depend on the salinity of the medium. Our results have shown that deletion of the mae gene encoding malic enzyme makes a significant contribution to the fumarate accumulation. The strain 20Z-2F with the deletion of only two genes, fumI and fumII, demonstrated delayed growth under methane in comparison with 20Z and 20Z-3E strains. The branching of the tricarboxylic acid cycle due to the adenylosuccinate shunt, as well as the presence of malic enzyme, provides metabolic flexibility to M. alcaliphilum, which allows the methanotroph to adapt to a variety of external conditions and, on the other hand, us to modify its genome to obtain valuable products.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atmospheric CO₂ flux and planktonic food web relationships in temperate marsh systems: insights from in situ water measurements.","authors":"Xaus Lucila, Moncelon Raphaël, Mayen Jérémy, Bergeon Lauriane, Dubillot Bénédicte, Pineau Philippe, Emery Claire, Vagner Marie, Robin Francois-Xavier, Azémar Frédéric, Tackx Michèle, Dupuy Christine, Polsenaere Pierre","doi":"10.1007/s10123-025-00650-x","DOIUrl":"https://doi.org/10.1007/s10123-025-00650-x","url":null,"abstract":"<p><p>While research has extensively investigated the dynamics of CO₂ water partial pressure (pCO₂) and planktonic food webs (PFWs) separately, there has been limited exploration of their potential interconnections, especially in marsh typologies. This study's objectives were to (1) investigated if pCO₂ and atmospheric CO₂ flux can be elucidated by PFW topologies, and (2) ascertain if these potential relationships are consistent across two distinct \"Blue Carbon\" ecosystems. Abiotic and biotic variables were measured in two contrasting wetlands at the Atlantic French coast: a saltwater (SM, L'Houmeau) and a freshwater marsh (FM, Tasdon). SM acted as a weak carbon source, with pCO₂ between 542 and 842 ppmv. Conversely, FM exhibited strong atmospheric CO₂ source or sink characteristics, varying with seasons and stations, with pCO₂ between 3201 and 114 ppmv. Five PFW topologies were linked to varying pCO₂ across the two ecosystems: three stable topologies ('biological winter', 'microbial', 'multivorous' PFW) exhibited consistently high pCO₂ values (FM: 971, 1136, 3020 ppmv; SM: 'biological winter' not observed, 842, 832 ppmv), while two transient topologies ('weak multivorous' and 'weak herbivorous') displayed lower and more variable pCO₂ values (FM: from 127 to 1402 ppmv; SM: from 638 to 749 ppmv). Seasonality emerged as an influencing factor for both pCO₂ dynamics and PFW. However, PFW in FM did not demonstrate a seasonal equilibrium state, potentially hindering a clearer understanding of the relationship between pCO₂ and PFW. This is the first documented association between PFW topologies and pCO₂ dynamics in \"Blue Carbon\" marsh environments.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143556880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling the potential of bioslurry and biogenic ZnO nanoparticles formulation as significant bionanofertilizer by ameliorating rhizospheric microbiome of Vigna radiata.","authors":"Abhinav Singh, Ritika Chauhan, Ram Prasad, Amay A Agrawal, Pankaj Sah, Arti Goel","doi":"10.1007/s10123-025-00649-4","DOIUrl":"https://doi.org/10.1007/s10123-025-00649-4","url":null,"abstract":"<p><p>Advancements in nanotechnology, particularly the use of bionanofertilizers, show promise for sustainable agriculture by enhancing soil health and reducing reliance on conventional fertilizers. This study explored the impact of a bioslurry and biogenic zinc oxide (ZnO) nanoparticle formulation on microbial diversity in the rhizosphere of Vigna radiata (mung bean) using 16S rRNA sequencing. High-quality reads from both untreated and treated soil samples revealed a dominance of Archaea, though its proportion was reduced in the treated sample (66% in untreated, 58% in treated). The treated soil showed an increased abundance of beneficial bacterial phyla, including Acidobacteria (+ 6%), Actinobacteria (+ 2%), and Firmicutes (+ 2%). Notably, Acidobacteria-6 and Chloroacidobacteria, essential for nutrient cycling, were enriched in treated soil. Alpha diversity (Chao1 and Shannon indices) was lower in treated samples, indicating selective enhancement of beneficial microbes. Functional analyses like Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and Statistical Analysis of Taxonomic and Functional Profiles (STAMP) analysis highlighted increased pathways related to motility, chemotaxis, and metabolic processes in the treated soil. These findings suggest that ZnO NPs and bioslurry treatment at 250 ppm improves soil microbial composition and functional attributes, supporting its potential as a bionanofertilizer for soil health restoration and enhanced plant growth.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143541292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fungal mediated production of novel metabolites of meloxicam and their tankyrase-2 inhibition potentials: an in silico study.","authors":"Srisailam Keshetti, Gurram Shyam Prasad","doi":"10.1007/s10123-025-00636-9","DOIUrl":"https://doi.org/10.1007/s10123-025-00636-9","url":null,"abstract":"<p><p>The current study focuses on the isolation of a thermophilic fungus capable of biotransforming meloxicam to produce novel metabolites with potential tankyrase inhibitory properties. The isolated strain is identified as Rhizomucor pusillus, confirmed through both morphological and molecular methodologies. The biotransformation process was monitored using high-performance liquid chromatography (HPLC) in conjunction with a two-stage fermentation approach. Previous research, along with LC-MS/MS analyses, has successfully characterized the metabolites generated, providing structural validation. This fungus enabled the conversion of meloxicam into four metabolites: 5-hydroxy methyl meloxicam (M1), 5-carboxy meloxicam (M2), and two previously unreported metabolites (M3 and M4), under controlled conditions of pH 6.0 and a temperature of 40 °C over a 3-day shaking culture period. The fungal strain R. pusillus has demonstrated the ability to generate notable metabolites of meloxicam, particularly M1 and M2, as evidenced by research conducted on mammals. Moreover, in silico analyses have revealed the presence of two novel metabolites that may inhibit tankyrase-2. This finding indicates that R. pusillus possesses an enzymatic system comparable to that found in mammals, facilitating the environmentally sustainable and economically viable production of metabolites. Additionally, this strain is capable of synthesizing substantial amounts of metabolites that could potentially exhibit pharmacological effects.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143523348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assembly of a synthetic microbial community to ferment rice (Oryza sativa) bran for aquaculture feedstuff.","authors":"Antonio de Oliveira Vieira, Juliano De Dea Lindner, Adriano Faria Palmieri, Caio Francisco Santana Farias, Scheila Anelise Pereira Dutra, Ivan De Marco, Marco Shizuo Owatari, Maurício Laterça Martins, José Luiz Pedreira Mouriño","doi":"10.1007/s10123-025-00651-w","DOIUrl":"https://doi.org/10.1007/s10123-025-00651-w","url":null,"abstract":"<p><p>Raw materials of plant origin, such as rice bran (Oryza sativa; RB), are promising alternatives to fishmeal in aquaculture feeds, offering a low-cost solution. However, due to antinutritional factors and reduced digestibility, direct use of RB is limited. Fermentation is an effective, cost-effective, and environmentally friendly technique that improves the nutritional quality of RB, enhancing nutrient availability and digestibility and reducing harmful compounds. Fermented RB improved growth, feed utilization, immune competence, and gut health, contributing to more sustainable aquaculture practices. The study aimed to evaluate the solid-state fermentation influence of a synthetic microbial community (SynCom) on RB (RBMC). The fermentation by the microbial consortium showed significant changes in RB physical-chemical composition and crude fiber and protein. Significant reductions were observed for ether extract, mineral matter, phosphate, phosphorus, and potassium compared with the naturally fermented RB (RBNF). Sodium, calcium, and iron contents increased by 43.03, 60.77, and 74.58%, respectively, compared to RBNF. A significant increase was observed in the fermented RBMC for essential and non-essential amino acids. Scanning electron microscopy revealed changes in the microstructure of the RB, in addition to the presence of microbial aggregates morphologically similar to the individuals used as inoculum. The RB fermentation using SynCom significantly improved the quality of the RB by-product feedstuff. The use of fermented RB in diet formulations for aquatic organisms is desirable because it enables the reuse of this industrial co-product, which is rich in nutrients and biological value.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143523343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phyto-and myco-chemical profiling, bioactivity, and in silico docking study of endophytic fungi and host-Setaria flavida.","authors":"R Nischitha, M B Shivanna","doi":"10.1007/s10123-025-00646-7","DOIUrl":"https://doi.org/10.1007/s10123-025-00646-7","url":null,"abstract":"<p><p>Endophytic fungi are known to produce a wide array of bioactive compounds with significant pharmaceutical potential. This study focuses on exploring the antioxidant properties of endophytic fungi associated with Setaria flavida (Retz.) Veldkamp, in Karnataka, India. The fungi were isolated and characterized using morphological and internal transcribed spacer (ITS) sequence analyses. Five endophytic isolates were screened for antioxidant activity using spectrophotometric and electrochemical methods. The ethyl acetate extracts of Curvularia protuberata and methanolic extract of S. flavida showed strong antioxidant activity against DPPH, ABTS, H₂O₂, and nitric oxide radicals. Further, C. protuberata and S. flavida metabolites were characterized by Orbitrap High-Resolution Liquid Chromatography-Mass Spectrometer (OHR LC-MS). Molecular docking studies revealed compounds: (22E)-stigmasta-3,5,22-triene, andrographolide, gingerol, nobiletin, retusin, tangeritin, 1-benzoyl-4-(3,5-dibromobenzoyl) piperazine, 2-pyrazolin-5-ol, 5-tridecafluorohexyl-3-methyl-1-(3-pyridylcarbonyl), dexamethasone, griseofulvin, and S-benzyl-N[(benzyloxy)carbonyl] cysteinyltyrosine with potent antioxidant activity, inhibiting enzymes like xanthin oxidase (3NRZ) lipoxygenase (1N8Q) and myeloperoxidase (1DNU). The study suggests that these endophytic fungi and host grass could lead to the production of promising drugs in the pharmaceutical industry.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143491965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the techno-functional properties of lactobacilli strains originated from Bos indicus and Bubalus bubalis calves for probiotic potential.","authors":"Sachin Kumar, Nutan Chauhan, Tejshi Chauhan, Sravani Balaga, Nitin Tyagi, Ashis Kumar Samanta","doi":"10.1007/s10123-025-00641-y","DOIUrl":"https://doi.org/10.1007/s10123-025-00641-y","url":null,"abstract":"<p><p>The current study was undertaken to isolate, characterize, and cluster lactobacilli strains of indigenous cattle (Bos indicus) and buffalo (Bubalus bubalis) calf origin to develop a species-specific multistrain potential probiotic adjunct. Bacterial strains were isolated from the feces of Bos indicus and Bubalus bubalis calves of different breeds, i.e., Sahiwal (SC), Tharparker (TP), and Gir (GC) cattle and Murrah buffalo (MB). The fecal samples were aseptically taken from five healthy calves (5-10 days old) of each breed (a total of 20 animals). Accordingly, 105 bacteria were isolated, 52 of which were catalase negative, Gram-positive, and vancomycin resistant. These isolates were presumed to be Lactobacillus species, and genus-specific PCR was used to confirm their identification. Among the 52 isolates, 22 strains demonstrated greater acid tolerance, while 29 isolates showed superior bile tolerance, with survivability greater than 90%. Fifteen isolates capable of tolerating both acid and bile were further selected, and their identities were confirmed via 16S rRNA sequencing. Cluster analysis of the phylogenetic tree revealed three different species: Ligilactobacillus salivarius (8), Ligilactobacillus agilis (1), and Limosilactobacillus reuteri (6). All lactobacilli strains showed coaggregation with Escherichia coli ATCC25922 and Salmonella arizonae ATCC13314. All the isolates were found non-hemolytic and non-mucinolytic. Principal component analysis (PCA) revealed that L. reuteri GC09, L. salivarius GC12, L. agilis MB08, L. salivarius MB14, L. reuteri SC01, and L. reuteri MB11 possessed the most desirable attributes of probiotics. Based on these findings, these strains could be used to develop multi-strain probiotic adjunct for calves.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143467940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Epidemiology, risk factors, and clinical characteristics of amoebic liver abscess: a systematic review and meta-analysis from India.","authors":"Syed Muhammad Sarosh Ghalib, Faizeaab Hashmi, Umra Fatima Zuberi, Sana Aqeel","doi":"10.1007/s10123-025-00645-8","DOIUrl":"https://doi.org/10.1007/s10123-025-00645-8","url":null,"abstract":"<p><p>Amoebiasis and its extraintestinal manifestation amoebic liver abscess (ALA) is an endemic disease in tropical and subtropical countries. However, no meta-analysis on the prevalence, associated risk factors, and clinical markers has been performed. This study aims to bridge this research gap. Based on our inclusion criteria, 18 studies were selected for analysis. Using the \"meta\" package in RStudio, forest plots, regression analysis, and funnel plots were used to represent the proportional meta-analysis, significance of the correlation, and quality and publication bias of the included studies, respectively. A high prevalence of ALA (67%, p = 1.762 × 10^-15) was noted in cases of liver abscess. ALA was significantly more prevalent in males (86%, p = 2.25 × 10^-8), individuals with poor socioeconomic conditions (75%, p = 0.02496), history of alcohol consumption (63%, p = 1.421 × 10^-8), and diabetic comorbidity (35%, p = 0.01169). There was a significant correlation with abdominal pain (91%, p = 1.286 × 10^-12), infected right lobe (81%, p = 0.002), fever (73%, p = 2.567 × 10^-12), hepatomegaly (69%, p = 1.223 × 10^-5), anemia (69%, p = 1.223 × 10^-5), and jaundice (11%, p = 0005258) in the affected individuals. We conclude that the above-stated risk factors and clinical markers are significantly associated with ALA and suggest that medical professionals in endemic regions must attribute liver abscess to be etiologically amoebic and correlate the disease manifestation with the risk factors and clinical markers. Further, research is needed to better understand disease manifestation.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143467939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biodiversity of strains belonging to the freshwater genus Aquirufa in a riparian forest restoration area in Salzburg, Austria, with a focus on the description of Aquirufa salirivi sp. nov. and Aquirufa novilacunae sp. nov.","authors":"Alexandra Pitt, Stefan Lienbacher, Johanna Schmidt, Meina Neumann-Schaal, Jacqueline Wolf, Hannah Wenng, Aharon Oren, Zoe Huber, Martin W Hahn","doi":"10.1007/s10123-025-00642-x","DOIUrl":"https://doi.org/10.1007/s10123-025-00642-x","url":null,"abstract":"<p><p>During a citizen science project, four freshwater habitats in a riparian forest restoration area in Salzburg, Austria, were sampled. The primary aim was to obtain bacterial strains of the genus Aquirufa, a group of typical and widespread freshwater bacteria. Numerous pure cultures of Aquirufa strains could be obtained, three of them originating from the river Salzach, a newly created pond and the lake Ausee represented new species. Strain 1-SAACH-A3^T was characterized by a genome size of 3.2 Mbp and a G + C value of 38.4 mol% and encoded genes predicted for nitrate uptake and nitrous oxide utilization. Strains BAHN-186B^T and 2-AUSEE-184A6 were characterized by a genome size of 2.4 Mbp and a G + C value of 42.4 and 42.2 mol%, respectively, and encoded genes predicted for the light-harvesting rhodopsin system. Calculated whole-genome average nucleotide identity values with Aquirufa type strains resulted in a maximum value of 93.65% for comparison of strain 1-SAACH^T with the type strain of Aquirufa ecclesiirivi, which is slightly under the proposed threshold of species demarcation. The calculated gANI value comparing strains BAHN-186B^T and 2-AUSEE-184A6 revealed 95.76%, thus a value slightly above the threshold. Further analyses revealed that the three new strains represent two new species, proposed here as Aquirufa salirivi sp. nov. with type strain 1-SAACH-A3^T (= DSM 117800^T = JCM 37097^T) and Aquirufa novilacunae sp. nov. with type strain BAHN-186B^T (= DSM 118143^T = JCM 37099^T). Analyses of 123 publicly available metagenomes and a metagenome of the lake Ausee resulted in no detection of A. salirivi sp. nov. In contrast, A. novilacunae sp. nov. could be detected in 15 water samples of rivers, mainly from Asia, but also from North America and Australia. The analyses suggested that the species occurs in most of these samples in low relative abundance, detections derived from metagenomes of water samples from the river Yangtze in the subtropical zone could be interpreted as occurrence in higher abundances.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143440810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}