16S rDNA Sequence Research Articles

Combined metabolomics and 16S rDNA sequence analyses of the gut microbiome reveal the action mechanism of Fructus Akebiae against hepatic fibrosis

ObjectivesTo explore the mechanism underlying the effect of Fructus Akebiae (FAE) against hepatic fibrosis in mice through combined network pharmacology, liver metabolomics, and 16S rDNA analyses of the gut microbiota.MethodsIn this study, we randomly divided mice into the control, model, FAE high-dose, FAE medium-dose, and FAE low-dose groups to analyze the pathological changes in the hepatic fibrosis and levels of the α-SMA, collagen 1, Nuclear Factor Kappa B (NF-κ B), Toll Like Receptor 4 (TLR4). The gut microbiota was analyzed through 16S rDNA sequencing analysis of liver metabolites using liquid chromatography-mass spectrometry. Furthermore, network pharmacology was used to determine the specific molecular regulation mechanism of FAE in hepatic fibrosis treatment.ResultsFAE treatment markedly improved the pathological changes in the hepatic fibrosis. Analysis revealed that FAE administration reversed the carbon tetrachloride (CCl4)-induced dysbiosis by increasing the abundance of Akkermansia and reducing that of Cyanobacteria. Additionally, metabolomic analysis showed that FAE treatment reversed the CCl4-induced metabolic disorders by regulating amino and nucleotide sugar metabolism. Furthermore, correlation analysis showed that Akkermansia and Verrucomicobiota were closely related to D-tolasaccharide and maltotetraose saccharide. Moreover, network pharmacology indicated that FAE might regulate the signaling pathway through the JUN/CASP3/NOS3/PTGS2/HSP90AA1 during treatment.ConclusionFAE may be a promising treatment for hepatic fibrosis, and its protective effects are associated with improvements in the microbiome and metabolic disorders.

Dynamic Spread of Antibiotic Resistance Determinants by Conjugation to a Human-Derived Gut Microbiota in a Transplanted Mouse Model

Background. Antibiotic-resistant (AR) bacteria pose an increasing threat to public health, but the dynamics of antibiotic resistance gene (ARG) spread in complex microbial communities are poorly understood. Conjugation is a predominant direct cell-to-cell mechanism for the horizontal gene transfer (HGT) of ARGs. We hypothesized that commensal Escherichia coli donor strains would mediate the conjugative transfer of ARGs to phylogenetically distinct bacteria without antibiotic selection pressure in gastrointestinal tracts of mice carrying a human-derived microbiota with undetectable levels of E. coli. Our objective was to identify a mouse model to study the factors regulating AR transfer by conjugation in the gut. Methods. Two donor E. coli strains were engineered to carry chromosomally encoded red fluorescent protein, and an ARG- and green fluorescent protein (GFP)-encoding broad host range RP4 conjugative plasmid. Mice were orally gavaged with two donor strains (1) E. coli MG1655 or (2) human-derived mouse-adapted E. coli LM715-1 and their colonization assessed by culture over time. Fluorescence-activated cell sorting (FACS) and 16S rDNA sequencing were performed to trace plasmid spread to the microbiota. Results. E. coli LM715-1 colonized mice for ten days, while E. coli MG1655 was not recovered after 72 h. Bacterial cells from fecal samples on days 1 and 3 post inoculation were sorted by FACS. Samples from mice given donor E. coli LM715-1 showed an increase in cells expressing green but not red fluorescence compared to pre-inoculation samples. 16S rRNA gene sequencing analysis of FACS GFP positive cells showed that bacterial families Lachnospiraceae, Clostridiaceae, Pseudomonadaceae, Rhodanobacteraceae, Erysipelotrichaceae, Oscillospiraceae, and Butyricicoccaceae were the primary recipients of the RP4 plasmid. Conclusions. Results show this ARG-bearing conjugative RP4 plasmid spread to diverse human gut bacterial taxa within a live animal where they persisted. These fluorescent marker strategies and human-derived microbiota transplanted mice provided a tractable model for investigating the dynamic spread of ARGs within gut microbiota and could be applied rigorously to varied microbiotas to understand conditions facilitating their spread.

Bithyniid snails (Gastropoda: Bithyniidae) infected with Xiphidiocercariae in Thailand include a new record of Bithynia siamensis siamensis as the intermediate host of Plagiorchis and Paralecithodendrium.

Bithyniids are freshwater snails that play a crucial role in the transmission of various parasitic trematodes of medical and veterinary importance. In this study, we explored the prevalence of cercarial trematode infections in bithyniid snails from Thailand and examined the species diversity of both the intermediate snail hosts and parasite larvae. A total of 688 bithyniid snails were collected from diverse natural habitats at 24 locations in 16 provinces across 5 regions of Thailand. The presence of larval trematode infections was examined using the cercarial shedding method. Both the collected snails and the emerging cercariae were identified at the species level using a combination of morphological and molecular techniques. The mitochondrial COI and 16S rDNA sequences of bithyniid snails, along with the ITS2 sequences of cercariae, were obtained via PCR amplification and sequencing. Three species of bithyniid snails were identified in this study: Bithynia funiculata, Bithynia siamensis siamensis, and Hydrobioides nassa. Among these species, B. s. siamensis exhibited the highest population density, followed by B. funiculata and H. nassa. The overall rate of cercarial infection in the bithyniid snails was relatively low, at 1.45%. H. nassa snails had the highest infection prevalence, at 11.11%, while B. s. siamensis had a prevalence of 1.39%. Only the morphological type of the xiphidiocercariae was detected. BLASTn searches in GenBank and phylogenetic trees based on xiphidiocercariae were used to classify the samples into four different families spanning two superfamilies of digenean trematodes. The genera Plagiorchis, Prosthogonimus, Paralecithodendrium, and cercaria of Renicolidae are reported for the first time in B. s. siamensis. Plagiorchis and Paralecithodendrium are significant genera of zoonotic trematodes. These findings indicate that B. s. siamensis and H. nassa can act as the first intermediate hosts for various parasitic trematodes in Thailand.

The co-occurrence patterns and assembly mechanisms of microeukaryotic communities in geothermal ecosystems of the Qinghai-Tibet Plateau

Geothermal spring ecosystems, as extreme habitats, exert significant environmental pressure on their microeukaryotic communities. However, existing studies on the stability of microeukaryotic communities in geothermal ecosystems across different habitats and temperature gradients are still limited. In this study, we used high-throughput 18S rDNA sequencing in combination with environmental factor analysis to investigate the co-occurrence patterns, assembly mechanisms, and responses to environmental changes of microeukaryotic communities in sediment and water samples from 36 geothermal springs across different temperature gradients in southern Tibet. The results show that with increasing temperature, the network stability of microeukaryotic communities in sediments significantly improved, while the stability in water communities decreased. The assembly mechanisms of microeukaryotic communities in both sediment and water were primarily driven by undominant processes within stochastic processes. Latitude and longitude were the key factors influencing changes in sediment community composition, while water temperature and electrical conductivity were the major environmental factors affecting water community composition. Additionally, the stability of the geothermal community network was closely related to its response to external disturbances: sediment communities, being in relatively stable environments, demonstrated higher resistance to disturbances, whereas water communities, influenced by environmental changes such as water flow and precipitation, exhibited greater dynamic variability. These findings not only enhance our understanding of the ecological adaptability of microeukaryotic communities in geothermal springs but also provide valuable insights into how microorganisms in extreme environments respond to external disturbances. This is especially significant for understanding how microeukaryotic communities maintain ecological stability under highly dynamic and stressful environmental conditions.

Fecal microbiota transplantation alleviates radiation enteritis by modulating gut microbiota and metabolite profiles.

This study investigates the safety and underlying mechanisms of fecal microbiota transplantation (FMT) in treating radiation enteritis (RE). A rat model of RE was established with six groups: NC, RT, H-FMT, modified FMT (M-FMT), L-FMT, and BTAC. The therapeutic effects of FMT were assessed using the Disease Activity Index (DAI), histological analysis, and biochemical tests, including ink-propelling, xylitol exclusion, and enzyme-linked immunosorbent assay (ELISA). Gut microbiota alterations and fecal metabolism were analyzed via 16S rDNA sequencing and targeted metabolomics. The results demonstrated that FMT, particularly in the M-FMT group, effectively alleviated RE by reducing DAI scores, histological damage, and inflammatory markers while enhancing enzyme activity, superoxide dismutase (SOD) levels, and intestinal absorption. FMT also modulated gut microbiota composition, increasing beneficial species, such as Blautia wexlerae and Romboutsia timonensis while decreasing Enterococcus ratti. Metabolomics analysis revealed that FMT influenced niacin, nicotinamide, and starch metabolism, with notable changes in pantothenic acid and fatty acid levels. Spearman correlation analysis further indicated that these microbial shifts were associated with improved metabolic profiles. Overall, FMT mitigates RE by regulating gut microbiota and metabolites, with pantothenic acid and fatty acids emerging as potential therapeutic targets. Further research is needed to explore the underlying mechanisms in greater detail.

New bitongling regulates gut microbiota to predict angiogenesis in rheumatoid arthritis via the gut-joint axis: a deep neural network approach

BackgroundRheumatoid arthritis (RA) is a persistent autoimmune disorder marked by inflammation and joint damage. Although current treatments, such as disease-modifying antirheumatic drugs (DMARDs), help control symptoms, they frequently cause substantial side effects, highlighting the urgent need for safer and more effective alternatives. Recent research indicates that gut microbiota might be pivotal in RA development through the “gut-joint axis,” presenting novel therapeutic possibilities.PurposeThis study seeks to explore the therapeutic potential of the traditional Chinese medicine (TCM) compound new bitongling (NBTL) for RA, with an emphasis on its capacity to regulate gut microbiota and suppress angiogenesis via the vascular endothelial growth factor (VEGF) signaling pathway.MethodsWe utilized a collagen-induced arthritis (CIA) rat model to assess the impact of NBTL. The study employed 16S ribosomal DNA (16S rDNA) sequencing to analyze gut microbiota composition, machine learning techniques to identify characteristic microbial taxa, and transcriptomic analysis (GSVA) to assess the impact on the VEGF signaling pathway. The findings were further validated through analysis with deep neural network models and in vivo/in vitro experiments, including western blot, immunofluorescence, and miRNA analysis.ResultsNBTL treatment markedly diminished inflammation in RA rats, evidenced by the reduced expression of TNF-α, IL-17, IL-6, and ASC in synovial tissues. Histopathological analysis confirmed alleviation of joint damage. Five characteristic microbial taxa, including f_Mycoplasmataceae, s_Metamycoplasma_sualvi, and g_Prevotellaceae_Ga6A1_group, were identified and associated with NBTL’s modulation of the VEGF pathway. Gene set variation analysis (GSVA) revealed significant downregulation of the VEGF signaling pathway following NBTL treatment. Subsequent experiments confirmed that NBTL inhibited VEGF and its receptors, VEGFR1 and VEGFR2, along with HIF-1α (hypoxia-inducible factor 1-alpha), thereby reducing angiogenesis. Additionally, NBTL upregulated miR-20a-5p and miR-223-3p, contributing to its anti-angiogenic effects.ConclusionNBTL exhibits significant therapeutic potential in RA by modulating gut microbiota and inhibiting the VEGF signaling pathway. These findings support NBTL’s use as a promising candidate for RA treatment, emphasizing the need for further research on its mechanisms and clinical application.

Continuous monitoring and comparative genetic analysis of attached outbreak species of Ulva prolifera in the Southern Yellow Sea.

With years of green tide outbreaks in the Southern Yellow Sea (SYS) and climate change, early findings over multiple years suggest that the green tide may originate from various pathways. Previous studies have identified attached outbreak species of U. prolifera in the intertidal zone along the SYS coast. However, there has been limited research tracking and monitoring their succession processes or conducting comparative genetic analyses with floating U. prolifera in corresponding years. Therefore, this study continuously monitors the succession process of attached outbreak species of U. prolifera along the SYS coast, utilizing morphological and molecular biological methods to investigate their phylogenetic relationship with floating U. prolifera. The findings suggest that the distribution of the attached outbreak species of U. prolifera occurred in the intertidal zone along the coast of Rudong, Jiangsu Province from February to April 2023. However, subsequent surveys up to March 2024 did not observe their presence again. Apart from May and June 2023, other months consistently exhibited a long-term presence of various species of attached macroalgae, including Ulva flexuosa, Ulva meridionalis, and Ulva linza. The morphological characteristics of the attached outbreak species closely resemble those of the floating U. prolifera. Genetic diversity analysis using ITS and 5S rDNA sequences revealed that all attached outbreak species and floating U. prolifera in the same year belong to the same haplotype with high conservation and consistency in their ITS and 5S rDNA sequences. This study also identified natural shedding among the attached outbreak species, confirming their potential as supplementary sources contributing to Yellow Sea green tide outbreaks along the SYS coast.

Valeriana jatamansi jones improves depressive behavior in CUMS mice by modulating vitamin B12-related ileal homeostasis.

Valeriana jatamansi Jones (V. jatamansi) is a traditional Chinese medicine (TCM). It was recorded in Diannan Bencao, Compendium of Materia Medica and some local medical books and was described as useful in treating insomnia, distraction, poor mental health, vomiting and diarrhea. To investigate whether the antidepressant effect of V. jatamansi may operate through modulating vitamin B12-related ileal homeostasis using a chronic unpredictable mild stress (CUMS) mouse model. A CUMS-induced depression model was established in mice for five weeks, after which V. jatamansi extracts were administered for three weeks. At week eight, the forced swimming test and novelty-suppressed feeding test were conducted. H&E staining assessed ileal pathology, while 16S rDNA sequencing analyzed changes in ileal microbiota. Additionally, B12 in serum, cubilin (CUBN) and amnionless (AMN) in ileal tissue, methionine synthase (MS) and homocysteine (Hcy) in the hippocampus were measured using ELISA, and the correlations between them and ileal microbiota were explored. Mice in the model group exhibited significant depressive behavior. However, after treatment with V. jatamansi, immobility time and feeding latency were improved. H&E staining demonstrated the repairing effect of V. jatamansi on the ileum regarding tissue damage. The alpha and beta diversity of the ileal microbiota were regulated and converged to the normal group. Additionally, V. jatamansi modulated B12, CUBN, AMN, MS, and Hcy levels. Correlation analysis showed that there are certain correlations between a variety of microorganisms and B12-related factors. These findings suggest that the mechanism of V. jatamansi in treating depression may be through repairing depression-associated intestinal damage. This repair process may affect the intestinal absorption and microbial production of B12. By reversing the reduction of serum B12, V. jatamansi ultimately reduces the infiltration of Hcy into the CNS.

Melatonin Ameliorates Age-Related Sarcopenia via the Gut-Muscle Axis Mediated by Serum Lipopolysaccharide and Metabolites.

Sarcopenia affects the quality of life and increases adverse outcomes in the elderly. However, as a potential safe and effective remedy to many age-related disorders, little is known about the protective effect of melatonin against sarcopenia, especially the underlying mechanisms of pathophysiology related to the gut-muscle axis. The young (4 months) and old-aged (24 months) wild-type C57BL/6J male mice were included in this study, of which the old-aged mice in the experimental group were treated with 10 mg/kg/day of melatonin for 16 weeks. After that, muscle strength, muscle mass and the cross-sectional area (CSA) of the gastrocnemius muscle fibres were measured. Then, the putative pathways, based on the data obtained from 16S rDNA sequencing of the gut microbiota, RNA sequencing of gastrocnemius muscle and serum untargeted metabolomics, were screened out by the integrated multiomics analysis and validated using immunohistochemistry, ELISA and TUNEL staining. C2C12 myoblasts were treated with LPS. Flow cytometric analysis and western blotting were applied to detect cell apoptosis and protein expressions of Tnfrsf12a and caspase8, respectively. In addition, the mediation analysis was carried out to infer the causal role of the microbiome in contributing to the skeletal muscle through metabolites. Melatonin treatment ameliorated age-related declines in muscle strength (p < 0.05), muscle mass (p < 0.01) and CSA of the gastrocnemius muscle fibres (p < 0.01), as well as changed the gut microbial composition (beta-diversity analysis; R = 0.513, p = 0.005). The integrated multiomics analysis implied two main mechanisms about the impact of melatonin-related modifications in the gut microbiota on sarcopenia. First, a lower serum lipopolysaccharide (LPS) level associated with the altered gut microbiota was observed in melatonin-treated mice (p < 0.001) and was most relevant to the transcription level of Tnfrsf12a in skeletal muscle (R = 0.926, p < 0.001). Further bioinformatics analyses and invitro experiments showed that LPS could contribute to skeletal muscle apoptosis by regulating the Tnfrsf12a/caspase-8 signalling pathway. Second, melatonin significantly altered serum metabolites (variable importance on projection (VIP) > 1.5, p < 0.05). Mediation models showed that changes in the gut microbiome also influenced skeletal muscle through these metabolites (27 linkages; BH-adjusted p < 0.05). Our study revealed functional insights and a putative causality for the role of the gut-muscle axis in the mechanism of melatonin ameliorating age-related sarcopenia, namely, inhibition of the LPS-induced Tnfrsf12a/caspase-8 signalling pathway or serum metabolites as intermediates in the gut-muscle axis.

Efficacy of toothpaste containing OPTIMEALTH® OR in inhibiting dental plaque and gingivitis: A randomized controlled trial.

This randomized double-blind, placebo-controlled clinical trial evaluated the effects of 2% OPTIMEALTH® OR toothpaste in regulating dental plaque microbiota and alleviating gingivitis. Subjects were randomly assigned to the placebo group and test group. They were instructed to brush their teeth with placebo toothpaste (placebo group) or OPTIMEALTH® OR toothpaste (test group) for a continuous 4 weeks. Clinical indices of plaque index, gingival index, and bleeding on probe (%) were examined, and images of dental plaque staining were captured at baseline and after 2 and 4 weeks. The plaque microbiome was analyzed by 16s rDNA amplicon sequencing at baseline and after 4 weeks. Thirty-two participants with similar characteristics were recruited. After using OPTIMEALTH® OR toothpaste for 4 weeks, a decrease of 27.05% (P < .01), 8.29% (P > .05), and 47.44% (P < .05) in plaque index, gingival index, and bleeding on probe (%) scores was observed compared to the baseline, respectively. The extent of decline in these indices is greater than that in the placebo group. A decrease in dental plaque could be observed after 2 and 4 weeks in the test group. The 16s rDNA sequencing results showed that the observed species index and Chao index, but not the Shannon index and beta diversity, were reduced significantly after using OPTIMEALTH® OR toothpaste for 4 weeks. In addition, compared with the placebo group, using OPTIMEALTH® OR toothpaste reduced the abundance of bacterial species such as Veillonella parvula and Prevotella denticola. Brushing teeth with 2% OPTIMEALTH® OR-fortified toothpaste could effectively reduce dental plaque and regulate plaque microbiota.

Description of a new species of Prostheceraeus Schmarda, 1859 and redescription of a poorly known species, Phrikoceros sagamianus (Kato, 1937) comb. n., with inference of their phylogenetic positions within Pseudocerotoidea (Platyhelminthes: Polycladida: Cotylea)

ABSTRACT The superfamily Pseudocerotoidea Lang encompasses Euryleptidae Stimpson, Pseudocerotidae Lang, and Stylostomidae Dittman. These families include conspicuous, flamboyant marine flatworms with a worldwide distribution. Here, we describe a new euryleptid species belonging to Prostheceraeus Schmarda, 1859, based on specimens collected by dredging at depths of 100–180 m off Misaki, Japan. The new species, Prostheceraeus fragum sp. n., is distinguished by its unique dorsal colouration in that oval red maculae are radially distributed along the translucent cream body periphery. Additionally, based on newly collected topotypic specimens, we transfer the poorly known pseudocerotid species Pseudoceros sagamianus Kato, 1937, to the genus Phrikoceros Newman and Cannon, 1996. These specimens possess (1) a pharynx with shallow, simple folds, (2) a deeply ruffled body margin, and (3) ear-like pseudotentacles with folds. Our molecular phylogeny, based on partial 18S and 28S rDNA sequences, yielded two key findings: (1) Pr. fragum sp. n. nested within the clade containing all other Prostheceraeus species, and (2) Phrikoceros sagamianus comb. n. formed a clade with all other Phrikoceros and Monobiceros species, distinct from the Pseudoceros clade. These results support the generic affiliations established through our morphological examinations. Furthermore, based on the resulting phylogenetic trees, we discuss the systematics of Euryleptidae in relation to Stylostomidae. http://www.zoobank.org/urn:lsid:zoobank.org:pub:F4EA3E5D-F3E6-440E-AAD7-D75E17FA11AE

First Report of Pantoea ananatis Causing Bacterial Leaf and Panicle Blight of Rice in Louisiana, USA.

In July 2023, panicle and leaf blight-like symptoms were observed from the rice (Oryza sativa) variety, PVL03, in research field plots in Louisiana (Rayne, LA 70578, USA; 30.21330⁰ N, 92.37309⁰ W). We observed that chlorosis started on the tips and spread throughout the whole leaf. We also observed panicle blight-like symptoms (grain discoloration of rice hulls) on infected rice plants at the heading stage, which ranged from dark brown to black. Disease incidences were approximately 70% in the observed plots. Five plants were sampled from five plots (one plant per plot). Leaf tissues including both symptomatic and healthy parts (~ 1 cm2) were surfaced sterilized and placed on CCNT medium, a semi-selective medium for the rice bacterial panicle blight pathogen Burkholderia glumae (Kawaradani et al., 2000), and on Luria-Bertani (LB) agar supplemented with cycloheximide (50 µg/ml) for non-selective isolation of bacteria. For the panicle samples, the surfaced sterilized rice kernels were dehulled and ground in sterile distilled H2O using a sterile mortar and pestle. The homogenate was spread on the CCNT media and LB agar supplemented with nitrofurantoin (50 µg/ml) and cycloheximide (50 µg/ml). After ~72 h at 41⁰C, round, smooth and yellow-colored bacterial colonies were observed on both media. The two isolates, one from an infected rice leaf (LPL-1) and the other from the infected rice panicles (LPP-1), were initially identified as Pantoea ananatis based on PCR-amplified 16S rDNA sequences (Weisburg et al., 1991). The taxonomic identity of these two isolates was further confirmed through whole genome sequencing (NCBI Accession ID: PRJNA1092676), which was performed through a hybrid sequencing approach using Oxford Nanopore sequencer & Illumina NextSeq2000 system (Plasmidsaurus Inc., South San Francisco, CA, USA). To satisfy Koch's postulates, we inoculated six one-month-old rice plants (cv. Kitaake) with LPL-1 and LPP-1, respectively, by pricking the stems with a sterile toothpick touched to the overnight grown bacterial culture on LB agar (~ 5-8 x 105 bacterial cells). This virulence assay was conducted twice, and rice plants inoculated with sterile distilled water were included as the negative control. By 27 days post inoculation (DPI), the inoculated plants developed symptoms on leaves and panicles, which were like the symptoms originally observed in the field, and additional symptoms such as shot holes and stem necrosis were also observed. From leaf and panicle samples of the artificially inoculated plants, we reisolated bacteria and confirmed the identity of the bacteria using the P. ananatis specific PCR primers PANA_1080 61F and PANA_1080 1009R (Asselin et al., 2016). To the best of our knowledge, this is the first report of bacterial panicle and leaf blight of rice caused by P. ananatis in Louisiana. Since P. ananatis is a recently emerging pathogen of rice worldwide, including the United States (Yu et. al., 2022; Lu et al., 2022; Luna et al., 2023), it is crucial to monitor the occurrence of this pathogen in other rice-growing areas as a potential threat to US rice production.

Limitations of 18S rDNA Sequence in Species-Level Classification of Dictyostelids

Dictyostelid species classification has traditionally relied on morphology, a time-intensive method requiring expert knowledge. This study evaluated the potential and limitations of using the 18S rDNA sequence for species-level classification. 18S rDNA sequences of 16 samples from the Dicty stock center, including 14 samples found in Thailand, were analyzed. Signature sequence analyses confirmed genus-level identification with high accuracy. These sequences were analyzed alongside 309 database entries retrieved from the GenBank database. The analyses confirmed genus-level identification accuracy but highlighted challenges in distinguishing species due to overlapping intraspecific and interspecific variations, negative barcoding gaps, and incorrectly grouped samples to putative taxa by species delimitation analyses. Species delimitation methods, including maximum likelihood (ML) phylogenetic analysis, achieved limited success, with ML showing the highest accuracy but not exceeding 50%. However, species with high barcoding gaps, such as Raperostelium and Rostrostelium, demonstrated potential for accurate classification. These findings support using 18S rDNA for genus-level identification and suggest its possible application for certain species. Expanded sampling is needed to improve species-level classification and to identify more robust DNA markers for dictyostelid diversity studies.

Mitigating Vibrio-Induced Skin Ulceration in Sea Cucumbers Using Probiotic Strains

Sea cucumbers are valuable in aquaculture, but their cultivation faces challenges from diseases such as skin ulceration syndrome caused by Vibrio alginolyticus (VA). This study aimed to isolate and identify probiotics capable of combating VA and improving sea cucumber’s growth performance. Pathogenic VA was identified, through 16S rDNA sequencing, confirming its high genetic similarity (&gt;99%) to Vibrio alginolyticus. Two Bacillus strains, Bacillus licheniformis YB-1, and Bacillus megaterium YB-2, were isolated as potential probiotics, with identification supported by 16S rDNA phylogenetic analysis and deposition in microbial culture collections. They demonstrated strong antibacterial activity against VA in vitro without exhibiting antagonism when combined. Probiotic tolerance to environmental stressors was observed, while feeding trials revealed significant growth improvements in sea cucumbers, with the highest specific growth rates observed at 1 × 106 CFU/mL for both strains. Immersion challenge tests showed that sea cucumbers treated with probiotics exhibited reduced symptoms of rotten skin syndrome and higher survival rates. The optimal combination of YB-1 and YB-2, with viable bacteria concentrations of 5 × 107 CFU/mL each, achieved a 55% survival rate after a VA challenge, demonstrating their synergistic efficacy. These findings suggest that YB-1 and YB-2 offer promising probiotic solutions for enhancing sea cucumber health and resistance to VA infections in aquaculture.

Identification, Pathogenicity, and Antimicrobial Resistance Analysis of Bacterial Pathogenesis Aeromonas hydrophila from Hybrid Sturgeon (Huso dauricus ♀ × A. schrenckii ♂) in Zhejiang, China

In 2019, a disease outbreak struck a hybrid sturgeon farm (Huso dauricus ♀ × A. schrenckii ♂) in Tiantai, Zhejiang province, leading to the deaths of 8000 sturgeons. The sturgeons exhibited reduced appetite, lethargic and uncoordinated swimming, and physical signs such as reddish petechiae and ulcers on the body and fins. Hemorrhagic spots were observed on the kidneys, spleen, and gonads, alongside reddish intestines with hemorrhagic ascites in the abdominal cavity. ST-1902 was isolated and identified as Aeromonas hydrophila through physiological and biochemical characterization and 16S rDNA sequence analysis. The pathogenicity of ST-1902 was confirmed through a challenge test, with a median lethal dosage (LD50) of 7.9 × 106 CFU/IND. Histopathological examination showed hyperplasia and neoplasm-like changes in the epicedial mesothelial tissues, enlarged and necrosis renal tissue, and serious hemosiderosis in spleen and gills. Virulent genes (Aer, Epa, Alt, Hly, and Act) were detected in ST-1902, corresponding to typical β-hemolysis, extracellular protease, and enterotoxin. Moreover, antimicrobial experiment detection indicated ST-1902 is sensitive to quinolones and phenicols but resistant to sulfamethoxazole, aminoglycoside antibiotics with Sul1, and Intl and Ant (3”)-I. These results suggest that A. hydrophila was the causative agent of the sturgeon disease and highlight the emerging threat it poses to the sturgeon industry.

Microbial Communities in Permafrost, Moraine and Deschampsia antarctica Rhizosphere Soils near Ecology Glacier (King George Island, Maritime Antarctic)

While the recession of glaciers in the Antarctic is of global concern under climate change, the impact of deglaciation on soil microbiomes is still limited. Here, soil samples were collected from permafrost (P), moraine (M) and Deschampsia antarctica rhizosphere (R) soils near Ecology Glacier (Antarctic), and their soil physicochemical properties and microbial communities (bacteria, archaea and fungi) were characterized. Our analyses showed that there were significant differences in the soil properties and microbial communities between the R samples and the P and M samples. Specifically, amplicon sequencing of 16S rDNA revealed high bacterial richness and diversity in the studied soils, which were dominated mainly by the phyla Proteobacteria, Actinobacteriota and Bacteroidota. In contrast, lower richness and diversity were observed in the archaeal communities, which were dominated by the phyla Chenarchaeota (M and R) and Thermoplasmadota (M). In addition, fungal community analysis revealed a lower richness and diversity (M and R), dominated by the phylum Ascomycota. Our observations are consistent with previous reports describing the relevant changes in soil microbial communities during glacial recession, including fewer microbial groups studied in soils (archaea and fungi). However, further studies are still needed to elucidate the contributions of microbial communities to soil formation and plant colonization in ice-free soils in Antarctica under global climate change.

Effects of Salmonella Typhimurium infection on intestinal flora and intestinal tissue arachidonic acid metabolism in Wenchang chickens

Salmonella infections can lead to intestinal inflammation and metabolic disorders in birds. However, whether arachidonic acid (ARA) metabolism is involved in Salmonella-induced intestinal inflammation remains unclear. This experiment investigated the changes in cecal flora and ARA metabolism in Hainan Wenchang chickens infected with S. Typhimurium using 16s rDNA sequencing and targeted metabolomics. The results showed that the levels of ARA metabolites were increased in the cecum tissue of Wenchang chickens after infection with S. Typhimurium, including prostaglandin E2 (PGE2), prostaglandin F2α (PGF2α), lipoxin A4 (LXA4), ± 8(9)-EET, ± 11(12)-EET, and ± 8,9-DiHETrE. The content of key enzymes for ARA production and metabolism (Phospholipase A2 PLA2 and Cyclooxygenase-2 COX-2) in chicken cecum tissues was increased after S. Typhimurium infection. The relative mRNA levels of inflammatory factors were also increased after infection, including Interferon-γ (IFN-γ), Transforming growth factor-β1 (TGF-β1), Interleukin-4 (IL-4), and Interleukin-6 (IL-6). In HD11 cells, the use of a cyclooxygenase (COX) inhibitor reduced the increased levels of COX-2 and PGF2α induced by S. Typhimurium infection and effectively reduced the inflammatory response. In addition, the number of beneficial genera (e.g., Bifidobacterium, Lactobacillus, and Odorobacterium) in the cecum of Wenchang chickens was significantly reduced after infection with S. Typhimurium. The present study revealed the structure of cecal flora in S. Typhimurium-infected Wenchang chickens. In addition, this study demonstrated that S. Typhimurium activates the ARA cyclooxygenase metabolic pathway, which in turn mediates the development of intestinal inflammation in Wenchang chickens. The results can provide data support and theoretical support for the prevention and control of avian salmonellosis.

Morphological and Molecular Characterization of Two Species of Ligophorus (Monogenea: Ancyrocephalidae) in Mullets from the Yucatán Peninsula, with Comments on the Geographical Distribution of L. mediterraneus

BackgroundLigophorus Euzet and Suriano, 1977 is a specious genus of ancyrocephalid monogeneans parasitizing mullets around the world, with most species distributed in the western Pacific and the Mediterranean Sea. Only nine out of the 62 species in the genus have been reported from the Americas, and from them, only two have been sequenced.MethodsWe analyzed two species of Mugil (L.) from Northern Yucatán Peninsula. Specimens of Ligophorus were sampled from the gills of their hosts. The morphology of the specimens was examined. In addition, 28S and ITS rDNA sequences were obtained and compared with previous sequences downloaded from GenBank.ResultsWe discovered two species of Ligophorus using morphological and molecular characters, L. mediterraneus, parasitizing the stripped mullet Mugil cephalus off the coast of Celestún, and L. yucatanensis, parasitizing the silver mullet M. curema in four coastal lagoons. Sequence data of the latter species are reported for the first time.ConclusionOur findings showed that two species of Ligophorus occur in mugilids of the Yucatán Peninsula. One represents a widely distributed marine species with records in the Mediterranean Sea and the Yucatán Peninsula, whereas the second one, L. yucatanensis, represents an endemic species restricted to coastal lagoons of the Yucatán Peninsula.

Gut microbiota and quantitative traits divergence at different altitude of long-tailed dwarf hamsters, Cricetulus longicaudatus

To investigate the community structure and diversity of gut microflora and their function in body mass regulation, as well as the effects of various locations on gut microbiota and Cricetulus longicaudatus body mass regulation at various elevations. We examined the diversity, abundance, and community structure of the gut microbiota of long-tailed dwarf hamsters from eight regions in Shanxi province during summer using 16S rDNA sequencing technology and analyzed the relationships between these microbiota and environmental variables as well as morphological indicators. The results revealed Firmicutes and Bacteroidetes as the dominant phyla at the phylum level, with Lactobacillus emerging as the predominant genus. We observed differences of gut microflora between different areas, and this diversity is affected by altitude. The high-altitude areas individuals had lower β diversity of gut microbiota than the low-altitude area. Moreover, the body and skull indexes of long-tailed dwarf hamsters also changed with altitude. The result presented in this study indicated that the body size of long-tailed dwarf hamsters conforms to Bergmann's law. And Providencia had significant correlation with body size. Finally, functional analysis of the gut microbiota showed changes in metabolic function that depended on elevation, and collinear network analysis showed how the gut microbiota interacts with each other. All of these results suggest that long-tailed hamsters are different depending on their altitude, with altitude being the main factor affecting both the structure of microbes and the way their metabolism works. This study shows that altitude has a big effect on the gut microbiota and phenotypic traits of long-tailed hamsters. It also shows how well this species can adapt to changes in altitude.

P0213 Salivary Veillonella parvula from Crohn’s Disease Patients Exacerbates Intestinal Inflammation

Abstract Background The gut microbiota plays a significant role in the development of inflammatory bowel disease (IBD). There is a close interaction between the oral and gut microbiota. However, the role of the "oral-gut" microbial axis in the development of IBD is not yet clear. Methods 1. Analyzed oral-gut microbiota patterns in 97 IBD patients using 16S rDNA sequencing and bioinformatics methods. 2. A mouse colitis model with DSS was used. It was gavaged with oral microbiota from CD patients to assess the impacts on colitis and gut microbiota. 3. Isolated specific differential bacteria, Veillonella, from CD patient saliva and evaluated their effects on DSS-induced colitis in mice. Results 1. IBD patients had a reduced core gut microbiota, lower diversity (P &amp;lt; 0.05), and increased abundance of potential pathogens such as Escherichia-Shigella. 2. CD patients showed more correlations between saliva and fecal microbiota, with the most significant correlation between Veillonella in saliva and Escherichia-Shigella in fecal (P=0.00018) . 3. The mice which were gavaged with saliva from CD patients showed significant weight loss (P &amp;lt; 0.0001), reduced colon length (P=0.03), increased histopathological scores (P=0.01), decreased expression of colonic mucosal barrier proteins ZO-1 and E-cadherin, and exacerbated gut microbiota dysbiosis . 4. The mice which were gavaged with Veillonella parvula from CD patients showed significant weight loss (P &amp;lt; 0.0001), reduced colon length (P=0.02), increased histopathological scores (P=0.02), decreased expression of colonic mucosal barrier proteins ZO-1 and E-cadherin, and exacerbated gut microbiota dysbiosis. Conclusion The interplay between the oral and gut microbiota potentially influences the progression of IBD, with oral bacteria such as Veillonella possibly intensifying intestinal inflammation in IBD patients by disrupting the gut microbiota balance. Targeted modulation of the gut microbiota and interference with oral-gut microbial interactions may offer a promising therapeutic strategy for managing IBD.