Intestinal microbial dysbiosis under nitrite stress in juvenile three-keeled pond turtles, Mauremys reevesii

Study information

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incomplete

study design

laboratory experiment

Citation

PMID PubMed identifier for scientific articles.

40739184

DOI Digital object identifier for electronic documents.

https://doi.org/10.1186/s12866-025-04198-8

URI Uniform resource identifier for web resources.

Authors

Tang H.B., Si Y.X., Li H.D., Dang W., Lu H.L.

Journal

BMC microbiology

Year

2025

Keywords:

Cultured freshwater turtle, Functional metagenomics, Intestinal microbial dysbiosis, Nitrite stress, Pathogenic prevalence

BACKGROUND: Nitrite is one of the primary pollutants in high-density aquaculture systems, and may cause various toxic effects (e.g., oxidative damage, metabolic and immune dysregulation, histological inflammation, etc.) on economically important aquaculture species, such as echinoderms, crustaceans and fish. Nitrite can also disrupt the intestinal function and microbiota in some fish and amphibians. However, intestinal physiological and microbial responses of cultured turtles under nitrite stress were rarely explored. METHOD: Twenty Mauremys reevesii juveniles were exposed to different nitrite levels and fed with a commercial diet. Their intestinal content samples were analyzed for microbial diversity and composition. RESULTS: Nitrite exposure reduced intestinal microbial diversity, with lower α-diversity values in higher-concentration exposed turtles. It also changed the microbial composition. After exposure, the abundances of Bacteroidetes and Firmicutes decreased, but that of Proteobacteria increased at the phylum level. Similarly, abundances of some potentially beneficial bacterial genera, e.g., Prevotella_1, Christensenellaceae_R-7, Muribaculaceae_ge, were shown to decrease, but those of putatively pathogenic genera, e.g., Halomonas, Nesterenkonia, increased at the genus level. Furtherly, potentially altered metabolic pathways (e.g., biosynthesis of ansamycins and vancomycin group antibiotics) were revealed by functional predictions of intestinal microbiota. CONCLUSION: This study highlighted intestinal microbial dysbiosis and prevalence of putatively pathogenic bacteria in cultured turtles under nitrite stress. Excessive levels of nitrite would alter the health status of aquatic animals by disrupting their intestinal microbiome.

Experiment 1

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incomplete

Curated date: 2025/10/17

Curator: Chumzine

Revision editor(s): Chumzine

Subjects

Location of subjects

China

Host species Species from which microbiome was sampled. Contact us to have more species added.

Mauremys reevesii

Body site Anatomical site where microbial samples were extracted from according to the Uber Anatomy Ontology

Intestine Bowel,Intestinal tract,Intestine,intestine

Condition The experimental condition / phenotype studied according to the Experimental Factor Ontology

Nitrite measurement Nitrite measurement,nitrite measurement

Group 0 name Corresponds to the control (unexposed) group for case-control studies

control

Group 1 name Corresponds to the case (exposed) group for case-control studies

1 mg/L-exposed group

Group 1 definition Diagnostic criteria applied to define the specific condition / phenotype represented in the case (exposed) group

Healthy juvenile turtles were randomly selected from fertilized M. reevesii eggs that were collected from a private turtle farm located in Huzhou (Zhejiang province, China). The eggs were incubated, hatched and reared in the lab to get the healthy samples used.

Group 0 sample size Number of subjects in the control (unexposed) group

5

Group 1 sample size Number of subjects in the case (exposed) group

5

Lab analysis

Sequencing type

16S

16S variable region One or more hypervariable region(s) of the bacterial 16S gene

V3-V4

Statistical Analysis

Data transformation Data transformation applied to microbial abundance measurements prior to differential abundance testing (if any).

relative abundances

Statistical test

Kruskall-Wallis

LEfSe

Significance threshold p-value or FDR threshold used for differential abundance testing (if any)

0.05

MHT correction Have statistical tests be corrected for multiple hypothesis testing (MHT)?

Yes

LDA Score above Threshold for the linear discriminant analysis (LDA) score for studies using the popular LEfSe tool

3

Alpha Diversity

Shannon Estimator of species richness and species evenness: more weight on species richness

increased

Signature 1

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incomplete

Curated date: 2025/10/17

Curator: Chumzine

Revision editor(s): Chumzine

Source: Fig. 3

Description: Taxonomic differences in intestinal microbiota in juvenile three-keeled pond turtles under nitrite stress and healthy group

Abundance in Group 1: increased abundance in 1 mg/L-exposed group

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Revision editor(s): Chumzine