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Probiotic legacy effects on gut microbial assembly in tilapia larvae

View Article: PubMed Central - PubMed

ABSTRACT

The exposure of fish to environmental free-living microbes and its effect on early colonization in the gut have been studied in recent years. However, little is known regarding how the host and environment interact to shape gut communities during early life. Here, we tested whether the early microbial exposure of tilapia larvae affects the gut microbiota at later life stages. The experimental period was divided into three stages: axenic, probiotic and active suspension. Axenic tilapia larvae were reared either under conventional conditions (active suspension systems) or exposed to a single strain probiotic (Bacillus subtilis) added to the water. Microbial characterization by Illumina HiSeq sequencing of 16S rRNA gene amplicons showed the presence of B. subtilis in the gut during the seven days of probiotic application. Although B. subtilis was no longer detected in the guts of fish exposed to the probiotic after day 7, gut microbiota of the exposed tilapia larvae remained significantly different from that of the control treatment. Compared with the control, fish gut microbiota under probiotic treatment was less affected by spatial differences resulting from tank replication, suggesting that the early probiotic contact contributed to the subsequent observation of low inter-individual variation.

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Principal coordinate analysis (PCoA) of the gut microbial communities based on the square root-transformed relative abundance data of OTUs.The relative distances of all points represent the relative dissimilarities of the samples according to the Bray Curtis index. Plots (a–c): ordinations of all gut samples from probiotic and control treatment from days 14, 21 and 28, respectively. The percentage of total variation explained by each PCo axis is shown in the parentheses.
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f3: Principal coordinate analysis (PCoA) of the gut microbial communities based on the square root-transformed relative abundance data of OTUs.The relative distances of all points represent the relative dissimilarities of the samples according to the Bray Curtis index. Plots (a–c): ordinations of all gut samples from probiotic and control treatment from days 14, 21 and 28, respectively. The percentage of total variation explained by each PCo axis is shown in the parentheses.

Mentions: Subsequent analyses of the gut samples from larvae raised in the probiotic chambers showed that B. subtilis was among the most dominant species, regardless of the observed differences in the relative abundance of B. subtilis in the corresponding water samples. At the end of the probiotic treatment (day 14), B. subtilis accounted for approximately half of all bacteria in the gut (average relative abundance). A comparison between the gut samples from control (C1, C2 and C3 tanks) and probiotic treatments (P-CH1 and P-CH2 chambers) indicated a clear difference in the composition of the gut microbiota (Fig. 3a). This difference reflected, in part, the high relative abundance of B. subtilis in the gut of larvae from the probiotic treatment (and the absence of these bacteria from the control), according to the SIMPER analysis results (contribution: 25%). Other discriminant OTUs were members of the genera Nocardia, Mycobacterium, Rhodococcus, Rhodanobacter and Halomonas (Table S3).


Probiotic legacy effects on gut microbial assembly in tilapia larvae
Principal coordinate analysis (PCoA) of the gut microbial communities based on the square root-transformed relative abundance data of OTUs.The relative distances of all points represent the relative dissimilarities of the samples according to the Bray Curtis index. Plots (a–c): ordinations of all gut samples from probiotic and control treatment from days 14, 21 and 28, respectively. The percentage of total variation explained by each PCo axis is shown in the parentheses.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037425&req=5

f3: Principal coordinate analysis (PCoA) of the gut microbial communities based on the square root-transformed relative abundance data of OTUs.The relative distances of all points represent the relative dissimilarities of the samples according to the Bray Curtis index. Plots (a–c): ordinations of all gut samples from probiotic and control treatment from days 14, 21 and 28, respectively. The percentage of total variation explained by each PCo axis is shown in the parentheses.
Mentions: Subsequent analyses of the gut samples from larvae raised in the probiotic chambers showed that B. subtilis was among the most dominant species, regardless of the observed differences in the relative abundance of B. subtilis in the corresponding water samples. At the end of the probiotic treatment (day 14), B. subtilis accounted for approximately half of all bacteria in the gut (average relative abundance). A comparison between the gut samples from control (C1, C2 and C3 tanks) and probiotic treatments (P-CH1 and P-CH2 chambers) indicated a clear difference in the composition of the gut microbiota (Fig. 3a). This difference reflected, in part, the high relative abundance of B. subtilis in the gut of larvae from the probiotic treatment (and the absence of these bacteria from the control), according to the SIMPER analysis results (contribution: 25%). Other discriminant OTUs were members of the genera Nocardia, Mycobacterium, Rhodococcus, Rhodanobacter and Halomonas (Table S3).

View Article: PubMed Central - PubMed

ABSTRACT

The exposure of fish to environmental free-living microbes and its effect on early colonization in the gut have been studied in recent years. However, little is known regarding how the host and environment interact to shape gut communities during early life. Here, we tested whether the early microbial exposure of tilapia larvae affects the gut microbiota at later life stages. The experimental period was divided into three stages: axenic, probiotic and active suspension. Axenic tilapia larvae were reared either under conventional conditions (active suspension systems) or exposed to a single strain probiotic (Bacillus subtilis) added to the water. Microbial characterization by Illumina HiSeq sequencing of 16S rRNA gene amplicons showed the presence of B. subtilis in the gut during the seven days of probiotic application. Although B. subtilis was no longer detected in the guts of fish exposed to the probiotic after day 7, gut microbiota of the exposed tilapia larvae remained significantly different from that of the control treatment. Compared with the control, fish gut microbiota under probiotic treatment was less affected by spatial differences resulting from tank replication, suggesting that the early probiotic contact contributed to the subsequent observation of low inter-individual variation.

No MeSH data available.


Related in: MedlinePlus