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Deep sequencing and ecological characterization of gut microbial communities of diverse bumble bee species.

Lim HC, Chu CC, Seufferheld MJ, Cameron SA - PLoS ONE (2015)

Bottom Line: The most abundant and prevalent (occurring in 92% of the samples) bacterial OTU, based on 16S rRNA sequences, closely matched that of the previously described Betaproteobacteria species Snodgrassella alvi.Bacteria that were first described in bee-related external environments dominated a number of gut bacterial communities, suggesting that they are not strictly dependent on the internal gut environment.Using light and fluorescent microscopy, we demonstrated that the gut bacteria form a biofilm on the internal epithelial surface of the ileum, corroborating results obtained from Apis mellifera.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, University of Illinois, Urbana, IL, 61801, United States of America.

ABSTRACT
Gut bacterial communities of bumble bees are correlated with defense against pathogens. Further understanding this host-microbe association is vitally important as bumble bees are currently experiencing global population declines, potentially due in part to emergent diseases. In this study, we used pyrosequencing and community fingerprinting (ARISA) to characterize the gut microbial communities of nine bumble species from across the Bombus phylogeny. Overall, we delimited 74 bacterial taxa (operational taxonomic units or OTUs) belonging to Betaproteobacteria, Gammaproteobacteria, Bacilli, Actinobacteria, Flavobacteria and Alphaproteobacteria. Each bacterial community was taxonomically simple, containing an average of 1.9 common (relative abundance per sample > 5%) bacterial OTUs. The most abundant and prevalent (occurring in 92% of the samples) bacterial OTU, based on 16S rRNA sequences, closely matched that of the previously described Betaproteobacteria species Snodgrassella alvi. Bacteria that were first described in bee-related external environments dominated a number of gut bacterial communities, suggesting that they are not strictly dependent on the internal gut environment. The ARISA data showed a correlation between bacterial community structures and the geographic locations where the bees were sampled, suggesting that at least a subset of the bacterial species may be transmitted environmentally. Using light and fluorescent microscopy, we demonstrated that the gut bacteria form a biofilm on the internal epithelial surface of the ileum, corroborating results obtained from Apis mellifera.

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Images of B. impatiens gut (A) from light (B, C and D) and fluorescent microscopy (E and F).(A) shows the whole alimentary canal and general locations where sectioning and imaging were made (multiple individuals were used to create the dissected gut and microscopy images). Section made at (1), (2) and (3) were used to produce images (B), (C) and (D), respectively. Fluorescent images (E) and (F) were produced by visualizing a portion of the ileum located between (1) and (2), and between (2) and (3), respectively. (B) shows both yeast and bacterial cells in the lumen, whereas (C) and (D) show only bacterial cells in the lumen. Villi and longitudinal folds composed of epithelial cells can be observed in (C) and (D), respectively. Insert in (C) shows a villus and bacterial cells (black dots) in greater detail. In (E) and (F), each fluorescing green spot represents one bacterial cell. Abbreviations: ba = bacteria; ep = epithelial cells; lu = lumen; mu = transverse muscle; yc = yeast cell.
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pone.0118566.g006: Images of B. impatiens gut (A) from light (B, C and D) and fluorescent microscopy (E and F).(A) shows the whole alimentary canal and general locations where sectioning and imaging were made (multiple individuals were used to create the dissected gut and microscopy images). Section made at (1), (2) and (3) were used to produce images (B), (C) and (D), respectively. Fluorescent images (E) and (F) were produced by visualizing a portion of the ileum located between (1) and (2), and between (2) and (3), respectively. (B) shows both yeast and bacterial cells in the lumen, whereas (C) and (D) show only bacterial cells in the lumen. Villi and longitudinal folds composed of epithelial cells can be observed in (C) and (D), respectively. Insert in (C) shows a villus and bacterial cells (black dots) in greater detail. In (E) and (F), each fluorescing green spot represents one bacterial cell. Abbreviations: ba = bacteria; ep = epithelial cells; lu = lumen; mu = transverse muscle; yc = yeast cell.

Mentions: In B. impatiens, we observed through light microscopy both yeast and bacterial cells in the lumen of the anterior part of the ileum (Fig. 6B). In the middle and posterior sections of the ileum, bacteria alone were found in the lumen (Fig. 6C and 6D). Based on fluorescent microscopy, these bacteria appeared to form a biofilm on the cuticular intima, a lining separating the lumen from the epithelial cells (Fig. 6E, F). Because of the presence of longitudinal folds in the posterior portion of the ileum, the distribution of bacteria in the posterior portion appeared to be less even when compared to the anterior portion.


Deep sequencing and ecological characterization of gut microbial communities of diverse bumble bee species.

Lim HC, Chu CC, Seufferheld MJ, Cameron SA - PLoS ONE (2015)

Images of B. impatiens gut (A) from light (B, C and D) and fluorescent microscopy (E and F).(A) shows the whole alimentary canal and general locations where sectioning and imaging were made (multiple individuals were used to create the dissected gut and microscopy images). Section made at (1), (2) and (3) were used to produce images (B), (C) and (D), respectively. Fluorescent images (E) and (F) were produced by visualizing a portion of the ileum located between (1) and (2), and between (2) and (3), respectively. (B) shows both yeast and bacterial cells in the lumen, whereas (C) and (D) show only bacterial cells in the lumen. Villi and longitudinal folds composed of epithelial cells can be observed in (C) and (D), respectively. Insert in (C) shows a villus and bacterial cells (black dots) in greater detail. In (E) and (F), each fluorescing green spot represents one bacterial cell. Abbreviations: ba = bacteria; ep = epithelial cells; lu = lumen; mu = transverse muscle; yc = yeast cell.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4359114&req=5

pone.0118566.g006: Images of B. impatiens gut (A) from light (B, C and D) and fluorescent microscopy (E and F).(A) shows the whole alimentary canal and general locations where sectioning and imaging were made (multiple individuals were used to create the dissected gut and microscopy images). Section made at (1), (2) and (3) were used to produce images (B), (C) and (D), respectively. Fluorescent images (E) and (F) were produced by visualizing a portion of the ileum located between (1) and (2), and between (2) and (3), respectively. (B) shows both yeast and bacterial cells in the lumen, whereas (C) and (D) show only bacterial cells in the lumen. Villi and longitudinal folds composed of epithelial cells can be observed in (C) and (D), respectively. Insert in (C) shows a villus and bacterial cells (black dots) in greater detail. In (E) and (F), each fluorescing green spot represents one bacterial cell. Abbreviations: ba = bacteria; ep = epithelial cells; lu = lumen; mu = transverse muscle; yc = yeast cell.
Mentions: In B. impatiens, we observed through light microscopy both yeast and bacterial cells in the lumen of the anterior part of the ileum (Fig. 6B). In the middle and posterior sections of the ileum, bacteria alone were found in the lumen (Fig. 6C and 6D). Based on fluorescent microscopy, these bacteria appeared to form a biofilm on the cuticular intima, a lining separating the lumen from the epithelial cells (Fig. 6E, F). Because of the presence of longitudinal folds in the posterior portion of the ileum, the distribution of bacteria in the posterior portion appeared to be less even when compared to the anterior portion.

Bottom Line: The most abundant and prevalent (occurring in 92% of the samples) bacterial OTU, based on 16S rRNA sequences, closely matched that of the previously described Betaproteobacteria species Snodgrassella alvi.Bacteria that were first described in bee-related external environments dominated a number of gut bacterial communities, suggesting that they are not strictly dependent on the internal gut environment.Using light and fluorescent microscopy, we demonstrated that the gut bacteria form a biofilm on the internal epithelial surface of the ileum, corroborating results obtained from Apis mellifera.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, University of Illinois, Urbana, IL, 61801, United States of America.

ABSTRACT
Gut bacterial communities of bumble bees are correlated with defense against pathogens. Further understanding this host-microbe association is vitally important as bumble bees are currently experiencing global population declines, potentially due in part to emergent diseases. In this study, we used pyrosequencing and community fingerprinting (ARISA) to characterize the gut microbial communities of nine bumble species from across the Bombus phylogeny. Overall, we delimited 74 bacterial taxa (operational taxonomic units or OTUs) belonging to Betaproteobacteria, Gammaproteobacteria, Bacilli, Actinobacteria, Flavobacteria and Alphaproteobacteria. Each bacterial community was taxonomically simple, containing an average of 1.9 common (relative abundance per sample > 5%) bacterial OTUs. The most abundant and prevalent (occurring in 92% of the samples) bacterial OTU, based on 16S rRNA sequences, closely matched that of the previously described Betaproteobacteria species Snodgrassella alvi. Bacteria that were first described in bee-related external environments dominated a number of gut bacterial communities, suggesting that they are not strictly dependent on the internal gut environment. The ARISA data showed a correlation between bacterial community structures and the geographic locations where the bees were sampled, suggesting that at least a subset of the bacterial species may be transmitted environmentally. Using light and fluorescent microscopy, we demonstrated that the gut bacteria form a biofilm on the internal epithelial surface of the ileum, corroborating results obtained from Apis mellifera.

Show MeSH
Related in: MedlinePlus