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Bacterial community diversity and variation in spray water sources and the tomato fruit surface.

Telias A, White JR, Pahl DM, Ottesen AR, Walsh CS - BMC Microbiol. (2011)

Bottom Line: The two water sources tested had a significantly different bacterial composition.Proteobacteria was predominant in groundwater samples, whereas in the significantly more diverse surface water, abundant phyla also included Firmicutes, Actinobacteria and Verrucomicrobia.Despite the major differences observed in the bacterial composition of ground and surface water, the season long use of these very different water sources did not have a significant impact on the bacterial composition of the tomato fruit surface.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Science and Landscape Architecture Department, University of Maryland, College Park, MD 21201, USA. atelias@umd.edu

ABSTRACT

Background: Tomato (Solanum lycopersicum) consumption has been one of the most common causes of produce-associated salmonellosis in the United States. Contamination may originate from animal waste, insects, soil or water. Current guidelines for fresh tomato production recommend the use of potable water for applications coming in direct contact with the fruit, but due to high demand, water from other sources is frequently used. We sought to describe the overall bacterial diversity on the surface of tomato fruit and the effect of two different water sources (ground and surface water) when used for direct crop applications by generating a 454-pyrosequencing 16S rRNA dataset of these different environments. This study represents the first in depth characterization of bacterial communities in the tomato fruit surface and the water sources commonly used in commercial vegetable production.

Results: The two water sources tested had a significantly different bacterial composition. Proteobacteria was predominant in groundwater samples, whereas in the significantly more diverse surface water, abundant phyla also included Firmicutes, Actinobacteria and Verrucomicrobia. The fruit surface bacterial communities on tomatoes sprayed with both water sources could not be differentiated using various statistical methods. Both fruit surface environments had a high representation of Gammaproteobacteria, and within this class the genera Pantoea and Enterobacter were the most abundant.

Conclusions: Despite the major differences observed in the bacterial composition of ground and surface water, the season long use of these very different water sources did not have a significant impact on the bacterial composition of the tomato fruit surface. This study has provided the first next-generation sequencing database describing the bacterial communities living in the fruit surface of a tomato crop under two different spray water regimes, and therefore represents an important step forward towards the development of science-based metrics for Good Agricultural Practices.

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Community analysis using principal coordinate analysis (PCoA) of unweighted UniFrac distance matrix. Across all methodologies assessed, (including the canonical UniFrac beta-diversity analysis), water samples cluster very well, yet the phyllosphere treatments are unable to be differentiated. Displayed color scheme: ps (green), pg (blue), ws (purple), wg (red). Percentage of variation explained by each principal coordinate is shown on respective axes.
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Figure 6: Community analysis using principal coordinate analysis (PCoA) of unweighted UniFrac distance matrix. Across all methodologies assessed, (including the canonical UniFrac beta-diversity analysis), water samples cluster very well, yet the phyllosphere treatments are unable to be differentiated. Displayed color scheme: ps (green), pg (blue), ws (purple), wg (red). Percentage of variation explained by each principal coordinate is shown on respective axes.

Mentions: Using various unsupervised approaches, water samples consistently clustered with their unique environments at all taxonomic levels (Figure 5). There was persistent difficulty distinguishing between fruit surface samples treated with surface or groundwater. Even the UniFrac metric, which arguably maintains the highest phylogenetic resolution of any method, was unable to resolve this issue (Figure 6). The concordance among our methodology and the CloVR-16S methods suggests that our results are not sensitive to modifications in the analysis protocol.


Bacterial community diversity and variation in spray water sources and the tomato fruit surface.

Telias A, White JR, Pahl DM, Ottesen AR, Walsh CS - BMC Microbiol. (2011)

Community analysis using principal coordinate analysis (PCoA) of unweighted UniFrac distance matrix. Across all methodologies assessed, (including the canonical UniFrac beta-diversity analysis), water samples cluster very well, yet the phyllosphere treatments are unable to be differentiated. Displayed color scheme: ps (green), pg (blue), ws (purple), wg (red). Percentage of variation explained by each principal coordinate is shown on respective axes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108269&req=5

Figure 6: Community analysis using principal coordinate analysis (PCoA) of unweighted UniFrac distance matrix. Across all methodologies assessed, (including the canonical UniFrac beta-diversity analysis), water samples cluster very well, yet the phyllosphere treatments are unable to be differentiated. Displayed color scheme: ps (green), pg (blue), ws (purple), wg (red). Percentage of variation explained by each principal coordinate is shown on respective axes.
Mentions: Using various unsupervised approaches, water samples consistently clustered with their unique environments at all taxonomic levels (Figure 5). There was persistent difficulty distinguishing between fruit surface samples treated with surface or groundwater. Even the UniFrac metric, which arguably maintains the highest phylogenetic resolution of any method, was unable to resolve this issue (Figure 6). The concordance among our methodology and the CloVR-16S methods suggests that our results are not sensitive to modifications in the analysis protocol.

Bottom Line: The two water sources tested had a significantly different bacterial composition.Proteobacteria was predominant in groundwater samples, whereas in the significantly more diverse surface water, abundant phyla also included Firmicutes, Actinobacteria and Verrucomicrobia.Despite the major differences observed in the bacterial composition of ground and surface water, the season long use of these very different water sources did not have a significant impact on the bacterial composition of the tomato fruit surface.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Science and Landscape Architecture Department, University of Maryland, College Park, MD 21201, USA. atelias@umd.edu

ABSTRACT

Background: Tomato (Solanum lycopersicum) consumption has been one of the most common causes of produce-associated salmonellosis in the United States. Contamination may originate from animal waste, insects, soil or water. Current guidelines for fresh tomato production recommend the use of potable water for applications coming in direct contact with the fruit, but due to high demand, water from other sources is frequently used. We sought to describe the overall bacterial diversity on the surface of tomato fruit and the effect of two different water sources (ground and surface water) when used for direct crop applications by generating a 454-pyrosequencing 16S rRNA dataset of these different environments. This study represents the first in depth characterization of bacterial communities in the tomato fruit surface and the water sources commonly used in commercial vegetable production.

Results: The two water sources tested had a significantly different bacterial composition. Proteobacteria was predominant in groundwater samples, whereas in the significantly more diverse surface water, abundant phyla also included Firmicutes, Actinobacteria and Verrucomicrobia. The fruit surface bacterial communities on tomatoes sprayed with both water sources could not be differentiated using various statistical methods. Both fruit surface environments had a high representation of Gammaproteobacteria, and within this class the genera Pantoea and Enterobacter were the most abundant.

Conclusions: Despite the major differences observed in the bacterial composition of ground and surface water, the season long use of these very different water sources did not have a significant impact on the bacterial composition of the tomato fruit surface. This study has provided the first next-generation sequencing database describing the bacterial communities living in the fruit surface of a tomato crop under two different spray water regimes, and therefore represents an important step forward towards the development of science-based metrics for Good Agricultural Practices.

Show MeSH
Related in: MedlinePlus