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McGarvey J.A.,Foodborne Toxin Detection and Protection Research Unit | Han R.,University of California at Davis | Connell J.H.,University of California Cooperative Extension | Stanker L.H.,Foodborne Toxin Detection and Protection Research Unit | Hnasko R.,Foodborne Toxin Detection and Protection Research Unit
Journal of Applied Microbiology | Year: 2015

Aims: To compare the bacterial populations on organically and conventionally grown almond drupes before and after hull split. Methods and Results: We constructed 16S rRNA gene libraries, containing approx. 3000 sequences each, from the bacteria from organically and conventionally grown drupes before and after hull split. We observed that before hull split both conventionally and organically grown drupes were colonized by relatively few types of bacteria that were mostly common phyllosphere-associated Proteobacteria. However, the organically grown drupes contained significantly more Alphaproteobacteria and the conventionally grown drupes contained significantly more Gammaproteobacteria. The conventionally grown drupes also contained significantly more sequences associated with the phylum Actinobacteria. After hull split, we observed a significant increase in bacterial diversity, with many newly appearing sequences that were not normally associated with the phyllosphere. Conclusions: Organic and conventional growing methodologies influence the types of bacteria on almond drupes and hull split results in a burst of microbial diversification. Significance and Impact of the Study: Production of organic produce is increasing due to consumer preferences, but it was unknown how this methodology affects the bacterial populations on almond drupes. This is the first study to compare the bacterial populations of organically and conventionally grown almond drupes. © 2015 The Society for Applied Microbiology.


Mcgarvey J.A.,Foodborne Toxin Detection and Protection Research Unit | Connell J.H.,University of California Cooperative Extension | Stanker L.H.,Foodborne Toxin Detection and Protection Research Unit | Hnasko R.,Foodborne Toxin Detection and Protection Research Unit
Journal of Applied Microbiology | Year: 2014

Aims: To describe the bacterial populations and their dynamics during the development of almond drupes. Methods and Results: We examined 16S rRNA gene libraries derived from the bacterial populations on almond drupes at three stages of development: (i) when the drupes were full sized, but before embryo development, (ii) when the drupe hulls first began to split and (iii) when the drupes were fully mature, but before harvesting. Our data revealed that the immature drupes were colonized by relatively few types of bacteria, belonging mostly to common phyllosphere-associated bacteria within the genera Pseudomonas, Pantoea, Methylobacterium and Sphingomonas. However, after the hulls first began to split, the level of bacterial diversity increased and continued to do so until the drupes were fully mature. At the last sampling period, we observed several sequences belonging to bacteria that are not usually associated with the phyllosphere, including some identical to Salmonella enterica. Conclusions: The bacterial populations on almond drupes before hull split were composed of relatively few types, most of which were commonly associated with the phyllosphere. However, after hull split, the level of microbial diversity increased, which was mostly due to increased levels of bacteria that are not normally associated with the phyllosphere, including Salm. enterica. Significance and Impact of the Study: This is the first report of the bacterial populations associated with almond drupes and their dynamics during development. Of specific significance is the observation that Salm. enterica was present on the drupes just prior to harvesting, which may represent a critical control point. Copyright © 2014 The Society for Applied Microbiology1166 June 2014 10.1111/jam.12464 Original Article Original Articles Plant Microbiology/Plant Health Microbiology © 2014 The Society for Applied Microbiology This article has been contributed to by US Government employees and their work is in the public domain in the USA.


PubMed | Foodborne Toxin Detection and Protection Research Unit
Type: Journal Article | Journal: Journal of applied microbiology | Year: 2014

To describe the bacterial populations and their dynamics during the development of almond drupes.We examined 16S rRNA gene libraries derived from the bacterial populations on almond drupes at three stages of development: (i) when the drupes were full sized, but before embryo development, (ii) when the drupe hulls first began to split and (iii) when the drupes were fully mature, but before harvesting. Our data revealed that the immature drupes were colonized by relatively few types of bacteria, belonging mostly to common phyllosphere-associated bacteria within the genera Pseudomonas, Pantoea, Methylobacterium and Sphingomonas. However, after the hulls first began to split, the level of bacterial diversity increased and continued to do so until the drupes were fully mature. At the last sampling period, we observed several sequences belonging to bacteria that are not usually associated with the phyllosphere, including some identical to Salmonella enterica.The bacterial populations on almond drupes before hull split were composed of relatively few types, most of which were commonly associated with the phyllosphere. However, after hull split, the level of microbial diversity increased, which was mostly due to increased levels of bacteria that are not normally associated with the phyllosphere, including Salm. enterica.This is the first report of the bacterial populations associated with almond drupes and their dynamics during development. Of specific significance is the observation that Salm. enterica was present on the drupes just prior to harvesting, which may represent a critical control point.

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