An Apple a Day: Which Bacteria Do We Eat With Organic and Conventional Apples?

Abstract

Apples are among the most consumed fruits world-wide. They represent a source of direct human exposure to bacterial communities, which is less studied. We analyzed the apple microbiome to detect differences between tissues and the impact of organic and conventional management by a combined approach of 16S rRNA gene amplicon analysis and qPCR, and visualization using fluorescence in situ hybridization and confocal laser scanning microscopy (FISH-CLSM). Each apple fruit harbors different tissues (stem, peel, fruit pulp, seeds, and calyx), which were colonized by distinct bacterial communities. Interestingly, fruit pulp and seeds were bacterial hot spots, while the peel was less colonized. In all, approximately 10 8 16S rRNA bacterial gene copy numbers were determined in each g apple. Abundances were not influenced by the management practice but we found a strong reduction in bacterial diversity and evenness in conventionally managed apples. In addition, despite the similar structure in general dominated by Proteobacteria (80%), Bacteroidetes (9%), Actinobacteria (5%), and Firmicutes (3%), significant shifts of almost 40% of bacterial genera and orders were monitored. Among them, especially bacterial signatures known for health-affecting potential were found to be enhanced in conventionally managed apples. Our results suggest that we consume about 100 million bacterial cells with one apple. Although this amount was the same, the bacterial composition was significantly different in conventionally and organically produced apples.

Effect of Washing, Waxing and Low-Temperature Storage on the Postharvest Microbiome of Apple

“…Previous research revealed spatial and temporal changes in the composition of the microbiome of different portions (peel, wound, calyx-end, stem-end) of apple fruit obtained at the point of consumer purchase (supermarket) and representing fruit grown using different approaches (organic vs. conventional) [10]. Similar research was recently conducted that focused on the bacterial composition of harvested apples in different fruit tissues and the impact of organic vs. conventional management practices [14]. These studies, however, could not discern when particular components of the microbiome became established or were altered, or the impact that different postharvest processing procedures had on the composition of the microbiome.…”

Optimization of a Method for the Concentration of Genetic Material in Bacterial and Fungal Communities on Fresh Apple Peel Surfaces

“…The epidermis excision method also was restricted to a small surface area of the apple (approximately 1 cm 2 ) based on input thresholds dictated by the extraction kit used in these experiments, reducing the likelihood of recovering a DNA sample that was representative of the peel microbiome. This downfall could be mitigated by subsampling each apple at several key areas (equator, shoulder, stem, and calyx) [ 27 , 59 ], which would quadruple costs associated with extraction, as each subsample would require individual processing.…”

“…In contrast to the relatively high abundance of microorganisms in the plant rhizosphere [ 26 ], microenvironments within the phyllosphere, specifically the carposphere, pose a significant barrier to high-quality microbiome research due to their low abundances of microorganisms, particularly on the fruit surface [ 27 ]. This is partially affected by conditions of the growing environment to which the aerial structures are exposed, including ultraviolet light exposure [ 28 ], limited nutrients and desiccation [ 29 ], and the physiological status of the plant [ 30 ].…”

Ingreso de alimentos al hospital: un problema que nos compete a todos

“…Las manzanas recién cosechadas y manejadas orgánicamente albergan una microbiota más diversa y uniforme, en comparación con las convencionales; la abundancia de casi 40% de los géneros y órdenes bacterianos difirió significativamente entre las manzanas de manejo orgánico y convencional. 8 La presencia de ciertos microorganismos está definida como un indicador de contaminación fecal, pero diversos organismos no se asocian necesariamente con material fecal en alimentos tales como verduras, frutas, algunos tipos de carne, postres, pescados, mariscos (la mayoría de los cuales fueron congelados) y cereales secos; esto podría indicar que los organismos coliformes en congelados o productos secos son capaces de iniciar el crecimiento en una forma relativamente no inhibitoria.…”