Next time once you eat an apple for extra fibre, flavonoids and flavour, remember that you simply also are gulping down about 100 million bacteria, and whether these are good or bad microbes may depend upon how the apples were grown.
Most microbes are inside the apple but the strains depend upon which bits you eat, and whether you go organic, say researchers, adding that organically-grown apples harbour more diverse and balanced bacteria which make them healthier and tastier than conventional apples.
"The bacteria, fungi and viruses in our food transiently colonise our gut. Cooking kills most of those , so raw fruit and vegetable are particularly important sources of gut microbes," said Professor Gabriele Berg from Graz University of Technology in Austria.
The study, published within the journal Frontiers in Microbiology, compared the bacteria in conventional store-bought apples with those in visually-matched fresh organic ones.
Stem, peel, flesh, seeds and calyx -- the straggly bit at rock bottom where the flower wont to be -- were analyzed separately. Overall, the organic and traditional apples were occupied by similar numbers of bacteria.
"Putting together the typical for every apple component, we estimate a typical 240-gram apple contains roughly 100 million bacteria," Berg informed.
The majority of the bacteria are within the seeds, with the flesh accounting for many of the rest .
So, if you discard the core, your intake falls to nearer 10 million.
The question is: Are these bacteria good for you?
"Freshly harvested, organically-managed apples harbour a significantly more diverse, more even and distinct bacterial community, compared to standard ones," explained Berg.
Specific groups of bacteria known for health-affecting potential also weighed in favour of organic apples.
"Escherichia-Shigella -- a gaggle of bacteria that has known pathogens -- was found in most of the traditional apple samples, but none from organic apples. For beneficial Lactobacilli -- of probiotic fame -- the reverse was true," said the researchers.
Methylobacterium, known to reinforce the biosynthesis of strawberry flavour compounds, was significantly more abundant in organic apples, "especially on peel and flesh samples, which generally had a more diverse microbiota than seeds, stem or calyx", said the researchers.
The results also mirrored findings on fungal communities in apples. "Our results agree remarkably with a recent study on the apple fruit associated fungal community, which revealed specificity of fungal varieties to different tissues and management practices," said Birgit Wasserman, lead author of the study.