Bacterial hotspots in your apple from seed to peel

The study compared organic and conventional apples, revealing distinct differences in their microbial profiles.
Bacterial hotspots in your apple from seed to peel

VISAKHAPATNAM: Next time you pick your apples, remember it is not just about the crunch; it is about the bacteria. Recent studies conducted by researchers from Graz University of Technology, Austria, have shed light on the diverse bacterial communities residing within these ubiquitous fruits.

According to their findings, an average 240-grams apple harbours approximately 100 million bacteria. Different parts of the apple (the stem, peel, fruit pulp, seeds, and calyx) host distinct bacterial communities. Fruit pulp and seeds were found to be bacterial hotspots, while the peel showed lower colonisation.

The study compared organic and conventional apples, revealing distinct differences in their microbial profiles. The bacterial communities in apples were primarily composed of Proteobacteria (80%), Bacteroidetes (9%), Actinobacteria (5%), and Firmicutes (3%). Despite the similar overall structure, almost 40% of bacterial genera and orders differed significantly between organic and conventional apples. While both types contain similar total counts of bacteria, the types of bacteria present vary significantly.

Conventional apples often host Escherichia coli and Shigella bacteria, although in low quantities, whereas these pathogens are notably absent in organic apples. Conversely, organic apples exhibit a more diverse and balanced microbial community, including beneficial bacteria such as Lactobacilli, which are associated with probiotic benefits.

The storage conditions post-harvest also influence the apple microbiome. Apples stored in controlled atmospheres show reduced growth of pathogenic fungi like Penicillium and Botrytis compared to those stored under ambient conditions. This suggests that storage practices can impact not only the fruit’s physical condition but also its microbial ecosystem.

Geographical location plays a role as well, shaping the microbial composition of apples grown in different regions. This diversity not only affects the flavour profile but also potentially influences their health-promoting properties.

One notable microbial player in organic apples is Methylobacterium, which enhances the biosynthesis of strawberry-like flavour compounds. This finding suggests that the microbial community in apples contributes not only to their nutritional content but also to their sensory appeal.

While these insights into the microbiome are promising, the researchers noted that further research is needed to fully understand how microbial diversity in apples translates into health benefits for consumers. They stated that understanding these dynamics could potentially lead to improved fruit storage practices, better crop management strategies, and enhanced consumer awareness of the nutritional and microbial aspects of fresh produce.

In sum, next time you enjoy an apple, remember that it is more than just a crunchy snack; it is a complex ecosystem of microbes that adds depth to both its flavour and potential health benefits.

100 million bacteria in one apple

Consuming a whole apple includes an approximate uptake of 100 million bacteria. However, freshly harvested, organically managed apples have a significantly more diverse and distinct microbiota as compared to the conventional ones. Organic apples have favourable health effects for the consumer, the plant and environment

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