# Does Organic Farming Increase Raspberry Quality, Aroma and Beneficial Bacterial Biodiversity?
## 4 Discussion  
### Diversity of Fruit-Associated Microbiomes  
Several studies demonstrated the influence of management practices on soil microbial composition and functions [52]. In recent years, the microbial communities in the phyllosphere have gained increasing attention [53]. Nonetheless, only a few studies have focused on the microbial communities hosted by fruits grown with different cultivation methods, mainly with the purpose of assessing risks to human health [29] or managing post-harvest crop storage [54].  
In this work, NGS analysis highlighted that IPM raspberry fruits were characterized by a higher bacterial biodiversity in comparison to organically grown ones, with _Brevibacillus_ (28% relative OTU abundance), _Methylobacterium_ (12%), _Rosenbergiella_ (18%) and _Sphingomonas_ (5%) being the most abundant genera. _Rosenbergiella_ and _Sphingomonas_ spp. were almost absent in organic fruits. _Rosenbergiella_ belongs to the family Enterobacteriaceaeae and has been detected in several plant species [55]. _Sphingomonas_ has been found in natural environments, such as soil and plants, and has been proven to possess multifaceted positive functions [56].  
The bacterial community of organic berries was dominated by the genus _Glucobacter_ (73%), followed by _Brevibacillus_ (14%) and _Methylobacterium_ (4%) (Figure 1). _Glucobacter_ was only found on organic fruits. This genus includes acetic acid bacteria known to live  
Figure 8: Characterization of volatile organic compound profiles, produced by assembling the emissions of single bacterial isolates from organic or IPM grown raspberries. Diagram shows (**a**) Principal Component (PC) 1 and 2 of principal component analysis (PCA) of the simulated fruits. Ellipses enclose confidence level = 95%. (**b**) loadings of the 20 \(m/z\) fragments showing highest correlation with PC1 in the PCA analysis.  
on a wide variety of fruits, and encompasses saprophytic, symbiotic, and pathogenic species [57]. In particular, some _Gluconobacter_ strains are known to cause postharvest fruit losses, by causing rotting and browning [58].  
Farming practices such as fertilizer or pesticide application shape microbiome compositions by modifying nutrient availability and ecological niches [59]. Although different research works suggest that organic cultivation promotes microbial biodiversity in the soil and on fruit surface [29; 60; 61], our results indicate that, in raspberry, IPM cultivation promoted bacterial biodiversity on fruit. It can be hypothesized that in crop systems with low inputs and disturbances, such as that of organic farming, microbial communities are dominated by few, highly adapted bacterial species able to outcompete potential generalist colonizers, thus becoming predominant. Indeed, the natural habitats of _Gluconobacter_ spp., the prevalent bacterial genera on organic fruits, are flowers and fruits [62].  
On the other hand, chemical pesticide application affects microorganisms in complex communities, opening ecological niches otherwise occupied by competing microorganisms [63], with microbial community dynamics depending on the chemical nature, rates and frequency of treatments.