Microbial transfers from permanent grassland ecosystems to milk in dairy farms in the Comt\xe9 cheese area

N Chemidlin Prévost-Bouré,C Letourneur,J Dumont,M Campedelli,V Nowak,B Karimi,P Guyot,F Gillet,Y Bouton,S Sadet-Bourgeteau,C Djemiel,M Brie,V Manneville

doi:10.1038/s41598-021-97373-6

Abstract

The specificity of dairy Protected Designation of Origin (PDO) products is related to their “terroir” of production. This relationship needs better understanding for efficient and sustainable productions preserving the agroecological equilibrium of agroecosystems, especially grasslands. Specificity of PDO Comté cheese was related to the diversity of natural raw milk bacterial communities, but their sources need to be determined. It is hypothesized that raw milk indigenous microbial communities may originate from permanent grazed grasslands by the intermediate of dairy cows according to the sequence soil–phyllosphere–teat–milk. This hypothesis was evaluated on a 44 dairy farms network across PDO Comté cheese area by characterizing prokaryotic and fungal communities of these compartments by metabarcoding analysis (16S rRNA gene: V3–V4 region, 18S rRNA gene: V7–V8 region). Strong and significant links were highlighted between the four compartments through a network analysis (0.34 < r < 0.58), and were modulated by soil pH, plant diversity and elevation; but also by farming practices: organic fertilization levels, cattle intensity and cow-teat care. This causal relationship suggests that microbial diversity of agroecosystems is a key player in relating a PDO product to its “terroir”; this under the dependency of farming practices. Altogether, this makes the “terroir” even more local and needs to be considered for production sustainability.

Highlights

The specificity of dairy Protected Designation of Origin (PDO) products is related to their “terroir” of production
Evidencing a causal relationship based on microbial transfers from grassland ecosystem to raw milk to understand the “terroir” effect requires the evaluation of its dependency on fertilization practices, i.e. whether fertilization practices affect microbial transfers from grassland ecosystem to raw milk
With a microbial point of view, this study focused on the sequence from permanent grassland to raw milk and identified high levels of prokaryotic and fungal richness in the four considered compartments: soil, phyllosphere, cow-teat and raw milk

Summary

Introduction

The specificity of dairy Protected Designation of Origin (PDO) products is related to their “terroir” of production. This leads to the hypothesis that microbial communities naturally occurring in raw milk may originate from grassland ecosystems through microbial transfers along the sequence soil–phyllosphere–cow-teat–raw milk Evidencing these microbial transfers from grassland ecosystem to raw milk in a causal relationship is critical to better understand the “terroir” effect, i.e. the drivers relating the specificity of a product to its area of production. The objectives of this study were to evaluate the microbial transfers from grassland compartments (soil and phyllosphere) to cow-teat and raw milk, and identify environmental drivers determining these transfers To reach these objectives, PDO Comté cheese dairy production was considered as a case study and a network of 44 farms was constituted at the scale of PDO Comté area (2300 km2) in the French Jura Mountains. Significant links between compartments can be interpreted as plausible microbial transfers from one compartment to another because of the experimental design and farmers practices

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Discussion

Conclusion