Comparative Study of the Bacterial Community of Organic and Conventional Milk

26 Pages Posted: 21 Sep 2023

See all articles by Nuno M. L. Paiva

Nuno M. L. Paiva

University of the Azores

Susana C. Ribeiro

University of the Azores

Henrique J. D. Rosa

University of the Azores

Celia Costa Gomes Silva

University of the Azores

Abstract

Organic milk is produced by cows that live on pasture without the use of pesticides or synthetic chemical fertilizers, thus contributing to animal welfare and environmental protection. The use of artificial fertilizers, pesticides and antibiotics, as used in conventional systems, can potentially affect the microbial communities in milk. However, the effects of different agricultural practices such as conventional and organic farming on the microbiota of milk have not been adequately researched. The aim of this study was therefore to investigate the effects of organic and conventional dairy farming on the microbial community of milk. Bacterial diversity was studied in 40 cow’s milk samples from farm milk tanks in two seasons – winter and spring - from ten organic and ten conventional farms. No differences in biodiversity indices were found between conventional and organic milk (p > 0.05). However, for conventionally produced milk, significant differences (p < 0.05) were found between seasons in the number of individuals and equivalence. The microbiota of milk from both production systems was dominated by Firmicutes, Proteobacteria, Actinobacteriota and Bacteroidota. The organic milk showed greater heterogeneity between farms, as reflected in the dispersion of diversity indices and the large variation in the relative abundances of the dominant genera. In contrast, conventionally produced milk showed a high degree of similarity within each season. In the conventional production system, the season also had a strong influence on the bacterial community, but this effect was not observed in the organic milk. The LEfSe analysis identified the genus Iamia as significantly (p < 0.05) more abundant in organic milk, but depending on the season, several other genera were identified that distinguished organic milk from conventionally produced milk. Of these, Bacillus, Iamia and Nocardioides were associated with the soil microbiota in organic farming.

Keywords: Raw milk, Microbiota, High-throughput sequencing, Organic farming, organic milk

Suggested Citation

Paiva, Nuno M. L. and Ribeiro, Susana C. and Rosa, Henrique J. D. and Silva, Celia Costa Gomes, Comparative Study of the Bacterial Community of Organic and Conventional Milk. Available at SSRN: https://ssrn.com/abstract=4573793 or http://dx.doi.org/10.2139/ssrn.4573793

Nuno M. L. Paiva

University of the Azores ( email )

Susana C. Ribeiro

University of the Azores ( email )

Henrique J. D. Rosa

University of the Azores ( email )

Celia Costa Gomes Silva (Contact Author)

University of the Azores ( email )

P.O. Box 1422
9501-801 Ponta Delgada
Portugal

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