The evolution of "-omics" technologies made us aware of the varied and complex assortments of microbes that inhabit living animals and of the reciprocal interactions they entertain among themselves and with their hosts [1]. Among these technologies, metagenomics enables the characterization of a microbial population in a culture-independent manner [2], providing a powerful means for identifying dominant and subdominant microbes and their dynamics in highly complex ecosystems. Animals host on their skin, gut, rumen, oro-pharyngeal, urinary and genital tracts a wide diversity of microbial communities that have evolved with them because of mutualistic interactions, playing crucial roles in their biology and health [3]. Recently, the mammary gland has also been included among the sites colonized by microorganisms [1]. The milk microbiota composition depends on both the composition of microbial ecosystems in direct contact with the milk and on various environmental microbial sources not directly in contact with the milk. Other studies also support the hypothesis that the presence of bacteria in milk is not due only to an external colonization, because bacterial isolates present in the mammary gland are genotipically different from those found on skin within the same host and the same bacterial species [1]. Most studies on milk microbiota focused on its changes during food production, on milk microbiota changes during mastitis or following antimicrobial treatment, and on the effects on milk microbiota of different therapy conditions during the dry period [4-5], that represents the most critical phases for udder health [6], especially for highly productive breeds. The milk microbiota in 6 Holstein Friesian and 3 Rendena cows, indigenous Italian dual-purpose alpine breed, reared in the same farm and under the same management conditions, with a special focus on the transition period to define bacterial groups prevalence with a plausible effect on mammary gland health, was compared. Four time points (dry-off, 1 d, 7-10 d and 30 d after calving) were considered, characterizing the microbiome for 117 milk samples with a somatic cell count lower than 200,000 cell/ml, to focus on physiological microbiome changes avoiding shifts due to suspected diseases. Microbial populations were deeply different in the two breeds along all the time points, with REN milk showing a significantly lower microbial biodiversity. The taxonomic profiles of both cosmopolitan and local breeds were dominated by Firmicutes, mostly represented by the Streptococcus genus, although in very different proportions (HF 27.5%, REN 68.6%). Profound differences in HF and REN cows were, also, evident from the metabolic predictive analysis from microbiome data. Lastly, only HF milk displayed significant changes in the microbial composition along the transition period, while REN maintained a more stable microbiota. In conclusion, in addition to the influence on the final characteristics of dairy products obtained from milk of the two breeds, differences in the milk microbiome might, also, have an impact on their mammary gland health. [1] Addis MF, et al. 2016. Mol BioSyst;12(8):2359-72. [2] Garrido-Cardenas JA, et al. 2017. Curr Genet; 63(5):819-29. [3] Sender R, et al. 2016. PLoS Biol;14(8):1-14. [4] Oikonomou G, et al. 2012. PLoS One;7(10), e47671. [5] Bonsaglia ECR, et al. 2017. Sci Rep; 7(1), 8067. [6] Oliver SP, et al. 1988. J Dairy Sci; 71(9), 2584-606. Review.
Microbioma del latte e biodiversità
Paola Cremonesi
2018
Abstract
The evolution of "-omics" technologies made us aware of the varied and complex assortments of microbes that inhabit living animals and of the reciprocal interactions they entertain among themselves and with their hosts [1]. Among these technologies, metagenomics enables the characterization of a microbial population in a culture-independent manner [2], providing a powerful means for identifying dominant and subdominant microbes and their dynamics in highly complex ecosystems. Animals host on their skin, gut, rumen, oro-pharyngeal, urinary and genital tracts a wide diversity of microbial communities that have evolved with them because of mutualistic interactions, playing crucial roles in their biology and health [3]. Recently, the mammary gland has also been included among the sites colonized by microorganisms [1]. The milk microbiota composition depends on both the composition of microbial ecosystems in direct contact with the milk and on various environmental microbial sources not directly in contact with the milk. Other studies also support the hypothesis that the presence of bacteria in milk is not due only to an external colonization, because bacterial isolates present in the mammary gland are genotipically different from those found on skin within the same host and the same bacterial species [1]. Most studies on milk microbiota focused on its changes during food production, on milk microbiota changes during mastitis or following antimicrobial treatment, and on the effects on milk microbiota of different therapy conditions during the dry period [4-5], that represents the most critical phases for udder health [6], especially for highly productive breeds. The milk microbiota in 6 Holstein Friesian and 3 Rendena cows, indigenous Italian dual-purpose alpine breed, reared in the same farm and under the same management conditions, with a special focus on the transition period to define bacterial groups prevalence with a plausible effect on mammary gland health, was compared. Four time points (dry-off, 1 d, 7-10 d and 30 d after calving) were considered, characterizing the microbiome for 117 milk samples with a somatic cell count lower than 200,000 cell/ml, to focus on physiological microbiome changes avoiding shifts due to suspected diseases. Microbial populations were deeply different in the two breeds along all the time points, with REN milk showing a significantly lower microbial biodiversity. The taxonomic profiles of both cosmopolitan and local breeds were dominated by Firmicutes, mostly represented by the Streptococcus genus, although in very different proportions (HF 27.5%, REN 68.6%). Profound differences in HF and REN cows were, also, evident from the metabolic predictive analysis from microbiome data. Lastly, only HF milk displayed significant changes in the microbial composition along the transition period, while REN maintained a more stable microbiota. In conclusion, in addition to the influence on the final characteristics of dairy products obtained from milk of the two breeds, differences in the milk microbiome might, also, have an impact on their mammary gland health. [1] Addis MF, et al. 2016. Mol BioSyst;12(8):2359-72. [2] Garrido-Cardenas JA, et al. 2017. Curr Genet; 63(5):819-29. [3] Sender R, et al. 2016. PLoS Biol;14(8):1-14. [4] Oikonomou G, et al. 2012. PLoS One;7(10), e47671. [5] Bonsaglia ECR, et al. 2017. Sci Rep; 7(1), 8067. [6] Oliver SP, et al. 1988. J Dairy Sci; 71(9), 2584-606. Review.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
