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Estudo comparativo da comunidade bacteriana do leite biológico e convencional
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Abstract(s)
O leite biológico certificado provém de vacas que vivem e se alimentam diariamente no pasto, sem o uso de pesticidas ou fertilizantes químicos sintéticos, contribuindo para a proteção do meio ambiente, bem-estar animal e desenvolvimento rural sustentável. Este é o primeiro estudo da comunidade microbiana do leite produzido nos Açores onde se comparam os sistemas de produção biológico e convencional. Foram coletadas 40 amostras de leite, sendo 20 de produção biológica e 20 de produção convencional em duas estações: inverno e primavera. A identificação da comunidade bacteriana foi realizada por amplificação da região hipervariável V3-V4 do gene 16S rRNA e sequenciação pela plataforma Illumina. As atribuições
taxonómicas para os ASVs foram determinadas usando o banco de dados SILVA. Não se observaram diferenças nos diferentes índices de biodiversidade (P>0.05) entre o leite convencional e biológico, embora se tenham registado uma redução no número de indivíduos (P<0,05) e aumento da equitabilidade (P<0,05), refletindo um menor número de espécies dominantes no leite produzido no modo convencional no inverno. Em ambos os sistemas de produção o leite apresentou uma microbiota dominada pelos filos Firmicutes, Proteobacteria, Actinobacteriota e Bacteroidota, destacando-se 13 géneros dominantes: Lactococcus,
Acinetobacter, Staphylococcus, Chryseobacterium, Pseudomonas, Macrococcus, Thermoanaerobaculaceae – Subgroup 10, Clostridium sensu stricto 1, Corynebacterium, Aerococcus, Romboutsia, Lachnospiraceae NK3A20 e Leuconostoc. O leite em modo de produção biológico apresentou também uma maior heterogeneidade entre explorações, refletida pela dispersão dos índices de diversidade e pela grande variação nas abundâncias relativas dos géneros dominantes observados nas diferentes amostras. Estes resultados foram confirmados pela análise PCoA, onde se registou uma dispersão das amostras produzidas em modo
biológico, em contraste com as amostras de leite produzido no sistema convencional, que apresentaram um elevado nível de similaridade tanto na primavera como no inverno. Neste sistema de produção, observou-se também uma clara separação da comunidade bacteriana entre o leite produzido no inverno e na primavera. Já no modo de produção biológico, devido à prática do pastoreio durante todo o ano, essa distinção não foi observável. A análise de LEfSe identificou alguns géneros como diferenciadores do modo de produção biológico. Destes, destacam-se os géneros Bacillus, Iamia e Nocardioides, associados à microbiota do solo nos sistemas de produção biológico, bem como o género Christensenellaceae group R7 com um potencial efeito benéfico para a saúde.
ABSTRACT: Certified organic milk comes from cows that live and are fed daily on pasture without the use of pesticides or synthetic chemical fertilisers. This contributes to environmental protection, animal welfare and sustainable rural development. This is the first study on the microbial community of milk produced in the Azores comparing organic and conventional production systems. Forty milk samples were taken, 20 from organic and 20 from conventional production in two seasons: Winter and Spring. Identification of the bacterial community was done by amplification of the hypervariable region V3-V4 of the 16S rRNA gene and sequencing with the Illumina platform. The taxonomic assignments of the ASVs were determined using the database SILVA. No differences were found in the different biodiversity indices between conventional and organic milk (P > 0.05), although the number of individuals decreased (P<0,05) and equitability increased (P<0,05), indicating a lower number of dominant species in the conventionally milk produced in winter. In both production systems, the milk had a microbiota dominated by the phyla Firmicutes, Proteobacteria, Actinobacteriota and Bacteroidota, with 13 dominant genera: Lactococcus, Acinetobacter, Staphylococcus, Chryseobacterium, Pseudomonas, Macrococcus, Thermoanaerobaculaceae – Subgroup 10, Clostridium sensu stricto 1, Corynebacterium, Aerococcus, Romboutsia, Lachnospiraceae NK3A20 and Leuconostoc. Organic milk also 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 the samples. These results were confirmed by the PCoA analysis, where a scattering of the organic samples was found, in contrast to the conventional milk samples, which showed a high degree of similarity in both spring and winter. In this production system, a clear separation of the bacterial community between the milk produced in winter and spring was also observed. In the organic production system, this distinction was not observed due to year-round grazing. The LEfSe analysis identified some genera as distinguishing features of the organic production method. Of these, the genera Bacillus, Iamia and Nocardioides stand out as being associated with soil microbiota in organic production systems, as well as the genus Christensenellaceae group R7 with a potential positive effect on health.
ABSTRACT: Certified organic milk comes from cows that live and are fed daily on pasture without the use of pesticides or synthetic chemical fertilisers. This contributes to environmental protection, animal welfare and sustainable rural development. This is the first study on the microbial community of milk produced in the Azores comparing organic and conventional production systems. Forty milk samples were taken, 20 from organic and 20 from conventional production in two seasons: Winter and Spring. Identification of the bacterial community was done by amplification of the hypervariable region V3-V4 of the 16S rRNA gene and sequencing with the Illumina platform. The taxonomic assignments of the ASVs were determined using the database SILVA. No differences were found in the different biodiversity indices between conventional and organic milk (P > 0.05), although the number of individuals decreased (P<0,05) and equitability increased (P<0,05), indicating a lower number of dominant species in the conventionally milk produced in winter. In both production systems, the milk had a microbiota dominated by the phyla Firmicutes, Proteobacteria, Actinobacteriota and Bacteroidota, with 13 dominant genera: Lactococcus, Acinetobacter, Staphylococcus, Chryseobacterium, Pseudomonas, Macrococcus, Thermoanaerobaculaceae – Subgroup 10, Clostridium sensu stricto 1, Corynebacterium, Aerococcus, Romboutsia, Lachnospiraceae NK3A20 and Leuconostoc. Organic milk also 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 the samples. These results were confirmed by the PCoA analysis, where a scattering of the organic samples was found, in contrast to the conventional milk samples, which showed a high degree of similarity in both spring and winter. In this production system, a clear separation of the bacterial community between the milk produced in winter and spring was also observed. In the organic production system, this distinction was not observed due to year-round grazing. The LEfSe analysis identified some genera as distinguishing features of the organic production method. Of these, the genera Bacillus, Iamia and Nocardioides stand out as being associated with soil microbiota in organic production systems, as well as the genus Christensenellaceae group R7 with a potential positive effect on health.
Description
Dissertação de Mestrado, Engenharia Zootécnica, 14 de julho de 2023, Universidade dos Açores.
Keywords
Microbiota DNA Bactérias Leite Biológico
Citation
Paiva, Nuno Miguel Lopes. (2022). "Estudo comparativo da comunidade bacteriana do leite biológico e convencional". 104 p. (Dissertação de Mestrado em Engenharia Zootécnica). Angra do Heroísmo: Universidade dos Açores, 2022. Disponível em http://hdl.handle.net/10400.3/7125