Microbiological characterization of raw goat milk from a small municipality in Brazil: identification of Gram-positive cocci by MALDI-TOF MS
Authors
-
Gustavo Luis de Paiva Anciens Ramos
Universidade Federal Fluminense
https://orcid.org/0000-0001-5631-9668
- Emily Cristine Candido da Silva Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro
- Lavínia Falcão de Araújo Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro
- Marcelo Soares de Moraes Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro
- Janaína dos Santos Nascimento Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro
DOI:
https://doi.org/10.70099/BJ/2026.03.02.1Keywords:
Staphylococcus aureus, dairy, mass spectrometryAbstract
Goat milk is a high-nutritional-value food, but it can also harbor several pathogenic microorganisms. It is not uncommon for this food to be consumed raw, which can pose health risks to consumers. In this study, we sought to verify the diversity of Gram-positive cocci (GPC), especially Staphylococcus sp., in raw milk sam-ples obtained in the region of Itaocara, RJ. Microbial identification of the nine samples was performed by mass spectrometry (MALDI-TOF) after isolation in selective culture media. MALDI-TOF analysis of the isolates from raw goat milk samples revealed the predominance of Staphylococcus spp., with emphasis on S. aureus and S. caprae. GPCs of other genera were also detected. Surprisingly, some of these microorganisms were isolated on selective media for Gram-negative bacteria, highlighting the importance of accurate confirm-atory identification methods such as MALDI-TOF. The detection of S. aureus, a relevant foodborne pathogen, and other species with spoilage or pathogenic potential, such as S. caprae and Mammaliicoccus sciuri, in six of the nine samples highlights potential microbiological risks associated with locally consumed raw goat milk. On the other hand, the presence of lactic acid bacteria (Lactococcus lactis, L. garvieae, and Enterococcus sp.), with technological potential for producing dairy products, was also observed. The recovery of Gram-positive cocci from media selective for Gram-negative bacteria reinforces the limitations of culture-based selectivity and highlights the importance of confirmatory identification methods such as MALDI-TOF MS. Keywords: Staphylococcus aureus, dairy product, mass spectrometry
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Copyright (c) 2026 Gustavo Luis de Paiva Anciens Ramos, Emily Cristine Candido da Silva, Lavínia Falcão de Araújo, Marcelo Soares de Moraes, Janaína dos Santos Nascimento (Author)
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