Banca de DEFESA: ALLANA LAIS ALVES LIMA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALLANA LAIS ALVES LIMA
DATE: 18/07/2024
TIME: 10:00
LOCAL: Plataforma Google Meet
TITLE:

Microbiome of dairy buffaloes: study of the interaction between the calf and the environment and the development of bacterial resistance

KEY WORDS:

Bubalus bubalis. Milk. Microbial ecology. Vertical transfer. Antimicrobial resistance.

PAGES: 71
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Reprodução Animal
SUMMARY:

This thesis divided into two chapters. In the first chapter, the hypothesis that the buffalo milk microbiome could share taxa with samples from their feces, pasture soil, and their calf's spittle was tested. Additionally, a potential correlation between generations was studied. For this purpose, milk, feces, and spittle samples were collected in triplicate from first and third lactation animals at peak lactation on a farm in the Marajó archipelago, Amazon, Pará-Brazil. Pasture soil was also sampled. All animals in the field were clinically healthy; macroscopic examination of milk secretion and the California Mastitis Test showed no reactive results. Milk somatic cell count showed significant differences between heifers and cows, suggesting that lifetime exposure to microrganisms may naturally increase somatic cells in their milk. Metabarcoding using rRNA 16S revealed significant differences in phylogenetic and ecological structure among all studied matrices. Beta-diversity analysis showed clustering among milk samples from first and third lactations, and similar patterns among feces and spittle samples. The most abundant phyla in biological samples were Firmicutes, Proteobacteria, and Bacteroidota. These taxa were found concurrently in at least two biological matrices but never in all three simultaneously. Firmicutes phylum was shared between soil and milk, and feces of cows and heifers. Additionally, Actinobacteria was abundant in soil, contrasting with biological samples. The studied samples exhibited a matrix-dependent pattern, and despite taxonomic sharing, no correlation could be established between buffaloes, regardless of their parity and their calves. In the second chapter, bioprospecting was conducted for Gram-negative strains resistant to tetracycline and beta-lactams, present in the microbiota of buffalo feces and pasture soil on a farm in the Marajó archipelago, Amazon, Pará-Brazil. Furthermore, the hypothesis of a correlation between this specific microbiota of buffalo generations and the environment was evaluated. Fecal samples were collected in triplicate from first (heifer - HF) and fourth parity (cow - CW) animals and their respective calves (heifer-calf [CFH] and cow-calf [CFC]). Pasture soil (S) was also collected in triplicate. For enterobacteria screening, collected samples were diluted and plated on selective media for Gram-negatives supplemented with antibiotics Ceftriaxone (CRO - 4µg/mL) or Tetracycline (TET - 16 µg/mL). The antifungal nystatin (48 μg/mL) was added to cultures to prevent fungal growth. Colonies grown on plates containing beta-lactams were subjected to replica-plating on plates containing antibiotics Cefepime (CFP - 16 µg/mL) and Imipenem (IMP - 4 µg/mL) to apply different selective pressures. The grown colonies were isolated and identified using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). No significant differences in counts of TET- and CRO-resistant colonies were observed in any of the studied groups (HF, CW, CFH, and CFC) or samples (soil and feces). In total, 91 bacterial strains were isolated, including 37 tetracycline-resistant strains, 27 CFP-resistant, and 27 IMP-resistant. Gram-negative strains were identified as Escherichia coli (TET [33 strains]; IMP [7 strains]), Ochrobactrum intermedium (TET [4 strains]; CFP [19 strains]; IMP [10 strains]), Achromobacter xyloxidans (CFP [5 strains]), and Stenotrophomonas maltophilia (CFP [3 strains]; IMP [10 strains]). Significant differences were observed in the number of isolates resistant to cefepime and imipenem between CFC and S compared to other groups. Cluster analysis based on antibiotic resistance profiles showed similarity between CFC and CW for IMP, and between CW, HF, and CFC with S for TET, IMP, and CFP, respectively. Gram-negative strains isolated from buffalo feces and pasture soil showed resistance to the studied antibiotics. Resistance profiles indicated similarity between adult animals and calves compared to soil, and similarity between calves and their mothers. This finding suggests sharing of resistant strains among animal generations and between animals and soil.

COMMITTEE MEMBERS:
Externo à Instituição - WALTER MARTIN ROLAND OELEMANN - UFRJ
Externa à Instituição - ALICE MARIA MELVILLE PAIVA DELLA LIBERA - USP
Externa à Instituição - ALYNE CRISTINA SODRE LIMA - IFAP
Externo à Instituição - DAMAZIO CAMPOS DE SOUZA - UNISUAM
Externo à Instituição - DIEGO ASSIS DAS GRAÇAS - UFPA
Externa à Instituição - JOANA MONTEZANO MARQUES - UFABC
Presidente - 1368855 - RINALDO BATISTA VIANA