Detection and Isolation of Psychrotrophic Acinetobacter spp. in Raw Milk from Ecuador: A Hidden Microbial Risk for...

Acinetobacter species are psychrotrophic microorganisms commonly associated with the spoilage of refrigerated raw milk and dairy products; the aim of this study is to determine the prevalence and spreading of Acinetobacter species isolated from raw milk collected in Ecuador. During the dry and rainy seasons, 400 raw milk samples were collected from dairy farms in the provinces of Pichincha and Manabí. Following genus-level qPCR detection, species-specific PCR screening detected to ten targeted Acinetobacter species in the enriched raw milk samples. Microbiological isolation was followed by 16S rRNA gene sequencing to confirm that the recovered colonies belonged to the genus Acinetobacter and to obtain preliminary taxonomic assignments. Correlations between bacterial presence and climatic season, province and farm size were analyzed; Acinetobacter spp. was detected in 342 of the 400 enriched raw milk samples (85.5%). A higher prevalence was observed in samples from Pichincha province, with A. lwoffii being the most prevalent species (88.89% of positive samples). Five species were isolated: A. lwoffii, A. baumannii, A. calcoaceticus, A. pittii and A. haemolyticus. The high prevalence and diversity of Acinetobacter species in Ecuadorian raw milk suggest widespread distribution of this genus in local dairy systems, highlighting its potential role in milk spoilage and reduced quality.