ABSTRACT
Milk is a rich food, source of several indispensable nutrients, much consumed by the population. Its quality and microbiota are influenced by several factors. The objective of the present study was to determine the microbiota of refrigerated raw milk and processed milk in dairy products in Vale do Taquari - RS, through genetic sequencing. Three types of milk were analyzed in two dairies in the region: raw refrigerated milk, which arrives at the dairies by means of tank trucks, pasteurized milk and milk treated by Ultra High Temperature (UHT). The determination of the milk microbiota was performed through sequencing of the 16S rRNA gene. The results showed that refrigerated raw milk has the highest number of microorganisms in the two dairy products, followed by pasteurized milk and milk sterilized by the UHT process, successively. Dairy processing 2 proved to be more efficient, especially for UHT treated milk, considerably reducing the microbiota. Eighty-seven species of the Bacteria Kingdom were identified and the samples showed considerable microbiological diversity. Psychrotrophic microorganisms such as Kurthia gibsonii were expressive in the samples. Lactic acid bacteria such as Streptococcus macedonicus were found in refrigerated raw milk and pasteurized milk and Streptococcus thermophilus in sterilized milk. Harmful species such as Bacillus cereus group, Aeromonas dhakensis and Acinetobacter haemolyticus were found in UHT treated milk from both dairy products, in addition to Aeromonas caviae, Enterobacter mori and Viridibacillus arenosi.
Index terms:
Microorganisms; metagenomics; genetic sequencing; milk quality; milk production
