Diversity of psychotrophic bacteria isolated from the milk cooling collective tanks and antibiotics resistance profile of the microorganisms isolates

Abstract

Psychotrophic bacteria were isolated from the wall, bottom and homogenization spade of cooling milk collective tank, after performing the hygienic procedure. These isolates were identified and characterized on the ability in producing protease, lipase and lecithinases, and also to determine the isolates susceptibility to antimicrobial agents. From 32 collective tanks, located in different cities in the South of Minas Gerais, the samples from their surface were collected by swab technique, which were analyzed by serial dilutions plated on trypticase soy agar and incubated at 7 ºC for 10 days. Then, the isolates were selected for performing biochemical identification using kits API 20NE (Biomérieux-Brazil) and Bactray I and II (Laborclin-Brazil). One hundred ninety-seven isolates were identified and characterized in relation to protease, lipase and lecithinase production. From these isolates, 21 were selected for testing the resistance to antibiotics. Bacterial countings from <1 to 108CFU/cm2 were detected, with the prevalence of Serratia sp., Klebsiella sp., besides some species of Pseudomonas genus. The identified isolates showed high proteolytic and lipolytic activity, although the lecithinase activity was less evident. The multidrug resistance was observed in 54% of isolates analyzed.