Enrichment procedure and isolation of bacteria
ATSW sample (10 ml) was transferred to nutrient Brain Hearth Infusion broth (90 ml) (Oxoid, Thermo Fisher Scientific, Inc., Waltham, MA, USA). The sample was incubated at 37°C with 220 rpm until turbidity was been detectable. For autumn sampling, the bacterial inocula were also incubated at 55 °C with 220 rpm. After the appropriate incubation, the broth culture was centrifugated at 3500 rpm for 10’ at room temperature, and serial dilutions were plated on differential and selective media as mentioned above. Separated colonies were then obtained by streaking on selective agar media for several times.