In the present study, listeria in dairy environmental samples were enumerated and isolated in order to find the source of its entry into milk. Based on that soil, dung, fodder and feed considered under solid dairy environmental samples collected from Livestock Farm Complex, Veterinary college, KVAFSU, Bengaluru showed listeria counts ranging from 2.49 to 4.56 log10cfu/g when serially diluted and PALCAM agar was used as selective medium. Soil had listeria count of 79% followed by fodder of 60%, dung of 52% and feed of 51% when compared with total bacterial count. The liquid non-milk dairy environmental samples like swab of udder, swab of handler, can rinse, pail rinse, water, urine and air exhibited 0.00 to 1.53 log10cfu/ml of listeria. Swab of udder had more listeria count compared to other samples, while air of milking parlour did not show the presence of listeria. Among liquid milk dairy environmental samples like aseptic milk, pail milk, can milk, chilled milk and pasteurized milk, listeria count ranged from 0.00 to 1.89 log10cfu/ml. Aseptic milk, pail milk and pasteurized milk samples did not reveal the presence of listeria while can milk and chilled milk samples had listeria. The presence of listeria in raw milk may be introduced through soil, dung, fodder, feed, udder swab, urine that showed the presence of listeria. A total of eighteen listeria isolates were obtained that was inclusive of three isolates each from soil, dung, chilled milk followed by two isolates from fodder; feed; swab of udder; can milk and one isolate from cow urine sample.

PALCAM, Listeria, Swab, Isolates, Milking Parlour

Among dairy environmental samples, soil, fodder, dung, feed while swab of udder, urine of milch animal, can milk and chilled milk showed the counts of listeria on PALCAM agar. A total of 18 number of isolates of listeria were obtained from the dairy environmental samples that revealed listeria counts. From this study it is evident that listeria may enter from dairy environmental samples into raw milk.

Sushmitha P., Ramachandra B., Sachindra Babu A. and Prabha R. (2023). Enumeration and Isolation of Listeria species from Dairy Environmental Samples. Biological Forum – An International Journal, 15(12): 149-153.