Microbiological studies on

A survey was undertaken to determine the prevalence ofAeromonas spp. in 75 random samples, 25 each of raw milk, localplain yoghurt and Domiati cheese collected from different dairyshops, supermarket and street peddlers in Diarb Negm and Zagazigcities, Egypt. The proteolytic and lipolytic activities of isolatedAeromonas spp. were investigated. Also, the effect of heat-treatment as well as effect of acidity and sodium chlorideconcentration on prevalence of Aeromonas bacteria was tested.8 (32.0%) out of examined raw milk samples containedAeromonas spp. using Aeromonas agar medium, the correspondingcount was ranged from 2.0 xl03 to 3.0 x104 with a mean value of9.8 x103/ml. Of 20 confirmed cultures isolated from raw milk. 8(40.0 %) of the isolated strains could be classified as A. trotafollowed by 5 (25.0 %) as A. hyDROPhila, 5 (25.0 %) as A. janda and2 (10.0 %) as A. caviae.Prevalence of Aeromonas spp. was proved in 11(44.0%) ofyoghurt and 5 (20.0%) in domiati cheese samples using Aeromonasagar medium. The mean value of Aeromonas spp. was 1.4 xl05 6.9xl03 and in yoghurt and domiati cheese, respectively. Of22 culturesisolated from yoghurt samples 8 (36.4%) could be classified as A.caviae, 5 (22.7%) as A. sobria, 4 (18.2%) as A. hyDROPhila, 3(13.6%) as A. trota and 2 (9.1 %) as A. schubertii. Classification ofthe 10 confirmed cultures isolated from cheese revealed that 3(30%) of the strains could be classified as A. hyDROPhila followedby 5 (50%) as A. caviae and 2 (20%) as A. trota.