Growth and thermo-resistance of yersinia enterocolitica, serotype 03

Abstract

The ínfluence of subs tracts at p H 5.0, 7.0 and 9.0 and incubation temperatures on the growth and thermoresistance of a s train of Yersinia eni.erocolitica serotype 03 was observed. For assessing growth af'ter inoculation of a gíven number of viable cells, cultures were observed at the end of 1, 3, 5, 7 and 30 days. At -15°C there was no multiplication, although the germ was viable ; at 42°C, it was destroyed before 24 hours ; at 25°C, the adaptation pcriod is shorter, as compa red with temperatures of 8° and 37°C. At p H 5.0, growth was favored and potato pectins were particularly unfavorable. Temperatures aí 68 and 72°C during 1, 2, 3, 4, 6 and 10 minutes was used for the thermoresistance. At p H 5. O, thermoresistance was greater. The presence of proteín, sugars and cellulose substracts favored the strain while potato pectins reduced that characteristic. After the latter tests, tubes were incubated at soe for days, Some substracts allowed a recovery from the thermal injury.