Effects of Temperature and Oxygen Tension on Growth of Escherichia coli in Milk

• Published in: Journal of dairy science Vol. 77; no. 11; pp. 3338 - 3346
• Main Authors: Goldberg, J.J., Bramley, A.J., Sjogren, R.E., Pankey, J.W.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.11.1994; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: Animals; artificial intramammary environment; BACTERIA; Biological and medical sciences; Cattle; CONTEO DE CELULAS; Culture Media; EQUIPO DE LABORATORIO; ESCHERICHIA COLI; Escherichia coli - growth & development; EXPERIMENTACION IN VITRO; EXPERIMENTATION IN VITRO; Food industries; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; LAIT; LECHE; Mammary Glands, Animal - microbiology; Mammary Glands, Animal - physiology; Mastitis, Bovine - microbiology; Mastitis, Bovine - physiopathology; MATERIEL DE LABORATOIRE; Milk - microbiology; Milk and cheese industries. Ice creams; Models, Structural; NUMERATION CELLULAIRE; OXIGENO; Oxygen - physiology; oxygen tension; OXYGENE; Statistics as Topic; Temperature; LPD; pO2; TSB; artificial intramammary environment; oxygen tension; Escherichia coli; temperature; GT; AIME; Mastitis; Microorganism growth; Oxygen; Temperature; Microbiological testing; Fermenter; Physical environment; Mammary gland diseases; Bioreactor; Batch process; Bacteria; Models; Mammary gland; Enterobacteriaceae; Milk
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(94)77275-1

An in vitro system was developed to mimic conditions within normal and mastitic mammary glands. The system consisted of a modified batch fermenter that allowed for manipulation of temperature, oxygen tension, and pH. Experiments in tryptose-soy broth and UHT-treated milk were conducted to evaluate growth characteristics of Escherichia coli P4 as physical conditions were manipulated. The effect of bacterial growth on oxygen tension and pH were also evaluated. Growth of E. coli was inhibited as temperature was increased from 37 to 41°C and as oxygen tension was decreased from microaerophilic to anaerobic levels. At bacterial populations >6 log10 cfu/ml, microaerophilic cultures became anaerobic. The pH followed a similar trend; however, after a significant decrease in pH, mean bacterial populations were 7.1 log10 cfu/ml in tryptosesoy broth and 8.2 log10 cfu/ml in UHT-treated milk. This dynamic model demonstrated potential use in evaluation of growth characteristics of mammary gland pathogens in the lactating mammary gland.