Growth of food-borne pathogenic bacteria in oil-in-water emulsions: I--Methods for investigating the form of growth.
Methods are presented for investigating the site and form of growth of bacteria in model oil-in-water emulsions and in dairy cream. Following growth of the bacteria, the continuous aqueous phase is gelled using agarose and the oil phase removed using a mixture of chloroform and methanol. Using this method, the authors have found that Listeria monocytogenes, Salmonella typhimurium and Yersinia enterocolitica grow in the form of colonies in concentrated oil-in-water emulsions. Colonies of L. monocytogenes and Y. enterocolitica also form in artificially-inoculated fresh and tinned dairy cream. If information about the precise site of growth is not required, the authors have discovered that intact colonies can be liberated from the model emulsions by dissolving away the oil phase with chloroform:methanol.
Parker
M L
ML
Institute of Food Research, Norwich Laboratory, Colney, UK.
Brocklehurst
T F
TF
Gunning
P A
PA
Coleman
H P
HP
Robins
M M
MM
D000473:Alkanes / Q000737:chemistry; D002725:Chloroform / Q000737:chemistry; D003470:Culture Media; D003611:Dairy Products / Q000382:microbiology; D004655:Emulsions; D005079:Excipients / Q000737:chemistry; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D000432:Methanol / Q000737:chemistry; D009821:Oils; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D012685:Sepharose / Q000494:pharmacology; D014871:Water Microbiology; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure
D000473:Alkanes; D003470:Culture Media; D004655:Emulsions; D005079:Excipients; D009821:Oils; D002725:Chloroform; D012685:Sepharose; C007932:n-hexadecane; D000432:Methanol