Enumeration of Escherichia coli in Frozen Samples After Recovery from Injury1

AUTOR(ES)

Ray, B.

RESUMO

More than 90% of the surviving cells of Escherichia coli NCSM were injured after freezing in water at -78 C. Injury was determined by the ability of cells to form colonies on Trypticase soy agar with yeast extract but not on violet red-bile agar and deoxycholate-lactose agar. Exposure of the injured cells to Brilliant Green-bile broth and lauryl sulfate broth prevented subsequent colony formation on Trypticase soy agar with yeast extract. The freeze-injury could be repaired rapidly in a medium such as Trypticase soy broth with yeast extract (TSYB). The repaired cells formed colonies on violet red-bile agar and deoxycholate-lactose agar and were not inhibited by Brilliant Green-bile broth and lauryl sulfate broth. At least 90% of the cells repaired in TSYB within 30 min at 20 to 45 C and began multiplication within 2 h at 25 C. When the cells were frozen in different foods, 60 to 90% of the survivors were injured. Repair of the injured cells occurred in foods during 1 h at 25 C, but generally repair was greater and more reproducible when the foods were incubated in TSYB. The study indicated that the repair of freeze-injured coliform bacteria should be accomplished before such cells are exposed to selective media for their enumeration.

Documentos Relacionados

• Injury and recovery of Escherichia coli after sublethal acidification.
• Precursor Ribosomal Ribonucleic Acid and Ribosome Accumulation In Vivo During the Recovery of Salmonella typhimurium from Thermal Injury1
• Coliform Behavior in Frozen Foods: I. Rapid Test for the Recovery of Escherichia coli from Frozen Foods
• Comparison of EC broth and medium A-1 for the recovery of Escherichia coli from frozen shucked snow crab.
• Detection and Enumeration of Fecal Indicator Organisms in Frozen Sea Foods12: I. Escherichia coli