A protocol for quantifying the birth, death and emigration rates of produce-associated bacteria, illustrated by its application to Salmonella enterica serovar Typhimurium on cultivated mushrooms.
Colony counts, counts of immunostained cells, fluorescent assays for cell viability and titration of a superinfecting bacteriophage were incorporated into a protocol for studying the growth kinetics of produce-associated bacteria in vivo. A set of equations was assembled for measuring the true rates of birth, death and emigration of the bacteria within the frame of a "transit growth" model, thus allowing the independent measurement of the carrying capacity of the substrate and of the overall productivity of the system. Implementation of the protocol on two species of cultivated mushrooms inoculated with Salmonella enterica serovar Typhimurium showed that large bacterial populations developed on Agaricus bisporus A15 but emigration was not detected, whereas resident populations on Agrocybe aegerita FAR142 amounted to 79.7%, 65.1% and 80.7% of the cultivable, dead and total bacterial cells produced, owing to emigration.
Ercolani
G L
GL
Istituto di Microbiologia Agraria e Tecnica, Università degli Studi di Bari, Via Amendolla 165a, 70126 Bari, Italy. ercolani@agr.uniba.it
D000363:Agaricales; D001435:Bacteriophages / Q000254:growth & development; D015169:Colony Count, Microbial; D008954:Models, Biological; D012486:Salmonella typhimurium / Q000254:growth & development*; D015163:Superinfection