Scientific Publications - Work Done by Microbiology Reader Bioscreen C

Janice Margaret Baker,
Factors affecting the growth of and toxin production by psychotrophic Bacillus cereus, Dissertation, University of Guelph (Canada), 1993, 209 pp.

ABSTRACT

Psychrotrophic Bacillus cereus were found in 30% (6/20) of raw and 72% (23/32) of pasteurized milk samples. Raw milk isolates (2/7; 28%) and pasteurized milk isolates (17/22; 77%) were able to produce diarrhoegenic toxin at 6$/sp/circ$C in brain heart infusion broth. Diarrhoegenic toxin was more stable in milk than broth when exposed to heat treatments similar to pasteurization. Response surface methodology was used to assess the combined effects of temperature (6-38$/sp/circ$C), pH (5.8-8), water activity (0.965-0.995), starch concentration (0-0.625%), and glucose concentration (0-1.8%) on the growth of, and diarrhoegenic toxin production by, a psychrotrophic strain of B. cereus in brain heart infusion broth. Temperature and water activity had the greatest effects on growth and toxin production. Interactions of factors were also significant. Predicted values compared favourably with observed values for growth, using a spectrophotometer to monitor growth. The Bioscreen C and Bactometer 64 were found to be useful for rapidly generating growth data.

(Abstract online)

© 2005 Transgalactic Ltd (manufacturer of Bioscreen C software) | Privacy Statement | P.O. Box 1393, 00101 Helsinki, Finland, phone: +358 9 85172920, fax: +358 9 8749481, e-mail: microbiology@bionewsonline.com
 

Last modified: May 25, 2005