Evaluation of different growth media for the recovery of the species of Alicyclobacillus
Letters in Applied Microbiology
Department of Food Science, Stellenbosch University, Stellenbosch, South Africa; Department of Biotechnology, University of the Western Cape, Bellville, South Africa; Department of Food Science, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
Aims: Five different isolation media, namely potato dextrose agar (PDA), orange serum agar (OSA), K agar, yeast-starch-glucose agar and Bacillus acidocaldarius medium were evaluated for the recovery of Alicyclobacillus spp. from inoculated diluted and undiluted fruit-juice concentrates. Methods and Results: Plates of PDA (pH 3.7), spread with vegetative cells (3.9 × 106 CFU ml-1) of Alicyclobacillus acidoterrestris from single-strength pear juice, recovered 2.9 × 106CFU ml -1 after 5 days at 50°C (74% recovery). The recovery of endospores from single-strength pear juice, after a heat treatment at 80°C for 10 min, was higher on spread plates of OSA (pH 5.5) at 50°C for 5 days (97% recovery). Conclusions: PDA (pH 3.7) and OSA (pH 5.5) at 50°C for 3-5 days recovered the highest numbers of vegative cells and endospores of Alicyclobacillus spp. from sterilized fruit juices and concentrates. Significance and Impact of the Study: The most appropriate synthetic media for the recovery of Alicyclobacillus species from inoculated fruit juices and concentrates are shown. © 2007 The Authors.
Bacteria; Cells; Fruit juices; Glucose; Heat treatment; pH effects; agar; bacterium; dilution; glucose; inoculation; sporulation; yeast; Alicyclobacillus; article; bacterial endospore; bacterial growth; bacterial strain; culture medium; heat treatment; nonhuman; vegetative growth; Agar; Bacteriological Techniques; Beverages; Culture Media; Gram-Positive Endospore-Forming Bacteria; Hydrogen-Ion Concentration; Species Specificity; Temperature; Vitis; Alicyclobacillus; Alicyclobacillus acidocaldarius; Alicyclobacillus acidoterrestris; Pyrus; Solanum tuberosum