A coordinated survey for Cronobacter and related organisms in powdered infant formula, follow up formula and infant foods was undertaken by 8 laboratories in 7 countries in recognition of and in response to the data needs identified in an FAO/WHO call for data in order to develop global risk management guidance for these products. The products (domestic and imported) were purchased from the local market and were categorised according to their principle ingredients. A total of 290 products were analysed using a standardised procedure of pre-enrichment in 225 ml Buffered Peptone Water (BPW), followed by enrichment in Enterobacteriaceae Enrichment (EE) broth, plating on the chromogenic Cronobacter Druggan-Forsythe-Iversen (DFI) agar and presumptive identification with ID 32 E. Presumptive Cronobacter isolates were identified using 16S rRNA gene sequence analysis. Aerobic plate counts (APC) of the products were also determined on nutrient agar. Fourteen samples had APC>10(5) cfu/g, 3 of which contained probiotic cultures. C. sakazakii was isolated from 27 products; 3/91 (3%) follow up formulas (as defined by Codex Alimentarius Commission), and 24/199 (12%) infant foods and drinks. Hence C. sakazakii was less prevalent in follow up formula than other foods given to infants over the same age range. A range of other bacteria were also isolated from follow up formulas, including Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumoniae, Citrobacter freundii, and Serratia ficaria. There was significant variation in the reconstitution instructions for follow up formulas. These included using water at temperatures which would enable bacterial growth. Additionally, the definition of follow up formula varied between countries.
When grown in the presence of benzoic acid, Saccharomyces cerevisiae was able to extrude [14C]benzoic acid when a pulse of glucose was given to preloaded cells. While octanoic, sorbic, hexanoic, salicylic, butyric and propionic acids were also inducers, ethanol and acetic acid were not. The mechanism of extrusion required energy and prior growth in the presence of the inducers. Diethylstilbestrol, an inhibitor of ATPases, prevented benzoic acid extrusion. Propionic acid was not actively extruded in cells adapted to either benzoic or propionic acid, behaving as an appropriate probe to measure intracellular pH. Even though the extrusion mechanism was active, benzoic acid entered the cells by a simple diffusion mechanism.
Please cite this article as: Alves, M., Gonçalves, T., Quintas, Célia. Microbial quality and yeast population dynamics in cracked green table olives ' fermentations, Food Control (2011), doi: 10.1016/ j.foodcont.2011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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