Quantification of Geotrichum candidum growth in co-culture with lactic acid bacteria
Abstract:The growth dynamics of filamentous fungus G. candidum was studied during the co-cultivation with the commercial lactic acid bacteria (LAB) culture Fresco. The experiments were carried out in milk and on the surface of a milk agar at the temperature ranging from 5 to 37°C. Ratkowsky model was used to describe the relationships of the fungal growth rate to the temperature during both, single and co-cultivation with LAB in milk. Simultaneous growth of LAB affected significantly the growth rate of the filamentous fungus. The growth of G. candidum was in average 39% slower in the co-culture than in the single cultivation. LAB pre-inoculated and growing in the solid medium did not show any significant inhibitory effect on the surface growth of G. candidum at all tested temperature. The precise data describing the growth of this cheese yeast-like fungus, G. candidum, may fill a gap in the field of quantitative food mycology and may be used for predicting its behavior in real conditions.
Effect of temperature and lactic acid bacteria on the surface growth of Geotrichum candidum
Hudecová A., Valík Ľ., Liptáková D., Pelikánová J., Čižniar M. (2011): Effect of temperature and lactic acid bacteria on the surface growth of Geotrichum candidum, Czech J. Food Sci., 29 (Special Issue): S61-S68.The surface growth of Geotrichum candidum isolated from ewes' lump cheese was studied on pure agar medium and that inoculated with lactobacillus rhamnosus GG and l. paracasei subsp. paracasei CCM 1753. The colony growth rates of fungus calculated from the growth curves were modelled in relation to temperature by the cardinal temperature model with inflection (CTMI). The following cardinal values resulted from the secondary model: t min = -3°C, t opt = 27.6°C, and t max = 35.4°C and optimal colony growth rate µ opt = 5.34 mm/day. A quantitative study also showed that the simultaneous growth of l. rhamnosus GG and l. paracasei subsp. paracasei CCM 1753 had either no or only a slight effect on the fungal growth rates, respectively. These results pointed out that other intrinsic or extrinsic factors should be applied for the protection of fresh cheeses against the undesirable growth of G. candidum.
The preparation of ewes’ lump cheese has been known in Slovakia for a long time. It is made from raw or pasteurized ewes’ milk, especially due to the activity of lactic acid bacteria. The encouragement of the acidification process by the starters is profitable to use with the respect to the quality of the product. In our study we focused on the growth analysis of Staphylococcus aureus and Escherichia coli in ewes’ cheeses prepared in laboratory conditions with or without addition of starter culture from raw or heat treated milk. According to our experimental data, the addition of the lactic acid bacteria culture and the following pH decrease on the levels lower than 5.0 for 1 to 2 days were able to inhibit the growth of S. aureus and E. coli on concentrations lower than 104 CFU/g required by European Union legislation. The growth data found in this work may provide the information for food technologists and microbiologists to get the studied organisms under the control. The growth dynamics of Geotrichum candidum was studied on the surface of the skim milk agar with respect to the temperature, pH and water activity/NaCl content. At pH ranging from 5.0 to 7.0, the fungus growth rates were similar, whereas the temperature and water activity represented by salt addition in concentration of 3 % influenced the growth significantly. The effect of incubation temperature on the surface growth rate was modelled with G-Twmodel. Designed model proved to be good predictor of fungus growth at used environmental conditions. As the filamentous fungus under study is commonly present on the surface of various cheeses, the quantitative data found in this work can provide useful information closely related to real fungus growth, e.g. calculation of time required for G. candidum to reach visible 3 mm colony. The predictions showed that, for example at 0 % NaCl content, such colonies were grown for 52.2, 30.7, 18.4, 14.4, 13.9 hat temperatures of 10, 14, 19, 23, 27 °C, respectively. This paper describes action art as one of the possible strategies for supporting seniors with disabilities in special education counseling. The text is complemented by the testimonies of seniors who were part of a national project aimed at integrating action arts into the different periods of a person. scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health. customersupport@researchsolutions.com 10624 S. Eastern Ave., Ste. A-614 Henderson, NV 89052, USA This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Copyright © 2024 scite LLC. All rights reserved. Made with 💙 for researchers Part of the Research Solutions Family.
doi:10.5219/109
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