Effect of controlled atmosphere gases (CO2, O2 and ethylene) on growth and survival of Aureobasidium pullulans
2012
Martínez-Romero, D. | Ramos, P. | Santos, M. | Barreiro, M.G. | Ferreira-Pinto, M.M.
Aureobasidium pullulans is one of the most common microorganism in pome fruits. Alternative biocontrol agents have been investigated with success and the yeast-like fungus A. pullulans (de Bary) Arnaud was reported to inhibit postharvest decay of fruit effectively. In our previous studies, an isolate of A. pullulans, obtained from leaves and fruits of 'Rocha' pear trees in Alcobaça, showed antagonistic properties against P. expansum during cold storage of pear fruits. Currently the pear cultivar 'Rocha' is harvested and stored in controlled atmosphere conditions and in some cases the pears are exposed to ethylene for its rapid marketing. At present, the effect of CO2, O2 and ethylene on the survival and growth of A. pullulans is not known. In this work, the effect of the different percentages of CO2 (0.03, 2 and 4%), O2 (21, 4 and 2%) and ethylene (0, 1×10(-3) and 2×10(-3)%) on A. pullulans inoculated in vitro or in vivo has been evaluated. The three gases tested did not inhibit A. pullulans growth in vitro. However the higher concentration of CO2 and the lower one of O2 reduced the growth of colony surface of A. pullulans at 21 and 27% respectively at 7 days of incubation. The in vivo experiments were conducted on inoculated pears with A. pullulans (2.5×10(6) CFU for wound). These fruits were stored at the same gaseous concentration tested in vitro. The growth and survival of A. pullulans did not change during storage of 'Rocha' pears with different percentages of gases. These results demonstrate that A. pullulans efficiency is maintained when fruits are ripened with ethylene or maintained to conditions of storage in controlled atmosphere.
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