Comparison of culture media for the recovery of airborne yeast in wineries

Abstract

The direct air sampling impaction method on agar was evaluated using aerobiocollectors for the recovery of yeasts present in the winery air. Three culture media with different composition and specificity were studied. In addition, a resuscitation phase was included before the culture in the specificity medium [in the case of the Dekkera-Brettanomyces Differential Medium (DBDM) medium]. Sampling was conducted at different times of the year and in different parts of the wineries, which were different in age and design. Both the Chloramphenicol Glucose Agar (CGA) and Agar Lysine AL media recovered yeasts from the air without any prior resuscitation phase. CGA was able to recover a higher number of colony-forming units of yeasts than the other media. Consequently, to estimate the number of yeasts present in winery air, the best choice of medium would be CGA. The AL medium permitted the growth of the greatest range of genera and species. If the aim is to study the diversity of yeasts present in the air, the most suitable medium is AL. Neither CGA nor AL proved suitable for recovering yeasts of the Brettanomyces genus. The DBDM medium was the only one which provided sufficient specificity for their recovery and identification from the air, although their special characteristics made a prior protocol of resuscitation necessary. Significance and Impact of the Study: Estimating the important role of the air in wineries as a medium for disseminating both useful and potentially harmful yeasts requires the right approach. Except at very specific moments (vinification time), the number of yeasts present in the air are small, and they are normally stressed. In this study, the Chloramphenicol Glucose Agar (CGA) medium is recommended for estimating the number of yeasts present in the air, the Agar Lysine (AL) medium for assessing their diversity and the Dekkera-Brettanomyces Differential Medium (DBDM) for detecting the Brettanomyces genus. Significance and Impact of the Study: Estimating the important role of the air in wineries as a medium for disseminating both useful and potentially harmful yeasts requires the right approach. Except at very specific moments (vinification time), the number of yeasts present in the air are small, and they are normally stressed. In this study, the Chloramphenicol Glucose Agar (CGA) medium is recommended for estimating the number of yeasts present in the air, the Agar Lysine (AL) medium for assessing their diversity and the Dekkera-Brettanomyces Differential Medium (DBDM) for detecting the Brettanomyces genus. © 2013 The Society for Applied Microbiology.