Acetic acid bacteria culture collection: significance and management

Acetic acid bacteria (AAB) occur in very specialized habitats such as plants, fruits and flowers, as well as several kinds of sugary or alcoholic substrates. In the last decades, some AAB species have been extensively investigated not only for foods and beverages but also others industrial biotechnology applications as the development of processes for high-value products or biosensors. The potential exploitation of AAB strain diversity requires the existence of culture collections which represent important biological resources for selection and genetic improvement of microbial cultures useful for biotechnological applications. The greatest hurdles to acetic acid bacteria study are related to their difficult isolation, thus several media and incubation conditions are necessary for successful cultivation and preservation of pure cultures. Furthermore culture collections have to evaluate microbial changes over time as well as guarantee appropriate tools in preserving ‘‘authentic’’ strains.These are also the tasks of the Food and Industrial Microbial Collection (FIMC) of the Department of Agricultural and Food Sciences (DipSAA) that, currently, holds about 300 AAB strains, above yeast and lactic acid bacteria strains, isolated from several matrices. Specifically, the AAB strains maintained in the collection have been isolated from musts, wines, various vinegars, solid-state fermentation matrix and kombucha tea. Different preservation techniques are used, ranging from continuous growth methods, for short-term maintenance, to cryopreservation methods at -80°C, for long-term maintenance and for avoiding genetic drift or instability. Full understanding of metabolic potential of the AAB strains collected is achieved by the integration of sequence data with transcriptional and functional studies. A “Strain Database” (www.renewx.org) and a Bioinformatics Software (GelCompare II - Applied Math) support all the information related to the strains starting from isolating source until the full characterization, as well as the collection management.