HOW DIFFERENT CARBON SOURCES ANDCONDITIONS MAKE AAB “WORKING” STRAINS:ACETOBACTER PASTEURIANUS STRAIN AB0220IN SUPERFICIAL ACETIFICATION SYSTEM ASCASE STUDY

Metabolic potential of acetic acid bacteria (AAB) is ofgreat interest for several fields of the bio-industry.Acetobacter pasteurianus species accounts strains relevantfor the production of both conventional and innovativefermented beverages. Strain AB0220 was isolated in2002 during a large spectrum of isolation work aimed tobuild up an AAB collection from superficial vinegar acetificationsystems. It was preserved for 9 years by shortand long time methods. Ethanol oxidation to acetic acidwas stable and confirmed, as well as acetate assimilationduring preservation. The strain do not produced cellulose.Cultivability checks showed persistence of phenotypictraits over the extended preservation time. Stability ofsubcultures related to the culture age and subcultures frequencyconfirmed the suitability of preservation at leastover a period of 9 years. Strain performance during superficialacetification, both in laboratory and industrial scale,was assayed. To this aim, the acetification ability wastested on different carbon sources and conditions mimingthe basic unit operation of superficial acetification technology.The performance of AB0220 during processeswas evaluated implementing a molecular and analyticalcontrol system. Under the experimental conditions, aceticacid, ethanol and pH were the main parameters dictatingthe conduction of scaling-up procedure. When fixingethanol content between 1 and 3% as upper and lowerlimits and 3% as the lower limit for acetic acid, suitableacidity (6-7%) was reached. The persistence of AB0220as starter over the time was evaluated after biofilm-enrichmentcultures on GYC plates. The biofilm, totally recoveredfrom plates, was processed for genomic DNAextraction. PCR/DGGE and ERIC/PCR were successfullyused to assess species and strain persistence respectively,during 178 days of acetification.