Proteome analysis of Acetobacter pasteurianus during acetic acid fermentation

Acetic acid bacteria (AAB) are Gram-negative, strictly aerobic microorganisms that show a unique resistance to ethanol (EtOH) and acetic acid (AcH). Members of the Acetobacter and Gluconacetobacter genera are capable of transforming EtOH into AcH via the alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) enzymes and are used for the industrial production of vinegar.Several mechanisms have been proposed to explain how AAB resist high concentrations of AcH, such as the assimilation of acetate through the tricarboxylic acid (TCA) cycle, the export of acetate by various transporters and modifications of the outer membrane. However, except for a few acetate-specific proteins, little is known about the global proteome responses to AcH.In this study, we used 2D-DIGE to compare the proteome of Acetobacter pasteurianus LMG 1262T when growing in glucose or ethanol and in the presence of acetic acid. Interesting protein spots were selected using the ANOVA p-value of 0.05 as threshold and 1.5-fold as the minimal level of differential expression, and a total of 53 proteins were successfully identified.Additionally, the size of AAB was reduced by approximately 30% in length as a consequence of the acidity. A modification in the membrane polysaccharides was also revealed by PATAg specific staining.

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► We studied the proteome expressed by A. pasteurianus when growing in glucose, ethanol or acetic acid.
► We analyse modifications in the membrane polysaccharides and the cell size.
► The main proteins responsive to acetic acid are Hsp20 and a protein of the Dps family.
► When growing in glucose, this strain produces a capsular polysaccharide that contains rhamnose.
► A. pasteurianus reduce their cell size in response to acetic acid.