Feasible acetic acid fermentations of alcoholic and sugary substrates in combined operation mode

Maria Gullo,Gabriele Zanichelli,Elena Verzelloni,Federico Lemmetti,Paolo Giudici

doi:10.1016/j.procbio.2016.05.018

Maria Gullo, Gabriele Zanichelli + Show 3 more

Open Access

https://doi.org/10.1016/j.procbio.2016.05.018

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Abstract

Starting from small-scale batch cultivations, acetic acid fermentations in static and submerged systems have been performed by a single acetic acid bacterial strain. To provide user-friendly selected starter cultures for industry, the versatility of these cultures in using different oxidation substrates under different conditions was assessed. In all cases, vinegars with the desired acetic acid, residual ethanol and reducing sugar contents were obtained.An appropriate small-scale batch cultivation subjected to strict process control was pivotal for obtaining the desired acetic acid concentrations and an active culture for submerged fermentation. This achievement enabled the generation of selected starter cultures for submerged vinegar production, which reached an acetic acid content of 8.00–9.00% (w/v), as well as prototype-scale vinegar production. The production of vinegars with reducing sugars in the range of 15.00–27.00 (% w/v) was achieved, and cellulose production was avoided. The dominance of the microbial culture in this process was shown via (GTG)5-PCR. These results are valuable for introducing the use of selected acetic acid bacteria cultures in industrial vinegar production.

Highlights

Acetic acid bacteria (AAB) fermentations are oxidative fermentations performed by AAB growing on carbon substrates under aerobic conditions [1]
Selected starter cultures produced in static fermentation mode In this study, strain AB0220 was chosen as a microbial culture because of its versatility in performing acetic acid fermentations under different conditions (Table 3)
This strain was successfully used at the industrial scale to produce vinegar [34], and the phenotypic stability of its subcultures after long storage times has been proven [20]. The observation that this strain could be used to generate starter cultures provided the basis for developing selected starter cultures (SSCs) suitable for use under different fermentation conditions

Summary

Introduction

Acetic acid bacteria (AAB) fermentations are oxidative fermentations performed by AAB growing on carbon substrates under aerobic conditions [1]. Consumer demand is strongly oriented towards sweet vinegars, which are generally obtained by blending sugars and vinegar, rarely by fermenting liquid media containing both sugar and ethanol [7]. For these vinegars, new fermentations performed by AAB with specific traits, such as the ability to grow in high-sugar environments without depleting the sugar and to produce cellulose from glucose, are required. The fermentative attributes of these species are well studied with respect to acetic acid production in conventional vinegars [8, 4, 9,10, 11, 12]

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