Ensuring constant oxygen supply during inoculation is essential to obtain reproducible results with obligatory aerobic acetic acid bacteria in vinegar production

Abstract: Since obligatory aerobic acetic acid bacteria in vinegar production suffer even from short oxygen depletion during traditional precultivation steps, the reproducibility of results in the main culture is insufficient. Thus, the aim of this paper is to establish a reproducible small scale cultivation method for obligatory aerobic acetic acid bacteria at industrially relevant high ethanol and acetic acid concentrations by ensuring constant oxygen transfer in the whole inoculation procedure. An acetic acid bacteria preculture was drained off from a laboratory-scale bioreactor into an aerated mobile bubble column and then transferred to an already shaking RAMOS shake flask device. Whereas the respiration curves of the traditionally processed acetic acid bacteria cultures were low and greatly diverged, those of the preculture transferred first into the bubble column and then into the already shaking flasks were high and coincided with one another. Furthermore, shutting off aeration in the mobile bubble column led to a rapid decrease in bacterial activity. In conclusion, traditional precultivation steps are not suitable for obligatory aerobic acetic acid bacteria in vinegar production. Maintaining constant oxygen transfer is necessary to guarantee the reproducibility of main culture experiments with such bacteria. [Copyright &y& Elsevier]