Effect of Sequential Acclimation to Various Carbon Sources on the Proteome of Acetobacter senegalensis LMG 23690T and Its Tolerance to Downstream Process Stresses

Abstract

Acetic acid bacteria are very vulnerable to environmental changes; hence, they should get acclimated to different kinds of stresses when they undergo downstream processing. In the present study, Acetobacter senegalensis LMG 23690 T , a thermo-tolerant strain, was acclimated sequentially to different carbon sources including glucose (condition Glc), a mixture of glucose and ethanol (condition EtOH) and a mixture of glucose and acetic acid (condition GlcAA). Then, the effects of acclimation on the cell proteome profiles and some phenotypic characteristics such as growth in culture medium containing ethanol, and tolerance to freeze-drying process were evaluated. Based on the obtained results, despite the cells acclimated to Glc or EtOH conditions, 86% of acclimated cells to GlcAA condition were culturable and resumed growth with a short lag phase in a culture medium containing ethanol and acetic acid. Interestingly, if A. senegalensis LMG 23690 T had been acclimated to condition GlcAA, 92% of cells exhibited active cellular dehydrogenases, and 59% of cells were culturable after freeze-drying process. Proteome profiles comparison by 2D-DiGE and MS analysis, revealed distinct physiological status between cells exposed to different acclimation treatments, possibly explaining the resulting diversity in phenotypic characteristics. Results of proteome analysis by 2D-DiGE also showed similarities between the differentially expressed proteins of acclimated cells to EtOH condition and the proteome of acclimated cells to GlcAA condition. Most of the differentially regulated proteins are involved in metabolism, folding, sorting, and degradation processes. In conclusion, acclimation under appropriate sub-lethal conditions can be used as a method to improve cell phenotypic characteristics such as viability, growth under certain conditions, and tolerance to downstream processes.

Acetobacter senegalensis isolated from mango fruits: Its polyphasic characterization and adaptation to protect against stressors in the industrial production of vinegar: A review

“…As the acetous fermentation progresses, different stresses impact the function, cultivability and viability of acetic acid production (Shafiei, Delvigne, & Thonart, 2013; Shafiei, Delvigne, Babanezhad, et al, 2013). In addition, different conditions during the upstream process, such as growth in the presence of different carbon sources or growth at a low pH, may affect the resistance of cells to stresses during the downstream process (Shafiei et al, 2019).…”

“…It was shown that the tolerance of AAB to high concentrations of ethanol and acetic acid (as the two main stressors) is dependent on several factors, such as the pH of the culture medium, available soluble oxygen, temperature, available nutrients and strains used (Ndoye, Weekers, et al, 2007; Ndoye et al, 2009). Shafiei et al (2019) showed that, in addition to the above‐mentioned factors, the acclimation of A. senegalensis cells in different carbon sources definitely affects the utilization of ethanol. In other words, A. senegalensis can grow in a culture medium containing glucose as the main carbon source.…”

“…Normally, the preparation of cells (i.e. the harvesting and washing of cells) and the freezing and drying processes can impose much stress on cells (Ndoye, Weekers, et al, 2007; Ndoye et al, 2009; Shafiei, Delvigne, & Thonart, 2013; Shafiei, Delvigne, Babanezhad, et al, 2013; Shafiei et al, 2019). Thus, this technique may result in changing the physicochemical state of membrane lipids or the structure of sensitive proteins (Shafiei, Delvigne, & Thonart, 2013; Shafiei, Delvigne, Babanezhad, et al, 2013).…”

“…However, the cell cultivability did not change and the cells maintained their capacity for multiplication after the freezing process. In contrast, drying caused serious damage to the cells; the majority of the cells lost their cultivability and entered a VBNC state (Shafiei, Delvigne, & Thonart, 2013; Shafiei, Delvigne, Babanezhad, et al, 2013; Shafiei et al, 2019). Interestingly, despite active cell respiration in freeze‐dried cells, cell cultivability was significantly affected.…”

“…Based on comprehensive research on the effect of culture media on the survival of A. senegalensis cells subject to stressors during the freeze‐drying process, it was revealed that the cultivation of A. senegalensis in ethanol cannot produce a biomass that can withstand harvesting and the freeze‐drying process. In contrast, using a mixture of glucose and acetic acid to cultivate cells enhances cell survival during the freeze‐drying process (Shafiei, Delvigne, & Thonart, 2013; Shafiei, Delvigne, Babanezhad, et al, 2013; Shafiei et al, 2019). The storage of cells after the freeze‐drying process may also cause cell death.…”