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Author: search.filters.author.Pornpukdeewatana, S.

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    Influence of calcium chloride in the high temperature acetification by strain Acetobacter aceti WK for vinegar
    (2015-11-01)
    Krusong, W.
    ;
    Kerdpiboon, S.
    ;
    Jindaprasert, A.
    ;
    Yaiyen, S.
    ;
    Pornpukdeewatana, S.
    Aims: To improve the thermotolerant properties (TTP) of acetic acid bacteria (AAB) cells for high temperature acetification. Methods and Results: At high temperature (36 ± 1°C), the acetification rate (ETA) is usually lower than at 30 ± 1°C. The addition of 0·15% calcium chloride (CaCl<inf>2</inf>) may decrease the negative effect of the increase of temperature from 30 ± 1°C to 36 ± 1°C on the ETA. The effect of CaCl<inf>2</inf> on the thermotolerant properties of acetic acid bacteria cells was investigated. The CaCl<inf>2</inf> increased the content of phospholipids (phosphotidylcholine and phosphatidylglycerol), fatty acids (cis-vaccenic acid, palmitic acid and myristic acid) and the activities of membrane-bound enzymes involved in acetification, alcohol dehydrogenase and aldehyde dehydrogenase. Transmission electron microscope images revealed a more compact cell wall with CaCl<inf>2</inf>. Process consistency at 36 ± 1°C was tested in nine sequential acetification cycles using 0·15% (w/v) CaCl<inf>2</inf>. High ETAs (9·33 ± 0·6; 8·67 ± 0·8 and 9·67 ± 0·7 g l<sup>-1</sup> day<sup>-1</sup>) were obtained during the last three cycles. Conclusions: The results confirm that changes of the content of lipid, activities of membrane-bound enzymes and cell-wall thickness occurred with added CaCl<inf>2</inf>. Significance and Impact of the Study: High temperature acetification (HTA) with additions of CaCl<inf>2</inf> was investigated. Significant reductions in the overall production costs result from lower cooling costs associated with HTA.
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    Impact of high initial concentrations of acetic acid and ethanol on acetification rate in an internal Venturi injector bioreactor
    (2015-03-01)
    Krusong, W.
    ;
    Yaiyen, S.
    ;
    Pornpukdeewatana, S.
    Aims: To evaluate the comparative impact of high initial concentrations of acetic acid (AA<inf>i</inf>) and of ethanol (ET<inf>i</inf>) on acetification rate (ETA). Methods and Results: Acetic acid bacteria (AAB) were cultivated in a 100-l internal Venturi injector bioreactor. To quantify the oxygen availability, the 1·0 l min<sup>-1</sup> air inflow rate for the start-up phase (25 l) while 3·0 l min<sup>-1</sup> for the operational phase (75 l) achieved a high oxygen transfer coefficient (k<inf>L</inf>a). Changes in cell wall by TEM images and the remained ADH and ALDH activities confirmed the high acid tolerance ability of AAB. While ETAs using high AA<inf>i</inf> at 65 g l<sup>-1</sup> could be processed of 9·57 ± 0·19 g l<sup>-1</sup> day<sup>-1</sup>, which is just higher than 9·12 ± 0·12 g l<sup>-1</sup> day<sup>-1</sup> using high ET<inf>i</inf> at 55 g l<sup>-1</sup>. The average biotransformation yields were at 96·3 ± 0·1% and 94·4 ± 0·1% for high AA<inf>i</inf> and ET<inf>i</inf>, respectively. Conclusions: Results confirm that high oxygenation was generated in the bioreactor. Both high AA<inf>i</inf> and ET<inf>i</inf> were important in increasing ETA under stress 100 g l<sup>-1</sup> total concentration. Significance and Impact of the Study: High acid-tolerant AAB contains the high ADH and ALDH activities causing higher ETAs in HIA process. It is a competitive commercialized acetification process.