Use of a Doehlert factorial design to investigate the effects of pH and aeration on the accumulation of lactones by Yarrowia lipolytica

摘要

To detect rate-limiting steps in the production of lactones by studying the combined effect of pH and aeration on their accumulation. A Doehlert experimental design was chosen to evaluate the accumulation of four lactones in the pH (3p"5-7p"3) and KLa (4p"1 hp# to 26 hp#) experimental domain. The accumulation of d-decalactone was higher at pH around 5 and increased at low aeration reaching 496 mg lp# at pH 6p"35 and KLa 4p"5 hp#. The specific accumulation increased at low aeration. The 3-hydroxy-d-decalactone accumulation was higher at low pH and high aeration conditions: 660 mg lp# at pH 4p"4 and 26 hp#. For dec-2-en-4-olide and dec-3-en-4-olide, lower amounts were reached (104 mg lp# and 66 mg lp#, respectively). Although the accumulation of the four lactones should be related to catalytic steps requiring oxygen, the accumulation of d-decalactone was higher in low aeration conditions whereas the one of 3-hydroxy-d-decalactone was promoted for high aeration. Decenolides accumulate independently of pH or aeration. This study gives new insights into the catabolism of lipids, such as the role of co-factor regulation and the fact that the 3-hydroxylactone dehydration step is insensitive to pH or aeration.