Use of n-hexadecane as an oxygen vector to improve Phaffia rhodozyma growth and carotenoid production in shake-flask cultures

Aims: To identify beneficial oxygen vectors for Phaffia rhodozyma in liquid cultures, and to evaluate their use to improve the oxygen transfer and carotenoid production in the yeast cultures. Methods and Results: Several liquid hydrocarbons were tested as oxygen vectors for improving the yeast growth and carotenoid production in shake-flask cultures of P. rhodozyma. While all nontoxic organic liquids (Log P: ≥5.6) showed a positive effect, n-hexadecane was proved to be the most beneficial for the yeast growth and carotenoid production. The addition of 9% (v/v) n-hexadecane to the liquid medium at the time of inoculation was found to be optimal, increasing the carotenoid yield by 58% (14.5 mg l-1vs 9.2 g l-1 in the control) and the oxygen transfer rate (OTR) by 90%. Conclusions: The addition of n-hexadecane to shake-flask cultures of P. rhodozyma significantly improved the oxygen transfer in culture, thus increasing the carotenoid production. Significance and Impact of the Study: Use of organic oxygen vectors such as n-hexadecane may be a simple and useful means for enhancing oxygen transfer and carotenoid production in liquid fermentation of P. rhodozyma.