Effect of temperature on d-arabitol production from lactose by Kluyveromyces lactis

Abstract

D-arabitol production from lactose by Kluyveromyces lactis NBRC 1903 has been studied by following the time courses of concentrations of cell mass, lactose, D: -arabitol, ethanol, and glycerol at different temperatures. It was found that temperature is a key factor in D-arabitol production. Within temperatures ranging from 25 to 39°C, the highest D-arabitol concentration of 99.2 mmol l(-1) was obtained from 555 mmol l(-1) of lactose after 120 h of batch cultivation at 37°C. The yield of D-arabitol production on cell mass growth increased drastically at temperatures higher than 35°C, and the yield reached 1.07 at 39°C. Increasing the cell mass concentration two-fold after 24 h of culture growth at 37°C, the D-arabitol concentration further increased to 168 mmol l(-1). According to the distribution of the metabolic products, metabolic changes related to growth phase were also discussed. The stationary-phase K. lactis cells in the batch culture that is started with exposing the precultured inoculum to high osmotic stress, high oxidative stress, and high heat stress are found to be preferable for D-arabitol production.