Improving α, ω-dodecanedioic acid productivity from n-dodecane and hydrolysate of Candida cells by membrane integrated repeated batch fermentation

The aim of the present study is to develop an effective production process for a, omega-dodecanedioic acid (DC12) biosynthesis using n-dodecane and hydrolysate of Candida cells as substrates by membrane integrated repeated batch fermentation. Cells and n-dodecane were simultaneously recycled during the filtration of fermentation broth (FB) with a 150 kDa ceramic membrane under a cross-flow velocity of 4 m/s and a trans-membrane pressure of 0.2 MPa, and it was also revealed that the cells in the broth could alleviate the membrane fouling during the FB filtration. Moreover, the hydrolysate of the collected cells could be successfully used as a nitrogen source to replace 50% yeast extract for decreasing the DC12 production cost. With repeated-batch culture in a membrane bioreactor, the maximal DC12 productivity could be enhanced by 57.8% compared with the batch culture, meanwhile n-dodecane and cells could be recovered and used for the next fermentation cycle.