In this work, a Cellvibrio pealriver-microalga co-cultivation mode was used to promote the growths of four microalgae by using xylan as feedstock. After 12 days of cultivation, the biomass concentrations of Chlorella sacchrarophila, Chlorella pyrenoidosa and Chlamydomonas reinhardtii in co-cultivation were equal to those in mixotrophic growth on glucose, and the Dunaliella was about 1.6-fold higher than that on glucose. The comparative transcriptomes analysis demonstrated that the xylose and xylan hydrolysates were catalyzed to some active substrates by C. pealriver via some functional enzymes; these active substrates are possibly responsible for the promotion of microalgal growth. This C. pealriver-microalga cocultivation mode is a potential method to produce low-cost microalgal biodiesel by using hemicellulose as feedstock. (C) 2015 Elsevier Ltd. All rights reserved.