Sophorolipids production from rice straw via SO3 micro-thermal explosion by Wickerhamiella domercqiae var. sophorolipid CGMCC 1576

A novel lignocellulose material, holocellulose from rice straw via the pretreatment of SO3 micro-thermal explosion, was developed to produce sophorolipids (SLs) with Wickerhamiella domercqiae var. sophorolipid CGMCC 1576. The influence factors of inoculum dose, yeast extract concentration and pH regulators (chemical regents used for adjusting/influencing pH) was investigated and discussed. Results showed that W. domercqiae can grow in the rice straw holocellulose hydrolysate, and acquire relative high SL yield of 53.70 +/- 2.61 g/L in shake flask culture. Inoculum dose, yeast extract concentration and pH regulator made obvious influence on fermentation parameters, especially on final broth pH and SLs production. Furthermore, there is a strong negative linear correlation existing between final broth pH and lactonic SL or ratio of lac SL/tot SL. Additionally, comparison between SL production and non-glucose carbon sources, culture methods, microbes in previous reports was carried out. These results will be benefit for acquiring SL mixture with suitable lac SL/tot SL ratio for specific purpose and scope economically.