Co-substrate fermentation of lignocellulose with added glucose and xylose to increase production of poly (β-l-malic acid)

Co-substrate fermentation has become an essential approach to achieving high-efficiency and low-cost production of poly (β-l-malic acid) (PMA). Herein, sustainable rubberwood (Hevea brasiliensis) hydrolysate (RWH) was co-fermented by A. pullulans to synthesize PMA using glucose and xylose as co-substrate carbon sources. Moreover, vitamin B was explored as nutrient supplementation in this study. Results showed that compared with the single RWH substrate, the PMA production of co-substrate fermentation increased by 38–52%. Furthermore, the addition of VB₆ promoted the utilization of substrates and shortened the fermentation cycle of PMA. During the scale-up fermentation, the PMA yield reached 0.50–0.54 g/g. Compared with traditional glucose culture medium, co-substrate fermentation improved the conversion rate of carbon sources and reduced PMA production cost by 14.9–36.6%. This work provides a new path for high-efficiency and economical industrial fermentation technology of PMA.