Regulation of Glucose Transporter Systems for Enhancing Citrate Production in Aspergillus niger

Abstract:

Citrate is one of the high-volume organic acids with the global production of 1.7 million tons annually mainly produced by microbial process using Aspergillus niger as natural producer. Glucose absorption was the first step of citrate fermentation and needed to be enhanced. The sugar transporters were analyzed based on transcriptome data，phylogenetic tree analysis and sequences alignment. The evm.model.unitig_0.1770 gene，whose relationship was the closest with KlHGT1，was predicted containing 11 transmembrane segments and named as HGT1. The growth test on glucose limited medium showed the diameter of HGT1 transformants were 50% to 150% larger than the diameter of H915-1. After addition of 30 g/L glucose into fermentation medium，the glucose consuming time of HGT1 transformants reduced for 12 h than that of H915-1. Finally，the citrate titer of HGT1 tranformant was increased for 14.7% comparing to H915-1，the fermentation time reduced for 6 h and the maximum specific citrate production rate increased for 29.5%.