High concentrations of sacharose lead to metabolic changes that favor the formation of co-products in ethanolic fermentation by Zymomonas mobilis

Abstract

Z. mobilis has attracted great biotechnology interest in recent decades due to its unique metabolism and the ability to produce bioethanol from simple sugars in an effectively and quickly way. Z. mobilis also produce other bioactive products as fructose, gluconic acid, sorbitol, levan, fructo-oligosaccharides. This study aimed to identify proteins differentially expressed by Z. mobilis ZAG-12 under fermentative conditions with low and high concentration of sucrose. Z. mobilis ZAG-12 was grown on SSDL in two fermentation conditions involving low (50g/L; 5%) or high (200g/L; 20%) sucrose concentrations. The bacteria were grown at 30°C without agitation under oxygen-limited conditions and cell growth was monitored by OD for 72 h. Sucrose, glucose, fructose, ethanol, sorbitol and levan were quantified in the fermentative liquid. The identification of differently expressed proteins were analyzed by Two-dimensional gel electrophoresis. The results showed that Z. mobilis ZAG-12 altered its protein expression and formation of products, such as ethanol and sorbitol, in response to a change in sucrose concentration. This response was characterized by proteomic analysis that detected 39 differentially expressed proteins, most related to transport and carbohydrate metabolism, amino acid metabolism and translation. The proteomic profile provided a better understanding of the physiological responses on how this promising microorganism redirects its metabolic flux to the production of ethanol and co-products.