An increasing of the efficiency of microbiological synthesis of 1,3-Propanediol from crude glycerol by the concentration of biomass

Abstract

Background: 1,3-Propylene glycol (1,3-PD), together with purified terephthalic acid, is used in the production of polytrimethylene terephthalate (PTT), an aromatic polyester that exhibits high elastic recoveries. 1,3-PD is employed also as a supplement with low solidification properties, a solvent and a lubricant in the form of propylene glycol. 1,3-PD is effectively synthesized by a microbiological way from crude glycerol generated during biodiesel producing. The main problem of this technology is using a high concentration of glycerol, which is a limiting factor for bacteria cells growth (especially in batch fermentation).

Results: In this work, the influence of different glycerol concentration in batch fermentation on C. butyricum DSP1 metabolism was investigated. Moreover, the biomass was concentrated for two times with the use of membrane module (in case of increasing kinetic parameters). Increased optical density of bacteria cells six times increased the productivity of 1,3-PD in cultivation with 20 g/L of glycerol at the beginning of the process, and more than two times in cultivation with 60-80 g/L. Also the possibility of complete attenuation of 140 g/L of crude glycerol in the batch fermentation was investigated. During the cultivation, changes of protein profiles were analyzed. The most significant changes were observed in the cultivation in the medium supplemented with 80 g/L of crude glycerol. They related mainly to the DNA protein reconstructive systems, protective proteins (HSP), and also the enzymatic catalysts connected with glycerol metabolic pathway.

Conclusions: The application of filtration module in batch fermentation of crude glycerol by C. butyricum DSP1 significantly increased the productivity of the process.