Two‐step salting‐out extraction of 1,3‐propanediol and lactic acid from the fermentation broth of Klebsiella pneumoniae on biodiesel‐derived crude glycerol

Abstract

Crude glycerol is a primary by-product in the biodiesel production process and its large surplus blocks the development of the biodiesel industry. In this study, crude glycerol was used as a substrate to co-produce 1,3-propanediol (1,3-PD) and lactic acid through fermentation of Klebsiella pneumoniae. The final concentrations of 1,3-PD and lactic acid were 62.6 and 33.4 g/L, respectively, and the total mass conversion yield was 55.7%. The two-step salting-out extraction method was adopted for the separation of 1,3-PD and lactic acid from the fermentation broth. In the first step of extraction, the maximal partition coefficient and recovery of 1,3-PD reached 9.81 and 92.4% under the optimal conditions of 30% isopropanol and 30% potassium carbonate. Subsequently, 28% ethanol was added into the salt phase to perform the second salting-out extraction at pH 6.5. The partition coefficient and recovery of lactic acid reached 1.27 and 73.8%, respectively. All cells and most of the proteins (98.5%) were finally removed. The results suggest that crude glycerol can be used as a promising feedstock to co-produce 1,3-PD and lactic acid from fermentation broths, and this could not only reduce the production cost but also promote the further development of the biodiesel industry.

Metabolism, morphology and transcriptome analysis of oscillatory behavior of Clostridium butyricum during long-term continuous fermentation for 1,3-propanediol production

“…Concentrations of biomass, glycerol, 1,3-PDO, butyrate, acetate, lactate and formate were determined as previously described [ 19 ]. Ethanol concentration was determined by gas chromatography (GC) [ 62 ]. Productions of H 2 and CO 2 were determined by GC using a thermal conductivity detector (Techcomp, 7900).…”

Microbial production of lactic acid

“…If one thus accepts the generation of by-products, the organism is suitable for the co-production of 1,3-propanediol and D-lactic acid, which may readily be separated from each other (Song et al 2013). Knocking out just two genes leading to 1,3-propanediol (dhaT and yqhD) and overexpressing a D-LDH led to 142 g D-lactic acid l -1 at a yield of 0.82 g/g glycerol (Feng et al 2014).…”

Functional characterization of bimetallic CuPdxnanoparticles in hydrothermal conversion of glycerol to lactic acid

“…Glycerol, a major byproduct of biodiesel production, can be catalytically transformed into lactic acid by chemical catalysis (Shen et al, , ; Shen, Yin, Wang, Lu, & Zhang, ) or biological fermentation (Hong et al, ; Song, Sun, Wei, & Xiu, ) as one of the cheapest sources. The global market size for glycerol was 2.47 million tons in 2014 and has been estimated to grow annually at 6.5% from 2015 to 2022 (Dai et al, ).…”