Metabolic profiles analysis of 1,3‐propanediol production process by Clostridium butyricum through repeated batch fermentation coupled with activated carbon adsorption

Abstract

1,3-propanediol production by Clostridium butyricum is a low productivity process due to the long time seed cultivation and thus hinders its industrial scale production. In the present study, repeated batch fermentation coupled with activated carbon adsorption strategy was first established which conduced not only to saving the time of seed cultivation and enhancing the productivity, but also to reducing the costs for the seed cultivation to achieve the purpose of 1,3-propanediol continuous production. The concentration of 1,3-propanediol from first to fourth cycle was 42.89, 45.78, 44.48, 42.39 (g/L), and the corresponding volumetric productivity was 2.14, 1.91, 1.85, 2.12 (g/L · h ) respectively. More importantly, a relatively complete schematic diagram of the proposed metabolic pathways was firstly mapped out based on the intracellular metabolites analysis through GC-MS. At the same time, metabolic pathway and principal components analyses were carried out to give us deep insight into metabolic state. Many metabolites occurred to response to the stress in Cycle II. Even resting body formed and lipid accumulated owing to the worsening environment in the group without activated carbon in Cycle III. Thus, it demonstrated that activated carbon provided a favorable microenvironment for Clostridium butyricum in the repeated batch fermentation process to achieve the purpose of 1,3-propanediol continuous production.

Adaptive evolution of Clostridium butyricum and scale‐Up for high‐Concentration 1,3‐propanediol production

“…As described by Zhang et al and Zeng et al, 1,3‐PDO production was an NADH‐needing process, and the NADH came from glycerol oxidative pathways which would synthesize acids, such as butyric acid and acetic acid, finally. Szymanowska‐Powalowska and Białas reported that 1,3‐PDO bioconversion process could be influenced by osmotic stress (high concentrations of glycerol), toxic stress (high concentrations of organic acids and 1,3‐PDO), mechanical stress and oxidative stress.…”

“…C. butyricum used in this study was screened from wild type and stored at 4°C in reinforced clostridial medium (RCM). The medium was performed according to our previous work with some modifications . The RCM medium contained (g/L): peptone 10; glucose 5; beef extract 10; yeast extract 3; NaCl 3; CH 3 COONa 3; soluble starch 1; cysteine hydrochloride 0.5.…”

“…The fermentation process was carried out as our previous work with some modification . 10% (vol/vol) culture of strain selected from adaptive evolution experiment was inoculated into 100 mL anaerobic serum bottles containing 50 mL RCM medium.…”

“…The detection of glycerol, 1,3‐PDO and lactic acid was achieved by refractive index detector while the formic acid, acetic acid and butyric acid were detected by UV‐detector. Operating conditions were as follows: sample volume 20 μL; mobile phase 0.5 mmol/L H 2 SO 4 ; flow rate 0.5 mL/min; column temperature 60°C; detector temperature 45°C . Each measurement was conducted three times repeatedly.…”

“…Crude glycerol, a by‐product from biofuel production process, has become a problem for its disposal cost . Thus, bio‐conversion of these by‐products to more valuable material has attracted considerable interest in recent years due to the advantages of being inexpensive, highly‐efficient, and environmentally friendly …”