High tolerance to glycerol and high production of 1,3‐propanediol in batch fermentations by microbial consortium from marine sludge

Abstract

1,3-Propanediol (1,3-PD) is a versatile bulk chemical and widely used as a monomer to synthesis polymers, such as polyesters, polyethers and polyurethanes. 1,3-PD can be produced by microbial fermentation with the advantages of the environmental protection and sustainable development. Low substrate tolerance and wide by-product profile limit microbial production of 1,3-PD by Klebsiella pneumonia on industrial scale. In this study, microbial consortia were investigated to overcome some disadvantages of pure fermentation by single strain. Microbial consortium named DL38 from marine sludge gave the best performance. Its bacterial community composition was analyzed by 16S rRNA gene amplicon high-throughput sequencing and showed that Enterobacteriaceae was the most abundant family. Compared with three K. pneumonia strains isolated from DL38, the microbial consortium could grow well at an initial glycerol concentration of 200 g/L to produce 81.40 g/L of 1,3-PD with a yield of 0.63 mol/mol. This initial glycerol concentration is twice the highest concentration by single isolated strain and more than the critical value (188 g/L) extrapolated from the fermentation kinetics for K. pneumonia. On the other hand, a small amount of by-products were produced in batch fermentation of microbial consortium DL38, especially no 2,3-butanediol detected. The mixed culture of strain W3, Y5 and Y1 improved the tolerance to glycerol and changed the metabolite profile of single strain W3. The batch fermentation with the natural proportion (W3: Y5: Y1 = 208: 82: 17) was superior to that with other proportions and single strain. This study showed that microbial consortium DL38 possessed excellent substrate tolerance, narrow by-product profile and attractive potential for industrial production of 1,3-PD.

Bioconversion of Raw Glycerol From Waste Cooking-Oil-Based Biodiesel Production to 1,3-Propanediol and Lactate by a Microbial Consortium

“…Seven consortia were involved in this paper, five of which were obtained through screening. And the other two named C2-2M (Zhou et al, 2017) and DL38 (Jiang et al, 2017a) were preserved in our lab. The inoculated activated sludge sample used in this work came from Lingshui River Sewage Treatment Co., Ltd., Dalian, China.…”

“…The seed media were used for selection of the consortia and seed culture. Seed medium components (Jiang et al, 2017a) contained: glycerol 20 g/L, K2HPO4·7H2O 4.454 g/L, KH2PO4 1.3 g/L, (NH4)2SO4 2.0 g/L, MgSO4·7H2O 0.2 g/L, yeast extract 1.0 g/L, 1 mL/L Fe2+ solution (HCl 4 mL/L, FeSO4·7H2O 5 g/L), 1 mL/L CaCl2 solution (20 g/L), 2.0 mL/L trace element A solution (HCl 0.9 mL/L, CuCl2·2H2O 20 mg/L, ZnCl2 70 mg/L, MnCl2·4H2O 100 mg/L, H3BO3 60 mg/L, CaCl2·6H2O 200 mg/L, NiCl2·6H2O 25 mg/L, NaMoO4·2H2O 35 mg/L), CaCO3 5.0 g/L. In seed media for microbial consortia culture, two types of raw glycerol were used as the carbon source; Water or tap water were used to prepare the media according to experimental objective.…”

“…The fermentation media were performed on basis of Jiang et al (2017a). Fermentation medium used for 1,3-PDO production contained: KH 2 PO 4 1.36 g/L, (NH 4 ) 2 SO 4 6.61 g/L, MgCl 2 ·6H 2 O 0.26 g/L, CaCl 2 ·6H 2 O 0.29 g/L, citric acid 0.42 g/L, yeast extract 2.0 g/L, 5 mL/L trace element B solution (CuCl 2 ·2H 2 O 0.47 g/L, ZnCl 2 0.68 g/L, MnCl 2 ·4H 2 O 0.17 g/L, H 3 BO 3 60 mg/L, NaMoO 4 ·2H 2 O 5 mg/L, FeCl 2 · 4H 2 O 3.97 g/L, CoCl 2 ·6H 2 O 0.47 g/L, HCl 10 mL/L).…”

“…Conversely, microbial consortium exhibits strong resistance to complex substrate, simplified operating conditions, adjustable metabolism and fewer by-products in glycerol fermentation (Dietz and Zeng, 2014; Sabra and Zeng, 2014; Jiang et al, 2017a,b; Zhou et al, 2017, 2018). The microbial consortium DL38 dominated by Klebsiella could endure an initial glycerol concentration of 200 g/L more than predicted value (188 g/L) (Zeng et al, 1994; Jiang et al, 2017a). The microbial consortium C2-2M, mainly consisted of Clostridiaceae , can produce the highest 1,3-PDO concentration of 82.66 g/L in fed-batch fermentation.…”

Effect of salt concentration on microbial communities, physicochemical properties and metabolite profile during spontaneous fermentation of Chinese northeast sauerkraut

“…The non‐volatile metabolites were analysed by Agilent 1100 HPLC (Agilent Technologies Co. Ltd., Santa Clara, CA) with a flow rate of 0·6 ml min −1 and 5 mmol l −1 sulphuric acid as the eluent (Jiang et al . 2017). The analysis of volatile metabolites (days 1, 7, 12 and 30) was performed using HS‐SPME/GC‐MS technique according to a previous report (He et al .…”