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

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 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 was the most abundant family. Compared with three 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 . 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.