Fermentation performance and mechanism of a novel microbial consortium DUT08 for 1,3-propandiol production from biodiesel-derived crude glycerol under non-strictly anaerobic conditions

In this study, a novel consortia DUT08 isolated from wastewater samples could efficiently covert crude glycerol to 1,3-propanediol (1,3-PDO) under anaerobic and microaerobic conditions. The physiological and biochemical characteristics of DUT08 indicated that it consisted of Clostridium (85.25%), Escherichia (12.54%), and Klebsiella (0.007%) with the neighbor-joining method of 16S rRNA gene sequences. In a batch fermentation under microaerobic conditions without nitrogen supply, 43.20 g/L 1,3-PDO with a yield of 0.39 g/g and a productivity of 0.98 g/(L.h) were obtained. In contrast, 61.49 g/L 1,3-PDO (0.55 g/g and 2.46 g/(L.h)) was produced with 0.2 vvm nitrogen supply for 1 h before and 2 h after inoculation, with increasing 1,3-PDO titer by 42.34%, yield by 41.03% and productivity by 151.02%. Three strains, strict anaerobic microbe of Clostridium butyricum DUT1, facultative microbe of Klebsiella pneumoniae DUT2 and Escherichia coli DUT3 were isolated. The function of E. coli DUT3 was found to deplete oxygen and provide anaerobic environment for C. butyricum DUT1. The function of K. pneumoniae DUT2 was found to not only deplete oxygen but also produce 1,3-PDO. Their modes of interaction were commensal and competitive. These results demonstrated the potential advantage of symbiosis and provided a promising strategy for 1,3-propandiol production.