Comparison of Clostridium beijerinckii NRRL B593 and Locally Isolated Klebsiella pneumoniae in Regards to Their Impact of Glucose as a Co-Substrate on 1,3-Propanediol Fermentation from Glycerol

Biodiesel production, which produces by-product of glycerol has increased significantly all over the world and now vast amount of glycerol have been considered as a waste-product. Among the economically viable and ecologically acceptable solutions for the safe disposal of this waste glycerol, biotechnological conversion of glycerol into a valuable bioplastic raw material, namely 1,3-Propanediol (1,3-PDO) seems to be very promising. In this study, locally isolated Klebsiella pneumoniae and Clostridium beijerinckii NRRL B593 were comparatively studied for their 1,3-PDO production potential either with co-substrate (1, 5, and 10 g glucose/L) without co-substrate together with waste glycerol (10 g glycerol/L). The results were important for understanding the effectiveness of co-substrate addition. It was found that use of co-substrate enhanced the molar yields of 1,3-PDO for both microorganisms (10 g glucose/L addition for K. pneumoniae and 5 g glucose/L for C. beijerinckii, respectively). The results also showed that both microorganisms almost completely consumed glycerol feed during the production of 1,3-PDO. 1,3-PDO production yields varied between 0.50 and 0.61 mol/mol. K. pneumoniae showed the highest value of production yields with 0.61 mol/mol when 10 g/L glucose was added. The addition of a co-substrate which enhances the microbial growth was found to be as a promising approach for further studies on 1,3-PDO. Furthermore, It was concluded that biotechnological conversion of waste glycerol into value added chemical is a promising alternative management approach for the environment friendly disposal of this waste.