Lactic acid production with undefined mixed cultures and the performance of bacterial communities

Lactic acid is an important industrial feedstock for synthesis of the bioplastic, polylactic acid (PLA). Currently most of lactic acid production was biosynthesized through pure cultures, which normally required a sterilized condition. For the first time, lactic acid was successfully produced through a novel one-step fermentation process by using undefined mixed cultures (sewage sludge from wastewater treatment plant) in our latest research. A useful quantity of pure lactic acid was also extracted and purified from the fermentation broth. The Illumina based sequencing technology was employed to characterize the performance of microbial communities in order to further investigate the mechanism of this novel lactic acid production process, and the results showed the abundance of Lactobacillus was increased from <0.1% to >95% during the fermentation.