Municipal wastewater treatment plants Targeted Locus (Loci)

Three undefined mixed cultures (activated sludge) from different municipal wastewater treatment plants were used as seed cultures in a novel lactic acid fermentation process fed with potato peel waste (PPW). Anaerobic sequencing batch fermenters were run under near identical conditions to produce predominantly lactic acid. Illumina sequencing was used to examine the 16S rRNA genes of bacteria in the three seed cultures and fermenters. Results showed that the structure of microbial communities of three seed cultures were different. All three fermentation products had unique community structures that were dominated (96%) by species of the genus Lactobacillus, while members of this genus constituted <0.1% in seed cultures. The species of Lactobacillus sp. differed between the three fermentations. Results of this study suggest the structure of microbial communities in lactic acid fermentation of PPW with undefined mixed cultures were robust and resilient, which opens the door to engineering processes for the microbial utilization of carbohydrate waste streams to produce lactic acid.