In order to create effective bioaugmentation formulations for improved wastewater treatment at low temperatures or under temperature-variable settings, psychophilic bacteria are excellent biocatalysts. Here, we investigated the impact of an artificial bacterial consortia's microbial diversity on the biomass gross yields (measured through OD600) and removal efficiency of soluble chemical oxygen demand (mg sCOD removed/mgs COD introduced) in synthetic, medium-strength wastewater using various biodiversity indices [based on Species Richness (SR), Phylogenetic Diversity (PD), and Functional Diversity (FD)]. We created artificial consortia from one to six 4 °Cisolated bacterial strains using combinatorial biodiversity experiments.In monocultures, tricultures, pentacultures, and hexacultures, respectively, increased species richness led to greater COD removal efficiency (i.e., 0.266 0.146, 0.542 0.155, 0.742 0.136, 0.822 0.019) and higher biomass gross yields (i.e., 0.065 0.052, 0.132 0.046, 0.173 0.049). Consideration of the metabolic profile (functional diversity) or evolutionary linkages also revealed this favourable relationship between biodiversity, COD elimination, and biomass gross output (phylogenetic diversity). The choice of a specific, top-performing species (Pedobacter sp.) as well as complementary usage of carbon resources by consortium members may be responsible for the beneficial effect of biodiversity on SOD removal efficiency (i.e., complementarity effects). Compared to SR and FD diversity metrics, PD diversity metrics among the biodiversity indices explained a greater variation in SOD removal. Our findings highlight the significance of adopting phylogenetically varied consortia with improved degrading capacity rather than single pure cultures for more successful bioaugmentation. Additionally, in psychrophilic circumstances, PD could be applied as an assembly rule to direct the composition of mixed cultures for wastewater bioaugmentation.
