How r-strategist & K-strategist microorganisms relate to wastewater system MLSS

​Prior to using metagenomics testing in wastewater, most engineers assumed the MLSS microbial had a constant microbial composition. MLSS would contain the fastest growing, best bacteria for a given influent. Occasional environmental or influent shift would alter the biomass, but it would always return to single ideal microbial mix.

With the use of metagenomics testing, Aster Bio has found that systems have a changing microbial makeup depending upon their position on the growth curve. 

Looking at the difference in K-strategist and r-strategist microorganisms allows use to understand the changes in MLSS composition. K-strategists have the ability to grow rapidly and thrive when “food” is plentiful. Biomass development from lag through log phase growth centers around the population explosion of K-strategists. In wastewater terms, a K-strategist has a fast doubling rate, tolerance to more toxic compounds, and thrives on a range of organics. Once the system reaches steady-state or decline phase growth the microbial population pressures start to favor r-rate strategists. Unlike K-strategists, the r-strategists have lower growth rates and ability to exploit ecological niches.