Did you know that 16S rRNA methods were first developed for environmental engineering? Lutgarde Raskin from the University of Michigan tells us how environmental engineers have embraced molecular microbial ecology. Specifically, environmental engineers have pioneered quantitative techniques. One of these methods from Lutgarde’s lab is the addition of internal standards to quantifiy gene counts in DNA sequencing – for example, to measure amounts of antibiotic resistant genes in different bioreactors.
Bioreactors make great systems for studying microbial ecology. Lutgarde used bioreactors to assess how community stability relates to functional stability. Contrary to what we might expect, maintaining a bioreactor with variable loading rates leads to a microbiome that is more resilient to disturbance, compared to maintaining a bioreactor under stable conditions. Another factor in bioreactors is biofilms that grow on membranes. Too much biofilm results in “fouling,” where the biofilm becomes to thick for the mechanics to function. However, the presence of a biofilm improves the amount of organic compounds remove from wastewater, and is actually a crucial part of the process. But, these biofilms do result in methane oversaturation, which is an unwanted consequence.
Promoting the growth biofilm in specific locations in the reactor to prevent methane from escaping and making the system more energy efficient will help make bioreactor maintenance more sustainable. There is lots more microbiome work to be done by environmental engineers!