Knowing how efficiently microbes in large bioreactors produce methane from brewery waste, there may soon be a way to shape these microbial communities to produce liquid biofuels.
With engineers at Anheuser-Busch InBev, which makes Budweiser beer and operates nine domestic beer breweries that treat wastewater in bioreactors, Cornell scientists at Cornell University took regular samples of bioreactor sludge from each of the facilities over the course of a year and, using state-of-the-art genome sequencing software, they analyzed more than 400,000 gene sequences of the microbes in the sludge.
Among the thousands of species of bacteria, the researchers identified 145 types unique to each of the nine facilities — showing each bioreactor hosted a specific microbial community. In their analysis they observed certain types of bacteria called syntrophs had surprisingly stable populations.
“The cool thing we found was that if you’re looking at these thousands of species of bacteria, it’s a very dynamic system with things dying off and replacing them,” Jeffrey J. Werner, a research associate and first author of a paper on the subject. “There are certain signature populations that are resilient. Even if they get disturbed, they come right back up.”
Typically inside these million-gallon bioreactor tanks, the microbial populations in the sludge interact and one of them produces methane gas. Anheuser-Busch InBev recoups 20 percent of its heat energy use through the methane produced, saving the company millions of dollars every year.
Largus T. Angenent, associate professor of biological and environmental engineering at Cornell, said where the genome surveys of these microbial communities could lead is exciting. Understanding their functions and how they change with environment — be it pH or temperature, for example — could lead to learning how to make the communities of microbes perform new functions.
In ongoing research, the Cornell engineers are looking to prevent methane production by the microbes, and instead, to shape the bacterial communities to produce carboxylates, which are a precursor to the alkanes found in fuels.
“We are going to shape these communities so they start making what we want,” Angenent said.