To better understand how bacteria impact the environment a
former University of California, Riverside graduate student spent nearly a year
building a system that replicates a human colon, septic tank and groundwater
and "fed" the colon three times a day during week long experiments to
simulate human eating.
Ian Marcus, who recently earned his Ph.D. from the UC
Riverside Bourns College of Engineering, said discussion of the research often
left people a bit perplexed.
"People would give a
because we're literally dealing with crap," Marcus said. "It has got
the smell. It has got everything."
How the idea came
The idea for the project came after Marcus noticed that scientists
typically study bacteria in an isolated environment under ideal growing
conditions. That presents a problem because bacteria typically proliferate in
microbial communities with other microorganisms such as archaea, fungi and
Marcus set out to solve that problem by creating a simulated
environment where the life cycle of bacteria (he used a pathogenic strain of E-coli in these experiments) and the microbial communities they live in can be
studied from the human colon to water treatment to groundwater.
In the past, researchers have simulated the gut of humans
and synthetic aquatic environments, but no one had combined the two, as far as
Marcus can tell.
By comparing his finding with those of researchers who
worked with bacteria in an isolated environment, Marcus found that the E-coli
strain in the microbial community may be less mobile in aquatic environments
and more prone to biofilm that than the isolated strain.
This means that the E-coli would linger longer in the
environment, since biofilm provides a refuge for all the microorganisms within
it. When the biofilm matures it sends out bacteria to colonise another surface
thus the bacteria could survive in the environment for longer periods of time.
"This means that pathogens could potentially linger
longer and over a long period of time travel greater distances in the
groundwater," Marcus said.
What the research
aims to find
Marcus said his research shows you should study
microorganisms as close to possible in their natural habitats.
Marcus, who worked in the lab of Sharon Walker, an associate
professor of chemical and environmental engineering, had his findings published
in a paper called "Linking Microbial Community Structure to Function in
Representative Simulated Systems" in the journal Applied Environmental
Microbiology. Co-authors were Walker, and Hailey A. Wilder and Shanin J. Quazi,
both former students in Walker's lab.
"It is a pleasure to work with a student who can think
outside of the box and bring in fresh ideas on how we can approach our
research," Walker said. "Ian's work has provided critical new insight
into how microbial communities behave in wastewater treatment and contribute to
biological contamination of water, which really changes the paradigm of how we
do research and manage our water resources."