Microbes Clean Up Wastewater
A microbial cleanser of water pollution does its best work when surrounded
by neither too many nor too few of its own kindand when it has developed
a taste for junk food.
This phenomenon, seen in an ARS laboratory, is stimulating new thinking
about finding and harnessing nature's talent for detoxifying industrial
wastewateran approach called bioremediation.
Baqar R. Zaidi, associate professor of marine microbiology at the University
of Puerto Rico, found the bacterium Pseudomonas putida
survivingbut not flourishingon nitrophenol wastes at a
petrochemical plant in Guayanilla, Puerto Rico. The plant had been closed
because of concern for the island's coastal waters environment.
Nitrophenols are generated by industries involved with dyes, explosives,
leather, paper, and wood. In high concentrations, they can be toxic to plants,
fish, and other life forms.
An industry/University of Puerto Rico consortium granted Zaidi support for
further research. And ARS chemists Richard V. Greene and Syed H. Imam at the
National Center for Agricultural Utilization Research (NCAUR) in Peoria,
Illinois, shared their laboratory facilities and expertise on biodegradation.
Included in the research was a strain of Corynebacterium bacteria
that Zaidi, while a postdoctoral researcher at Cornell University, had isolated
from Cayuga Lake near Ithaca, New York.
By culturing each strain in a series of otherwise sterile liquid diets with
increasingly large amounts of nitrophenols, Zaidi developed strains of each
that could survive only if they had their needed dose of the toxic soup. But in
a nonsterile environment more like the real world, only the P.
putidaadded in amounts not too large nor too smallreduced
nitrophenol concentrations to levels regarded as nonpolluting.
"Until we did this research, we had thought that bioremediation on
highly concentrated pollutants would also work at lower levels," says
That assumption could cause some good microbes to be overlooked.
And the finding may encourage more on-site bioremediationbefore
wastewater is released into the environment. The scientists envision sequential
steps, with different microbes taking turns digesting toxic organic molecules.
The research was begun through NCAUR's Outreach Programs, in which ARS
scientists are encouraged to develop collaboration with scientists at 1890
Land-Grant Institutions. -- By Ben Hardin, ARS.
Scientists mentioned in this story are at the USDA-ARS
Center for Agricultural Utilization Research, 1815 N. University St.,
Peoria, IL 61604; phone (309) 6816335, fax (309) 681-6689
"Microbes Clean Up Wastewater" was published in the
issue of Agricultural Research magazine.