Countless Microbes in Hog Manure
By Ben Hardin
March 3, 2000
Getting down and dirty may
be the best way to figure out which microbes are causing the offensive odors
that plague hog manure pits. Agricultural
Research Service scientists are taking that approach to sort out the
microbes that produce offensive smells from those that produce methane, an
odorless greenhouse-effect gas.
In mid-1999, ARS scientists at the National Center for Agricultural Utilization
Research began dipping into hog manure pits. When examining these samples,
they found a rich assortment of microbes. The researchers are seeking to know
them by their DNA--a unique genetic profile--as well as by classical
biochemical features. So far theyve deciphered more than 100 DNA
sequences from 180 pure cultures in a group of microbes called eubacteria.
What the scientists most want to know is which eubacteria are the real
stinkers--and what causes their numbers to rise or fall. That would be a
fundamental step toward helping the livestock industry live in harmony with
rural and urban neighbors. And reducing odors might go hand-in-hand with
improving pork production efficiency because odors are produced mainly from
feed thats not fully digested.
The scientists ferreted out about 100 microbial DNA sequences directly from
materials such as slurries of manure. These sequences included those from at
least seven groups of methane- producing microbes of a type called
archaebacteria. Only about half the groups have relatives in genera known to
science. Archaebacteria live where there is little or no oxygen.
As the NCAUR scientists identify microbes that produce certain odors most
abundantly, they will compare their data with findings from ARS colleagues at
Ames, Iowa, who are analyzing odors from air samples near livestock operations.
Although the NCAUR scientists are focusing on the pit storage environment, what
they learn may be applied to research on manure that is composted or processed
ARS is the USDAs chief scientific
An article about the research appears in the March issue of Agricultural Research magazine.
Scientific contact: Michael A. Cotta and Terence R. Whitehead, ARS
National Center for Agricultural Utilization Research, Peoria, Ill., phone
(309) 681-6567, fax (309) 681-6686, firstname.lastname@example.org and