Bacteria Break Kidney Stone-Oxalate
Oxalate is a substance that can lead to the formation of kidney stones if
absorbed from the diet too quickly.
At the National Animal Disease Center in Ames, Iowa, ARS microbiologist
Milton J. Allison and chemist Albert L. Baetz have helped lay the groundwork
for medical research that may offer some relief to people who suffer from
Some 20 years ago, Allison was one of the first researchers to study
bacteria that can break down oxalates in livestock forages. Now, the two
researchers are concentrating on an oxalate-degrading bacterium called
Oxalobacter formigenes that lives in the digestive tracts of cattle,
sheep, and humans.
"This bacterium consumes only oxalate for its energy and growth. It is
able to live in the large intestine of humansbut not in the
smallbecause it can't tolerate any amount of air," says Allison.
He and Baetz have isolated two oxalate-busting enzymes from the bacterium.
Their collaborative research with Peter Maloney, a microbiologist at Johns
Hopkins University in Baltimore, Maryland, provided an understanding of how the
bacterium gets its energy and grows in the anaerobic environment of the rumen
of cattle and the large intestine of humans.
Studies on the oxalate-degrading bacterium at ARS' Poisonous Plant Research
Laboratory in Logan, Utah, helped solve a mystery for western cattle ranchers
who have lost livestock to the lethal halogeton plant, also loaded with
Halogeton infests rangeland in seven western states. Cattle and sheep
grazing freely on the weed become severely ill and die. But researchers at
Logan showed that sheep could safely graze small amounts of this toxic plant
because bacteria in their stomachs break down the oxalate, making it harmless.
(See "Grazing Poisonous Plants," Agricultural Research, May
1986, p. 6-10.)
Medical researchers suspect some humans may ward off formation of kidney
stones because their intestines contain high numbers of oxalate-degrading
bacteria. But like the cattle which consumed and absorbed too much oxalate at
once, other people may have difficulty when too many oxalate-containing foods
"Several other researchers have published data supporting the concept
that oxalate use by these intestinal bacteria may protect people against kidney
stone disease. But further medical studies to examine this relationship are
needed," says Allison. By Linda Cooke, ARS,
Allison is in the USDA-ARS
Animal Disease Center, 2300 Dayton Road, Ames IA 50010; phone (515)
663-7200, fax (515) 663-7458.
"Bacteria Break Kidney Stone-Oxalate Link" was
published in the October
1995 issue of Agricultural Research magazine.