Beginning with lab-grown samples of E. lenta some cultured in the presence of digoxin, some in its absence Turnbaugh and Haiser tested to see if certain genes were activated by the presence of the drug.
"We identified two genes that were expressed at very low levels in the absence of the drug, but when you add the drug to the culturesthey come on really strong," Turnbaugh said. "What's encouraging about these two genes is that they both express what are called cytochromes enzymes that are likely capable of converting digoxin to its inactive form."
Though he warned that more genetic testing is needed before the results are definitive, Turnbaugh said other experiments support these initial findings.
The researchers found only a single strain of E. lenta the only one that contained the two genes they'd earlier identified was capable of inactivating digoxin. In tests using human samples, bacterial communities that were able to inactivate the drug also showed high levels of these genes.
"We were able to confirm that simply looking for the presence of E. lenta is not enough to predict which microbial communities inactivate digoxin," Turnbaugh said. "We found detectable E. lenta colonization in all the human fecal samples we analyzed. But by testing the abundance of the identified genes we were able to reliably predict whether or not a given microbial community could metabolize the drug."
In addition to being able to predict whether a given microbial community would inactivate the drug, Turnbaugh and colleagues identified a possible way to halt the process.
"It was previously shown that in the lab E. lenta grows on the amino aci
|Contact: Peter Reuell|