Gene Transfer Between Unrelated Bacteria

Applied Genetics News,  March, 2001  

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Oral biologists at the University at Buffalo (UB) School of Dental Medicine (Buffalo, NY) have found that oral bacteria can exchange genes, raising the possibility that organisms in the oral cavity can be transformed from harmless to destructive, and from antibiotic-susceptible to antibiotic-resistant. Their findings were presented at the annual meeting of the American Association for Dental Research.

"Our studies demonstrated genetic exchange between two markedly distinct oral bacteria-an oral spirochete and a streptococcus," says Howard Kuramitsu, UB professor of oral biology and microbiology and senior author on the study. "Therefore, exchange between two closely related bacteria, such as the one responsible for dental caries -Streptococcus mutans-and the harmless Streptococcus gordonii is highly probable."

Kuramitsu and Bingyan Wang, a post-doctoral researcher, used an erythromycin-resistant plasmid as a marker of gene transfer. The researchers cultivated Streptococcus gordonii in the presence of the plasmid alone and separately with the bacteria Treponema denticola harboring the plasmid marker. After a period of cultivation, they detected genes from the marker plasmid within S. gordonii under both growth scenarios. Isolation of plasmids from the latter strain could be followed by transformation into Escherichia coli.

"These findings could be important in the transfer of antibiotic resistance between plaque organisms, as well as with more harmful bacteria that temporarily colonize the oral cavity," Kuramitsu says.

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COPYRIGHT 2001 Gale Group