P3-149 Host-Specific Insertion Sequences within 16S rDNA of Intestinal Bacteria as Genetic Markers for Tracking Sources of Fecal Contamination in Produce

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Zhenyu Shen, University of Missouri, Columbia, MO
Chao Zhang, University of Missouri, Columbia, MO
Guolu Zheng, Lincoln University, Jefferson City, MO
Azlin Mustapha, University of Missouri, Columbia, MO
Mengshi Lin, University of Missouri, Columbia, MO
Dong Xu, University of Missouri, Columbia, MO
Introduction: Fecal pollution in produce poses a risk to human health as feces may carry foodborne pathogens that can result from feces-contaminated irrigation water or improper use of animal manure as fertilizer. Identification of the sources of fecal contamination is important for elimination of fecal pollution in produce and prevention of foodborne disease outbreaks.  Previously, we identified two insertion sequences (ISs) in Faecalibacterium16S rDNA that are highly associated with chicken and turkey feces.

Purpose: This study aimed to identify ISs specific to other host species within 16S rDNA of intestinal bacteria via bioinformatics tools, and to develop polymerase chain reaction (PCR) assays to evaluate the ISs’ host specificities.

Methods: A total of over 223,000 16S rDNA sequences from 72 species of human and animal intestinal bacteria were obtained from the Ribosomal Database Project 10. The ISs were extracted from these sequences and subjected to host-specificity analysis in silico. PCR assays were then developed and used to further evaluate host specificities of the ISs, using the pooled fecal DNA extracted from fecal samples of various animal hosts including human, chicken, turkey, beef cattle, dairy cattle, sheep, goat, horse, and pig.  

Results: A total of eight ISs within variable regions of the 16S rDNA has been identified and appeared to be host specific in silico. The PCR assays demonstrated that three of the eight ISs were associated with specific host species. The Mitsuokella-IS1 was only present in feces of human and pig, the Bacteroides-IS1 in beef cattle and pig, and the Prevotella-IS1in human, beef cattle, and pig. 

Significance: These results suggest that the three ISs may be useful in identification of the sources of fecal pollution in produce, which would allow for proper steps to be undertaken to alleviate potential produce safety risks.