Identification of feces by detection of Bacteroides genes.
In forensic science, the identification of feces is very important in a variety of crime investigations. However, no sensitive and simple fecal identification method using molecular biological techniques has been reported. Here, we focused on the fecal bacteria, Bacteroides uniformis, Bacteroides vulgatus and Bacteroides thetaiotaomicron, and developed a novel fecal identification method by detection of the gene sequences specific to these bacteria in various body (feces, blood, saliva, semen, urine, vaginal fluids and skin surfaces) and forensic (anal adhesions) specimens. Bacterial gene detection was performed by real-time PCR using a minor groove binding probe to amplify the RNA polymerase β-subunit gene of B. uniformis and B. vulgatus, and the α-1-6 mannanase gene of B. thetaiotaomicron. At least one of these bacteria was detected in the feces of 20 donors; the proportions of B. uniformis, B. vulgatus and B. thetaiotaomicron were 95, 85 and 60%, respectively. Bacteroides vulgatus was also detected in one of six vaginal fluid samples, but B. thetaiotaomicron and B. uniformis were not detected in body samples other than feces. Further, we applied this method to forensic specimens from 18 donors. Eighteen anal adhesions also contained at least one of three bacteria; B. uniformis, B. vulgatus and B. thetaiotaomicron were detected in 89, 78 and 56%, respectively, of the specimens. Thus, these bacteria were present at a high frequency in the fecal and forensic specimens, while either B. uniformis or B. vulgatus was detected in all samples. Therefore, B. uniformis and B. vulgatus represent more appropriate target species than B. thetaiotaomicron for the identification of fecal material. If B. vulgatus and/or B. uniformis are detected, it is likely that the sample contains feces. Taken together, our results suggest that the use of molecular biological techniques will aid the detection of feces in forensic practice, although it is possible that the samples contained both feces and vaginal fluid.
Forensic Science Laboratory of Yamanashi Prefectural Police H.Q., 312-4 Kubonakajima, Isawa, Fuefuki, Yamanashi 406-0036, Japan. nakanishi@384.jp
Hiroaki
H
Nakanishi
Hideki
H
Shojo
Takeshi
T
Ohmori
Masaaki
M
Hara
Aya
A
Takada
Noboru
N
Adachi
Kazuyuki
K
Saito
D000328:Adult; D001439:Bacteroides / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers; D005243:Feces / Q000382:microbiology*; D053803:Forensic Genetics; D005798:Genes, Bacterial; D006801:Humans; D060888:Real-Time Polymerase Chain Reaction
D017931:DNA Primers