U.S. flag

An official website of the United States government, Department of Justice.

Exploring Soil Bacterial Communities for Forensic Applications: A Genomics Approach

NCJ Number
Date Published
186 pages
This study examined how the characteristics of soil can best be used in forensic applications.

The DNA profiles of bacteria present in a soil sample enable forensic examiners to distinguish among soils from different locations. Although bacterial profiles can be produced using several molecular methods, terminal restriction fragment length polymorphism (T-RFLP) analysis has been used most often to produce forensically relevant profiles; however, the current report proposes an alternative to T-RFLP analysis, i.e., comprehensive restriction fragment length polymorphism analysis (C-RFLP). This typing method uses high performance liquid chromatography (HPLC) in order to separate and visualize unlabeled DNA fragments. Neither method, however, readily allows forensic scientists to extrapolate which types of bacteria are present in the soil sample in question. Knowing the molecular identity of a peak in a DNA profile (i.e., which bacterial group is responsible for the presence of observed peaks) provides an additional layer of potentially useful information. This study used 454 high throughput sequencing in order to survey 14 soil samples, cataloging the major and minor components to soil bacterial communities. From these DNA libraries, five bacterial groups were selected as candidates for group-specific bacterial typing. Researchers then determined the forensic potential of using such targeted analysis. DNA from soils was amplified by using group-specific primers, digested with a restriction enzyme, and resolved using HPLC. The data indicate that group-specific profiles can be produced and used for forensic comparison due to the sufficient genetic variability within groups tested. Ultimately, research on group-specific typing will assist in the development of a multiplex kit for use in crime labs nationwide. 31 figures, 22 tables, and 77 references

Date Published: January 1, 2010