Analytical Services - Coliphage Testing

A partial listing of SMI services is presented below.   SMI has made a commitment to research in new detection methods.   In the event that testing services are needed that do not appear in this document, please contact our Project Management team to discuss your needs.

Genotyping of Male-Specific Coliphages Into Genogroups

Coliphages are bacterial viruses that reproduce within the coliform group of bacteria.

"Male-specific" coliphages represent a subset that specifically target the E. coli bacteria that express physical appendages or spikes - these appendages, the sex pili, are used by bacteria during the process of sexual conjugation to exchange genetic information across bacterial

species.  Male-specific coliphages target the surface of the bacterial pili as their initial point of infection.  Because the pili are expressed only by male strains of bacteria under elevated temperature conditions, the presence of male-specific coliphages in water is more likely to be associated with the presence of fecal pollution that has originated from the gastrointestinal tract

of warm-blooded animals.  Therefore, these viruses are presumed to serve as more effective indicators of fecal pollution than the coliform group of bacteria which under some circumstances may multiply in the environment, resulting in an overestimate of the level of pollution that has occurred.

SMI scientists have extensive experience in the study of coliphages as microbiological indicators and were instrumental in the development of the methods currently approved by the USEPA for detecting coliphages in water.  As part of its ongoing research mission, SMI has extended the

utility of these methods to further classify coliphage isolates into genogroups associated with specific human or animal hosts.  SMI can now perform specific tests to identify the strains of coliphages that are present in source waters so that its clients can characterize the origin of fecal pollutants impacting a water body.

Coliphage Source Tracking by Oligoprobe Hybridization

Coliphages isolated from water sources can be enumerated using techniques such as USEPA Method 1602.  However, this method does not provide detailed information on the host organisms that originally excreted the microorganisms.  SMI has extended the utility of the traditional enumerative methods for detecting coliphages by commercializing molecular techniques that can classify coliphage isolates into prototype genogroups.  The genetic material extracted from coliphage isolates is hybridized to one of several short labeled sequences of synthetic DNA that

are labeled enzymatically.  The bound viral nucleic acids are then visualized colorimetrically to distinguish the different genogroups.  Binding signatures make it possible to classify virus isolates into one of four distinct coliphage groups.  Coliphages that correspond to human feces are statistically associated with phage groups 2 and 3, whereas animal coliphages are associated

primarily with phage groups 1 and 4.  By performing this genogrouping technique, SMI can classify fecal pollutants as originating from animal or human sources.

Depending upon the data requirements of the project, a defined number of male-specific coliphage

isolates from water samples can be subjected to hybridization analyses.  Please contact a project manager for inquiries on sampling and pricing.

For further information about SMI's services, please feel to contact a project manager at (574) 277-4078.