WRRCTR No.154 Clostridium perfringens as an Indicator of Stream Water Quality

Abstract

The mCP medium devised by Bisson and Cabelli in 1979 was used to recover Clostridium perfringens from sewage and streams. This membrane filtration method proved to be uncomplicated and reliable. Of 98 presumptively positive colonies recovered from various stream samples. 89 or 91% were confirmed as C. perfringens by using biochemical tests, whereas only 1 of 29 (3%) of the presumptively negative colonies was subsequently confirmed as C. perfringens. The quality of streams receiving treated and chlorinated sewage effluent was determined by analyzing the effluent entering the stream as well as stream samples above and below the effluent discharge site for fecal coliform (FC), fecal streptococcus (FS. and C. perfringens (CP). Chlorination was shown to drastically reduce the concentrations of FC and FS, but not CP in the sewage effluent. As a result, the concentrations of FC and FS in the chlorinated effluent were less than the natural concentrations of these bacteria in the stream, whereas the same effluent contributed significantly more CP than was naturally present in the stream. Thus, analysis of stream water for CP, but not FC or FS, clearly indicated the input of effluent into the stream. Moreover, the FC:CP ratio was useful in determining the quality and distance of a major source of pollution within a stream.