FECAL STREPTOCOCCI AS FECAL POLLUTION INDICATORS - A REVIEW .1. TAXONOMY AND ENUMERATION

The faecal streptococci are the most commonly used alternative or adju nct to coliform bacteria as faecal pollution indicators. They are a gr oup of coccoid bacteria, naturally inhabiting the gut of warm-blooded animals and humans. Their potential as faecal pollution indicators was recognised in the 1890s, but it was 50 years before the accumulated k nowledge of their taxonomy and sanitary significance, together with th e development of isolation and enumeration methods, allowed their prac tical application in water pollution research and management. There is still much disagreement over the classification of the group. Many wo rkers now place some species in a separate genus, Enterococcus, and it is likely that this revised nomenclature will be incorporated into th e next edition of Bergey's Manual. Of the enumeration methods availabl e (plate count, MPN, and membrane filtration), the mE-EIA membrane fil tration method, which recovers enterococci (a subset of faecal strepto cocci) is probably the most important, because it is the basis of curr ent United States Environmental Protection Agency recommendations on b athing water standards. However, there appears to be no universally ac cepted ''best method'' for the isolation of faecal streptococci from n atural waters. Biochemical and serological identification methods are commercially available, and research has begun into the use of DNA-bas ed techniques for identifying faecal streptococcal strains and faecal sources.