The presence of which of the following is used as an indicator for recent fecal contamination of water?

Fecal Streptococci comprises Streptococcus faecalis, Streptococcus bovis, Streptococcus equinus, and Streptococcus avium. Since fecal streptococci commonly inhabit the intestinal tract of humans and warm-blooded animals, they are used to detect fecal contamination in water. It is also used as an indicator for recent contamination of water. The fecal coliform to fetal streptococci ratio (FC/FS ratio) >=4 indicates a contamination of human origin, where as a ratio of <0.7 is indicative of animal pollution. This ratio is only valid for recent (24 h) fecal pollution.