Stormwater May 2012 : Page 27
Figure 6. Enterococcus speciation of isolates from storm drain water during biofilm growth Enterococcus Speciation of Biofi lms Grown on Concrete. Figure 7 presents the results of the speciation analysis con-ducted on isolates collected from the concrete coupon biofi lms during early biofi lm development. The results show that 30% of isolates originated from likely fecal sources ( E. faecalis and E. faecium ). These species are represented by the red solid fi ll and black border in Figure 7. One-third of the species originated from likely environmental sources ( E. casselifl avus , E. gallina-rum, and P. pentasauceus ) (Badgley et al. 2010a). These environ-mental sources are represented by the graded fi ll in Figure 7. The presence of one isolate identifi ed as S. epidermidis , a spe-cies closely correlated with human fl ora, may be the result of Figure 7. Enterococcus speciation of isolates from early storm drain biofilms grown on concrete cross contamination during processing (Queck and Otto 2008). Of the isolates, 22% could not be identifi ed (low discrimination organisms), but were likely E. mondii , an environmental species, which was not identifi ed through the VITEK method. Figure 8 presents the results of enterococcus species identi-fi cation from mature biofi lms grown on concrete coupons. The results show that fecal-associated species (represented by the red solid fi ll and black border in Figure 8 for E. faecalis and E. faecium ) contributed over 40% of the biofi lm population. How-ever, the biofi lm showed a signifi cant presence of nonfecal spe-cies; almost 40% of the species were associated with a strain of enterococcus commonly found in birds ( Streptococcus gallolyti-cus ), while 20% were likely to be species associated with soils, May 2012 www.stormh2o.com 27