The use of carbon-utilization profiling to determine sources of fecal contamination in a central Texas watershed

Figures & data

Figure 1 Fecal and sewage sampling locations. Counties where fecal and sewage samples were collected are in gray.

Figure 2 North Bosque River Watershed. Letters denote designated water sampling sites.

Table 1 Number of samples collected and number of isolates analyzed from each sample type.

Number of Samples Source	Number of E. coli Collected	Number of E. coli Isolated	Included in Study
Cattle	382	3606	816
Companion	66	573	107
Goat	103	945	161
Horse	21	182	39
Poultry	30	295	580
Sewage	342	2493	55
Sheep	30	292	56
Wild Deer	54	519	101
Total	1028	8905	1915
Water	100	943	910

Figure 3 Unweighted Pair Group Method with Arithmetic Mean (UPGMA) dendrogram of E. coli isolated from various source categories based on carbon substrate utilization patterns (Bionumerics). Because of the large sample size (n = 2825), a condensed dendrogram using a 45% cut-off value is presented to show the 8 major groups.

Table 2 Jackknife analysis of the carbon substrate utilization library.

	Classification (%)
Source Category	Cattle	Comp	Goat	Horse	Poultry	Sewage	Sheep	Deer
Cattle	78.6 *	1.6	5.0	0.4	1.6	7.2	2.1	3.6
Comp	25.9	42.6	3.7	0.9	2.8	18.5	2.8	2.8
Goat	28.6	1.9	55.3	1.2	1.2	10.6	1.2	0.0
Horse	33.3	5.1	2.6	12.8	5.1	23.1	2.6	15.4
Poultry	40.0	10.9	0.0	1.8	29.1	1.8	1.8	14.6
Sewage	21.4	5.3	4.7	1.0	0.7	62.8	0.7	3.5
Sheep	28.6	1.8	12.5	1.8	3.6	8.9	37.5	5.4
Deer	28.7	6.9	4.0	0.0	2.0	9.9	1.0	47.5
ARCC	45.8

Table 3 Specificities for the carbon-utilization library (%), by source category.

Source Category	Specificity
Cattle	75
Companion	97
Goat	95
Horse	99
Poultry	98
Sewage	91
Sheep	98
Wildlife	96
Average Specificity	94

Figure 4 Geometric mean concentrations of E. coli at each sample site for the entire sampling period. Black dashed line represents the USEPA Long Term Geometric Mean Limit for Contact Recreation(126 E. coli/100 mL).

Figure 5 – Identification of water E. coli isolates using the carbon substrate utilization library.