This study characterized the fecal indicator bacteria (FIB), including
Escherichia coli (E. coli) and Enteroccocus (ENT), disseminated over
time in the Bay of Vidy, which is the most contaminated area of Lake
Geneva. Sediments were collected from a site located at similar to 500 m
from the present waste water treatment plant (WWTP) outlet pipe, in
front of the former WWTP outlet pipe, which was located at only 300 m
from the coastal recreational area (before 2001). E. coil and ENT were
enumerated in sediment suspension using the membrane filter method. The
FIB characterization was performed for human Enterococcus faecalis (E.
faecalis) and Enterococcus faecium (E. faecium) and human specific
bacteroides by PCR using specific primers and a matrix-assisted laser
desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).
Bacterial cultures revealed that maximum values of 35.2 x 10(8) and 6.6
x 10(6) CFU g(-1) dry sediment for E. coil and ENT, respectively, were
found in the sediments deposited following eutrophication of Lake Geneva
in the 1970s. whereas the WWTP started operating in 1964. The same
tendency was observed for the presence of human fecal pollution: the
percentage of PCR amplification with primers ESP-1/ESP-2 for E. faecalis
and E. faecium indicated that more than 90% of these bacteria were from
human origin. Interestingly, the PCR assays for specific-human
bacteroides HF183/HF134 were positive for DNA extracted from all
isolated strains of sediment surrounding WWPT outlet pipe discharge. The
MALDI-TOF MS confirmed the presence of general E. coli and predominance
E. faecium in isolated strains. Our results demonstrated that human
fecal bacteria highly increased in the sediments contaminated with WWTP
effluent following the eutrophication of Lake Geneva. Additionally,
other FIB cultivable strains from animals or adapted environmental
strains were detected in the sediment of the bay. The approaches used in
this research are valuable to assess the temporal distribution and the
source of the human fecal pollution in aquatic environments. (C) 2011
Elsevier Inc. All rights reserved.