BEACHNET==> 3 new AEM articles: entero growth in sand; bacteroidales in gulls; E. coli in waterfowl

[Meredith Nevers <mnevers@usgs.gov>]

Title:
Growth of Enterococci in Unaltered, Unseeded Beach Sands Subjected to Tidal
Wetting

Authors:
Yamahara, KM; Walters, SP; Boehm, AB

Author Full Names:
Yamahara, Kevan M.; Walters, Sarah P.; Boehm, Alexandria B.

Source:
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 75 (6): 1517-1524 MAR 2009

Language:
English

Document Type:
Article

Abstract:
Enterococci are indicator bacteria used to assess the risk of acquiring
enteric disease from swimming in marine waters. Previous work identified
beach sands as reservoirs of enterococci which can be transported from
the sand to the sea, where they may instigate beach advisories. The present
study establishes that naturally occurring enterococci can replicate in
beach sands under environmentally relevant conditions. In unseeded, nonsterile
microcosm experiments, it was shown that intermittent wetting of sands
by seawater, like that which would occur at the high tide line, stimulates
the transient replication of enterococci at rates of 0.20 to 0.63 per day
(equivalent to doubling times of 1.1 to 3.5 days). Replication was not
observed in control microcosms that were not subjected to wetting. Enterococci
were enumerated using both culture-dependent (membrane filtration and mEI
media) and culture-independent (quantitative PCR [QPCR], 23S rRNA gene
based) techniques, which allowe!
 d tracking of both culturable and total enterococcus populations. Inhibition
of QPCR and DNA extraction efficiencies were accounted for in the interpretation
of the QPCR results. The results provide evidence that enterococci may
not be an appropriate indicator of enteric disease risk at recreational
beaches subject to nonpoint sources of pollution.

ISSN:
0099-2240

IDS Number:
415FY



Title:
Bacteroidales Diversity in Ring-Billed Gulls (Laurus delawarensis) Residing
at Lake Michigan Beaches

Authors:
Jeter, SN; McDermott, CM; Bower, PA; Kinzelman, JL; Bootsma, MJ; Goetz,
GW; McLellan, SL

Author Full Names:
Jeter, Sonja N.; McDermott, Colleen M.; Bower, Patricia A.; Kinzelman,
Julie L.; Bootsma, Melinda J.; Goetz, Giles W.; McLellan, Sandra L.

Source:
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 75 (6): 1525-1533 MAR 2009

Language:
English

Document Type:
Article

Abstract:
This study investigated the occurrence and diversity of Bacteroidales fecal
bacteria in gulls residing in the Great Lakes region. Members of this bacterial
order have been widely employed as human and bovine host-specific markers
of fecal pollution; however, few studies have focused on gulls, which can
be a major source of fecal indicator bacteria and pathogens at beaches.
We found a low but consistent occurrence of Bacteroidales in gulls at five
beaches in three different counties spanning the Wisconsin shoreline of
Lake Michigan. The percentages of gulls positive for Bacteroidales were
4 to 8% at beaches in the southern part of the state and 8 to 50% at beaches
in the north. Sequencing of 931 clones from seven gull Bacteroidales 16S
rRNA gene libraries revealed a large amount of diversity in both individual
and pooled gull fecal samples. Two libraries constructed from pooled gull
fecal samples (n = 5 and n = 6) did not have a greater richness of sequences
than individual s!
 amples, suggesting that even within a single gull diversity is high and
an extensive sequencing effort is needed to characterize the populations.
Estimates of the numbers of operational taxonomic units (OTUs) for the
libraries obtained using different similarity levels revealed a large amount
of microdiveristy with a limited number of OTUs at the 95% similarity level.
Gull sequences were clustered by the beach from which they were collected,
suggesting that there were geographic effects on the distribution of Bacteriodales.
More than 53% of the 16S rRNA gene sequences from gulls at the southern
beaches were associated with the family Porphyromonadaceae, primarily the
genus Parabacteroides, whereas sequences from gulls at the northern beaches
were comprised of Bacteroidaceae and Prevotellaceae sequences. Comparison
of gull sequences with sequences from goose, canine, raccoon, and sewage
sources revealed distinct clusters of closely related gull sequences; however,
these sequ!
 ences were widely dispersed across a dendrogram that included !
 all othe
r sources, including previously characterized gull Bacteroidales from other
studies, suggesting that geographic influence or simply sample representation
plays a greater role in the observed population structure than strictly
the host gut environment.

ISSN:
0099-2240

IDS Number:
415FY



Title:
Escherichia coli Populations in Great Lakes Waterfowl Exhibit Spatial Stability
and Temporal Shifting

Authors:
Hansen, DL; Ishii, S; Sadowsky, MJ; Hicks, RE

Author Full Names:
Hansen, Dennis L.; Ishii, Satoshi; Sadowsky, Michael J.; Hicks, Randall
E.

Source:
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 75 (6): 1546-1551 MAR 2009

Language:
English

Document Type:
Article

Abstract:
Populations of Escherichia coli from juvenile and adult ring-billed gulls,
juvenile common terns, and adult Canada geese were sampled over 6 years
at five locations on Lake Superior (Duluth, MN, and Wisconsin) and Lake
Michigan (Wisconsin, Illinois, and Indiana) to determine the extent of
spatial and temporal variability in E. coli strains. Strain identity was
determined using horizontal fluorophore-enhanced repetitive element palindromic
DNA fingerprinting. Multivariate statistics were used to determine if spatial
or temporal changes in E. coli populations occurred in waterfowl species.
Pairwise multivariate analyses of variance revealed that E. coli populations
of adult gulls from three regions of Lake Michigan and the Wisconsin shore
of Lake Superior were similar to one another but different from an E. coli
population of gulls from the Duluth region of Lake Superior. Juvenile and
adult gulls from the Duluth area harbored different E. coli populations.
The E. coli strains !
 from juvenile gulls, however, were similar to those found in juvenile
terns obtained from the same island rookery. Temporal changes in E. coli
populations from several waterfowl species were also demonstrated for this
site. Although portions of source tracking databases might be successfully
used in other geographic regions, it is clear that juvenile birds should
not be the sole source of E. coli strains used for source tracking databases,
and multiple-year libraries should be constructed in order to identify
the potential sources of E. coli in the environment.

ISSN:
0099-2240

IDS Number:
415FY
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