Product Citations and Abstracts

The phylogenetic and physiological diversity of sulphate-reducing bacteria inhabiting a salt marsh rhizosphere were investigated. Sulpnate-reducing bacteria were isolated from a salt marsh rhizosphere using enrichment cultures with electron donors thought to be prevalent in the rhizosphere of Spartina alterniflora. The relationship between phylogeny and nutritional characteristics of 10 strains was investigated. None of the isolates had 16S rRNA sequences identical to other delta subclass sulphate-reducers, sharing 85.3 to 98.1% sequence similarity with 16S rRNA sequences of their respective closest relatives. Phylogenetic analysis placed two isolates, obtained with ethanol as an electron donor, within the Desulfovibrionaceae. Seven isolates, obtained with acetate, butyrate, propionate, or benzoate, were placed within the Desulfobacteriaceae. One isolate, obtained with butyrate, fell within the Desulfobulbus assemblage, which is currently considered part of the Desulfobacteriaceae family. However, due to the phylogenetic breadth and physiological traits of this group, we propose that it be considered a new family, the "Desulfobulbusaceae." The isolates utilised an array of electron donors similar to their closest relatives with a few exceptions. As a whole, the phylogenetic and physiological data indicate isolation of several sulphate-reducing bacteria which might be considered as new species and representative of new genera. Comparison of the Desulfobacteriaceae isolates; 16S rRNA sequences to environmental clones originating from the same study site revealed that none shared more than 86% sequence similarity. The results provide further insight into the diversity of sulphate-reducing bacteria inhabiting the salt marsh ecosystem, as well as supporting general trends in the phylogenetic coherence of physiological traits of delta Proteobacteria sulphate reducers.

Hemmer, Michael J., Christopher J. Bowman, Becky L. Hemmer, Stephanie D. Friedman, Dragoslav Marcovich, Kevin J. Kroll and Nancy D. Denslow. 2002. Vitellogenin mRNA Regulation and Plasma Clearance in Male Sheepshead Minnows, (Cyprinodon variegatus) After Cessation of Exposure to 17B-Estradiol and p-Nonylphenol. EPA/600/J-01/429. Aquat. Toxicol. 58(1-2):99-112. (ERL,GB 1137).

Research was conducted to determine the kinetics of hepatic vitellogenin (VTG) mRNA regulation and plasma VTG accumulation and clearance in male sheepshead minnows (Cyprinodon variegatus) during and after cessation of exposure to either 17b-estradiol (E2) or para-nonylphenol (NP). Adult fish were continuously exposed to aqueous measured concentrations of 0.089 and 0.71 µg E2 per l, and 5.6 and 59.6 µg NP per l for 16 days using an intermittent flow-through dosing apparatus. Fish were sampled on days 8 and 16 of exposure followed by sampling at discrete intervals for up to 96 days post-exposure. At each interval five fish were randomly sampled from each concentration and hepatic VTG mRNA and serum VTG levels for individual fish determined by slot blot and direct enzyme-linked immunosorbent assay (ELISA), respectively. Exposure to E2 and NP resulted in a dose dependent increase in hepatic VTG mRNA and plasma VTG over the course of the 16 day exposure period. Mean plasma VTG levels at day 16 were >100 mg/ml for both high doses of E2 and NP, and >20 mg/ml for the low exposure treatments. Within 8 days post-exposure, hepatic VTG mRNA levels returned to baseline in both high and low E2 treatments but remained elevated 2-4 fold in the NP treatments. Due to a shortened sampling period, a clearance rate for plasma VTG in the 5.6 µg NP per l treatment could not be determined. In the 0.089 µg E2/L, 0.71 µg E2 per l, and 59.6 µg NP per l treatments, VTG levels began decreasing within 4 days after exposure cessation and exhibited an exponential rate of elimination from plasma. Clearance rates for 0.71 µg E2 per l and 59.6 µg NP per l were not significantly different (P = 0.47), however, both demonstrated significantly higher rates of clearance (P < 0.02) than observed in the 0.089 µg E2 per l treatment. Our results indicated that hepatic VTG mRNA rapidly diminishes after cessation of estrogenic exposure in sheepshead minnows, but plasma VTG clearance is concentration and time dependent and may be detected at measurable levels for months after initial exposure to an estrogenic compound.

Genthner, Fred J., Joseph B. James, Diane F. Yates and Stephanie D. Friedman. 2005. Use of Composite Data Sets for Source-Tracking Enterococci in the Water Column and Shoreline Interstitial Waters on Pensacola Beach, Florida. Mar. Pollut. Bull. 50(7):724-32. (ERL,GB 1212).

Sources of Enterococcus faecalis isolates from Pensacola Beach, FL were identified using a library-based approach by applying the statistical method of average similarity to single and composite data sets generated from separate analyses. Data sets included antibiotic resistance analysis (ARA), rep-fingerprints, and fatty acid methyl ester (FAME) profiles. Use of a composite data set composed of ARA and rep-fingerprints, added to the confidence of the identifications. The addition of FAME data to composite data sets did not add to the confidence of identifications. Source identification was performed to better understand risk associated with higher densities of enterococci found in swash zone interstitial water (SZIW) as compared to adjacent bathing water on Pensacola Beach, FL. The "swash zone" is that area of the beach continually washed over by waves. As the potential sources of enterococci were limited in this environment, only two library units, sea gull and human, were constructed. Identification of beach isolates using a composite data set indicated a sea gull origin. The clonality of the beach isolates suggested that the beach environment selects certain subspecies of E. faecalis.

Borawski, Jason, Stephanie D. Friedman, Diane F. Yates, Alfred P. Dufour and Fred J. Genthner. 2001. Enterococci in the Water Column and Shoreline Interstitial Waters at Beaches on the Gulf of Mexico and Santa Rosa Sound, Pensacola, Florida. Presented at the 2001 Annual Meeting of the American Society for Microbiology, 20-24 May 2001, Orlando, FL. 1 p. (ERL,GB R801).

Interstitial water in the swash zone, that area of a beach where waves continuously wash up on the sand, is suspected of accumulating microbes. If pathogens are concentrated in the interstitial water or if they grow, they may pose a health risk, especially for children. This study compared densities of enterococci in the swash zone intersitial water to densities of enterococci in the adjacent bathing water at selected locations along Pensacola Beach, Florida. At each site, water samples were collected from the water column at a depth of 0.5 m, where the depth of the water column was 1.0 m. Swash zone water samples were obtained from holes 50 to 70 cm deep, that were dug in the sand 1.0 to 1.5 m from the shoreline. Enterococci, salinity, temperature, pH, dissolved oxygen and dissolved organic carbon were measured. At all sites, dissolved organic carbon and enterococci densities were higher in the swash zone interstitial water than in the water column. Analysis of paired swash zone/water column enterococci densities indicated that one of six beaches sampled possessed enterococci densities in the interstitial water of the swash zone that were significantly (p<0.05) higher than those in the water column. These data suggest that microbes in the swash zone interstitial water may pose an increased risk to bathers.

Genthner, Barbara R. Sharak, Stephanie D. Friedman and Richard Devereux. 1997. Reclassification of Desulfovibrio desulfuricans Norway 4 as Desulfomicrobium norvegicum comb. nov. and Confirmation of Desulfomicrobium escambiense (corrig., Formerly "escambium") as a New Species in the Genus Desulfomicrobium. Int. J. Syst. Bacteriol. 47(3):889-892. (ERL,GB X891).

Desulformicrobium escambiense, Desulformicrobium baculatum, Desulformicrobium apsheronum, and Desulfovibrio desulfuricans Norway 4 are closely related as determined by a 16S rRNA comparison (levels of relatedness, 0.976 to 0.997) and are distinct on the basis of levels of DNA-DNA similarity (11.1 to 27.4%), genomic restriction fragment length polymorphism patterns, and certain phenotypic characteristics. We proposed that Desulfovibrio desulfuricans Norway 4 be renamed Desulformicrobium norvegicum comb. nov.