Betty H. Olson

Health Effects Associated With Recreational Coastal Water Use: Urban Versus Rural California

We compared rates of reported health symptoms among surfers in urban North Orange County (NOC) and rural Santa Cruz County (SCC), California, during 2 winters (1998 and 1999) to determine whether symptoms were associated with exposure to urban runoff. NOC participants reported almost twice as many symptoms as SCC participants during the 1998 winter. In both study years, risk increased across symptom categories by an average of 10% for each 2.5 hours of weekly water exposure. Our findings suggest that discharging untreated urban runoff onto public beaches can pose health risks.

Cyclospora cayetanensis: a review of an emerging parasitic coccidian

Cyclospora cayetanensis is a sporulating parasitic protozoan that infects the upper small intestinal tract. It has been identified as both a food and waterborne pathogen endemic in many developing countries. It is an important agent of Travellers Diarrohea in developed countries and was responsible for numerous foodborne outbreaks in the United States and Canada in the late 1990s. Like Cryptosporidium, infection has been associated with a variety of sequelae such as Guillain-Barré syndrome, reactive arthritis syndrome (formally Reiter syndrome) and acalculous cholecystitis. There has been much debate as to where to place C. cayetanensis taxonomically due to its homology with Eimeria species. To date, the only genomic DNA sequences available are the ribosomal DNA of C. cayetanensis and three other species; within these a high degree of homology has been observed. This homology and the lack of sequence data from other Cyclospora species have hindered identification methods.

Influence of physicochemical and operational parameters on Nitrobacter and Nitrospira communities in an aerobic activated sludge bioreactor.

To understand how to optimize performance of a partially nitrifying plant, the dynamics of Nitrospira and Nitrobacter abundance were studied over a 1 year period using quantitative polymerase chain reaction (qPCR) and their relative contributions to nitrite oxidation assessed including the affects of temperature and dissolved oxygen (DO). Correlation coefficients linking shifts in the community composition of nitrite-oxidizing bacteria (NOB) to operational or environmental variables indicated Nitrospira was significantly and negatively correlated to nitrite concentrations (r = -0.45, P < 0.01) and DO (r = -0.46, P < 0.01), while temperature showed a strong positive correlation (r = 0.59, P < 0.0001). However, the Nitrobacter portion of the total NOB populations showed a positive correlations with DO (r = 0.38, P < 0.01) and hydraulic retention time (HRT) (r = 0.33, P < 0.05), as well as being negatively correlated with temperature (r = -0.49, P < 0.001) suggesting specific niche adaptations within the NOB community. Nitrospira was dominant being better adapted to the low DO and shorter sludge retention times (SRT) of this plant, while Nitrobacter increased in abundance during the winter months, when temperatures were lower and DO concentrations higher. Principal component analysis (PCA) results supported these findings by the close proximity of Nitrospira and temperature biplots of PC1 and PC2 as well as grouping Nitrobacter, NO(2)(-)-N, HRT, and DO in the loadings together. The clustering of samples from specific dates also exhibited a strong seasonality.

Evaluation of Nanocopper Removal and Toxicity in Municipal Wastewaters

Bench scale studies were performed to evaluate removal and toxicity of copper nanoparticles (CuNPs) and copper ions in activated sludge biomass. The data indicated that, under the test conditions, copper nanoparticles were removed more effectively (∼95%) than copper ions (30-70%) from the wastewater. Mechanisms of CuNP removal were further investigated by equilibrating CuNP and copper ion in activated sludge filtrate (0.45 μm). The predominant mechanisms of copper removal appear to be aggregation and settling (CuNP) or precipitation (copper ion) rather than biosorption. Most probable number (MPN) test data indicated that addition of 10 mg/L of copper ion was toxic to both coliform and ammonia oxidizing bacteria in the wastewater while no inhibitory effects were observed with the addition of the same amount of copper nanoparticles. Respirometry data indicated a 55% decrease in respiration rate when 10 mg/L ionic copper was added. However, no significant decrease in respiration rate was observed in the presence of copper nanoparticles. The toxicity of copper to activated sludge microorganisms appears to be a function of the concentration and characteristics of copper remaining in solution/suspension.

Homology of Escherichia coli R773 arsA, arsB, and arsC Genes in Arsenic-Resistant Bacteria Isolated from Raw Sewage and Arsenic-Enriched Creek Waters

ABSTRACT The occurrence and diversity of the Escherichia coli R773 ars operon were investigated among arsenic-resistant enteric and nonenteric bacteria isolated from raw sewage and arsenic-enriched creek waters. Selected isolates from each creek location were screened for ars genes by colony hybridization and PCR. The occurrence of arsA, arsB, and arsC determined by low-stringency colony hybridization (31 to 53% estimated mismatch) was 81, 87, and 86%, respectively, for 84 bacteria isolated on arsenate- and arsenite-amended media from three locations. At moderate stringency (21 to 36% estimated mismatch), the occurrence decreased to 42, 56, and 63% for arsA, arsB, and arsC, respectively. PCR results showed that the ars operon is conserved in some enteric bacteria isolated from creek waters and raw sewage. The occurrence of the arsBC genotype was about 50% in raw sewage enteric bacteria, while arsA was detected in only 9.4% of the isolates (n = 32). The arsABC and arsBC genotypes occurred more frequently in enteric bacteria isolated from creek samples: 71.4 and 85.7% (n = 7), respectively. Average sequence divergence within arsB for six creek enteric bacteria was 20% compared to that of the E. coli R773 ars operon. Only 1 of 11 pseudomonads screened by PCR was positive for arsB. The results from this study suggest that significant divergence has occurred in the ars operon among As-resistant E. coli strains and in Pseudomonas spp.

Relationship among turbidity, particle counts and bacteriological quality within water distribution lines

Abstract The turbidity standard for water quality was evaluated in relation to total particle counts, heterotrophic plate counts and epifluorescence direct cell counts of three different municipal drinking-waters. Turbidity and particle counts were directly proportional. There was no predictable relationship between bacteriological quality and turbidity or particle counts. Heterotrophic plate counts under-estimated epifluorescence direct cell counts by a factor of at least 500. Water quality degradation occurred in municipal drinking-water systems because of intermittent short duration events that resulted in high turbidity, particle counts and heterotrophic plate counts. Further, for all parameters measured variability increased with distance traveled within a pipe except for ground water.

Microbiology of Potable Water

Publisher Summary This chapter describes the microbiology of potable water from a historical as well as an ecological perspective. The historical perspective reacquaints with the insights and endeavors of investigators who preceded researchers in the quest for protection and understanding of the microbial quality of water. The ecological perspective is reviewed as it applies to applied ecology, which attempts to explain why and how organisms move from one ecosystem to another and the mechanisms which prevent or enhance such movement. “Ecosystem” is defined as each unique environment, i.e., source waters, treatment plants, or distribution systems. Once this view is adopted, the subject of potable water microbiology becomes a series of discrete yet intimately linked parts. One can imagine the source water, treatment plants, and the distribution system as separate ecosystems linked together by the continuous flow of water from its origin to the consumer. This chapter identifies the critical linkages and how they function in each of these systems. It endeavors to report not only the state of knowledge of microbiology, but also the importance of chemistry and engineering aspects, in each compartment of the potable water system.

Occurrence of Genes Associated with Enterotoxigenic and Enterohemorrhagic Escherichia coli in Agricultural Waste Lagoons

ABSTRACT The prevalence among all Escherichia coli bacteria of the LTIIa toxin gene and STII toxin gene, both associated with enterotoxigenic E. coli, and of three genes (stxI, stxII, and eaeA) associated with enterohemorrhagic E. coli was determined in farm waste disposal systems seasonally for 1 year. Single- and nested-PCR results for the number of E. coli isolates carrying each toxin gene trait were compared with a five-replicate most-probable-number (MPN) method. The STII and LTIIa toxin genes were present continuously at all farms and downstream waters that were tested. Nested-MPN-PCR manifested sensitivity increased over that of single-MPN-PCR by a factor of 32 for LTIIa, 10 for STII, and 2 for the stxI, stxII, and eaeA genes. The geometric mean prevalence of each toxin gene within the E. coli community in waste disposal site waters after nested MPN-PCR was 1:8.5 E. coli isolates (1:8.5 E. coli) for the LTIIa toxin gene and 1:4 E. coli for the STII toxin gene. The geometric mean prevalence for the simultaneous occurrence of toxin genes stxI, stxII, and eaeA, was 1:182 E. coli. These findings based on total population analysis suggest that prevalence rates for these genes are higher than previously reported in studies based on surveys of single isolates. With a population-based approach, the frequency of each toxin gene at the corresponding disposal sites and the endemic nature of diseases on farms can be easily assessed, allowing farmers and public health officials to evaluate the risk of infection to animals or humans.

Methods for Detecting Genetically Engineered Microorganisms in the Environment

The ability to monitor accurately genetically engineered microorganisms (GEMs) is critical in determining their potential impact on a given environment. Many articles have delineated the crucial issues surrounding the release of GEMS (Rissler, 1984; Alexander, 1986; Strauss et al 1985; Gillett et al, 1986; Lenski, 1987). Five major concerns are repeatedly referred to by various authors: (1) incorporation of the novel gene or genes into natural microorganisms, (2) ability of the novel organism to survive in the environment, (3) ability of the novel organism to multiply in the environment, (4) interaction of the novel organism with biological systems that could be injurious to other organisms, and (5) the assessment of harm caused by the organism. The ability to address the first four of these concerns is dependent upon the development of appropriate methodologies. The types of ecological questions that are dependent on adequate methodological techniques for answers are shown in Table I. These questions must be answered before the release of GEMs can become as routine a practice as is now the case for the use of licensed pesticides.

Effect of 2-hydroxybenzoate on the rate of naphthalene mineralization in soil

The effect of 2-hydroxybenzoate (2-OHB, salicylate) on the mineralization rate of [14C]naphthalene, the population density of naphthalene-degrading bacteria, and the concentration of genes encoding for naphthalene dioxygenase in a soil bacterial community was investigated. Six different concentrations of 2-OHB (10, 20, 50, 100, 150 and 200 μg g−1 soil) were tested in 100-g portions of soil. The addition of 10, 20 or 50 μg 2-OHB g−1 soil produced a general increase in total soil bacterial population density, whereas the addition of 100 μg or 200 μg 2-OHB g−1 soil specifically increased the proportion of naphthalene degraders relative to the total population. The addition of 50 μg 2-OHB g−1 soil produced a fourfold increase (the maximum observed) in the rate of naphthalene mineralization relative to the rate in unamended soil. The concentration of 2-OHB (≤ 100 μg/g) added to soil correlated with the population density of naphthalene degraders (r=0.961). Addition of up to 200 μg 2-OHB g−1 correlated with the abundance of DNA sequences homologous to known naphthalene dioxygenase genes (nahAB) (r=0.958). However, mineralization of [14C]naphthalene was stimulated significantly only by the addition of 50 μg 2-OHB g−1 soil. Results of the mineralization experiments were supported by the detection of nahAB mRNA extracted directly from soil. The specificity of the effect of 2-OHB on naphthalene biodegradation was confirmed in a control experiment using equivalent concentrations of 4-OHB which repressed naphthalene mineralization by about 50%. Addition of ammonium nitrate to the soil also increased the rate of naphthalene mineralization. Ammonium nitrate added together with 2-OHB reduced the mineralization enhancement effect of either compound alone. The study confirmed that specific induction of biodegradative genes can enhance chemical pollutant removal in situ.