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Aims Interactions with water bacteria affect the incorporation of pathogens into biofilms and thus pathogen control in drinking water systems. This study was to examine the impact of static vs flow conditions on interactions between a pathogen and a water bacterium on pathogen biofilm formation under laboratory settings. Methods and Results A pathogen surrogate Escherichia coli and a drinking water isolate Stenotrophomonas maltophilia was selected for this study. Biofilm growth was examined under two distinct conditions, in flow cells with continuous medium supply vs in static microtitre plates with batch culture. E. coli biofilm was greatly stimulated ( c. 2-1000 times faster) with the presence of S. maltophilia in flow cells, but surprisingly inhibited ( c. 65-95% less biomass) in microtitre plates. These divergent effects were explained through various aspects including surface attachment, cellular growth, extracellular signals and autoaggregation. Conclusions Interactions with the same water bacterium resulted in different effects on E. coli biofilm formation when culture conditions changed from static to flow. Significance and Impact of Study This study highlights the complexity of species interactions on biofilm formation and suggests that environmental conditions such as the flow regime can be taken into consideration for the management of microbial contamination in drinking water systems. [ABSTRACT FROM AUTHOR]

Рассмотрен метод решения многокритериальных транспортных задач. Предложена итерационная процедура, в которой начальный план задачи является оптимальным по основному из критериев. На последующих итерациях реализуется уступка по основному из критериев с целью улучшения значения дополнительных. Процедура продолжается до получения компромиссного решения. Рассмотрены примеры решения задачи. [ABSTRACT FROM AUTHOR]

Raskin L, Schwenter F, Freytsis M, Tischkowitz M, Wong N, Chong G, Narod SA, Levine DA, Bogomolniy F, Aronson M, Thibodeau SN, Hunt KS, Rennert G, Gallinger S, Gruber SB, Foulkes WD. Characterization of two Ashkenazi Jewish founder mutations in MSH6 gene causing Lynch syndrome. Founder mutations are an important cause of Lynch syndrome and facilitate genetic testing in specific ethnic populations. Two putative founder mutations in MSH6 were analyzed in 2685 colorectal cancer (CRC) cases, 337 endometrial cancer (EnCa) cases and 3310 healthy controls of Ashkenazi Jewish (AJ) descent from population-based and hospital-based case-control studies in Israel, Canada and the United States. The carriers were haplotyped and the age of the mutations was estimated. MSH6*c.3984_3987dupGTCA was found in 8/2685 CRC cases, 2/337 EnCa cases, and 1/3310 controls, consistent with a high risk of CRC (odds ratio (OR) = 9.9, 95% confidence interval (CI) = 1.2-78.9, p = 0.0079) and a very high risk of EnCa (OR = 19.6, 95%CI = 1.8-217.2, p = 0.0006). MSH6*c.3959_3962delCAAG was identified in 3/2685 CRC cases, 2/337 EnCa cases and no controls. Each mutation was observed on separate conserved haplotypes. MSH6*c.3984_3987dupGTCA and MSH6*c.3959_3962delCAAG probably arose around 585 CE and 685 CE, respectively. No carriers were identified in Sephardi Jews (450 cases and 490 controls). Truncating mutations MSH6*c.3984_3987dupGTCA and MSH6*c.3959_3962delCAAG cause Lynch syndrome and are founder mutations in Ashkenazi Jews. Together with other AJ founder mutations, they contribute substantially to the incidence of CRC and EnCa and are important tools for the early diagnosis and appropriate management of AJ Lynch syndrome patients. [ABSTRACT FROM AUTHOR]

This article presents information on tests used in the assessment of developmentally disabled children. Two of the most widely used intelligence tests for children recently have been revised (WISC-R in 1974) or restandardized (the Stanford-Binet in 1972). It is important to understand the various relationships between these tests because important decisions frequently are made on the basis of their scores. The Binet and the WISC-R are used commonly by school psychologists, psychometrists, and clinical psychologists as two of the most important tests in their battery. It is hoped that the data presented for children with developmental disabilities will help these professionals to understand the various relationships between the Binet and WISC-R for this population.

Variable conditions on active construction sites make erosion and sediment control a necessity and a challenge. A large number of non-structural products and materials are available to help prevent storm water runoff and control sediment movement to streams. The objective of this study was to determine what materials were available in California, what materials were used and how much of the most used products were applied to the soil. Data are from four mail surveys of Certified Erosion Control Specialists, contractors, consultants, and product manufacturers. Response to the surveys was 15 percent from the contractors and erosion control professionals and 23 percent from the manufacturers. From the surveys, we gathered data on 493 materials used by 155 respondents. Wattles, logs and rolls were used by the largest percentage of respondents (83 percent), followed by blankets (63 percent), mulch (56 percent), dust suppressants (36 percent), tackifiers (30 percent), soil drying agents (18 percent), and soil binders (14 percent). [ABSTRACT FROM AUTHOR]

An anaerobic migrating blanket reactor (AMBR) was seeded with flocculent biomass from a digester and fed a substrate consisting of volatile fatty acids and sucrose to study granulation. After three months of operation, a mature granular blanket developed in the reactor. Moreover, fibers of approximately 1 cm long had become prevalent in the AMBR. Scanning electron microscopy (SEM) and light microscopy revealeda very dense structure consisting of bundles of filaments resemblingMethanosaeta cells. Further studies with fluorescence in-situ hybridization (FISH), showed that Methanosaeta concilii was the predominantmicroorganism in these fibers. [ABSTRACT FROM AUTHOR]

Accurate estimates of microbial population concentrations and the direct, in situ determination of kinetic parameters could improve the calibration and validation of existing mechanistic mathematical modelsof biological nutrient removal activated sludge systems. Oligonucleotide probe hybridizations show promise for measuring concentrations and in situ specific growth rates of microbial populations. The most common targets for oligonucleotide probes are the phylogenetically conserved ribosomal RNA molecules. Recent advances in hybridization techniques have improved the quantitative nature of ribosomal RNA based assays. However, correlations between concentrations of 'theoretical' microbial populations predicted by mechanistic models and quantitative information obtained with oligonucleotide probe hybridizations are not yet developed. Future work should develop such correlations, while addressing the limitations of the molecular assays. (c) 1999 IAWQ Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

A quantitative method was developed for estimating Gordona mass in activated sludge foam and mixed liquor samples. The technique involvesin situ hybridization with a genus-specific fluorescently labeled oligonucleotide probe calibrated on pure cultures of Gordona. The immunofluorescent technique of Hernandez et al. was modified to allow staining with fluorescently labeled antibody and hybridization probes. The results of this technique were compared to those from membrane hybridization studies using radioactively-labeled oligonucleotide probes.Quantitative membrane hybridizations, in situ hybridizations, and antibody staining resulted in significantly different levels of Gordonain activated sludge foam, activated sludge mixed liquor, return activated sludge, and anaerobic digester sludge. Simultaneous staining with labeled antibodies and oligonucleotide probes provide a definitiveidentification for Gordona, and represents a new approach for in situ studies of this organism's role in foaming. ) 1998 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

Four laboratory-scale sequencing batch reactors (SBRs) were operatedto evaluate whether bioaugmentation with Acinetobacter spp. can be used to improve start-up and performance of enhanced biological phosphorus removal (EBPR) systems. Two of the SBRs were bioaugmented duringstart-up by adding pure cultures of Acinetobacter spp., the third reactor received an amendment of activated sludge from a laboratory-scale EBPR system, and the fourth reactor, receiving no amendment, served as a control. Various chemical parameters were measured to monitor the performance of the four SBRs. Oligonucleotide probes of nested phylogenetic specificity were designed to quantify the contribution of Acinetobacter to EBPR. The probes were characterized for use in quantitative membrane hybridizations and fluorescent in situ hybridizations. Data from hybridizations with samples collected from the SBRs showdeclining levels of Acinetobacter spp. over the experiment. All fourreactors achieved significant phosphorus removal and 90% nitrification after three days of operation. The results do not show a positive correlation between levels of Acinetobacter and successful EBPR. ) 1998 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

Examines the effects of micronutrient composition on the growth rate of microbial populations in wastewater treatment systems. Concentration and redox state of iron; Impact of the micronutrient composition of the influent wastewater on the microbial community structure in wastewater treatment systems.

Aims: Optimization of full-scale, biological perchlorate treatment processes for drinking water would benefit from knowledge of the location and quantity of perchlorate-reducing bacteria (PRB) and expression of perchlorate-related genes in bioreactors. The aim of this study was to quantify perchlorate removal and perchlorate-related genes ( pcrA and cld) and their transcripts in bioreactors and to determine whether these genes or transcripts could serve as useful biomarkers for perchlorate treatment processes. Methods and Results: Quantitative PCR (qPCR) assays targeting pcrA and cld were applied to two pilot-scale, fixed-bed bioreactors treating perchlorate-contaminated groundwater. pcrA and cld genes per microgram of DNA were two- to threefold higher and three- to fourfold higher, respectively, in the bioreactor showing superior perchlorate-removal performance. In a laboratory-scale bioreactor, quantities of pcrA and cld genes and transcripts were compared under two distinct performance conditions ( c. 60 and 20% perchlorate removal) for a 5-min empty bed contact time. cld genes per microgram of DNA were approximately threefold higher and cld transcripts per microgram of RNA were approximately sixfold higher under the higher perchlorate-removal condition. No differences in pcrA genes or transcripts per microgram of DNA or RNA, respectively, were detected between the c. 60 and 20% perchlorate-removal conditions, possibly because these assays did not accurately quantify pcrA genes and transcripts in the mixed culture present. Conclusions: Quantities of cld genes and transcripts per microgram of DNA and RNA, respectively, were found to be higher when perchlorate removal was higher. However, quantities of pcrA and cld genes or transcripts were not found to directly correlate with perchlorate-removal rates. Significance and Impact of the Study: To our knowledge, this study represents the first application of qPCR assays to quantify perchlorate-related genes and transcripts in continuous-flow bioreactors. The results indicate that cld gene and transcript quantities can provide insights regarding the quantity, location and gene expression of PRB in bioreactors. [ABSTRACT FROM AUTHOR]

The microbial processes involved in two-phase anaerobic digestion were investigated by operating a laboratory-scale acid-phase (AP) reactor and analyzing two full-scale, two-phase anaerobic digesters operated under mesophilic (35 WC) conditions. The digesters received a blend of primary sludge and waste activated sludge (WAS). Methane levels of 20% in the laboratory-scale reactor indicated the presence of methanogenic activity in the AP. A phylogenetic analysis of an archaeal 16S rRNA gene clone library of one of the full-scale AP digesters showed that 82% and 5% of the clones were affiliated with the orders Methanobacteriales and Methanosarcinales, respectively. These results indicate that substantial levels of aceticlastic methanogens (order Methanosarcinales) were not maintained at the low solids retention times and acidic conditions (pH 5.2-5.5) of the AP, and that methanogenesis was carried out by hydrogen-utilizing methanogens of the order Methanobacteriales. Approximately 43, 31, and 9% of the archaeal clones from the methanogenic phase (MP) digester were affiliated with the orders Methanosarcinales, Methanomicrobiales, and Methanobacteriales, respectively. A phylogenetic analysis of a bacterial 16S rRNA gene clone library suggested the presence of acetate-oxidizing bacteria (close relatives of Thermacetogenium phaeum, 'Syntrophaceticus schinkii,' and Clostridium ultunense). The high abundance of hydrogen consuming methanogens and the presence of known acetate-oxidizing bacteria suggest that acetate utilization by acetate oxidizing bacteria in syntrophic interaction with hydrogen-utilizing methanogens was an important pathway in the second-stage of the two-phase digestion, which was operated at high ammonium-N concentrations (1.0 and 1.4 g/L). A modified version of the IWA Anaerobic Digestion Model No. 1 (ADM1) with extensions for syntrophic acetate oxidation and weak-acid inhibition adequately described the dynamic profiles of volatile acid production/degradation and methane generation observed in the laboratory-scale AP reactor. The model was validated with historical data from the full-scale digesters. [ABSTRACT FROM AUTHOR]

Abstract: A multi-compartment anaerobic bioreactor, designated the anaerobic migrating blanket reactor (AMBR), did not perform well in terms of chemical oxygen demand (COD) removal after an increase in sulfate load, compared to a conventional upflow anaerobic sludge blanket (UASB) reactor. The trophic structures of the bioreactors were characterized by analyzing the electron flows, formation and consumption of fermentation intermediates and terminal product (methane and hydrogen sulfide) formation. Critical performance parameters were linked to operational perturbations such as increase in sulfate load and changes in flow reversal schemes in the AMBR. Both of these manipulations affected the microbial communities, which were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis targeting the bacterial and archaeal domains. The less stable AMBR did not produce granular biomass, and in response to increased sulfate concentrations, experienced a reversal in the distribution of hydrogenotrophic methanogens that correlated with a shift in electron flow from butyrate to propionate. As this shift occurred, bacterial populations such as butyrate-producing clostridia, became predominant, thus leading to reactor imbalance. The stable UASB reactor developed and retained granules and maintained a relatively stable archaeal community. Sulfate perturbation led to the selection of a novel bacterial group (Thermotogaceae), which was most likely well adapted to the increasingly sulfidogenic conditions in the bioreactor. [Copyright &y& Elsevier]

A laboratory-scale anaerobic sequencing batch reactor (ASBR) was fed a synthetic wastewater containing glucose to study the effects of the antimicrobial tylosin on treatment performance. Measurements of methane, volatile fatty acids, and COD concentrations suggested that the addition of 1.67 mg/L and 167 mg/l of tylosin to the synthetic wastewater inhibited propionate oxidizing syntrophic bacteria and aceticlastic methanogens. The latter is presumed to be an indirect effect. A modified version of the IWA Anaerobic Digestion Model No. 1 (ADM1) with extensions for microbial storage and hydrolysis of reserve carbohydrates, and tylosin liquid--solid mass transfer and inhibition adequately described the dynamic profiles observed in the ASBR. [ABSTRACT FROM AUTHOR]

Biological hydrogen production by anaerobic mixed communities was studied in laboratory-scale bioreactors using sucrose as the substrate. A bioreactor in which a fraction of the return sludge was exposed to repeated heat treatments performed better than a control bioreactor without repeated heat treatment of return sludge and produced a yield of 2.15 moles of hydrogen per mole of sucrose, with 50% hydrogen in the biogas. Terminal restriction fragment length polymorphism analysis showed that two different Clostridium groups (comprised of one or more species) were dominant during hydrogen production. The relative abundance of two other non-Clostridium groups increased during periods of decreased hydrogen production. The first group consisted of Bifidobacterium thermophilum, and the second group included one or more of Bacillus, Melissococcus, Spirochaeta, and Spiroplasma spp. [ABSTRACT FROM AUTHOR]

Abstract: Membrane fouling was evaluated in a side stream anaerobic membrane bioreactor (AnMBR) operated for the treatment of swine manure. The AnMBR consisted of an external tubular polyethersulphone ultrafiltration membrane module (diameter = 12 mm) connected to a six-liter mixed bioreactor. The system was operated for 135 days without chemical membrane cleaning resulting in a membrane flux of 5–10 L/m2 h. Membrane fouling was dominated by a loosely attached fouling layer, which could be removed by flushing the tubular membrane. Intensive chemical cleaning after the 135 days of continuous operation resulted in an irreversible resistance of 3×1012 1/m, equivalent to 1.3 times the resistance of the new membrane. More frequent chemical membrane cleaning using HNO3 could not prevent the development of irreversible fouling. Equilibrium calculations and scanning electron microscopy with energy dispersive spectroscopy demonstrated that inorganic precipitation contributed to fouling of the membrane surface and in the membrane pores. [Copyright &y& Elsevier]

Demonstrates the possibility of classifying various populations in activated sludge based on their substrate type. Activated sludge models; Correlation between cellular RNA level and the growth rate; Monitoring of the RNA level of Acinetobacter and Gordonia.

Describes the use of ribosomal RNA targeted hybridization to determine the identity and abundance of microbial populations in activated sludge systems. Microbial ecology of activated sludge; Municipal wastewater; Oligonucleotide probe hybridization; Structured biomass model.

A correction to the article "Syntrophic acetate oxidation in two-phase (acid-methane) anaerobic digesters," by T. Shimada, E. Morgenroth, M. Tandukar, S.G. Pavlostathis, A. Smith, L. Raskin, and R.E. Kilian is presented.

Small subunit (SSU) ribosomal RNA (rRNA) genes of four Gordona (Nocardia) amarae strains were sequenced and compared to the sequence of the G. amarae type strain obtained from the Ribosomal Database Project(RDP). Comparative sequence analysis showed (hat the five strains represent two lines of evolutionary descent: Group 1 consists of strains NM23 and ASAC1 and Group 2 contains strains SE-6, SE 102, and ASF3.To determine the abundance of G. amarae in activated sludge systerns, we designed three oligonucleotide probes: a species-specific probe for G. amarae, a probe specific for Group 1 and a probe targeting Group 2. The probes were characterized by performing dissociation temperature and specificity studies. Using these probes, two other strains,strains SE-149B and RBI, also were found to be part of Group 1. We used these probes along with previously designed probes in membrane hybridizations to determine the abundance of G. amarae, Group 1, Group 2, Bacteria, Mycobacterium complex, and Gordona in samples from foaming episodes. We demonstrated that the Mycobacterium complex. the genus Gordona, and G. amarae strains were present in significantly greater concentrations in activated sludge foam than in mixed liquor. ) 1998 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]