Nonphotosynthetic pigmented bacteria in a potable water treatment and distribution system

The occurrence of pigmented bacteria in potable water, from raw source water through treatment to distribution water, including dead-end locations, was compared at sample sites in a large municipal water system. Media used to enumerate heterotrophic bacteria and differentiate pigmented colonies were standard method plate count (SPC), m-SPC, and R2A agars, incubated up to 7 days at 35 degrees C. The predominant pigmented bacteria at most sample locations were yellow and orange, with a small incidence of pink organisms at the flowing distribution site. Seasonal variations were seen, with the yellow and orange organisms shifting in dominance. SPC agar was the least productive medium for both heterotroph counts and pigmented bacteria differentiation. At the flowing distribution site, percentages of pigmented bacteria on SPC medium ranged from 2.3 to 9.67 times less than on m-SPC and from 2.3 to 9.86 times less than on R2A. At the same site, seasonal trends in the percentage of pigmented bacteria were the same for m-SPC and R2A media, and the highest and lowest percentages occurred in the fall and winter, respectively. At site 6, there appeared to be an inverse relationship between the yellow and orange pigmented groups, but upon analysis, this did not hold and all correlations between yellow and orange pigmented bacteria were positive. The study results indicate that pigmented bacteria could readily be detected by using plate counting media developed for heterotroph enumeration in potable waters with incubation periods of 7 days. Pigmented bacteria can be used as an additional marker for monitoring changes in water quality. High numbers of heterotrophs, including pigmented forms, were found at dead-end locations, usually in the absence of a free chlorine residual and when the water temperature was greater than 16 degrees C. The association of some pigmented bacteria with nosocomial and other infections raises concern that the organisms may have originated from the potable water supply. High levels of pigmented bacteria could pose an increased health risk to immunologically compromised individuals. Therefore, the bacterial quality of the distribution water should be controlled to prevent the development of high concentrations of heterotrophic plate count bacteria, including the pigmented forms.     

Nonphotosynthetic pigmented bacteria in a potable water treatment and distribution system.

The occurrence of pigmented bacteria in potable water, from raw source water through treatment to distribution water, including dead-end locations, was compared at sample sites in a large municipal water system. Media used to enumerate heterotrophic bacteria and differentiate pigmented colonies were standard method plate count (SPC), m-SPC, and R2A agars, incubated up to 7 days at 35 degrees C. The predominant pigmented bacteria at most sample locations were yellow and orange, with a small incidence of pink organisms at the flowing distribution site. Seasonal variations were seen, with the yellow and orange organisms shifting in dominance. SPC agar was the least productive medium for both heterotroph counts and pigmented bacteria differentiation. At the flowing distribution site, percentages of pigmented bacteria on SPC medium ranged from 2.3 to 9.67 times less than on m-SPC and from 2.3 to 9.86 times less than on R2A. At the same site, seasonal trends in the percentage of pigmented bacteria were the same for m-SPC and R2A media, and the highest and lowest percentages occurred in the fall and winter, respectively. At site 6, there appeared to be an inverse relationship between the yellow and orange pigmented groups, but upon analysis, this did not hold and all correlations between yellow and orange pigmented bacteria were positive. The study results indicate that pigmented bacteria could readily be detected by using plate counting media developed for heterotroph enumeration in potable waters with incubation periods of 7 days. Pigmented bacteria can be used as an additional marker for monitoring changes in water quality. High numbers of heterotrophs, including pigmented forms, were found at dead-end locations, usually in the absence of a free chlorine residual and when the water temperature was greater than 16 degrees C. The association of some pigmented bacteria with nosocomial and other infections raises concern that the organisms may have originated from the potable water supply. High levels of pigmented bacteria could pose an increased health risk to immunologically compromised individuals. Therefore, the bacterial quality of the distribution water should be controlled to prevent the development of high concentrations of heterotrophic plate count bacteria, including the pigmented forms.     

Biological treatment of oilfield-produced water: A field pilot study

A field test was conducted on a hydrolysis acidification/bio-contact oxidation system (HA/BCO) to treat oilfield-produced water with high salinity. By operating the biodegradation system for three months with a hydraulic retention time (HRT) of 32 h and a volumetric load of 0.28 kg COD m³ d^?1, the treatment process achieved mean removal efficiencies of 63.5% for chemical oxygen demand (COD), 45% for NH₃-N, 79.5% for total suspended solid (TSS), and 68.0% for total petroleum hydrocarbon (TPH). GC/MS was used to analyze relative changes of components of main organic waste in a process indicating that the influent wastewater contained organic compounds from C₁₂H₂₆ to C₃₅H₇₂, which could be degraded effectively with the coordinated action of hydrolysis acidification and aerobic treatment. The use of maize powder can enhance environmental adaptability of microorganisms and biodegradation ability and is recommended as a nutrient supplement to maintain good treatment performance.     

Deterioration in bacteriological quality of water through fish farms

S.H. DAVIS AND R. GOULDER, 1993. Abundance of bacteria, as direct counts and colony-forming units, bacterial metabolism, and extracellular enzyme activity, increased in water flowing through trout farms in NE England. Seven of 12 farms had settling lagoons but these did not counteract the deterioration in bacteriological quality.     

Effect of ambient temperature storage on potable water coliform population estimations

The effect of the length of time between sampling potable water and performing coliform analyses has been a long-standing controversial issue in environmental microbiology. The issue is of practical importance since reducing the sample-to-analysis time may substantially increase costs for water analysis programs. Randomly selected samples (from those routinely collected throughout the State of Wisconsin) were analyzed for total coliforms after being held at room temperature (20 +/- 2 degrees C) for 24 and 48 h. Differences in results for the two holding times were compared with differences predicted by probability calculations. The study showed that storage of the potable water for up to 48 h had little effect on the public health significance of most samples containing more than two coliforms per 100 ml.     

Effect of ambient temperature storage on potable water coliform population estimations.

The effect of the length of time between sampling potable water and performing coliform analyses has been a long-standing controversial issue in environmental microbiology. The issue is of practical importance since reducing the sample-to-analysis time may substantially increase costs for water analysis programs. Randomly selected samples (from those routinely collected throughout the State of Wisconsin) were analyzed for total coliforms after being held at room temperature (20 +/- 2 degrees C) for 24 and 48 h. Differences in results for the two holding times were compared with differences predicted by probability calculations. The study showed that storage of the potable water for up to 48 h had little effect on the public health significance of most samples containing more than two coliforms per 100 ml.     

The fate of Escherichia coli through water treatment and in distribution

The removal of E. coli bacteria at each stage of water treatment is presented, showing how the filtration stages contribute most to reduction of bacterial numbers in the water. At treatment works without filtration stages, the emphasis is put on catchment management to limit contamination of the raw water and ensure that the numbers of viable E. coli in the source water remain low. Routine monitoring of the raw water provides data on seasonal trends in numbers of E. coli bacteria and allows effective management of supply. In the UK there is no evidence that E. coli grows in the water distribution system, whether in the planktonic stage or within biofilms (O'Neill et al. 1997). The detection of E. coli in the distribution system is rare and prompts a thorough investigation. Repeat samples are taken from the point which originally failed, along with a number of hydraulically linked samples including samples from hydrants. The response to the detection of E. coli is discussed. A series of experiments carried out on a pilot pipe system is briefly described and the results discussed in relation to the routine samples taken in the Thames Water Supply area.     

Profiling bacterial survival through a water treatment process and subsequent distribution system

AIMS: To profile fractions of active bacteria and of bacteria culturable with routine heterotrophic plate count (HPC) methods through a typical water treatment process and subsequent distribution system. In doing so, investigate how water treatment affects both bacterial abundance and diversity, and reveal the identities of active bacteria not detected by traditional HPC culture. METHODS AND RESULTS: Profiling active fractions was performed by flow cytometric cell sorting of either membrane-intact (BacLight kit) or enzymatically active (carboxyfluorescein diacetate, CFDA) bacteria, followed by eubacterial 16S rDNA-directed PCR and denaturing gradient gel electrophoresis (DGGE). Water treatment significantly reduced active bacterial numbers detected by the BacLight kit and CFDA assay by 2.89 and 2.81 log respectively. Bacterial diversity was also reduced from > 20 DGGE bands in the active fractions of reservoir water to only two bands in the active fractions of finished water. These two bands represented Stenotrophomonas maltophila, initially culturable by HPC, and a Burkholderia-related species. Both species maintained measurable traits of physiological activity in distribution system bulk water but were undetected by HPC. CONCLUSIONS: Flow cytometric cell sorting with PCR-DGGE, to assess water treatment efficacy, identified active bacteria from a variety of major phylogenetic groups undetected by routine HPC. Following treatment S. maltophila and a Burkholderia-related species retained activity and entered distribution undetected by HPC. SIGNIFICANCE AND IMPACT OF THE STUDY: Methods used here demonstrate how water treatment operators can better monitor water treatment plant efficacy and assess distribution system instability by the detection and identification of active bacteria recalcitrant to routine HPC culture.     

Application of metabolomics to understanding biofilms in water distribution systems: a pilot study

Biofilms formed in pipes are known to contribute to waterborne diseases, accelerate corrosion and cause aesthetic taste and odour issues within the potable water supply network. This paper describes a pilot study, undertaken to assess the potential of using metabolomics to monitor bacterial activity in biofilms of an urban water network. Using samples from a water mains flushing programme, it was found that a profile of intracellular and extracellular metabolites associated with microbial activity could be obtained by analysing samples using gas chromatography mass spectrometry. Chemometric analysis of the chromatograms in conjunction with data from the mass spectrometer showed that it is possible to differentiate between biofilms from different pipe materials and planktonic bacteria. This research demonstrates that metabolomics has the potential for investigating biofilms and other microbial activity within water networks, and could provide a means for enhancing monitoring programmes, understanding the source of water quality complaints, and optimising water network management strategies.     

A bacteriological profile of bottled water sold in Bangladesh

Four different brands of bottled water had counts of aerobic bacteria ranging from 10³ to 10⁶ colony forming units/100 ml. Pathogens isolated includedPseudomonas (in all brands),Alcaligenes andEscherichia coli (each in three brands), andKlebsiella, Enterobacter andShigella (each in two brands). All four brands were judged to be unsatisfactory by accepted health standards.     

Incidence of coliphage in potable water supplies

Samples of drinking water from different sources in greater Cairo, Egypt, and bottled drinking water were tested for total coliform, fecal coliform, and coliphage populations. Of the 147 samples tested, 4 samples were positive for both total coliforms and coliphage, 65 samples were negative for total coliforms, fecal coliforms, and coliphage, and 78 samples were positive for coliphage and negative for total coliforms and fecal coliforms. The incidence of coliphage in these potable water supplies reflects the probability of human pathogenic virus survival in these waters also.     

Incidence of coliphage in potable water supplies

[This corrects the article on p. 1632 in vol. 54.].     

A new medium for the enumeration and subculture of bacteria from potable water

Plate count agar is presently the recommended medium for the standard bacterial plate count (35 degrees C, 48-h incubation) of water and wastewater. However, plate count agar does not permit the growth of many bacteria that may be present in treated potable water supplies. A new medium was developed for use in heterotrophic plate count analyses and for subculture of bacteria isolated from potable water samples. The new medium, designated R2A, contains 0.5 g of yeast extract, 0.5 g of Difco Proteose Peptone no. 3 (Difco Laboratories), 0.5 g of Casamino Acids (Difco), 0.5 g of glucose, 0.5 g of soluble starch, 0.3 g of K2HPO4, 0.05 g of MgSO4 X 7H2O, 0.3 g of sodium pyruvate, and 15 g of agar per liter of laboratory quality water. Adjust the pH to 7.2 with crystalline K2HPO4 or KH2PO4 and sterilize at 121 degrees C for 15 min. Results from parallel studies with spread, membrane filter, and pour plate procedures showed that R2A medium yielded significantly higher bacterial counts than did plate count agar. Studies of the effect of incubation temperature showed that the magnitude of the count was inversely proportional to the incubation temperature. Longer incubation time, up to 14 days, yielded higher counts and increased detection of pigmented bacteria. Maximal bacterial counts were obtained after incubation at 20 degrees C for 14 days. As a tool to monitor heterotrophic bacterial populations in water treatment processes and in treated distribution water, R2A spread or membrane filter plates incubated at 28 degrees C for 5 to 7 days is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence of coliphage in potable water supplies.

Samples of drinking water from different sources in greater Cairo, Egypt, and bottled drinking water were tested for total coliform, fecal coliform, and coliphage populations. Of the 147 samples tested, 4 samples were positive for both total coliforms and coliphage, 65 samples were negative for total coliforms, fecal coliforms, and coliphage, and 78 samples were positive for coliphage and negative for total coliforms and fecal coliforms. The incidence of coliphage in these potable water supplies reflects the probability of human pathogenic virus survival in these waters also.     

Legionella incidence and density in potable drinking water supplies

The incidence and density of Legionella spp. in raw water, water at various stages of treatment, and in potable distribution water were determined by direct immunofluorescence. The number of cells reacting with Legionella-specific fluorescent antibody conjugates in raw waters ranged from about 10(4) to 10(5) cells/liter, whereas the concentrations of fluorescent antibody-positive cells in the distribution waters were generally 10- to 100-fold lower than in the raw source waters. No viable or virulent Legionella strains were isolated from either the source or distribution waters. However, Legionella spp. are infrequently isolated from water at temperatures below 15 degrees C as was the case in the system surveyed in this study.     

A new medium for the enumeration and subculture of bacteria from potable water.

Plate count agar is presently the recommended medium for the standard bacterial plate count (35 degrees C, 48-h incubation) of water and wastewater. However, plate count agar does not permit the growth of many bacteria that may be present in treated potable water supplies. A new medium was developed for use in heterotrophic plate count analyses and for subculture of bacteria isolated from potable water samples. The new medium, designated R2A, contains 0.5 g of yeast extract, 0.5 g of Difco Proteose Peptone no. 3 (Difco Laboratories), 0.5 g of Casamino Acids (Difco), 0.5 g of glucose, 0.5 g of soluble starch, 0.3 g of K2HPO4, 0.05 g of MgSO4 X 7H2O, 0.3 g of sodium pyruvate, and 15 g of agar per liter of laboratory quality water. Adjust the pH to 7.2 with crystalline K2HPO4 or KH2PO4 and sterilize at 121 degrees C for 15 min. Results from parallel studies with spread, membrane filter, and pour plate procedures showed that R2A medium yielded significantly higher bacterial counts than did plate count agar. Studies of the effect of incubation temperature showed that the magnitude of the count was inversely proportional to the incubation temperature. Longer incubation time, up to 14 days, yielded higher counts and increased detection of pigmented bacteria. Maximal bacterial counts were obtained after incubation at 20 degrees C for 14 days. As a tool to monitor heterotrophic bacterial populations in water treatment processes and in treated distribution water, R2A spread or membrane filter plates incubated at 28 degrees C for 5 to 7 days is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)     

橡胶种植与饮水短缺:西双版纳戈牛村的案例

西双版纳大面积种植橡胶引起的负面生态影响受到广泛关注.采用问卷调查和实地调查方法分析了景洪市戈牛行政村的橡胶种植与饮水短缺问题.结果表明:橡胶种植面积的大幅度增长与村寨人畜饮水短缺是同步的;2009年因收获橡胶产品的水资源消耗量为1995年的3.4倍;52.7%的村民认同橡胶种植导致饮水短缺,但只有5.4%的村民自愿减少橡胶面积以缓解水资源问题.有必要强化研究橡胶树生产胶汁的水分消耗,以及如何调动橡胶种植者参与解决橡胶种植的水生态问题.