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D van der Kooij

Publications and source records attributed to D van der Kooij.

16 recordsLinked to original sources
PubMed2003

Elucidation and control of biofilm formation processes in water treatment and distribution using the Unified Biofilm Approach.

Controlling biological processes in water treatment and distribution is a major challenge to water supply companies. In the Netherlands, the use of chlorine-based disinfectants in water treatment is limited as much as possible and treated water is distributed without disinfectant residual in most cases. Biofilm formation processes in water treatment and distribution are studied using adenosinetriphosphate (ATP) as the parameter for active biomass. ATP measurements are applied to assess biofilm concentrations in distribution systems, in the biofilm monitor to determine the biofilm formation rate of treated water, in the biomass production potential test to determine the effect of pipe materials on microbial growth and in membrane systems to quantify biofouling. The use of a single parameter enables to compare biofilm concentrations in all situations and contributes to the understanding and control of biofilm formation processes in water treatment and distribution. This approach has been designated as the Unified Biofilm Approach.

Adenosine Triphosphate↗
PubMed1995

Bromate reduction by denitrifying bacteria.

In the presence of bromide, ozonation as applied in water treatment results in the formation of bromate, an ion with carcinogenic properties. The reduction of bromate by mixed bacterial populations as well as pure cultures was studied under laboratory conditions. Bromate was reduced to bromide by a mixed bacterial population with and without a preceding nitrate reduction step in an anaerobically incubated medium with ethanol as the energy and carbon source at 20 and 25 deg C. The predominating bacteria isolated from the batches showing bromate reduction were identified as Pseudomonas spp. Strains of Pseudomonas fluorescens reduced BrO(inf3)(sup-) to Br(sup-) but at a much lower rate than the mixed bacterial population did. Nitrate is a preferred electron acceptor for the bromate-reducing bacteria. Bromate reduction did not occur in the presence of NO(inf3)(sup-), and the rate of bromate reduction was at least 100 times lower than the rate of nitrate reduction. Bromate was completely converted to Br(sup-), indicating that intermediates, e.g., BrO(inf2)(sup-), did not accumulate during bromate reduction.

Journal Article↗
PubMed1992

Typing of Aeromonas strains from patients with diarrhoea and from drinking water.

Aeromonas strains (187) from human diarrhoeal stools and from drinking water (263) in The Netherlands were typed by three different methods. Biotyping alone was found to be of little value for epidemiological studies because 84% of all strains belonged to only 10 biotypes. Common biotypes could be further differentiated by serotyping. Gas-liquid chromatography of cell wall fatty acid methyl esters (FAME) was useful for species identification as well as for typing: 86% of all strains could be identified to the species level, and within this group 92% of all identifications corresponded with the biotype. Cluster analysis and principal component analysis of FAME profiles could be used for comparison of strains from different sources and gave the same general conclusions as bio- and serotyping. There was little overall similarity between Aeromonas strains from human (diarrhoeal) faeces and from drinking water, differences being most pronounced for Aeromonas caviae and least for A. sobria.

Aeromonas↗
PubMed1991

Nutritional requirements of aeromonads and their multiplication in drinking water.

Aeromonads can utilize a wide range of low molecular-weight compounds, including amino acids, carbohydrates and long-chain fatty acids at a concentration of a few micrograms per liter. Utilization of biopolymers such as gelatin, casein and amylose is slow at this concentration level. The concentration of substrates available for an A. hydrophila strain in drinking water was usually below 10 micrograms of C/l. The autochthonous bacteria utilized these substrates more rapidly than the aeromonads. The multiplication of aeromonads in drinking water during distribution is therefore explained by their growth on biomass components in the biofilm and in sediments in the pipes.

Aeromonas↗
PubMed1988

Nutritional versatility and growth kinetics of an Aeromonas hydrophila strain isolated from drinking water.

The nutritional versatility and growth kinetics of Aeromonas hydrophila were studied to determine the nature and the growth-promoting properties of organic compounds which may serve as substrates for the growth of this organism in drinking water during treatment and distribution. As an initial screening, a total of 69 different organic compounds were tested at a concentration of 2.5 g/liter as growth substrates for 10 A. hydrophila strains. Of these strains, strain M800 attained the highest maximum colony counts in various types of drinking water and river water and was therefore used in further measurements of growth at low substrate concentrations. A mixture of 21 amino acids and a mixture of 10 long-chain fatty acids, when added to drinking water, promoted growth of strain M800 at individual compound concentrations as low as 0.1 microgram of C per liter. Mixtures of 18 carbohydrates and 18 carboxylic acids clearly enhanced growth of the organism at individual compound concentrations above 1 microgram of C per liter. Growth measurements with 63 individual substrates at a concentration of 10 micrograms of C per liter gave growth rates of greater than or equal to 0.1/h with two amino acids, nine carbohydrates, and six long-chain fatty acids. Ks values were determined for arginine (less than or equal to 0.3 micrograms of C per liter), glucose (15.9 micrograms of C per liter), acetate (11.1 micrograms of C per liter), and oleate (2.1 micrograms of C per liter). The data obtained indicate that biomass components, such as amino acids and long-chain fatty acids, can promote multiplication of aeromonads in drinking water distribution systems at concentrations as low as a few micrograms per liter.

Aeromonas↗
PubMed1988

Properties of aeromonads and their occurrence and hygienic significance in drinking water.

In the Netherlands, aeromonads in drinking water have attracted much attention in recent years. This development was caused by a sudden increase of the Aeromonas density in the drinking water of the municipal Dune Waterworks of The Hague and reports about the possible health significance of these organisms in drinking water. Literature data indicate that representatives of the motile Aeromonas species A. hydrophila, A. sobria and A. caviae generally have been observed in larger percentages of diarrheal feces than in normal stools, with isolation rates ranging from less than 1% to more than 20%. These data and the virulence properties of the aeromonads, viz. hemolytic activity, cytotoxicity and enterotoxicity, as tested in the suckling mouse assay or the rabbit ileal loop, strongly suggest that these aeromonads are potential enteric pathogens for susceptible hosts, including young children and immunocompromised persons. Aeromonads are ubiquitously present in fresh water environments, with densities depending on pollution with sewage, trophic state and temperature. About 100 years ago, bacteria identical with Aeromonas spp. have already been isolated from drinking water. Depletion of free chlorine residuals in drinking water generally results in increasing Aeromonas densities, particularly in the summer months. Investigations in the Netherlands have shown that Aeromonas densities in drinking water increase with increasing residence time. Furthermore, the aeromonads constitute a minor fraction of the heterotrophic bacterial population in drinking water. Growth measurements with pure cultures of A. hydrophila revealed that certain compounds, e.g. oleate as present in soft soap, promote the growth of the organism at substrate concentrations of a few micrograms per liter. Based on a number of surveys on the presence of aeromonads in drinking water, the health authorities in the Netherlands have defined so-called indicative maximum values for Aeromonas densities in drinking water i.e. 20 CFU/100 ml in drinking water at the production plant and 200 CFU/100 ml in drinking water during distribution. Further research is necessary (i) to elucidate the health significance of aeromonads in drinking water and (ii) to define measures for limiting Aeromonas densities in drinking water.

Aeromonas↗
PubMed1985

Determination of the concentration of maltose- and starch-like compounds in drinking water by growth measurements with a well-defined strain of a Flavobacterium species.

The growth kinetics of Flavobacterium sp. strain S12 specialized in the utilization of glycerol, and a number of oligo- and polysaccharides were determined in batch-culture experiments at 15 degrees C in pasteurized tap water supplied with very low amounts of substrates. Kss for the growth on maltotriose, maltotetraose, maltopentaose, and maltohexaose were 0.03 microM or less and below those for glucose (1.5 microM) and maltose (0.16 microM). Kss for starch, amylose, and amylopectin were 8.4, 25.6, and 11.0 micrograms of C per liter, respectively. A yield of 2.3 X 10(7) CFU/micrograms of C on the oligo- and polysaccharides was calculated from the linear relationships observed between maximum colony counts in pasteurized tap water and the concentrations (usually below 25 micrograms of C per liter) of supplied compounds. The maximum colony counts of strain S12 grown in various types of raw water and tap water revealed that raw water contained only a few micrograms of maltose- and starch-like compounds per liter; in tap water the concentrations were all below 1 microgram of C and usually below 0.1 microgram of C per liter. The application of starch-based coagulant aids gave increased concentrations of maltose- and starch-like compounds in the water during treatment, but these concentrations were greatly reduced by coagulation and sedimentation, rapid sand filtration, and slow sand filtration.

Flavobacterium↗
PubMed1984

Substrate utilization by an oxalate-consuming spirillum species in relation to its growth in ozonated water.

The nutritional versatility of a vibrio-shaped, oxalate-utilizing isolate, strain NOX, obtained from tap water supplied with low concentrations of formate, glyoxylate, and oxalate, was determined by growth experiments with low-molecular-weight carbon compounds at high (grams per liter) and very low (micrograms per liter) concentrations. The organism, which was identified as a Spirillum species, appeared to be specialized in the utilization of a number of carboxylic acids. Yields of 2.9 x 10 CFU/mug of oxalate C and 1.2 x 10 CFU/mug of acetate C were obtained from growth experiments in tap water supplied with various low amounts of either oxalate or acetate. A substrate saturation constant of 0.64 muM oxalate was calculated for strain NOX from the relationship between growth rate and concentration of added oxalate. Maximum colony counts of strain NOX grown in ozonated water (dosages of 2.0 to 3.2 mg of O(3) per liter) were 15 to 20 times larger than the maximum colony counts of strain NOX grown in water before ozonation. Based on the nutritional requirements of strain NOX, it was concluded that carboxylic acids were produced by ozonation. Oxalate concentrations were calculated from the maximum colony counts of strain NOX grown in samples of ozonated water in which a non-oxalate-utilizing strain of Pseudomonas fluorescens had already reached maximum growth. The oxalate concentrations obtained by this procedure ranged from 130 to 220 mug of C/liter.

Journal Article↗
PubMed1983

Nutritional versatility of a starch-utilizing Flavobacterium at low substrate concentrations.

A starch-utilizing yellow-pigmented bacterium, isolated from tap water, was tested for the utilization of 64 natural compounds at a concentration of 1 g/liter by measuring colony growth on agar media. Only 12 carbohydrates and glycerol promoted growth. Growth experiments with the organism in pasteurized tap water supplied with mixtures of substrates at concentrations of 1 or 10 micrograms of C of each substrate per liter, followed by separate experiments with a number of carbohydrates at 10 micrograms of C per liter showed that of these 64 natural compounds only sucrose, maltose, raffinose, starch, and glycerol promoted growth at very low concentrations. Also maltotriose, -tetraose, -pentaose, -hexaose, and stachyose, which were not included in the mixtures, enhanced growth, and generation times of 3 to 5 h at 10 micrograms of C per liter were observed. The organism, which was tentatively identified as a Flavobacterium species, thus appeared to be highly specialized in the utilization of glycerol and a number of oligo- and polysaccharides at very low concentrations.

Flavobacterium↗
PubMed1982

Multiplication of fluorescent pseudomonads at low substrate concentrations in tap water.

Two fluorescent pseudomonads, strains P17 and P500, belonging to different biotypes were tested for growth in tap water supplied with different concentration of acetate and glutamate, low concentrations (10 and 20 micrograms of C per liter) of various other substrates and mixtures of related substrates, the latter being present in amounts of 1 microgram of C per liter each. Amino acids appeared to be excellent substrates for both isolates, but many other substrates were utilized at very low concentrations as well. Saturation constants (Ks) of P17 with acetate, arginine, aspartate, glutamate, lactate, succinate, malonate, p-hydroxybenzoate and glucose were all below 1 microM. The Ks values of strain P500 were about 5 times larger than those of P17. Since especially P17 is able to use a large number of different substrates at low concentrations, assessment of maximal colony counts of this organism by growth experiments in various types of tap water may give information about the concentrations of easily assimilable organic carbon.

Acetates↗
PubMed1982

Growth of Pseudomonas aeruginosa in tap water in relation to utilization of substrates at concentrations of a few micrograms per liter.

Five Pseudomonas aeruginosa strains were tested for the utilization of 47 low-molecular-weight compounds as their sole sources of carbon and energy for growth at a concentration of 2.5 g/liter. Of these compounds, 31 to 35 were consumed. Growth experiments in tap water at 15 degrees C were carried out with one particular strain (P1525) isolated from drinking water. This strain was tested for the utilization of 30 compounds supplied at a concentration of 25 microgram of C per liter. The growth rate (number of generations per hour) of strain P1525 in this tap water was approximately 0.005 h-1, and with 10 compounds it was larger than 0.03 h-1. An average yield of 6.2 x 10(9) colony-forming units per mg of C was obtained from the maximum colony counts (colony-forming units per milliliter). The average yield and maximum colony count of strain P1525 grown in tap water supplied with a mixture of 45 compounds, each at a concentration of 1 microgram of C per liter, enabled us to calculate that 28 compounds were utilized. Growth rates of two P. aeruginosa strains (including P1525) in various types of water at 15 degrees C were half of those of a fluorescent pseudomonad. The concentrations of assimilable organic carbon calculated from maximum colony counts and average yield values amounted to 0.1 to 0.7% of the total organic carbon concentrations in five types of tap water. The assimilable organic carbon percentages were about 10 times larger in river water and in water after ozonation.

Acetates↗
PubMed1981

Utilization of low concentrations of starch by a flavobacterium species isolated from tap water.

Experiments in well-cleaned glass flasks revealed that addition of starch in concentrations of 10 and 25 mug of substrate C per liter to the filtrate of slow sand filters stimulated the development of a yellow-pigmented bacterium which was identified as a Flavobacterium species. The isolate was able to multiply in tap water without substrates added, but addition of starch and glucose in amounts as low as 1 mug of substrate C per liter clearly enhanced growth. The substrate affinities of the Flavobacterium for these compounds were 3.9 mug of starch C and 3.3 mug of glucose C per liter. The results of this study indicate that microorganisms which rapidly utilize starch at a level of a few micrograms per liter commonly occur in water.

Journal Article↗
PubMed1980

Growth of Aeromonas hydrophila at Low Concentrations of Substrates Added to Tap Water.

The ability of an Aeromonas hydrophila isolate obtained from filtered river water to grow at low substrate concentrations was studied in batch experiments with tap water supplied with low concentrations of substrates. Growth was assessed by colony count determinations. The isolate only multiplied in the used tap water (2 to 3 mg of dissolved organic carbon per liter) after the addition of a small amount of an assimilable carbon compound. d-Glucose especially caused growth of the organism even at initial concentrations below 10 mug of C per liter. At initial glucose concentrations below the K(s) value (12 mug of C per liter), generation times and yield (colony-forming units per milligram of substrate-C) were nonlinear with 1/initial glucose concentrations and initial glucose concentrations, respectively. From these observations, the maintenance coefficient m was calculated (m = 0.015 mg of glucose per mg [dry wt] per h at 12 degrees C). At initial concentrations below the K(s) value of starch (73 mug of C per liter), no growth was observed, but complete use of starch occurred in these situations after the addition of 10 mug of glucose-C per liter. The results of this study show that information of ecological significance may be obtained by very simple batch experiments. Moreover, the isolate studied may be used in growth experiments to assess the maximum concentration of glucose which might be present in water, particularly tap water.

Journal Article↗
PubMed1979

Characterization and classification of fluorescent pseudomonads isolated from tap water and surface water.

A total of 665 fluorescent pseudomonads, isolated from surface water and from different types of tap water, were classified into 22 groups defined by the results of the following 5 tests: hydrolysis of casein or gelatin, production of N2 from NO3-, and growth on sucrose, ethanol and D-sorbitol, respectively. Differences in colonial morphology and in the degree of proteolysis revealed that these groups were inhomogeneous. A more detailed subdivision was achieved by adding the following characters: growth on L-arabinose, D-mannitol, mesoinositol, and adonitol, respectively, and hydrolysis of Tween-80. Repeating the tests for hydrolyzing enzymes, denitrification, and growth on the carbohydrates and alcohols with strains stored in the laboratory for 1 to 3 years revealed that most characters, except hydrolysis of Tween-80, denitrification, and growth on sucrose, were very stable. Forty-five biotypes of the fluorescent pseudomonads were defined, based on the results of the repeated tests and the results of tests on nine aromatic compounds. The observed changes of some characters in a number of isolates did not diminish the value of this classification, but indicated that close relationships exist between many biotypes. About half of the biotypes described in this paper are similar to those defined by Stanier, Palleroni and Doudoroff (1966) and by Doudoroff and Palleroni (1974a), confirming the wide-spread occurrence of well-definable biotypes of fluorescent pseudomonads. Representatives of some biotypes were most frequently isolated from surface water and from tap water prepared from surface water. Tap water prepared from anaerobic or aerobic ground water contained representatives of biotypes which were typical of these water types. Some pseudomonads were found to grow especially in filters. The observed relationships between origin of the fluorescent pseudomonads and their classification into biotypes as defined in this paper supported the presented classification.

Alcohols↗
PubMed1977

The occurrence of Pseudomonas spp. in surface water and in tap water as determined on citrate media.

Citrate-utilizing bacteria were counted in 289 samples of tap water derived from either surface water or ground water and in 32 samples of raw or partially treated surface water by using media containing ferric ammonium citrate as the carbon and energy source. The citrate-utilizing bacteria constituted only small minorities of the colony counts on Lab-Lemco agar at 25 C in both tap water and surface water. A total of 1071 isolates were obtained, of which 979 were able to utilize citrate. Characterization of the citrate-utilizing isolates revealed that 90% of these bacteria were arginine dihydrolase-positive and belonged to the genera Pseudomonas (84.3%) and Aeromonas (5.7%). The genus Pseudomonas was represented by fluorescent pseudomonads (66.3%), non-fluorescent glucose-utilizing pseudomonads (12.1%) and P. alcaligenes (5.9%). None of the isolates was identified as P. aeruginosa. It is suggested that the pseudomonads and the aeromonads are not adapted to low substrate concentrations. Enumeration of the citrate-utilizing bacteria in tap water therefore may give information on the efficiency of water treatment techniques as regards the substrate removal.

Aeromonas↗