Biomedical subjects

W Dott

Publications and source records attributed to W Dott.

At least 73 records · Page 4Linked to original sources

PubMed1985

[Qualitative and quantitative determination of bacterial populations in an aquatic environment. 7. Development of bacterial growth on raw materials exposed to potable water].

Refined steel plates coated with different materials that contained available organic compounds led to a microbial growth on the surface. Even plastics and bitumen which were used in the sphere of drinking water showed after an exposure time of three months up to 192 ml slime per square meter. The number of viable bacteria within the Aufwuchs was in the range of 10(7) cfu/ml. The production of slime increased with time. The relation of carbohydrate and protein content significantly changed from 2 at the beginning to 30 after 12 months of incubation the bitumen coating test plates. This indicates an increase synthesis of carbohydrate containing extracellular polymeric substances during the late phase of growth. The bacteria isolated from the Aufwuchs mainly belonged to the genera Pseudomonas, Flavobacterium, Acinetobacter, Caulobacter, sheated bacteria and other gramnegative physiologically nonreactiv roads. During exposure of the plates the relation changed within the bacterial communities of the main groups. Comparing the bacteria communities of inlet and outflow water it became evident that the later one was influenced by bacteria of the Aufwuchs.

Bacteria↗

PubMed1985

[Qualitative and quantitative determination of bacterial populations in an aquatic environment. 8. Variation of the species spectrum during a drinking-water treatment process].

Water treatment processes such as aeration, gravel filtration, ozonation, activated-carbon filtration and chlorination causes variation in the number of bacteria as well as the development or die off of specific species. The number of bacteria was always reduced to a large extent if ozone or chlorine were applied whereas after filtration process often an increasing number of bacteria could be observed in the effluent. Despite of the differing bacterial counts a reduction of the variety of species was found during all treatment process. Whereas the raw water contained a heterogeneous spectrum of copiotrophic and oligotrophic bacteria the treated water contained mainly slow growing oligotrophic bacteria which didn't express any physiological activities.

Bacteria↗

PubMed1985

[Microbiological studies of groundwater polluted with hydrocarbons. 2. Determination of bacterial in vitro activity].

The injected water and the groundwater withdrawn by the E-wells contained bacteria with higher 'in vitro'-total activity (30-50%) than the groundwater taken from the middle part of the flushing area. The determination of single-activities resulted in a similar distribution of bacterial communities. Denitrifying and nitrate-reducing bacteria were present in the polluted groundwater (10-100% of isolates). After transforming these values in CFU/ml they correspond to the MPN/ml of both groups. Furthermore bacteria were found, which could use hydrocarbons as their only carbon source under aerobic and anaerobic conditions; there were different percentage of hydrocarbon-degrading bacteria in the groundwater of the three sampling points. Totally 2-70% of all isolates were aerobe hydrocarbon-degrading bacteria, 1-12% nitrate-reducing and 1-13% denitrifying hydrocarbon-metabolizing bacteria.

Aerobiosis↗

PubMed1984

[Microbiological studies of ground water polluted with hydrocarbons. 1. Quantitative and qualitative distribution of bacterial populations].

The groundwater, polluted with hydrocarbons, showed large cell numbers during one year of examination: 10(3)-10(4) CFU/ml grown on N-agar after 5 days at 20 degrees C, 10(4)-10(5) CFU/ml grown on water-agar after 8 weeks at 20 degrees C and total cell numbers of 10(5)-10(7)/ml. The bacteria, which were isolated from N-agar, were chiefly Pseudomonas, Flavobacterium, Acinetobacter, and other gramnegative species, Arthrobacter and Bacillus as members of grampositive bacteria. Furthermore the following "physiological' groups were found in the groundwater: ammonium-oxidizing bacteria (MPN 10(1)-10(2)/ml), sulfur-oxidizing bacteria (MPN 10(1)-10(4)/ml), nitrate-reducing bacteria (MPN 10(3)-10(6)/ml), denitrifying bacteria (MPN 10(1)-10(4)/ml), spores of aerobe spore-forming bacteria (2-30/ml), spores of anaerobe spore-forming bacteria (0.2-0.4/ml), manganese-oxidizing bacteria (10(3)-10(4) CFU/ml) and Actinomycetes (0.1-1.0 CFU/ml).

Acinetobacter↗

PubMed1983

[Qualitative and quantitative determination of bacterial populations in aquatic habitats. 6. Germ regrowth and drinking water].

Regrowth of bacteria in the sphere of drinking water is dependent on time (stagnation of the water in the distribution system) and on the absence or inefficiency of disinfectants e.g. chlorine and chlorinedioxid. Traceable amounts of assimilable organic carbon are not a presupposition for the multiplication of the bacteria. Even in bidistilled water growth of bacteria could be observed. Under laboratory conditions it was shown that the number of bacteria increased to 10(4) per ml after a 4-days-incubation at 20 degrees C. In particular the multiplication is concerned with the autochton bacterial flora of the water e.g. pseudomonas species. As a result of the identification of the bacteria it was observed that the increase number of bacteria was accompanied by a decrease of individual species. After 6-days'-incubation of the water samples pseudomonas-species like P. fluorescens and P. cepacia were the predominating bacterial forms. The number of Gram-positive bacteria decreased significantly during incubation.

Bacteria↗

PubMed1983

[Qualitative and quantitative determination of bacterial populations in aquatic habitats. 5. Comparison of 2 rapid sand filters].

The bacterial examinations of raw water and the effluent of two rapid sand filters showed differences with respect to the colony count, the identified species and the activity of the isolated bacteria. The raw waters of the treatment plants Si and Me are originated from an oligotrophic artificial lake and from ground-water respectively. The two raw waters contained only low numbers of bacteria, whereas the effluents of the filters showed a considerable increase of the bacterial counts. The results indicate a development of microbial populations in the filters. Furthermore there were also differences between the two filters examined. The first one led to the growth of Pseudomonas- and Flavobacterium species, the second one to Flavobacterium, Chromobacterium and Acinetobacter species. Comparing the raw water and the effluent, a reduction of special and total physiological activities of the isolated bacteria could be observed in filter I, whereas there wasn't any change in filter II.

Bacteria↗

PubMed1982

[Methylotrophic bacteria in the sphere of drinking water. 1. Communication: comparison of the bacterial count of the water derived from different treatment plants].

Raw water, biological filters as well as supply water of 11 different treatment plants were examined with respect to the occurrence of methylotrophic bacteria. Although these organisms could be found in all samples, there were considerable differences in relation to the countable numbers. Methane containing raw waters showed only very low numbers of methylotrophic bacteria, whereas after aeration and passing the biological filters the effluent contained high numbers of these organisms. No correlation could be observed between colony count of the heterotrophic bacteria and the number of methylotrophic bacteria. A rapid method for determination of the methylotrophic bacteria on solid media, using the different colony size depending on incubation with and without a C1-compound, is quite inaccurate and uncertain.

Bacteria↗

PubMed1982

[Faecal streptococci as indicator organisms of drinking water].

The rules of the European Economic Community to harmonize the hygienic quality of drinking water write out the faecal streptococci as indicator organisms. This operating definition of the faecal streptococci prohibits its taxonomic limitation to enterococci or group D streptococci. Therefore, we have undertaken studies concerning the methods for routine examinations. Comparative investigations of selective enrichment broths showed no significant differences of the end concentration of glucose in the range of 0.5-1.0% and of sodium azide in the range of 0.02-0.05%. 36 degrees C was a better incubation temperature than 44 degrees C and the results were better after 24 h than after 48 h. Comparative investigations of selective plating media showed less selectivity of the bile-aesculin agar and gentamicinthallous-carbonate agar than that on the one hand of citrate-azide-tween-carbonate agar, KF streptococcal agar or Slanetz-Bartley enterococcal agar, and on the other hand of kanamycin-aesculin-azide agar. All together the kanamycin-aesculin-azide agar seems to be a little better than the other media (Table 2) 356 strains of faecal streptococci were isolated from the studied media. More than 20 characteristics were investigated and, there upon, the strains were differentiated (Table 3). S. faecalis predominates in human materials, i.e. urine, S. faecium and S. durans were isolated specially from sewage and waste water (Table 4). The single species of faecal streptococci grow specificly on the different selective media, and therefore, each agar specimen prefers the one or other species more or less selectively (Table 5).

Azides↗

PubMed1982

[Methylotrophic bacteria in the sphere of drinking water. 2. Communication: biochemical/physiological and morphological characterisation of the isolated bacteria].

720 bacteria from 18 water samples were isolated under conditions which are expected to be selective for methylotrophic bacteria. The water samples derived from 11 different water plants including 5 which had to treat methane containing groundwater. All isolates had been characterized by 130 properties using the morphological features of the colonies and the cells as well as physiological and biochemical tests. Numerical and classical principles of taxonomy were applied to the data. Only 20% of the isolated bacteria pointed out to be methylotrophic, even the portion of obligate methylotrophic organisms was only 1%.

Bacteria↗

PubMed1982

[Microbial colonization of lining materials and building materials in the drinking water supply. 10. The behavior of a polyamide pipe in use and under laboratory conditions].

After the installation of a new rising-pipe the count of bacteria in the water of a well increased temporarily. After a working period of 25 months the pipe was removed and microbiologically examined. On the inside and the outside of the pipe surface microbial growth could be observed. After the first increase of colony count in the water a comparable polyamid-pipe was tested microbiologically under laboratory conditions. In this case growth on the surface could also be found at 3 successive inspections.

Bacteria↗

PubMed1981

[Microbial settlement of paint- and building-materials in the sphere of drinking water. 7. Communication: long time observations in two drinking water reservoirs coated by epoxy resin (author's transl)].

In two potable water reservoirs with an epoxy resin lining an increase of the colony count in the water and a visible microbial growth on the surface could be observed. The slime consists of bacteria and fungi. In one case higher organisms like protozoa were found too. The growth of microorganisms is caused by organic compounds of the epoxy resin which can be deteriorated by microorganisms. After a period of 3 years both materials still promote microbial growth on the surface.

Animals↗

PubMed1981

[Hygienic quality of lakes which are used as open-air bath. 2. Communication: Comparison of biochemical typed Escherichia coli strains isolated from lake water and bird excrements (author's transl)].

368 strains of Escherichia coli were isolated from lakewaters and bird excrements (mainly black-headed gulls) using mandatory methods for drinking water examination. All strains were further characterized by 43 biochemical physiological and 30 morphological features. Besides the API 30 E Enterobacteriaceae system and the Roche Enterotube system of biochemical testing were used comparatively. The analysis using numerical methods for taxonomy pointed out that a single biotop could be characterized by the small physiological variation of the strains.

Animals↗

PubMed1981

[Occurrence and significance of Actinomycetes in drinking water (author's transl)].

Different species of Actinomycetes could be found in the raw-water depending on the origin of the water. The process of water-treatment influenced the total count and the various species in a different mode. Actinomycetes were also isolated from slime which has been formed by microbial growth on PVC coated walls in reservoirs. The typical earthy-musty odour was only found in the genera Streptomyces, were as some species of Nocardia are able to produce a phenolic odour.

Actinomycetales↗

PubMed1981

[Qualitative and quantitative examination of bacteria found in aquatic habitats. 3. Communications: Recording the data for identification and analysing by numerical methods (author's transl)].

A sheet for optical page mark was developed to transfer the large amount of identification criteria, necessary for quantitative and qualitative determination of bacterial populations, to the computer-assisted analysis. Empirical and numerical methods are used for the taxonomic evaluation. Different metrics are applied to the different groups of criteria. The clusters were formed by the single-linkage method. An example is given to explain how cluster analysis and formal descriptions are an useful aid for the classification of bacteria.

Bacteria↗

PubMed1981

[Qualitative and quantitative examinations of bacterial found in aquatic habitats. 4. Communication: Comparison of the bacteria of the water an its layer of scum both derived from a reservoir for drinking water (author's transl)].

The bacteriological examination of the water from a reservoir and its thin layer of scum (Neuston) showed considerable differences with respect to the colony count and the identified species. The sample from the surface contained 10(6) bacteria per ml. 77% of the isolated species belonged to the genus Pseudomonas. Where as the bacterial count of the water was below 10(3) per ml. In this case gram-negative, oxidase-negative, yellow-pigmented, motile rods belonging to the genus Xanthomonas were isolated most frequently.

Bacteria↗

PubMed1981

[Identification of bacteria from use-surface disinfectant solutions and their sensibility against disinfectants (author's transl)].

The investigations are concerned with bacteria which had been isolated from use-surface disinfectant solutions originated from 19 disinfection dosage apparatus of different hospitals and from 8 taps of a centralised disinfection dosage apparatus in an other hospital. The greatest part of the isolated bacteria belonged to the genus Pseudomonas. Beyond it there were yellow-pigmented bacteria like Xanthomonas, Flavobacterium and Micrococcus. After subculture on solid peptone-containing media most of the isolated bacteria turned out to be sensitive to the disinfection solutions in a concentration range, that had been applied in the dosage apparatus. The examination of 6 disinfectants showed, that there were considerable differences in the efficiency to kill the bacteria. Even one preparation pointed out to be absolutely ineffective at applied concentrations.

Bacteria↗

PubMed1980

[Behaviour of indicator bacteria in microbial slime on surfaces of walls in drinkingwater-reservoirs (author's transl)].

Slime formed by microbial activity on surfaces of a tightening compound (Silicon) and Epoxid-Coating in the sphere of drinking-water does not support survival of bacteria like E. coli, S. marcescens, P. aeruginosa, S. aureus and B. subtilis. The enterobacteriaeceae remained countable over a period of nine weeks, P. aeruginosa even eighteen weeks. Whereas the grampositive Bacteria died during the short time of one week. Autoclaved slime promoted the growth of the gramnegative bacteria.

Bacillus subtilis↗

PubMed1980

[Hygienic quality of lakes which are used as open-air bath. I. Communication: seasonal variation of total colony count, the number of Escherichia coli and coliforms (author's transl)].

Four lakes situated in the recultivated area of the Rhenish brown-coal district were examined bacteriologically during a period of one year. Total colony count and the number of Escherichia coli and coliforms were determined and compared with the influence of meteorological factors and human and animal impacts.

Animals↗