[The success of hygiene in the last 40 years].

In Germany, the last period of the Second World War and the following years were characterized by deficiencies of hygiene which had not occurred previously in Middle Europe during the 20th century. There were focuses of typhus, typhoid fever, tuberculosis, diphtheria, scarlet fever, and meningitis. Insufficiencies in the removal of faeces caused high incidences of shigellosis, hepatitis A, and ascariasis.

[Induction of microbial growth on the walls of plastic tubes by drinking water].

Drinking water flowing through flexible plastic tubes (PVC) causes the development of a thin film-like coating within 24 h. At this stage microorganisms could either not or rarely be seen. After 48 h the number of microorganisms has become greater.

[Microbial colonization of the walls of a copper pipeline in a central disinfection dosage unit].

Part of a copper-pipe taken from an 11 years old central disinfection dosage apparatus was investigated by Scanning Electron Microscopy. The pipe was covered by a thin paste-like coating. SEM revealed two distinct layers.

[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.

[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.

[Microbial settlement of paint- and building-materials in the sphere of drinking water. 9. Communication: experimental examination of cement mortar for the lining with tiles (author's transl)].

The observation of a microbial growth in form of macrocolonies upon the joints of a tiled drinking water reservoir caused the microbiological testing of different pure mineral and some plastic containing cement mortar. Besides the conditions allowing the growth of macrocolonies on tiled plates with a construction like in a reservoir were examined.

[Microbial settlement of paint- and building-materials in the sphere of drinking-water. 6. Communication: Experimental examination of chlorcaoutchouc paints under working conditions and in laboratory tests (author's transl)].

Five different chlorcaoutchouc coating materials were microbiologically tested. All materials showed a visible microbial growth on the surface. The amount of slime decreased with the increase of age of the coat of paint.

[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.

[Qualitative and quantitative examination of bacteria found in aquatic habitats. 2. Communication: application of miniturizid multitest systems for identification and biochemical typing of bacteria using a multi-point method (author's transl)].

A large number of bacteria were characterized and identified using a miniturized multi-test system and an automatic inoculator. This testsystem is suitable for ecological studies to get information about the qualitative and quantitative composition of bacterial populations. More than that a biochemical typing of bacteria is possible.

[Trace metals in sewage sludge. Regional survey (author's transl)].

A regional survey of sewage sludge compositions was conducted in the Rhein-Sieg-Kreis, including the city of Bonn. Sludge samples were obtained from 28 treatment plants. The following metals and metalloids have been measured by AAS: Fe, Zn, Cu, Cr, Ni, Pb, Cd, Hg, As, Se.

[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.

[Microbial settlement of paint- and building-materials in the sphere of drinking water. 3. Macrocolonies on the joint in a drinking-water-reservoir covered with tile (author's transl)].

The microbial growth in form of macrocolonies on the joint of a drinking-water-reservoir covered with tile could be observed repeatedly. The slime was examined microbiologically. The origin of the carbon sources was determined by radiocarbon test.

[Microbial settlement of paint- and building-materials in the sphere of drinking-water. 4. Communication: Examination of tightening compounds under working conditions (author's transl)].

Tightening compounds which were used in the sphere of drinking-water led to a microbial settlement that differs in points of quantity and quality depending on the kind of material. Twelve compounds on the base of Silicon, one on the base of Thiokol and one Epoxid were examined.

[Microbial settlement of paint- and building-materials in the sphere of drinking-water. 2. Information: experimental examination of bitumen paint under working conditions (author's transl)].

A bituminous coating material for drinking water reservoirs was applied on testing plates for a microbial examination. In function of the chlorine content of the water a microbial slime layer could be found on the testing plates. The amount of slime became less in course of the time or was not produced at all, when the plates were desiccated before the experiment for some months.

[Microbial settlement of paint- and building-materials in the sphere of drinking-water. 1. Information: long time observation of a bitumen paint in a drinking-water-reservoir (author's transl)].

In a drinking water reservoir with a freshly applied bituminous coating a microbial settlement was found on the walls. Its development was observed over a period of 23 months. The slime on the walls consisted of bacteria and fungi and was secondarily colonized by protozoa and nematodes.