The ability of 5 aquatic Hyphomycetes to produce Amylase, Pectinase and Cellulase was investigated. All the tested strains were weak producers of Amylase and good producers of Pectinase, whereas degradation of Cellulose was only found with two strains.
Ergometrical investigations with standard stress show that negatively charged air increases carbon dioxide exhalation. Thereby work-acidosis is decreased and the centers of the circulatory system are relieved.
From the emission rates of the bacterial cooling tower emission determined in field measurements (see Comm. II) the mortality rate of enterbacteria on soil, grass and solid surfaces and the mortality rate in the atmosphere taken from literature the immission rates and the long-term effect on microbial surface flora were calculated and compared with our own measurements. The values used in the calculations include large margins for error. The atmospheric germ counts determined by experiment were no higher than the calculated values; they fluctuated in terms of concentration between 20 KBE m-3 and 200 KBE m-3 in ranges which were measured in areas with little or no anthropogenic influences. The maximum long-term surface load which occurs under these assumptions is 2.3.10(5) KBE M-2. This relatively small additional load (approx. 10(-3%) would hardly be noticeable in a number of colonies of approximately 10(10) KBE m-2 normally occurring in soil and grass samples.
The present paper reports on laboratory tests for the determination of the reduction rate of micro-organisms. The investigations were carried out with a pure culture of E. coli, a germ type from the enterobacterial group. By a suitable variation of the thermodynamic parameters it was possible to simulate the conditions through which the cooling tower plume passes inside the chimney of the cooling tower and when it mixes with ambient air. The results allow the following changes in the germ counts in the plume of a wet cooling tower to be expected: 1. As long as the cooling tower plume contains droplets, the capacity of the carried germs to form colonies does not change materially. 2. In the case of unsaturated plumes we must distinguish between two situations: a) The tests in which the germ suspension was sprayed into unsaturated air without any admixture of secondary air, did not demonstrate any dependence of the reduction rate on the relative humidity. b) In contrast to this, the tests in which the germ-carrying droplets were evaporated by admixing a stream of unsaturated secondary air, showed that the capacity to form colonies clearly decreased with diminishing relative air humidity. Case b) is of importance for the dissemination and immission of germs from cooling towers, because here, too, the visible plume initially laden with drops is dried by the admixture of unsaturated ambient air.
The second in the series "Microbial emission, immission and changes in the germ count in the cooling water of wet cooling towers" describes measuring methods and results of the measurements for determining the emission values and the changes in the germ count in the cooling system. The content of colony-forming units (KBE) in the cooling water varied widely, depending on the germ content of the surface water and the preparation of the cooling water (filtration, chemical conditioning). In summer the KBE values were as a rule higher than the values recorded in winter (factor of about 10). The introduction of cooling tower water into the surface water thus did not result in any noticeable changes in germ content, either in summer or in winter. An emission rate of 8.3 10(7) KBE/s (CSA) measured at the top of the cooling tower was the maximum emission value recorded. This resulted in a total germ content in the plume of 1.2 . 10(4) KBE/m3. In order to place this finding into perspective, it should be noted that fluctuations in the KBE values of the air of considerably more than 1000 KBE/m3 can occur because of biological release and meteorological conditions alone (see IVth communication). The KBE-P values recorded (content of particles with units which are capable of forming colonies) in the plume were of the same order as the KBE values. From this it can be concluded that the drops of cooling water which are swept away with the plume are normally only charged with individual colony-forming units. It is worth noting that the KBE values of the plume are only indirectly dependent on the KBE values of the cooling water used in the cooling tower.
More than 24 inactivators were tested for their suitability against 14 disinfectant substances by a quantitative suspension test. Even simple inactivators were found to be efficace: 0.1% cysteine and 0.5% sodium thiosulfate for mercuric chloride and the iodophor; 0.1% sodium sulfite for these two substances and for the QAC in the lower concentration; 1.0% polysorbate 80 for hexylresorcinol, o-phenylphenol and the QAC in the lower concentration; 0.5% sodium thioglycolate for mercuric chloride, the iodophor and chloramine-T. The inactivator active against most disinfectants was the combination LPHT or 0.3% lecithin / 3.0% polysorbate 80 /0.1% histidine / 0.5% sodium thiosulfate. Also active were: LPWT (0.5% lecithin / 1.0% polysorbate 80 /1.0% Lubrol W / 1.0% sodium thiosulfate), LPT (2.0% lecithin / 2.0% polysorbate 80 / 0.5% sodium thiosulfate) and PS (3.0% polysorbate 80 / 3.0% saponin).
Campaings to control the German cockroach, Blattela germanica, were conducted at 14-day intervals over a period of 5.5 months on two merchant vessels of similar size and type. On one ship only the chemical "Gertoks", carbamate insecticide containing 1% propoxur was applied, and on the second ship two preparations simultaneously, a chemical and a biological--"Biotrol 25 W" containing Bacillus thuringiensis. - In order to assess the success of the control, the extent of infestation in the accomodation was determined immediately before and 24 h after the spraying. - The susceptibility of the cockroaches caught on the ships, to the two preparations applied, was also determined. It was found that "Gertoks" was an efficient preparation, the biopreparation "Biotrol 25 W" being less efficient. - A certain increase in resistance of the cockroaches to both preparations, was noted. - The above observations indicate that a considerable drop in numbers of population of cockroaches can be achieved if the ship's crew carry out systematic thorough spraying of ships quarters infested by cockroaches, with Gertoks". They also confirm previous suggestions that complex method in B. germanica control on board ships is possible, using chemical and biological preparations containing Bac. thuringiensis spores simultaneously.
The sub-acute inhalation toxicity of furfural was studied in Syrian golden hamsters. Four groups of ten males and ten females each were repeatedly exposed to furfural vapour at concentrations of 0, 20, 115 and 552 ppm (0, 77, 448 and 2165 mg/m3 air) respectively for 6 hours/day, 5 days/week during a period of 13 weeks. At the highest exposure level furfural induced irritation of the eyes and nose, slight growth retardation and atrophy along with hyperplasia of the olfactory epithelium in the nasal cavity. At 115 ppm atrophy and hyperplasia of the olfactory epithelium were the only adverse effects observed that could be attributed to furfural. No compound-related alterations were detected at the lowest exposure concentration of 20 ppm (77 mg/m3 air) which was, therefore, accepted as a no-toxic effect level.
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