Zur Lebensfähigkeit und Überlebensfähigkeit allochthoner und autochthoner Bakterien im Boden nach einer Superinfektion: Zur Tenazität allochthoner Warmblütlerbakterien im Boden

Abstract

Summary (1) 1. The behaviour of hygienic suspect allochthonic bacteria has been studied on the example of E. coli and coliform bacteria, respectively, in modeltests in the soil. The purpose of this work was to find out the dependence of the viability and the rate of dying, respectively, from different factors. This is important in relation to a longtime contamination of the soil and the danger of environmental pollution by infiltration into the groundwater. (1) 2. The behaviour of the allochthonic microorganisms has been studied in relation to the autochthonic soil-microorganisms. After superinfection of the soil the numbers in both bacteria groups decrease. The autochthonic bacteria were only diminished to a distinct number in conformity with their natural presence in the soil. This corresponds to the ecophysiological life possibilities of the respective autochthonic species in the soil. In contrast to that the allochthonic microorganisms are completely eliminated out of the soil population after a certain time. (1) 3. The investigations for viability and surviability of the allochthonic microorganisms have been studied on the example of colibacteria. It was demonstrated that these organisms are only viable a distinct time in the soil and that their tenacity is the resultant between a certain promotion in the soil and the sum of negative factors of interaction. (1) 4. The dying rate of E. coli mainly depends on the biological activity of the soil, that means of the concurrence effect of the autochthonic microorganisms. Nearly all the factors which promote this effect decrease the chance of viability of E. coli. This could be clearly observed by the influencing factors temperature and pH. (1) 5. Therefore it is not right to take the tenacity of coliform bacteria etc. as absolute amount and to deduce from that hygienic and technological arrangements for the sewage and liquid manure disposal because the survival time is determined by complex acting factors in relation to the starting number of microorganisms by infecting the soil. (1) 6. The most important factors are: quantity and quality of organic substances, soil temperature, soil type, and as a complex factor the biological activity. (1) 7. In winter the survival time of coliform bacteria and other allochthonic organisms is the resultant of two factors: (1) 1. the “conserving action” of lower temperatures and (1) 2. the killing of a considerable part of microorganisms by freezing and rethawing of soil frost. (1) 8. Altogether the investigations demonstrate that by a higher and longer treatment with sewage and liquid manure, this means with greater quantities of organic materials, there is no principle change of the soil environment. The soil environment is also in such cases not sufficient suitable for the promotion of allochthonic microorganisms, the soil is sufficient biologically buffered and maintains its purification power even by a longer and higher treatment with epidemic hygienic suspect material (sewage, liquid manure etc.).