A method for enumerating chloraniline-degrading microorganisms in soil processing from the substrate half-degradation period
1995
Vasil'eva, G.K. | Surovtseva, Eh.G. | Semenyuk, N.N. | Glagolev, M.V. | Panikov, N.S.
Decomposition dynamics of chloranilines (CA) in liquid media and soil suspensions inoculated with pure cultures able to degrade these compounds was studied. A strong dependence was established (with correlation 0.69 - 0.99) between the CA half-decomposition time, t0.5, and the logarithm of the initial concentration of CA-degrading microorganisms, x0. This dependence was approximated by a linear equation logx0=c-dt0.5, where c and d are empirical coefficients. As shown by kinetic analysis, this relationship holds if microorganism growth on the introduced substrate proceeds exponentally with a constant specific growth rate, Mm, and a constant biomass yield, Y, and without a lag phase. In this case, the coefficients c and d of the regression equation are equal to log(Ys0/2) and Mmloge, respectively, where s0 is the initial CA concentration in the solution. On this basis, a method for determining the total amount of CA-degrading microorganisms in soil was proposed. It consists of measuring the CA half-degradation time in the soil suspension and calculating the value of x0 with the use of coefficient c and d obtained for freshly grown bacterial strains. The proposed method is very sensitive, accurate, and yields reproducible results. It is easy to implement, and the analysis time does not normally exceed 4 to 6 days. The lower threshold for detection of CA-degrading microorganisms in soil is 10** (-11) mg/g soil, which corresponds to a population density of less than one cell per gram of soil
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