Bioremediation Of Atrazine Contaminated Soil Using Bioaugmentation Technology And Dynamics Analysis Of Bacterial Community

In this article, we studied the bioremediation of atrazine contaminated soil usingbioaugmentation technology and the soil microbial population dynamics in laboratoryconditions. We used different research methods, including the traditional research methods, themethod of physiological and biochemical techniques and modern molecular methods. Theresults could be summarized as follows:1. The residues dynamic of atrazine in the soil was researched. Results found that addingdegrader HB-5accelerates the removal of atrazine in the soil, the degradation half-life ofatrazine in natural soil was20.8d, thus the group plusing bacteria was6.3d. It was3.3timesfaster than the natural degradation.2. Using a simple, intuitive method, which plate colony count, to study the effects ofatrazine and its degrader HB-5on soil microbial populations. The experiment results show that:the population of soil bacteria and fungi were decreased with the incubation time. The growthof bacteria and fungi in the soil were inhibited by atrazine, the degrading bacteria significantlyincreased the number of bacteria in the soil, but the effect on soil fungi not obviously.3. Using the chloroform fumigation method study on atrazine and its degrader HB-5onthe soil microbial biomass carbon. The results showed: adding degrader HB-5significantlyincreased soil microbial biomass carbon, it indicated HB-5of survival and growth in the soil.There was not significant on soil microbial biomass carbon of atrazine, indicated that theconcentration of10mg·kg-1of atrazine not effect on soil microbial apparently.4. Adopting the Biolog ECO plates analysis of atrazine and its degrader HB-5on soilmicrobial functional diversity. With extended incubation time, AWCD values for eachtreatment group showing a decreasing trend, so the overall ability of use carbon sources in theBiolog ECO plates was on the decline of the soil microbial, and thus the microbial diversity insoil were reducing. This was consistent with the result of the plate count and the microbialbiomass carbon. There was higher relative utilization in carbohydrates, amino acids, carboxylicacids of soil microbial, contrast with the lower relative utilization in amines and phenols. Inthis study, the degradation bacteria HB-5significant increase of soil microbial Shannon index,Simpson index, however the impact on McIntosh index was appeared in the major early in the experiment (0-14d), moreover it has been returned to control level at the late experiment.Effects of atrazine on microbial McIntosh index was obvious, McIntosh index has been lowerthan the control group, and showed a significant difference in the experiment. Effects ofatrazine on microbial Shannon index appeared early in the experiment, and returned to controllevels in the later (56,70d), atrazine effects on microbial Simpson index was not obvious.5. Effects of atrazine and its degrader HB-5on soil microbial community structure werestudied by PCR-DGGE technology. The experiment results show that: the dominant bacteria insoil samples mainly belong to Proteobacteria, Bacteroidetes, Actinobacteria, Acidobacteriaand Verrucomicrobia. In the experiment, degradation bacteria stimulated Acidobacteriabacterium, and inhibition of the Proteobacteria bacterium, and no significant of Bacteroidetesand Actinobacteria bacterium, which indicated the influence of atrazine on the dominantbacteria in soil was not obvious. Verrucomicrobia strain was present in each process in thegroup in the early experiments, but disappeared in the late, this showed that the bacterium didnot adapt to the environment very well, and was gradually phased out.