Typical Organochlorine Pesticide-degrading Composite Bacterium Construction And Its Remediation Effect On Contaminated Soil

Chlorobenzene structure of organochlorine pesticides is relatively stable and biological enzyme in the body is difficult to degradation.Therefore,organochlorine pesticide molecular would be accumulated in plant and animal body disappearing slowly which through biological enrichment and food chain may further enrichment and diffusion.Organochlorine pesticides can enter our body through the food chain and accumulate in tissues such as liver,kidney and heart.To the person's acute toxicity mainly to stimulate the nerve center,chronic poisoning by loss of appetite,weight loss,sometimes also can cause the cerebellum disorders and hematopoietic organ dysfunction.Futhermore,some organochlorine pesticides have teratogenic,carcinogenic and mutagenic hazards.Nowadays,for organochlorine pesticides removal in soil especially crop planting soil has carried out a lot of research,using microbial approach to remediate organochlorine pesticide contaminated soil have many advantages compared with other methods.The study in screening effective microorganism and its degradation characteristics of degradation of organic pollutants has practical significance.This paper survey the pesticide residue and heavy metal pollution in the soil,aiming at Panax notoginseng planting soil of yunnan province and the jiangxi yingtan peanut planting soil pollution.We have quintozene(PCNB)and acetochlor as the typical organochlorine pesticides research object,selecting a strain of acetochlor degradation bacteria and constructing a composite bacterium.Effect of composite bacterium was studied about remove organochlorine main research results summarized as follows:1.The results show that,P.notoginseng planting soil is mainly affected by heavy metal Cd,Cr,As,Cu,Hg,Pb,Ni,Zn and other elements of different degree of pollution,including the As Cu Cd and Pb pollution is most prominent.Cr,Cu enrichment phenomenon exists with the time increasing of P.notoginseng planting.Main kinds of pesticide residue in soil are PCNB and chlorpyrifos.Heavy metal is Cd of peanut continuous cropping obstacle soil,one of the main pesticide residues is acetochlor.Both of the soil types are ferruginous soil.2.Adopt the method of enrichment culture and in the perennial use of acetochlor peanut trials field,a kind of strain was screened which can make use of acetochlor grow as the sole carbon source.Sequencing results showed that the strain belongs to rhizobium genus,physiological,biochemical and molecular biology identification show that the bacteria is a new one,named for its rhizobium ning ZL-27.The bacteria inoculating in inorganic salt liquid medium which acetochlor as the sole carbon source and the concentration of 200 mg/kg cultivated after 5 days,removal rate of acetochlor was 76.3%.The bacteria inoculating in soil which acetochlor concentration of 2.37 mg/kg cultivated after 40 d,removal rate of acetochlor was 27%.According to the results of the impact factors,the high concentration As has obvious inhibitory effect of the bacteria.Several other heavy metals also have certain inhibition,but the effect is not obvious.ZL-27 is not sensitive to temperature and sensitive to pH changes,the optimum pH of 7.0.3.We have screened a cupriavidus sp.strain called YNS-85 who can degraded PCNB.Experiment proved that the bacteria can with acetochlor degradation bacteria ZL-27 forming a compound bacterium agent.Both kinds of bacteria can coexist and be able to degrade PCNB and acetochlor in soil at same time.Inorganic salt medium for carbon source concentration consists with 20 mg/kg of PCNB and 30mg/kg of acetochlor,the degradation of compound bacterium agent to PCNB was65.77% and to acetochlor was 86.1% within three days.The 40-days potting soil degradation experiment results showed that the removal rate of acetochlor by ZL-27 was 30.91%,the removal rate of PCNB was 62.72%,the removal rate of acetochlor was 10.23% compared with CK.4.There is a situ experiment of repair about PCNB degradation in Wenshan.A short-term field experiment(one year)was conducted to explore the potential role of a pentachloronitrobenzene(PCNB)-degrading bacterial isolate,Cupriavidus sp.YNS-85,in the remediation of a PCNB-contaminated soil in which Panax notoginseng was grown.There were three treatments:(1)control soil without YNS-85 inoculation,(2)soil with 0.15 kg m-2 of solid bacterial inoculum(A),and(3)soil with0.3 kg m-2of solid bacterial inoculum(B).Soil enzyme activities comprising catalase and fluorescein diacetate(FDA)esterase activities were determined by spectrophotometry.In addition,counts of cultivable bacteria,fungi and actinomycetes were conducted by the plating of serial dilutions,and the microbial biodiversity of the soil was investigated by a BIOLOG analysis.The experimental results show that thesoil PCNB concentrations decreased significantly by 50.3 and 74.2 %,respectively,in treatments A and B compared with the uninoculated control.Soil catalase activity decreased in the presence of the bacterial isolate.FDA esterase activity decreased in treatment A but increased in treatment B.There was no significant change in plant biomass,the diversity of the soil microbial community,or physicochemical properties of the soil between the control and isolate-inoculated groups.