Survival Effects Of Arsenic-reducing Bacteria In Arsenic Contaminated Soil Under The Condition Of Root Exudates

Arsenic is a common metal in nature,and its compounds are all highly toxic,which is very harmful to human production and life.In recent years,human activities have become increasingly active,resulting in arsenic pollution of different extents and degrees in global soils.Arsenic compounds in the soil have poisonous effects on plants and microorganisms,and they will enter the human body through the food chain through the enrichment of crops,and have the effect o f causing teratogenic and carcinogenicity to humans.Therefore,the removal of arsenic in soil has become an urgent issue and a major problem that the scientific research community urgently needs to solve.The current bioremediation of arsenic pollution re mediation method is the most effective and the most environmentally friendly method.In particular,the combination of plants and microorganisms is more efficient than single phytoremediation and microbial remediation,and its environment-friendly characteristics are being studied by researchers.We welcome.Plants can enrich arsenic into plants through enrichment,and humans can harvest plants,achieve arsenic recovery,and reduce arsenic content in soil.Arsenic-reducing bacteria can reduce pentavalent arsenic to trivalent arsenic,enhancing the enrichment effect of plants.In this repair method,the ability of arsenic-reducing bacteria to survive and reduce will affect the effect of arsenic contaminated soil by plants and microorganisms.The arsenic valence transformation also has an impact on soil enzyme activity.However,so far there have been few reports in this field at home and abroad.Therefore,this article innovatively proposed the effect of root exudates on the survival of arsenic-reducing bacteria in arsenic-contaminated soil.Obtain the following results:(1)The addition of rape,pakchoi,and wheat root exudates in arsenic-contaminated soil can affect the viability of arsenate-reducing bacteria SY6and TS28.Different root exudates have differe nt effects on the viability of arsenate-reducing bacteria SY6 and TS28.Root exudates of rape and Pakchoi can promote the survival of SY6 to a certain extent,and wheat root exudates have no obvious effect on the survival of SY6.Three concentrations of three root exudates all promote TS28.The addition of rape and Pakchoi root exudates in arsenic-contaminated soil can promote the survival of arsenate-reducing bacteria SY6.The tt_d value increased from the original 5.74 to 5.86(rape)and 8.26(pakchoi)but the addition of wheat root exudates did not significantly promote Survival of SY6 has little change in the tt_d value.The addition of three root exudates all promoted the survival of TS28,with tt_d values ranging from 4.55 to 5.88(rape),6.16(pakchoi),and6.14(wheat).This is because the addition of three kinds of root exudates in the soil can provide nutrients for the reducing bacteria,which in turn can promote their survival.Different root exudates contain different substances and have different effects on the survival of the reducing bacteria.(2)Adding low and medium concentrations of rapeseed,pakchoi,and wheat root exudates in the leachate of arsenic-contaminated soil can promote the survival of SY6and TS28.For SY6,the tt_d value increased from 35.2 to 44.5(rape),39.6(pakchoi),35.8(wheat);for TS28,the tt_d value increased from the original 24.65 to 44(rape),51.86(pakchoi),and 50.7(wheat).However,the high concentration of three root exudates inhibited the survival of two arsenate reducing bacteria.For SY6,the tt_d value decreased from 35.2 to 10.29(rape),12.0(pakchoi),and 13.56(wheat);For TS28,the tt_d value decreased from the original 24.65 to 11.34(rape),16.7(pakchoi),and 13.3(wheat).This shows that the addition of low and medium concentrations of three root exudates can prolong the survival time of arsenic-reducing bacteria in arsenic-contaminated soil extracts.High concentration of root exudates can shorten the survival of arsenate-reducing bacteria in arsenic-contaminated soil extracts time.(3)The reducing characteristics of arsenic-reducing bacteria are affected by their ability to survive,basically showing the stronger ability to survive and the stronger reduction characteristics.The addition of root exudates to some extent increased the reducing characteristics of the reducing bacteria.Moreover,the reducing power of SY6 and TS28 is different,and their reducing power is also affected by the effects of root exudates.The main components of various root exudates have different effects on the reducing characteristics of the two reducing bacteria,which are reflected in:C itric acid and oxalic acid inhibit the reducing characteristics of the reducing bacteria,while the addition of malic acid enhances the reducing properties.The addition of sugars and amino acids also enhances the reducing properties.However,because the soil is a complex system,changes in the arsenic valence in the soil are various and it cannot be asserted that the reduction of pentavalent arsenic is only related to reducing bacteria.(4)Arsenic pollution inhibited the activity of urease,catalase,acid phosphatase,dehydrogenase and sucrase in soil.Adding root exudates can slow down the inhibitory effect of arsenic contamination on soil enzyme activity.This may be because root exudates can increase the activity of microorganisms in the soil.The higher the microbial activity in the soil,the higher the enzyme activity.The sensitivity of different soil enzymes to trivalent arsenic and pentavalent arsenic is different.Urease is more sensitive to trivalent arsenic than pentavalent arsenic.Catalase is less sensitive to trivalent arsenic and pe ntavalent arsenic.Phosphatase the sensitivity to pentavalent arsenic is greater than trivalent arse nic.Dehydrogenase is more sensitive to trivalent arsenic than pentavalent arsenic.Sucrose is more sensitive to trivalent arsenic than pentavalent arsenic.