The use of nitrification inhibitors has been suggested as a strategy to decrease cadmium(Cd)accumulation in crops.However,the most efficient nitrification inhibitor for mitigating crop Cd accumulation remains to be elucidated,and whether and how changes in soil microbial structure are involved in this process also remains unclear.To address these questions,this study applied three commercial nitrification inhibitors,namely,dicyandiamide(DCD),3,4-dimethylpyrazole phosphate(DMPP),and nitrapyrin(NP),to pakchoi.The results showed that both DCD and DMPP(but not NP)could efficiently decrease Cd concentrations in pakchoi in urea-and ammonium-fertilized soils.In addition,among the three tested nitrification inhibitors,DMPP was the most efficient in decreasing the Cd concentration in pakchoi.The nitrification inhibitors decreased pakchoi Cd concentrations by suppressing acidification-induced Cd availability and reshaping the soil microbial structure;the most effective nitrification inhibitor was DMPP.Ammonia oxidation generates the most protons during nitrification and is inhibited by nitrification inhibitors.Changes in environmental factors and predatory bacterial abundance caused by the nitrification inhibitors changed the soil microbial structure and increased the potential participants in plant Cd accumulation.In summary,our study identified DMPP as the most efficient nitrification inhibitor for mitigating crop Cd contamination and observed that the soil microbial structural changes caused by the nitrification inhibitors contributed to decreasing Cd concentration in pakchoi.

Dental caries is the local destruction of hard tooth tissue caused by acidic byproducts generated by cariogenic bacteria,primarily Streptococcus mutans,which ferment free sugars in the presence of host factors,dietary components,and environmental conditions.A main feature of dental caries is the formation of dental plaque biofilm,which significantly improves the resistance of bacteria to drugs and host immunity.Traditional anti-caries drugs mainly exert anti-biofilm functions indirectly through antibacterial activities.However,they tend to interfere with the symbiotic microbiota while inhibiting cariogenic bacteria,which may cause imbalance within the oral microbial system.With increasing attention paid to the homeostasis of oral microbiota,new types of anti-caries drugs have been developed,such as natural extracts,artificially synthesized small molecules,and oligonucleotides.They act on key targets to inhibit the formation of biofilm substrates or regulate the interactions between oral microorganisms,thereby efficiently inhibiting biofilm formation.These drugs do not have bactericidal effects.Nevertheless,they exert indirect antimicrobial effects by interfering with biofilm substrate formation or microbial interactions.The optimization of delivery carriers,combination drug therapy,and biomimetic design further enhance the efficacy of these new types of anti-caries drugs.This article provides a review of the prevention and treatment principles and key targets of dental plaque biofilm.We also discussed the types,mechanisms of action,and development trends of relevant drugs.