TiO₂ nano particles (NPs) are one of the most produced nanoparticles in the world which are increasingly being released in to the soil. Soils are exposed to various level of concentration of TiO₂ NPs, which has raised concern over the adverse influence on soil microbial community, in turn on ecosystem functions. Although, increasing number of studies on ecotoxicological effect of TiO₂ NPs are coming up recently, however, a common conscience has yet to be reached regarding the impact of TiO₂ NPs on soil microbial community and processes. Moreover, very few studies have targeted soil enzymes which are being considered as sensitive indicator of soil health. Therefore, the present study has been carried out to estimate the ecotoxicological effect of various doses of TiO₂ NPs (5, 10, 20, 40, 80, 100 mg kg⁻¹ soil) on different soil enzymes and microbial community structure. Results revealed that soil enzyme activities and microbial biomass had a uniform trend where the value increased up to the dose of 20 mg TiO₂ NPs kg⁻¹ soil and there onwards reduced drastically up to 100 mg TiO₂ NPs kg⁻¹ soil dose. On the contrary, soil respiration and metabolic quotient kept increasing up to 100 mg TiO₂ NPs kg⁻¹ soil dose indicating sub-lethal stress on microbial community. Nevertheless, the structure of microbial community had slightly different trend where the biomass of total phospho lipid fatty acid (PLFA), Gram positive, Gram negative bacteria, fungi, actinomyctetes and anaerobes were found to be increased up to dose of 80 mg TiO₂ NPs kg⁻¹ soil, but, significantly declined at 100 mg TiO₂ NPs kg⁻¹ soil dose. Furthermore, temperature effect on TiO₂ NPs toxicity had exhibited a less negative impact at 40 °C rather than at 25 °C. In addition alteration index (AI3), an integrated indicator of C, N, P cycling of soils as well as a well-documented indicator of soil pollution, has been found to be regulated by soil respiration, clay content, anaerobe and eukaryote for AI3-Acid Phos. and by fungi to bacteria ratio, soil respiration, microbial biomass and Gram positive bacteria for AI3-Alk. Phos. Overall, the study provided valuable information regarding ecotoxicological impact of environmentally relevant concentrations of TiO₂ NPs in clay loam soils as well as improved our perception regarding the impact of NPs on soil functioning.

TiO ₂纳米颗粒（NPs）是世界上生产最多的纳米颗粒之一，并越来越多地释放到土壤中。土壤暴露于不同浓度的TiO ₂ NPs中，这引起了人们对土壤微生物群落进而对生态系统功能的不利影响的担忧。尽管近来有关TiO ₂ NPs的生态毒理学研究的研究越来越多，但是，关于TiO ₂的影响尚未达成共识。NPs在土壤微生物群落和过程中。而且，很少有针对土壤酶的研究被认为是土壤健康的敏感指标。因此，已经进行了本研究以估计各种剂量的TiO ₂ NPs（5、10、20、40、80、100 mg kg ^-1土壤）对不同土壤酶和微生物群落结构的生态毒理作用。结果表明，土壤酶活性和微生物生物量具有一致的趋势，在20 mg TiO ₂ NPs kg ^-1土壤中，其值增加，然后急剧下降，直至100 mg TiO ₂ NPs kg ^-1。土壤剂量。相反，土壤呼吸和代谢商持续增加至100 mg TiO ₂ NPs kg ^-1土壤剂量，表明对微生物群落的亚致死压力。然而，微生物群落的结构略有不同，在总剂量为80 mg TiO ₂ NPs时，总磷脂质脂肪酸（PLFA），革兰氏阳性，革兰氏阴性细菌，真菌，放线菌和厌氧菌的生物量会增加。kg ^-1土壤，但在100 mg TiO ₂ NPs kg ^-1土壤剂量下显着下降。此外，温度对TiO _2的影响NPs的毒性在40°C而不是25°C时显示出较小的负面影响。此外，还发现改变指数（AI3）是土壤C，N，P循环的综合指标以及有据可查的土壤污染指标，并且受AI3的土壤呼吸，粘土含量，厌氧菌和真核生物的调节-酸性磷酸 并根据真菌与细菌的比例，土壤呼吸，微生物生物量和革兰氏阳性细菌来确定AI3-Alk。Phos。总体而言，该研究提供了有关粘土壤土中与环境有关的TiO ₂ NPs浓度的生态毒理学影响的有价值的信息，以及改善了我们对NPs对土壤功能的影响的认识。