University of Tabriz Water and Soil Science 2008-5133 34 3 2024 09 22 Pollution induced community tolerance (PICT) in soil microorganisms subjected to the oxy-tetracycline Pollution induced community tolerance (PICT) in soil microorganisms subjected to the oxy-tetracycline 199 213 18479 10.22034/ws.2021.38104.2323 FA Masumeh Hasanalizadeh Soil science-Agriculture college-Tabriz university-Tabriz city-Iran Naser Aliasgharzad Academic member Shahin Oustan Academic member Journal Article 2020 01 25 Microorganisms make changes to their lives, when they are exposed to contaminants; these changes include physiological and genetical changes. Antibiotics are used in the livestock industry as well as in medicine. Among several methods for assessing the risks of contamination of soil ecosystems; one of which is the pollution induced community tolerance. This study, the effects of different levels of OTC on microbial activity were investigated in a silty loam soil. Different levels of OTC (10, 20, 30, 40 and 50 mg.kg-1) were applied to the pots containing 2 kg of soil with three replications and kept at room temperature for 120 days. The soil moisture level was adjusted to 50-70% of field capacity. Soil Dehydrogenase activity as an indicator of soil microbial activity was measured at 3, 7, 15, 30, 60, 90 and 120 days of incubation. The ΔIC50 diagram was plotted against different soil OTC concentrations for each time point and the trend of microbial tolerance changes was evaluated. The results showed with increasing incubation time and concentration of OTC, induction of tolerance in the microbial population was gradually enhanced. Overall the increase of tolerance in microbial population started on day 15 and reached the highest values on days 30 and 60 at OTC concentration of 50 mg.kg-1 OTC. A marked change in the slope of ΔIC50 was occurred on day 30 at 30 mg.kg-1 OTC which can be regarded as critical level of OTC in soil at this time point which led to occurrence of microbial tolerance. Microorganisms make changes to their lives, when they are exposed to contaminants; these changes include physiological and genetical changes. Antibiotics are used in the livestock industry as well as in medicine. Among several methods for assessing the risks of contamination of soil ecosystems; one of which is the pollution induced community tolerance. This study, the effects of different levels of OTC on microbial activity were investigated in a silty loam soil. Different levels of OTC (10, 20, 30, 40 and 50 mg.kg-1) were applied to the pots containing 2 kg of soil with three replications and kept at room temperature for 120 days. The soil moisture level was adjusted to 50-70% of field capacity. Soil Dehydrogenase activity as an indicator of soil microbial activity was measured at 3, 7, 15, 30, 60, 90 and 120 days of incubation. The ΔIC50 diagram was plotted against different soil OTC concentrations for each time point and the trend of microbial tolerance changes was evaluated. The results showed with increasing incubation time and concentration of OTC, induction of tolerance in the microbial population was gradually enhanced. Overall the increase of tolerance in microbial population started on day 15 and reached the highest values on days 30 and 60 at OTC concentration of 50 mg.kg-1 OTC. A marked change in the slope of ΔIC50 was occurred on day 30 at 30 mg.kg-1 OTC which can be regarded as critical level of OTC in soil at this time point which led to occurrence of microbial tolerance. https://water-soil.tabrizu.ac.ir/article_18479_1efa80ec4b10af9a73f92083dab82cef.pdf