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To evaluate the effects of ciprofloxacin(CIP) residues on the microbiological characteristics of soil,the microbial biomass carbon(MBC) and carbon-source metabolic functions of the soil microbial communities exposed to CIP were studied by the method of chloroform fumigation extraction and Biolog technology.The results showed that the content of MBC of groups treated with CIP(wCIP≥0.1μg/g) were significantly distinguished from that of CK,and they were decreased with the increasing concentration of CIP in soil,the content of MBC in soil exposed to 100μg/g CIP decreased 58.69%.Moreover,the carbon-source metabolic functions of the soil microbial communities exposed to CIP significantly decreased,too.Under the application of CIP,the microbial utilization rate of carbon sources,including carbohydrates,carboxylic acids,amino acids,polymers,phenols,and amines decreased.However,the carbon-source metabolic capacity and diversity of the soil microbial communities exposed to 0.1μg/g,1μg/g,10μg/g and 100μg/g CIP were significantly influenced,in different patterns.I.e.,the carbon-source metabolic functions of the soil microbial communities exposed to 0.1μg/g,1μg/g and 10μg/g CIP for 7 and 21-day were significantly lowered but no significant difference found after 35-day exposure to 0.1μg/g,1μg/g and 10μg/g CIP,while that exposed to 100μg/g CIP for 7,21,and 35-day were all significantly lowered.It was concluded that a certain accumulation of CIP in soil,for instance,100μg/g CIP performed irreversible and long-term effects on the metabolic functions of the soil microbial communities.