Abstract: Low-temperature microorganisms have broad application prospects in the long-term, efficient and stable restoration of contaminated media in high latitude and high altitude areas of China. However, the mining of strain resources in specific scenarios is still in its infancy. In this paper, enrofloxacin, one of the common quinolone antibiotics in contaminated soil, was chosen as an aimed contaminants. Four enrofloxacin degrading bacteria of Z (Providencia sp.), H5 (Enterobacter sp.), H35 (Providencia sp.) and Y (Alcaligenes sp.), which were efficient to degrade enrofloxacin at low-temperature, were screened in the soil collected from the livestock and poultry manure stored locality in low-temperature areas. Among them Y was a halophile. Their degradation efficiency was evaluated. The results show that the four strains could grow in a neutral to low alkali environment (livestock and poultry manure stored locality) and a temperature range of 4-15 ℃. The growth of the four strains and their degradation for enrofloxacin were inhibited significantly under low temperature conditions. The natural degradation rates of enrofloxacin were 10.9%, 22.8% and 40.6%, respectively, at 4, 8 and 15 ℃. At 4 ℃, the degradation rate of enrofloxacin by Z, H5, H35 and Y with the dosage of 5% reached the peak on the 14th day, which were 33.4%, 42.1%, 38.1% and 34.3% respectively. However, except H35 ( peaked 56.5% on the 14th day), the degradation rate of enrofloxacin by Z, H5 and Y peaked on the 12th day with the same dosage at 8 ℃, which were 49.6%, 47.9% and 48.1%, respectively. In summary, all of the four strains could be used for the remediation of enrofloxacin contaminated media in low-temperature areas, which provided technical support for the remediation of antibiotic-contaminated soil in high latitude and high altitude regions of China.

Key words: livestock and poultry manure, enrofloxacin, low-temperature degrading bacteria, bioremediation, soil, degradation