The effects of residual tetracycline on soil enzymatic activities and plant growth

Abstract

A pot trial was carried out to investigate the adverse effects of tetracycline (TC) on soil microbial communities, microbial activities, and the growth of ryegrass (Lolium perenne L). The results showed that the presence of TC significantly disturbed the structure of microbial communities and inhibited soil microbial activities in terms of urease, acid phosphatase and dehydrogenase (p < 0.05). Plant biomass was adversely influenced by TC, especially the roots with a reduction of 40% when compared with the control. Furthermore, TC decreased the assimilation of phosphorus by the plant although the concentration of phosphorus was increased by 20% due to decreased plant biomass. TC seemed to increase the concentration of dissolved organic carbon (by 20%) in soil. The findings implied that the agricultural use of animal manure or fishpond sediment containing considerable amounts of antibiotics may give rise to ecological risks.

Keywords:

• Soil
• tetracycline
• bacteria
• fungi
• Lolium perenne L
• plant growth

Acknowledgments

The authors would like to thank Dr. Jinshu Zheng for helpful suggestions and critical comments on the clean-up procedure and the RPHPLC-DAD analytical method for TC detection. Financial support from the Academic Link of Deutscher Akademischer Austausch Dienst (DAAD) and Research Grants Council of Hong Kong (GER/JRS/05-06/01) is gratefully acknowledged.