The Effects of Funneliformis mosseae and Serendipita indica on the Accumulation of Tetracycline and Chlortetracycline in Lettuce (Lactuca sativa) and Recovering Soil Microbial Activities

摘要

Antibiotic accumulation in plants and soils is an increasing problem in agriculture and is receiving more attention. However, the effects of beneficial symbiotic fungi on the accumulation of antibiotics in plant organs and recovering soil microbial activities have not been adequately investigated. For these purposes, a pot experiment was conducted as a completely randomized design with a factorial arrangement and three replicates. The first factor was the fungus type (non-inoculated control, Funneliformis mosseae, and Serendipita indica) and the second factor was the types of antibiotics (without antibiotics, 50 and 100 mg kg~(-1) of tetracycline or chlortetracycline). We measured the accumulation of antibiotics in shoots of lettuce (Lactuca sativa) and microbial activities (activities of urease, dehydro-genase, catalase, total enzyme activity (TEA) index, and microbial biomass carbon (MBC)) in soil. Both levels of tetracycline and chlortetracycline diminished the shoot dry biomass of lettuce and root colonization with F. mosseae and S. indica. Inoculation of lettuce with both symbiotic fungi improved plant growth in soils amended with antibiotics compared to non-inoculated treatment. F. mosseae and S. indica increased the accumulation of antibiotics in the shoots. For example, the F. mosseae and S. indica increased the accumulation of tetracycline at the amended level of 100 mg kg~(-1) by 44.6% and 55.9% compared to the non-inoculated control treatment, respectively. Both fungi recovered urease activity and TEA index and did not affect oxidoreductase activity and MBC in soil. Enzyme activities positively correlated with shoot dry biomass, and negatively correlated with antibiotic accumulation in the shoots. We concluded that symbiotic fungi probably control lettuce growth and antibiotic accumulation in shoots by altering rhizosphere enzyme activities.