Effect of tetracycline residue on rhizosphere microbes and nutrients of soybean sprouts

Abstract:

[Objective] To explore the effect of soil tetracycline on the growth and development, rhizosphere microbes, and nutrients of soybean sprouts, and to lay a theoretical basis for evaluating the influence of antibiotic residue on vegetable cultivation and preventing and controlling antibiotic contamination in soil-vegetable system. [Methods] We simulated different levels of tetracycline (0, 25, 50 mg/kg) in soil and determined the tetracycline in soybean sprouts by high performance liquid chromatography (HPLC). The nutrients in soybean sprouts were measured with physicochemical methods and rhizosphere microbes were elucidated by high-throughput sequencing.[Results] Tetracycline accumulation in soybean sprouts rose with the increase in the level of tetracycline in soil, and the distribution followed the order of root>hypocotyl>cotyledon. Tetracycline residue in soil significantly inhibited the development and biomass of root and hypocotyl, vitamin C synthesis, and antioxidant activity of soybean sprouts, particularly the vitamin C synthesis. To be specific, on the fifth day of growth, vitamin C content in soybean sprouts cultivated in soil with 25 mg/kg and 50 mg/kg tetracycline was 41.35% and 49.80% lower than that of the control, respectively. Moreover, tetracycline residue significantly affected the microbial community structure in rhizosphere of soybean sprouts, especially the nitrogen cycling-related genera. Specifically, the relative abundance of Acinetobacter and Thermus significantly increased and that of Pseudoxanthomonas and Hydrogenophaga reduced. [Conclusion] Tetracycline residue in soil suppressed the growth of soybean sprouts, rhizosphere microbial community structure, and important nutrients such as vitamin C.

Key words:tetracycline residue;soybean sprouts;rhizosphere microbes;nutritional quality