Combined Bioremediation of Bensulfuron-Methyl Contaminated Soils With Arbuscular Mycorrhizal Fungus and Hansschlegelia zhihuaiae S113

Over the past decades, because of large-scale bensulfuron-methyl (BSM) application, environmental residues of BSM have massively increased, causing severe toxicity in rotation-sensitive crops. The removal of BSM from the environment has become essential. In this study, the combined bioremediation of the arbuscular mycorrhizal fungi (AMF) Rhizophagus intraradices and BSM-degrading strain Hansschlegelia zhihuaiae S113 of BSM-polluted soil was investigated. BSM degradation by S113 in the maize rhizosphere could better promote AMF infection in the roots of maize, achieving an infection rate of 86.70% on the 36th day in the AMF + S113 + BSM group. Similarly, AMF enhanced the colonization and survival of S113 in maize rhizosphere, contributing 4.65 x 10(5) cells/g soil on the 15th day and 3.78 x 10(4) cells/g soil on the 20th day to a population of colonized-S113 (based possibly on the strong root system established by promoting plant-growth AMF). Both S113 and AMF coexisted in rhizosphere soil. The BSM-degrading strain S113 could completely remove BSM at 3 mg/kg from the maize rhizosphere soil within 12 days. AMF also promoted the growth of maize seedlings. When planted in BSM-contaminated soil, maize roots had a fresh weight of 2.59 +/- 0.26 g in group S113 + AMF, 2.54 +/- 0.20 g in group S113 + AMF + BSM, 2.02 +/- 0.16 g in group S113 + BSM, and 2.61 +/- 0.25 g in the AMF group, all of which exceeded weights of the control group on the 36th day except for the S113 + BSM group. Additionally, high-throughput sequencing results indicated that simultaneous inoculation with AMF and strain S113 of BSM-polluted maize root-soil almost left the indigenous bacterial community diversity and richness in maize rhizosphere soil unaltered. This represents a major advantage of bioremediation approaches resulting from the existing vital interactions among local microorganisms and plants in the soil. These findings may provide theoretical guidance for utilizing novel joint-bioremediation technologies, and constitute an important contribution to environmental pollution bioremediation while simultaneously ensuring crop safety and yield.

Automated summary

This study investigated the combined bioremediation of arbuscular mycorrhizal fungi (AMF) and BSM-degrading strain to remove BSM from contaminated soil. The results showed that the BSM-degrading strain effectively removed BSM from the maize rhizosphere soil and promoted AMF infection and crop growth. The high-throughput sequencing results indicated that the indigenous bacterial community in the soil remained unaltered after simultaneous inoculation with AMF and the BSM-degrading strain.