Screening of pyrene degradation bacteria strain from the Kochia scoparia roots and its potential for promoting growth

Abstract

The endophytic bacteria were isolated from the roots of polycyclic aromatic hydrocarbon (PAHs)-tolerant plant. We investigated their ability of PAHs degradation and plant growth promo-ting, with the aim to provide theoretical support for bacterial-plant cooperative soil remediation. Kochia scoparia living in coking plant area were selected for strains isolation. Eight endophytic bacteria strains, which used pyrene and 1-aminocyclopropane-1-carboxylic acid (ACC) as sole carbon and nitrogen source, were isolated from the roots of K. scoparia. Three endophytic bacteria, KSE4, KSE7 and KSE8, displayed high degradation efficiency in pyrene degradation experiment. They were identified as Bacillus sp., Pseudomonas sp., and Sphingobacterium sp., respectively. The abili-ties of those three strains to produce ACC deaminase and their effects on seed germination of K. scoparia were examined under pyrene stress through liquid culture tests. The results showed that the activity of ACC deaminase decreased with increasing pyrene concentration (0-15 mg·L-1). KSE7 had the strongest promotion effect. When pyrene concentration reached to 15 mg·L-1, the germination rate and bud length of K. scoparia increased by 44.8% and 61.1%, respectively. Our results indicated that KSE7 is a promising bacterial strain for soil remediation in coking plant area.