Enhancement of dicarboximide fungicide degradation by two bacterial cocultures of Providencia stuartii JD and Brevundimonas naejangsanensis J3

Abstract

Bioremediation is commonly conducted by microbial consortia rather than individual species in natural environments. Biodegradation of dicarboximide fungicides in brunisolic soil were significantly enhanced by two bacterial cocultures of Providencia stuartii JD and Brevundimonas naejangsanensis J3. The cocultures degraded 98.42 %, 95.44 %, and 96.81 % of 50 mg/L dimethachlon, iprodione, and procymidone in liquid culture within 6 d respectively, whose efficiency was 1.23 and 1.26, 1.25 and 1.23, and 1.24 and 1.24 times of strains JD and J3, respectively. The cocultures could effectively degrade dimethachlon, iprodione and procymidone to simple products. Moreover, the cocultures immobilized in a charcoal-alginate-chitosan carrier obviously surpassed free cocultures in terms of degradability, stability and reusability. In the field brunisolic soils treated by immobilized cocultures, 96.74 % of 20.25 kg a.i./ha dimethachlon, 95.02 % of 7.50 kg a.i./ha iprodione and 96.27 % of 7.50 kg a.i./ha procymidone were degraded after 7 d, respectively. Moreover, the lower half-lifes (1.53, 1.59 and 1.57 d) by immobilized cocultures were observed, as compared to free cocultures (3.60, 4.03 and 3.92 d) and natural dissipation (21.33, 20.51 and 20.09 d). This study highlights that strains JD and J3 have significant synergetic degradation advantages in rapid bioremediation of dicarboximide fungicide contamination sites.

Keywords: Biodegradation; Cocultures; Dicarboximide fungicides; Immobilization; Microbial consortium.