Enhanced Culture in Static Batch Systems for Benzo[a]pyrene Degradation by Bjerkandera Adusta SM46 under Acidic and Saline Conditions

Abstract

Biodegradation of high-molecular weight polycyclic aromatic hydrocarbons (PAHs) is biologically difficult to degrade due to its recalcitrant characteristics such as low solubility in water and inhibition effect. In the present study, we used an enhanced culture system (ECS) for Bjerkandera adusta SM46 on benzo[a]pyrene (BaP) degradation under acidic (pH 4.5) and saline conditions (pH 8.2). The ECS using Tween 80 (T-80) and MnSO4 enhanced both the ligninolytic enzyme activities and degradation rate by the fungus. The optimum condition was obtained at a concentration for MnSO4 of 0.4-0.9 mM and for T-80 of 0.45-0.70%, which increased degradation more than 87% at day 30 (pH 4.5). The ECS could also be applied under a saline condition for up to 82% degradation. Mangan peroxidase (MnP) and lignin peroxidase (LiP) showed high activities at pH 4.5 (110.9 and 79.9 U/L, respectively). Moreover, laccase and MnP showed higher activities (75.6 and 130.0 U/L, respectively) at saline pH 8.2 indicating stress condition stimulation. * Corresponding AuthorTel.: +81-89-9469864; E-mail: tatibana@agr.ehime-u.ac Using rice straw also enhanced the BaP degradation rate by the fungus via cell growth promotion. This study suggests that an ECS treatment and rice straw co-substrate system could potentially enhance PAH degradation for a static batch system under both an acidic and a salinealkaline stress condition.