کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6306817 | 1618821 | 2016 | 7 صفحه PDF | دانلود رایگان |
- The tolerance of fungus to Pb was enhanced significantly after acclimatization.
- The acclimated strain could accumulate Pb as high as 165.0 mg gâ1.
- Pb could induce the mycelia to produce malonaldehyde and H2O2.
- Catalase and glutathione might play an important role in elimination of the toxicity.
Wastewater contaminated with heavy metals is a world-wide concern. One biological treatment strategy includes filamentous fungi capable of extracellular adsorption and intracellular bioaccumulation. Here we report that an acclimated strain of filamentous fungus Pleurotus ostreatus HAU-2 can withstand Pb up to 1500 mg Lâ1 Pb, conditions in which the wildtype strain cannot grow. The acclimated strain grew in liquid culture under 500 mg Lâ1 Pb without significant abnormity in biomass and morphology, and was able to remove significant amounts of heavy metals with rate of 99.1% at 200 mg Lâ1 and 63.3% at 1500 mg Lâ1. Intracellular bioaccumulation as well as extracellular adsorption both contributed the Pb reduction. Pb induced levels of H2O2, and its concentration reached 72.9-100.9 μmol gâ1 under 200-1000 mg Lâ1 Pb. A relatively higher malonaldehyde (MDA) concentration (8.06-7.59 nmol gâ1) was also observed at 500-1500 mg Lâ1 Pb, indicating that Pb exposure resulted in oxidative damage. The fungal cells also defended against the attack of reactive oxygen species by producing antioxidants. Of the three antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), CAT was the most responsive and the maximal enzyme activity was 15.8 U mgâ1 protein. Additionally, glutathione (GSH) might also play a role (3.16-3.21 mg gâ1 protein) in detoxification under relatively low Pb concentration (100-200 mg Lâ1). Our findings suggested that filamentous fungus could be selected for increased tolerance to heavy metals and that CAT and GSH might be important components of this tolerance.
Journal: Chemosphere - Volume 150, May 2016, Pages 33-39