Heavy metal ions affecting the removal of polycyclic aromatic hydrocarbons by fungi with heavy-metal resistance

Abstract

The co-occurrence of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) is very common in contaminated environments. It is of paramount importance and great challenge to exploit a bioremediation to remove PAHs in these environments with combined pollution. We approached this question by probing the influence of HMs coexisting with PAHs on the removal of PAHs by Acremonium sp. P0997 possessing metal resistance. A removal capability for naphthalene, fluorene, phenanthrene, anthracene, and fluoranthenepresentalone (98.6, 99.3, 89.9, 60.4, and 70 %, respectively) and in a mixture (96.9, 71.8, 67.0, 85.0, and 87.9 %, respectively) was achieved in mineral culture inoculated with Acremonium sp. P0997, and this strain also displayed high resistance to the individual HMs (Mn(2+), Fe(2+), Zn(2+), Cu(2+), Al(3+), and Pb(2+)). The removal of individual PAHs existing in a mixture was differently affected by the separately tested HMs. Cu(2+)enhanced the partition process of anthracene to dead or alive mycelia and the contribution of the biosorption by this strain but imposed a little negative influence on the contribution of biodegradation to the total removal of anthracene individually in a culture. However, Mn(2+) had an inhibitory effect on the partition process of anthracene to dead or alive mycelia and decreased the contributions of both biosorption and biodegradation to the total anthracene removal. This work showcased the value of fungi in bioremediation for the environments with combined pollution, and the findings have major implications for the bioremediation of organic pollutants in metal-organic mixed contaminated sites.

Heavy metals species affect fungal-bacterial synergism during the bioremediation of fluoranthene

“…The syringe columns were covered with sterile aluminum foil at the top and sealed with a 0.2-μm closed membrane filter with a cap at the bottom to inhibit air enter into the syringe, respectively, and then placed in a vertical position during experiments. The mineral medium was designed to be no any carbon and nitrogen source to maintain bacterial survival during experiments (Ma et al 2014). All sand was pre-washed with 0.1 M HCl and distilled water three times before and after each experiment to avoid possible binding of the metal or organic products.…”

“…P0997 (CCTCC M 2013569) was chosen as model organism with hydrophilic mycelial surfaces demonstrating PAH degradation and resistance to Cu 2+ and Mn 2+ (Ma et al 2014). B. subtilis (CCTCC AB 2014248) was used as the bacterial motile strain, which had also been confirmed to resist Cu 2+ and Mn 2+ and degrade PAHs in our laboratory (Ma et al 2015).…”

“…Stock solutions of individual MnSO 4 and CuSO 4 , and fluoranthene (HPLC grade) and the individual working solutions were prepared as described in our previous report (Ma et al 2014). Stock solutions of the individual HMs at a concentration of 5000 mg/L were prepared by dissolving MnSO 4 and CuSO 4 separately in deionized water.…”

“…To recover fluoranthene from sand in this study for fluoranthene quantification, an ultrasonic extraction method was used, which was confirmed to recover 99-105 % (n = 5, RSD < 5%) of fluoranthene. Fluoranthene analysis was determined by a reverse-phase HPLC on a C 18 column (ZORBAX Eclipse XDB-C18 4.6 mm × 150 mm, 5 μm, Agilent Technologies) using Agilent 1200HPLC (Japan) equipped with a dual pump and a UV-Vis detector (254 nm) as described in our previous report (Ma et al 2014).…”

“…Fluoranthenedegrading strains of the fungus Acremonium sp. P0997 and the bacterium Bacillus subtilis, which both have resistance to both Cu 2+ and Mn 2+ were selected based on the absence of mutual antagonistic effects, as confirmed previously in our laboratory (Ma et al 2014). This work aims to (i) investigate the synergistic effect of a PAH-degrading fungus-bacterium consortium on fluoranthene degradation, (ii) determine the influence of separate HMs on both the synergistic effect of fluoranthene degradation and the fungus-facilitated bacterial movement, and (iii) elucidate the mechanisms through which HMs affect the synergistic biodegradation effect of fluoranthene.…”