Mycoremediation: a treatment for heavy metal-polluted soil using indigenous metallotolerant fungi.

Bioleaching of heavy metals from industrial contaminated soil using metallotolerant fungi is the most efficient, cost-effective, and eco-friendly technique. In the current study, the contaminated soil samples from Hattar Industrial Estate revealed a total lead (Pb) and mercury (Hg) concentration of 170.90 mg L-1 and 26.66 mg L-1, respectively. Indigenous metallotolerant fungal strains including Aspergillus niger M1, Aspergillus fumigatus M3, Aspergillus terreus M6, and Aspergillus flavus M7 were isolated and identified by pheno- and genotyping. A. fumigatus and A. flavus of soil sample S1 showed higher efficiency for Pb removal (99.20% and 99.30%, respectively), in SDB medium. Likewise, A. niger and A. terreus of soil sample S2 showed higher efficiency for Hg removal (96% and 95.50%, respectively), in YPG medium. Furthermore, the maximum uptake efficiency for Pb removal (8.52 mg g-1) from soil sample S1 was noticed for A. fumigatus in YPG medium, while the highest uptake efficiency (4.23 mg g-1) of A. flavus M2 strain was observed with CYE medium. Similarly, the maximum uptake efficiency of 0.41 mg g-1 and 0.44 mg g-1 for Hg removal from soil sample S2 was found for A. niger and A. terreus strains, respectively, in CYE medium. Thus, in order to address the major issue of industrial waste pollution, indigenous fungal strains A. fumigatus (M1) and A. terreus (M7), isolated in this study, could be used (ex situ or in situ) to remediate soils contaminated with Pb and Hg.

Cloning and characterization of pyruvate carboxylase gene responsible for calcium malate overproduction in Penicillium viticola 152 and its expression analysis.

In this study, a pyruvate carboxylase gene (PYC) from a marine fungus Penicillium viticola 152 isolated from marine algae was cloned and characterized by using Genome Walking method. An open reading frame (ORF) of The PYC gene (accession number: KM593097) had 3582bp encoding 1193 amino acid protein (isoelectric point: 5.01) with a calculated molecular weight of 131.2757kDa. A putative promoter (intronless) of the gene was located at -666bp and contained a TATA box, several CAAT boxes, the 5'-SYGGRG-3' and a 5'-HGATAR-3' sequences. A consensus polyadenylation site (AATAAA) was also observed at +10bp downstream of the ORF. The protein deduced from the PYC gene had no signal peptide, was a homotetramer (4), and had the four functional domains. Furthermore, PYC protein also had three potential N-linked glycosylation sites, among them, -N-S-T-I- at 36 amino acid, -N-G-T-V- at 237 amino acid, and -N-G-S-S- at 517 amino acid were the most possible N-glycosylation sites. After expression of the PYC gene of P. viticola 152 in medium supplemented with CSL and biotin, it was found that the specific pyruvate carboxylase activity in MA production medium supplemented with CSL was much higher (0.5U/mg) than in MA medium supplemented with biotin (0.3U/mg), suggesting that optimal concentration of CSL is required for increased expression of the PYC gene, which is responsible for high level production of malic acid in P. viticola 152 strain.