Resistance to and Accumulation of Heavy Metals by Actinobacteria Isolated from Abandoned Mining Areas

Abstract

Accumulation of high concentrations of heavy metals in environments can cause many human health risks and serious ecological problems. Nowadays, bioremediation using microorganisms is receiving much attention due to their good performance. The aim of this work is to investigate heavy metals resistance and bioaccumulation potential of actinobacteria strains isolated from some abandoned mining areas. Analysis of mining residues revealed that high concentration of zinc “Zn” was recorded in Sidi Bouatman, Arbar, and Bir Nhass mining residues. The highest concentration of lead “Pb” was found in Sidi Bouatman. Copper “Cu,” cadmium “Cd,” and chromium “Cr” were found with moderate and low concentrations. The resistance of 59 isolated actinobacteria to the five heavy metals was also determined. Using molecular identification 16S rRNA, these 27 isolates were found to belong to Streptomyces and Amycolatopsis genera. The results showed different levels of heavy metal resistance; the minimum inhibitory concentration (MIC) recorded was 0.55 for Pb, 0.15 for Cr, and 0.10 mg·mL−1 for both Zn and Cu. Chemical precipitation assay of heavy metals using hydrogen sulfide technic (H2S) revealed that only 27 isolates have a strong ability to accumulate Pb (up to 600 mg of Pb per g of biomass for Streptomyces sp. BN3).

An Alternative Approach on Bioremediation of Heavy Metals in Tannery Effluents Waste Using Streptomyces Sp.

“…Similar studies were reported on the ability of Streptomyces sp. to degrade heavy metals as reported by El Baz et al [26]. The present study revealed that marine Streptomyces sp.…”

Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance

“…As much as 73.58% of the isolated bacteria strains were able to grow in the presence of 0.1 mM of mercury and when grown in the presence of 0.01, 0.02, 0.04 and 0.07 mM of MeHg, the percentage resistance were 71.5%, 59.6%, 48.08% and 30.77% respectively. El Baz et al [111], isolated 59 HM-resistant bacteria from various abandoned mining sites in Morocco that belong to Amycolaptosis and Streptomyces genera. Their results showed different levels of HM resistance, the MIC recorded in mM was 1.66 for Pb, 0.51 for Cr and 0.53 for both Zn and Cu.…”

“…Bioremediation of metals using growing bacteria cells allow both biosorption and bioaccumulation to occur simultaneously. Several authors have reported metal bioaccumulation by bacterial cells as a promising approach for clean-up of metal polluted sites [111]. Wei et al [33], reported intracellular accumulation of four HM by bacteria strain CCNWRS33-2 isolated from root nodule of Lespedeza cuneate in gold mine tailings in China.…”

Cloning and Expression of the Chitinase Encoded by ChiKJ406136 from Streptomyces Sampsonii (Millard & Burr) Waksman KJ40 and Its Antifungal Effect

“…In the purified components, soil isolates of S. sampsonii can produce heptaene polyene antibiotics [18,27], In addition, S. sampsonii has been shown to produce hydrolytic enzymes, such as amylase, chitinase, protease, and lipase [19]. Studies at the molecular level have focused on strain identification and the phylogenesis of related species [28][29][30][31][32][33][34][35]. The complete genome sequence of Streptomyces sampsonii KJ40 was recently described by our lab [36], resulting in the discovery of a large number of gene encoding chitinases and enzymes involved in secondary metabolite production.…”