Evaluation and enhancement of heavy metals bioremediation in aqueous solutions by Nocardiopsis sp. MORSY1948, and Nocardia sp. MORSY2014

Abstract

An analysis of wastewater samples collected from different industrial regions of Egypt demonstrated dangerously high levels of nickel (0.27–31.50 mg L−1), chromium (1.50–7.41 mg L−1) and zinc (1.91–9.74 mg L−1) in the effluents. Alarmingly, these heavy metals are among the most toxic knownones to humans and wildlife. Sixty-nine Actinomycete isolates derived from contaminated sites were evaluated under single, binary, and ternary systems for their biosorption capacity for Ni2+, Cr6+ and Zn2+ from aqueous solutions. The results of the study identified isolates MORSY1948 and MORSY2014 as the most active biosorbents. Phenotypic and chemotypic characterization along with molecular phylogenetic evidence confirmed that the two strains are members of the Nocardiopsis and Nocardia genera, respectively. The results also proved that for both the strains, heavy metal reduction was more efficient with dead rather than live biomass. The affinity of the dead biomass of MORSY1948 strain for Ni2+, Cr6+ and Zn2+ under the optimized pH conditions of 7, 8 and 7, respectively at 40 °C temperature with 0.3% biosorbent dosage was found to be as follows: Ni2+ (87.90%) > Zn2+ (84.15%) > Cr6+ (63.75%). However, the dead biomass of MORSY2014 strain under conditions of pH 8 and 50 °C temperature with 0.3% biosorbent dose exhibited the highest affinity which was as follows: Cr6+ (95.22%) > Ni2+ (93.53%) > Zn2+ (90.37%). All heavy metals under study were found to be removed from aqueous solutions in entirety when the sorbent dosage was increased to 0.4%.

Molecular Identification and Nickel Biosorption with the Dead Biomass of Some Metal Tolerant Fungi

“…On the other side, A. terreus AHM21696 at 50 ppm Ni 2+ was totally removed after treatment for 24 h and at 100 ppm Ni 2+ was reduced by 99.65 and 100 after 2 and 4 h of treatments, respectively but 100 % Ni 2+ removal was observed at Ni 2+ concentrations of 150 ppm and 200 ppm (Table 4). Greater premier concentration affords improved leading impose to overcome all mass transmit tolerance of metal ions between the aqueous and solid phase, resulting in greater probability of collision between metal ions and sorbents [1,2]. In agreement with our results Shantha and Poonkothai suggested that the effectiveness of Ni 2+ uptake by Rhizopus species was evaluated after 7 days of fungal species inoculation in graded concentrations (25%, 50%, 75% and 100%) of the Ni 2+ electroplating effluent [19].…”

“…These heavy metals at elevated concentrations in the environment specifically in different water resources is of main concern in respect of their extremely toxicity to biological systems, bioaccumulation in them, non-environmental decomposable and menace to human, animal and plant life [1,2].…”

Biosorption and Bioaccumulation Abilities of Actinomycetes/Streptomycetes Isolated from Metal Contaminated Sites

“…However, some metals are toxic even at minimal concentrations and can cause chromosomal mutations (beryllium), reduction in growth rate (antimony), cell lysis (silver) or deactivation of enzymes (arsenic), for example. Other examples of metals that are considered to be toxic to humans, as well as to the environment, are nickel, chromium, copper, zinc, mercury, lead, and cadmium [1,2]. Natural processes which introduce heavy metals into the environment are volcanic eruptions, erosions, comets, weathering of minerals, ocean evaporation, and combustion.…”

“…In another study conducted by El-Gendy et al [2], 69 actinomycetes isolated from polluted sites in Egypt were evaluated for metal-removing potential in single, binary and ternary metal systems. In a single metal system, all the isolates tested showed appreciable Cr(VI) removal, ranging from 9.1% to 59.4%.…”

“…El-Gendy and El-Bondkly [2], on the other hand, performed a heavy metal (Ni(II), Cr(VI), Zn(II)) remediation experiment using Nocardiopsis sp. MORSY1948 and Nocardia sp.…”