Biosorption of nickel, cobalt, zinc and copper ions by Serratia marcescens strain 16 in mono and multimetallic systems

The metallurgical industry is one of the main sources of heavy metal pollution, which represents a severe threat to life. Metals can be removed from aqueous solutions by using microbial biomasses. This paper analyses the heavy metal biosorption capacity of Serratia marcescens strain 16 in single and multimetallic systems. The results obtained show that Co(II), Ni(II) and Zn(II) biosorption in monometallic systems is two to three times higher than in the presence of bi-metallic and multimetallic solutions. Fourier transform infrared spectroscopy confirmed that carbonyl, carboxyl and hydroxyl were the main functional groups, as well as the amide bands I and II involved in metal uptake, which are present in external structures of the bacterial cell. The results obtained demonstrated the viability of S. marcescens strain 16 as a biosorbent for the design of eco-friendly technologies for the treatment of waste liquor.

Physicochemical and molecular characterization of heavy metal–tolerant bacteria isolated from soil of mining sites in Nigeria

Background Mining for precious metals is detrimental to the composition of soil structure and microbial diversity distribution and is a health risk to human communities around the affected communities. This study was aimed at determining the physical and chemical characteristics and diversity of bacteria in the soil of local mining sites for biosorption of heavy metals. Results Results of physical and chemical characteristics showed mean pH values and percentage organic carbon to range from 7.1 to 8.2 and 0.18 to 1.12% respectively with statistical significance between sampling sites (P ≤ 0.05). Similarly, cation exchange capacity, electrical conductivity, moisture, total nitrogen, and carbon/nitrogen ratio (C:N) in the soil ranged between 1.52 to 3.57 cmol/kg, 0.15 to 0.32 ds/m, 0.14 to 0.82%, 0.10 to 0.28%, and 1.7 to 4.8 respectively. The highest heavy metal concentration of 59.01 ppm was recorded in soils obtained from site 3. The enumeration of viable aerobic bacteria recorded the highest mean count of 4.5 × 106 cfu/g observed at site 2 with statistical significance (P ≤ 0.05) between the sampled soils. Alcaligenes faecalis strain UBI, Aeromonas sp. strain UBI, Aeromonas sobria, and Leptothrix ginsengisoli that make up 11.2% of total identified bacteria were able to grow in higher amended concentrations of heavy metals. The evolutionary relationship showed the four heavy metal–tolerant bacteria identified belonged to the phylum Proteobacteria of class Betaproteobacteria in the order Burkholderiales. Heavy metal biosorption by the bacteria showed Alcaligenes faecalis strain UBI having the highest uptake capacity of 73.5% for Cu. Conclusion In conclusion, Alcaligenes faecalis strain UBI (MT107249) and Aeromonas sp. strain UBI (MT126242) identified in this study showed promising capability to withstand heavy metals and are good candidates in genetic modification for bioremediation.

Biosorption of Cadmium by fungi isolated from Bharalu river, Assam

Heavy metal pollution in the aquatic ecosystem poses a serious threat to the human health and aquatic biodiversity around. There is urgent need to remediate heavy metals contaminated wastewater through eco friendly ways. Fungi and other microorganisms have been reported to have promising potential to remove heavy metals from wastewater through biosorption. Thus the present work aimed to isolate tolerant fungal species from different sites of a polluted river Bharalu in Assam. After preliminary screening, out of a total of 15 fungal isolates obtained, 4 isolates Aspergillus niger, Aspergillus flavus, Aspergillus fumigates and Colletotrichum gloeosporioides were selected for further study. Tolerance limit of the isolates for Cadmium (Cd) was carried out at concentrations ranging from 100 ppm to 1000 ppm. Results showed that the maximum tolerance was observed in Colletotrichum gloeosporioides (approx. 8.8 mm), followed by Aspergillus flavus (approx. 5.8 mm) at 400ppm. The biosorption efficiency at 400ppm revealed that the maximum Cd concentration was absorbed by fungal biomass of Colletotrichum gloeosporioides (12.83 mg/g) and the minimum by Aspergillus niger (3.91 mg/g). Molecular identification was carried out followed by PCR amplification of the fungal biomass showing highest absorption. The sequence obtained was submitted in the GenBank using BANkIt with accession number-MN714368 which showed high similarities with Colletotrichum gloeosporioides. This results indicated that fungus are promising and potential sources for metal biosorption and detoxification.

Removal of Heavy Metals (Cd2+, Cu2+, Ni2+, Pb2+) from Aqueous Solution Using Hizikia fusiformis as an Algae-Based Bioadsorbent

This study investigated the applicability of algae (Hizikia fusiformis, Green gracilaria, and Codium fragile) for removing heavy metals (Cd2+, Cu2+, Ni2+, and Pb2+) from aqueous solutions. Among the algae, H. fusiformis was chosen as a bioadsorbent and modified with NaOH and HCl. The results showed that the biosorption capacity of H. fusiformis improved significantly after treatment with NaOH; however, H. fusiformis modified with HCl did not achieve the expected value. The NaOH treatment enhanced the biosorption of metals on the treated H. fusiformis because of the hydrolysis reaction producing carboxylic (–COOH) and hydroxyl groups (–OH). The kinetics for Cd2+, Cu2+, Ni2+, and Pb2+ biosorption well fitted to pseudo-first-order, pseudo-second-order, and Elovich models, with R2 of >0.994. The Freundlich model provided a good fit for the equilibrium biosorption of Cd2+, Cu2+, and Ni2+ by both algae and the Langmuir model for Pb2+. The maximum biosorption of metals was in the order Pb2+ >> Cu2+ ≈ Ni2+ > Cd2+, with qmax of 167.73, 45.09, 44.38, and 42.08 mg/g, respectively. With an increase in the solution pH, metal biosorption was enhanced, and considerable enhancement was observed in the pH range of 2–4. Thus, H. fusiformis is expected to be considered a superior candidate for metal biosorption.

Treatment of Rhenium-Containing Effluents Using Environmentally Friendly Sorbent, Saccharomyces cerevisiae Biomass

Yeast Saccharomyces cerevisiae biomass was applied for rhenium and accompanying elements (copper and molybdenum) removal from single- and multi-component systems (Re, Re-Mo, Re-Cu, and Re-Mo-Cu). Yeast biomass was characterized using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The effects of biosorption experimental parameters such as solution pH (2.0–6.0), rhenium concentration (10–100 mg/L), time of interaction (5–120 min), and temperature (20–50 °C) have been discussed in detail. Maximum removal of rhenium (75–84%) and molybdenum (85%) was attained at pH 2.0, while pH 3.0–5.0 was more favorable for copper ions removal (53–68%). The Langmuir, Freundlich, and Temkin isotherm models were used to describe the equilibrium sorption of rhenium on yeast biomass. Langmuir isotherm shows the maximum yeast adsorption capacities toward rhenium ions ranged between 7.7 and 33 mg/g. Several kinetic models (pseudo-first-order, pseudo-second-order, and Elovich) were applied to define the best correlation for each metal. Biosorption of metal ions was well-fitted by Elovich and pseudo-first-order models. The negative free energy reflected the feasibility and spontaneous nature of the biosorption process. Saccharomyces cerevisiae biomass can be considered as a perspective biosorbent for metal removal.

Heavy Metal Removal by Magnetospirillum Strains and its Possible Use in the Treatment of Tannery Effluents

Heavy metals pose a serious threat to the environment and their continuous accumulation cause ecological imbalance. Biosorption of heavy metals by bacteria is a conventional process. However, the meagre performance of bacterial biomass in situ limits their applications. Magnetotactic bacteria are microaerophilic organism that possesses an active metal transport system for the biomineralization of iron oxide particles. On this basis, this work investigates the ability of chosen Magnetospirillum strains, viz, MSR-1 RJS2, RJS5, RJS6, and RJS7 to uptake the heavy metals through biomineralization. Metals such as cadmium, lead, zinc, manganese, nickel, chromium, and cobalt were supplemented independently (1 ppm and 10 ppm) in previously optimized MS1 media as a sole electron donor and its utilization by the bacteria were determined by Atomic Absorption Spectroscopy (AAS). Further, the optimal time/days and metal concentration for efficient biosorption were optimized. All the strains were grown in presence of metals and the growth pattern was found to be unaltered due to metal concentration. The AAS analysis revealed metal biosorption (1 ppm) by all five strains. RJS5 strain utilized all the metals viz, cadmium (95.8%), manganese (39.3%), lead (58%), nickel (57%), zinc (55%), chromium (27.5%) and cobalt (78%). Similarly, RJS2 strain showed metal biosorption in cadmium (26.4%), manganese (28%), lead (96%), nickel (30%), zinc (9.2%), chromium (51%) and cobalt (48%). The strain MSR-1 displayed biosorption of five metals- chromium (100%), cadmium (55%), manganese (12%), cobalt (40%) and nickel (4%). Both RJS6 and RJS7 displayed significant biosorption of six metals˗ cadmium (52%), manganese (17.2%), nickel (10%), zinc (34%), chromium (100%) and cobalt (59%) and cadmium (24%), manganese (22%), nickel (7.8%), zinc (40%), chromium (69%) and cobalt (28%) respectively. Metal biosorption in MSR-1 was higher in 10 ppm than 1 ppm concentration. Moreover, metals – lead and nickel biosorption was more evident in 10 ppm concentration by MTBs. RJS5 being the effective strain was exposed to a high concentration of lead, cadmium, and zinc. AAS analysis revealed the biosorption of lead (93.42%) at a 50 ppm concentration. The strains were further exposed for metal biosorption from tannery effluents. RJS6 showed higher biosorption of metals compared to other strains with nickel (88%) and zinc (81%). RJS2 displayed significant biosorption of manganese (82%) and cobalt (96%). The other three strains MSR-1, RJS5, and RJS7 showed moderate biosorption of metals from tannery effluent. The MTB strains showed biosorption against all the metals from tannery effluent. The ability of these strains to remove heavy metals from industrial waste can be further explored for a clean environment.