Multimetal bioremediation from aqueous solution using dead biomass of Mucor sp. NRCC6 derived from detergent manufacturing effluent

Unveiling the potential of Aspergillus terreus SJP02 for zinc remediation and its driving mechanism

In present study, 15 morphologically different fungi isolated from rhizopheric soils of an industrial area were screened for their Zn2+ removal efficiency from aqueous solution. Isolate depicting highest potential was molecularly identified as Aspergillus terreus SJP02. Effect of various process parameters viz. biosorbent dose, contact time, temperature, agitation rate, pH and initial Zn2+ concentration on the fungal sorption capacity were studied. The biosorbent exhibited maximum Zn2+ sorption capacity of 10.7 ± 0.2 mg g- 1 in 60 min. Desorption studies showed 71.46% Zn2+ recovery rate in 120 min with 0.01 N HNO3, indicating efficient metal recovery for reuse and subsequent reutilization of spent mycosorbents. Acid digestion study suggested adsorption being the primary mechanism accounting for 87% Zn2+removal. It was further confirmed by the FE-SEM and EDX analysis. FTIR analysis suggested involvement of amino, hydroxyl, carbonyl, and phosphate functional groups of fungal cell wall in adsorption. The experimental results were in accordance with the tested isotherm and kinetic models, and suggested the role of physical adsorption for Zn2+ removal. Noteworthy, the present study showed better sorption capacity in considerably shorter equilibration time compared to previous reports and advocate potential utilization of A. terreus SJP02 for bioremediation of Zn2+ contaminated wastewater at industrial scale.

Fundamentals of bio-based technologies for selective metal recovery from bio-leachates and liquid waste streams

The number of metal-containing waste streams resulting from electronic end-of life products, metallurgical by-products, and mine tailings to name but a few, is increasing worldwide. In recent decades, the potential to exploit these waste streams as valuable secondary resources to meet the high demand of critical and economically important raw materials has become more prominent. In this review, fundamental principles of bio-based metal recovery technologies are discussed focusing on microbial metabolism-dependent and metabolism-independent mechanisms as sustainable alternatives to conventional chemical metal recovery methods. In contrast to previous reviews which have partially addressed this topic, a special focus will be given on how fundamental principles of bio-based recovery technologies can influence the selectivity and specificity of metal recovery. While conventional methods for metal recovery show benefits in terms of economic affordability, bio-based recovery technologies offer advantages in terms of efficiency and environmentally friendliness. Modifications and adaptations in the processes of biosorption, bioaccumulation and bioelectrochemical systems are highlighted, further emphasizing the application of metal-binding peptides and siderophores to increase selectivity in the recovery of metals. Single metal solutions or mixtures with a low complexity have been the focus of previous studies and reviews, but this does not reflect the nature of complex industrial effluents. Therefore, key challenges that arise when dealing with complex polymetallic solutions are addressed and the focus is set on optimizing bio-based technologies to recover metals efficiently and selectively from bio-leachates or liquid waste streams.

Bioremediation petroleum wastewater and oil-polluted soils by the non-toxigenic indigenous fungi

Soil and wastewater samples contaminated by petroleum-related industries were collected from various locations in Saudi Arabia, a country known for its vast oil reserves. The samples were analyzed for their physicochemical properties, including the presence of metals, petroleum hydrocarbons, and aromatic compounds. A total of 264 fungal isolates were analyzed and categorized into eight groups of Aspergillus (194 isolates) and four groups of Penicillium (70 isolates). The potential of these fungal groups to grow in oil or its derivatives was investigated. Two isolates, Aspergillus tubingensis FA-KSU5 and A. niger FU-KSU69, were utilized in two remediation experiments-one targeting wastewater and the other focusing on polluted soil. The FA-KSU5 strain demonstrated complete removal of Fe3+, As3+, Cr6+, Zn2+, Mn2+, Cu2+ and Cd2+, with bioremediation efficiency for petroleum hydrocarbons in the wastewater from these sites ranging between 90.80 and 98.58%. Additionally, the FU-KSU69 strain achieved up to 100% reduction of Co2+, Ba2+, B3+, V+, Ni2+, Pb2+ and Hg2+, with removal efficiency ranging from 93.17 to 96.02% for aromatic hydrocarbons after 180 min of wastewater treatment. After 21 days of soil incubation with Aspergillus tubingensis FA-KSU5, there was a 93.15% to 98.48% reduction in total petroleum hydrocarbons (TPHs) and an 88.11% to 97.31% decrease in polycyclic aromatic hydrocarbons (PAHs). This strain exhibited the highest removal rates for Cd2+ and As3+ followed by Fe3+, Zn2+, Cr6+, Se4+ and Cu2+. Aspergillus niger FU-KSU69 achieved a 90.37% to 94.90% reduction in TPHs and a 95.13% to 98.15% decrease in PAHs, with significant removal of Ni2+, Pb2+ and Hg2+, followed by Co2+, V+, Ba2+ and B3+. The enzymatic activity in the treated soils increased by 1.54- to 3.57-fold compared to the polluted soil. Although the mixture of wastewater and polluted soil exhibited high cytotoxicity against normal human cell lines, following mycoremediation, all treated soils and effluents with the dead fungal biomass showed no toxicity against normal human cell lines at concentrations up to 500 µL/mL, with IC50 values ≥ 1000 µL/mL. SEM and IR analysis revealed morphological and biochemical alterations in the biomass of A. tubingensis FA-KSU5 and A. niger FA-KSU69 when exposed to petroleum effluents. This study successfully introduces non-toxigenic and environmentally friendly fungal strains play a crucial role in the bioremediation of contaminated environments. Both strains serve as low-cost and effective adsorbents for bio-remediating petroleum wastewater and oil-contaminated soil. Heavy metals and hydrocarbons, the primary pollutants, were either completely removed or reduced to permissible levels according to international guidelines using the dead biomass of FA-KSU5 and FA-KSU69 fungi. Consequently, the environments associated with this globally significant industry are rendered biologically safe, particularly for humans, as evidenced by the absence of cytotoxicity in samples treated with A. tubingensis FA-KSU5 and A. niger FA-KSU69 on various human cell types.

Evaluation of resistance patterns and bioremoval efficiency of hydrocarbons and heavy metals by the mycobiome of petroleum refining wastewater in Jazan with assessment of molecular typing and cytotoxicity of Scedosporium apiospermum JAZ-20

Jazan Industrial Economic City (JIEC) is located on the Red Sea coast in the province of Jazan, southwest of Saudi Arabia anchors diverse heavy and secondary industries in the energy, water desalination, petroleum, aluminum, copper, refineries, pharmaceuticals and food manufacturing fields. These various industries generate a large quantity of industrial wastewaters containing various toxicants. The present work represents ecologically beneficial alternatives for the advancement of environmental biotechnology, which could help mitigate the adverse impacts of environmental pollution resulting from petroleum refining effluents. The mycobiome (32 fungal strains) isolated from the industrial wastewater of the refinery sector in Jazan were belonged to five fungal genera including Fusarium, Verticillium, Purpureocillium, Clavispora and Scedosporium with a distribution percentage of 31.25, 21.88, 15.63, 12.50 and 18.75 %, respectively. These isolates showed multimetals tolerance and bioremoval efficiency against a large number of heavy metals (Fe2+, Ni2+, Cr6+, Zn2+, As3+, Cu2+, Cd2+, Pb2+, Ag+ and Hg2+) along with potent bioremediation activity toward crude oil and the polycyclic aromatic hydrocarbons. Interestingly, the mycobiome resistance patterns obtained against different classes of fungal antibiotics including azole (fluconazole, itraconazole, voriconazole, posaconazole, isavuconazole and ketoconazole), echinocandin (anidulafungin, caspofungin and micafungin) and polyene (amphotericin B) drugs proved the prevalence of antibiotic resistance among the mycobiome of refinery industry in Saudi Arabia is relatively low. The fungal isolate under isolation code JAZ-20 showed the highest bioremoval efficiency against heavy metals (90.8-100.0 %), crude oil (89.50 %), naphthalene (96.7 %), phenanthrene (92.52 %), fluoranthene (100.0 %), anthracene (90.34 %), pyrene (85.60 %) and chrysene (83.4 %). It showed the highest bioremoval capacity ranging from 85.72 % to 100.0 % against numerous pollutants found in a wide array of industrial effluents, including diclofenac, ibuprofen, carbamazepine, acetaminophen, sulfamethoxazole, bisphenol, bleomycin, vincristine, dicofol, methyl parathion, atrazine, diuron, dieldrin, chlorpyrifos, profenofos and phenanthrene. The isolate JAZ-20 was chosen for molecular typing, cytotoxicity assessment, analysis of volatile compounds and optimization investigations. Based on phenotypic, biochemical and phylogenetic analysis, strain JAZ-20 identified as Scedosporium apiospermum JAZ-20. This strain is newly discovered in industrial effluents in Saudi Arabia. Fungal strain JAZ-20 consistently produced various types of saturated and unsaturated fatty acids. the main fatty acids were C14:0 (1.95 %), iso-C14:0 (2.98 %), anteiso-C14:0 (2.13 %), iso-C15:0 (9.16 %), anteiso-C15:0 (11.75 %), C15:0 (7.42 %), C15:1 (2.37 %), anteiso-C16:0 (3.4 %), C16:0 (10.3 %), iso-C16:0 (9.5 %), C17:1 (1.36 %), anteiso-C17:1 (8.64 %), iso-C18:0 (11.0 %), C18:0 (3.63 %), anteiso-C19:0 (3.78 %), anteiso-C20:0 (2.0 %), iso-C21:0 (2.44 %), C23:0 (1.15 %), and C24:0 (2.17 %). These fatty acids serve as natural and eco-friendly antifungal agents, promoting fungal resistance and inhibiting the production of mycotoxins in the environment. Despite being an environmental isolate, its cytotoxicity was assessed against both normal and cancerous human cell lines. The IC50 values of JAZ-20 extract were 8.92, 10.41, 20.0, 16.5, and 40.0 μg/mL against WI38, MRC5, MCF10A, HEK293 and HDFs normal cells and 43.26, 33.75, and 40.0 μg/mL against liver (HepG2), breast (A549) and cervix (HeLa) cancers, respectively. Based on gas chromatography-mass spectrometry (GC-MS), analysis the extract of S. apiospermum JAZ-20 showed 47 known volatile compounds (VOCs) for varied and significant biological activities. Enhancing the bioremoval efficiency of heavy metals from actual refining wastewater involves optimizing process parameters. The parameters optimized were the contact time, the fungal biomass dosage, pH, temperature and agitation rate.

Spent brewer's yeast as a selective biosorbent for metal recovery from polymetallic waste streams

While the amount of electronic waste is increasing worldwide, the heterogeneity of electronic scrap makes the recycling very complicated. Hydrometallurgical methods are currently applied in e-waste recycling which tend to generate complex polymetallic solutions due to dissolution of all metal components. Although biosorption has previously been described as a viable option for metal recovery and removal from low-concentration or single-metal solutions, information about the application of selective metal biosorption from polymetallic solutions is missing. In this study, an environmentally friendly and selective biosorption approach, based on the pH-dependency of metal sorption processes is presented using spent brewer's yeast to efficiently recover metals like aluminum, copper, zinc and nickel out of polymetallic solutions. Therefore, a design of experiment (DoE) approach was used to identify the effects of pH, metal, and biomass concentration, and optimize the biosorption efficiency for each individual metal. After process optimization with single-metal solutions, biosorption experiments with lyophilized waste yeast biomass were performed with synthetic polymetallic solutions where over 50% of aluminum at pH 3.5, over 40% of copper at pH 5.0 and over 70% of zinc at pH 7.5 could be removed. Moreover, more than 50% of copper at pH 3.5 and over 90% of zinc at pH 7.5 were recovered from a real polymetallic waste stream after leaching of printed-circuit boards. The reusability of yeast biomass was confirmed in five consecutive biosorption steps with little loss in metal recovery abilities. This proves that spent brewer's yeast can be sustainably used to selectively recover metals from polymetallic waste streams different to previously reported studies.