Removal mechanism of Pb(II) by Penicillium polonicum: immobilization, adsorption, and bioaccumulation

Abstract

currently, lead (pb) has become a severe environmental pollutant and fungi hold a promising potential for the remediation of pb-containing wastewater. the present study showed that Penicillium polonicum was able to tolerate 4 mmol/L Pb(II), and remove 90.3% of them in 12 days through three mechanisms: extracellular immobilization, cell wall adsorption, and intracellular bioaccumulation. in this paper. the three mechanisms were studied by Raman, X-ray diffraction analysis (XRD), scanning electron microscopy (SeM), fourier transform infrared spectroscopy (ftiR) and transmission electron microscopy (teM). the results indicated that pb(ii) was immobilized as lead oxalate outside the fungal cell, bound with phosphate, nitro, halide, hydroxyl, amino, and carboxyl groups on the cell wall, precipitated as pyromorphite [pb 5 (po 4) 3 Cl] on the cell wall, and reduced to Pb(0) inside the cell. These combined results provide a basis for additionally understanding the mechanisms of pb(ii) removal by P. polonicum and developing remediation strategies using this fungus for lead-polluted water. The discharge of Pb-containing wastes from increased industrialization and human activities have resulted in negative impacts on the environment 1. Lead (Pb) upsets ecosystems, and endangers human health through bioaccumulation within the food chain 2. Consequently, various physicochemical treatment methods such as precipitation, coagulation, ionic exchange, inverse osmosis and adsorption have been used to remediate environmental Pb-containing contamination 3. However, such conventional methods involve either high operational costs or ineffective removal of Pb(II) at ppm levels, and may also cause secondary pollution during the repair process 4,5. In contrast, bioremediation has unique advantages, including adequate availability of materials, low cost, and no secondary pollution. Therefore, bioremediation continues to attract significant attention for the development of remedial alternatives 6-8. Over the last decade, filamentous fungi have emerged as versatile bioremediation agents owing to their adaptability to extreme conditions of pH, temperature, and nutrient availability as well as tolerance to high metal concentrations 9,10. A variety of fungal species with the ability to remove Pb(II) from aqueous solutions. For example, the Pb(II) uptake capacity for Saccharomyces cerevisiae 11 , Mucor rouxii 1 , Aspergillus niger 12 and Penicillium polonicum 13 is reported as 85.6, 74.6, 34.4 and 75.2 mg/g, respectively, indicating that the filamentous fungi have promising potential to be used for the Pb(II) polluted sewage treatment. Under stress from high concentrations of Pb(II), filamentous fungi possess various mechanisms for the removal of Pb(II) from aqueous systems 14 , One such mechanism is extracellular immobilization. In the presence of Pb(II) stress, various metabolic processes are stimulated and Pb(II) is chelated by excreted metabolites. Low molecular weight organic acids (LMWOAs) such as oxalic acid may play a significant role in...

Heavy Metal Remediation by Dry Mycelium Membranes: Approaches to Sustainable Lead Remediation in Water

“…However, no significant shifts were observed for C–H stretching and bending modes, suggesting no chemical interactions between Pb­(II) ions and the fatty acids on the cell wall. These observed chemical shifts are consistent with previous literature − performed on Pb­(II)-adsorbed live mycelia (Table ), signifying that electrostatic interactions between the Pb­(II) ions and proteins located along the hyphae cell wall are the primary drivers for the Pb­(II) sorption. This also indicates that the dry mycelium retains the functional activity similar to live mycelium.…”

Effect of amino acids on biomineralization of lead ions by Aspergillus niger

“…Numerous fungi, including Paecilomyces javanicus , Pestalotiopsis sp., Fusarium oxysporum , and Rhizopous oryzae , have been found to produce biominerals (Ahluwalia & Goyal, 2007; Das et al, 2012; Rhee et al, 2016; Yin et al, 2016). Similarly, strains isolated from heavily contaminated sites have exhibited biomineralization capabilities (Dhami et al, 2017; Qian et al, 2017; Xu, Hao, Xu, & Lu, 2020).…”

Solubilization of struvite and biorecovery of cerium by Aspergillus niger

“…It is well known that biomineralization can occur as a result of interactions between microbes and metal species in both solid and aqueous forms (Francis 1998 ; Rawlings et al 2003 ). Microbial biomineralization has been taken advantage of in recent years because of its environmentally friendly nature and cost-effectiveness, and therefore has potential applications for the removal of environmental pollutants and the recovery of precious metals from wastes (Liang and Gadd 2017 ; Yang et al 2019 ; Li et al 2020a , b ; Xu et al 2020 ). Geoactive fungi play an important role in the biomineralization of a broad range of minerals and have been investigated for their potential in the recycling of elements and biosynthesis of new biomaterials (Gadd 2007 ; Liang and Gadd 2017 ; Kang et al 2020 , 2021 ).…”