Finding the best combination of autochthonous microorganisms with the most effective biosorption ability for heavy metals removal from wastewater

Abstract

The presence of heavy metals (HMs) in the environment represents a serious environmental problem. In this regard, this work was conceived with the aim of finding, among indigenous microorganisms, the species and their combinations with the best biosorption activity for the following HMs: zinc, lead, cadmium, copper, and nickel. The experiment was carried out in several steps: (1) isolation and identification of microbial strains from the Central Effluent Treatment Plant’s wastewater; (2) studying the interaction of microorganisms and the ability to form biofilms in 96-well plates; (3) testing the resistance of biofilms to HMs; (4) testing the growth of biofilms on AMB media carriers in the presence of HMS; and (5) biosorption assay. The selected strains used in this study were: Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera, and Saccharomyces cerevisiae. The best biofilm producers in control medium were K. oxytoca/S. odorifera (KS), followed by K. oxytoca/S. odorifera/S. cerevisiae (KSC), and E. cloacae/K. oxytoca/S. odorifera (EKS) after 10 days of incubation. Mixed cultures composed of three species showed the highest resistance to the presence of all tested metals. The best biosorption capacity was shown by KSC for Cu2+ (99.18%), followed by EKS for Pb2+ (99.14%) and Cd2+ (99.03%), K. oxytoca for Ni2+ (98.47%), and E. cloacae for Zn2+ (98.06%). This research offers a novel approach to using mixed biofilms for heavy metal removal processes as well as its potential application in the bioremediation of wastewater.

Zinc-Based Nanoparticles Reduce Bacterial Biofilm Formation

“…Moreover, P. aeruginosa strain CCM 3955 overexpresses a flagellin matrix that causes the agglomeration of silver NPs to avoid direct contact, which is bactericidal ( 25 ). K. oxytoca shows high resistance to diverse metals, including Zn, and robust biofilm formation in wastewater ( 29 ), providing a plausible explanation to the persistence of this bacterium in handwashing reservoirs and its ability to cause disease in immunocompromised individuals in contact with these environmental sources. It is also important to explain that the MIC and MBC concentrations of Zn NPs that inhibited and killed planktonic bacteria were the same, because the XTT reduction assay and CFU determinations typically correlate, even though either approach measure different parameters, such as metabolic activity and viability.…”

Investigation of the simulated microgravity impact on heavy metal biosorption by Saccharomyces cerevisiae

“…A similar study was conducted by Jakovljević et al. ( 2022 ) on the absorption of several metals by the biofilm of some individuals and combinations of microorganisms. The results showed that the Pb and Cd absorption by S. cerevisiae alone and K. oxytoca/S.…”

“…odorifera/S. cerevisiae combination was above 95% after 10 days (Jakovljević et al., 2022 ). Therefore, in future studies, the metal biosorption in SMG using biofilm can be investigated.…”

Copper-Contaminated Substrate Biosorption by Penicillium sp. Isolated from Kefir Grains

“…Jakovljević et al [ 30 ] studied the relationship between microorganisms and their ability to form biofilms to biosorb zinc, lead, cadmium, copper, and nickel. Inès et al [ 31 ] demonstrated the potential use of newly identified lipopeptides produced by Bacillus mojavensis BI2 for the bioremediation of heavy metals in contaminated water.…”