title: Modelling growth of, and removal of Zn and Hg by a wild microalgal consortium.
abstract: Microorganisms isolated from sites contaminated with heavy metals usually possess a higher removal capacity than strains from regular cultures. Heavy metal-containing soil samples from an industrial dumpsite in Northern Portugal were accordingly collected; following enrichment under metal stress, a consortium of wild microalgae was obtained. Their ability to grow in the presence of, and their capacity to recover heavy metals was comprehensively studied; the datasets thus generated were fitted to by a combined model of biomass growth and metal uptake, derived from first principles. After exposure to 15 and 25 mg/L Zn(2+) for 6 days, the microalgal consortium reached similar, or higher cell density than the control; however, under 50 and 65 mg/L Zn(2+), 71% to 84% inhibition was observed. Growth in the presence of Hg(2+) was significantly inhibited, even at a concentration as low as 25 μg/L, and 90% inhibition was observed above 100 μg/L. The maximum amount of Zn(2+) removed was 21.3 mg/L, upon exposure to 25 mg/L for 6 day, whereas the maximum removal of Hg(2+) was 335 μg/L, upon 6 day in the presence of 350 μg/L. The aforementioned mechanistic model was built upon Monod assumptions (including heavy metal inhibition), coupled with Leudeking-Piret relationships between the rates of biomass growth and metal removal. The overall fits were good under all experimental conditions tested, thus conveying a useful tool for rational optimisation of microalga-mediated bioremediation.
authors.affiliation: CBQF/Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal.
authors.forename: Cristina M
authors.initials: CM
authors.lastname: Monteiro
authors.forename: Teresa R S
authors.initials: TR
authors.lastname: Brandão
authors.forename: Paula M L
authors.initials: PM
authors.lastname: Castro
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Malcata
mesh_terms: D001673:Biodegradation, Environmental; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007700:Kinetics; D008628:Mercury / Q000378:metabolism*; D058086:Microalgae / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D008628:Mercury; D015032:Zinc