Biosorption of lead using pretreated cells of Aspergillus species

Abstract

Microbial bioremediation is an emerging technology for environmental cleanup. Application of living biomass for metal binding depends on nutrient type and concentration, environmental conditions and cell age. In addition, living biomass may be subject to toxic effect of heavy metals at elevated concentrations. To overcome the disadvantages; non-viable or dead biomass is preferred. To test these hypothesis three fungal strains were isolated from effluent of chemical and pharmaceutical industry using SDA agar. Identification of the above isolates was carried out and was identified to be predominant strains of Aspergillus i.e. (Aspergillus niger and Aspergillus flavus). Further preliminary test was performed to check the tolerance of the fungi to different metal salts of lead, copper, chromium, zinc, nickel, cadmium using 1mM concentration. All three fungal species showed tolerance to metal salts like lead nitrate, zinc sulphate and cupric sulphate above 20 mM. Furthermore minimum inhibitory concentration was determined against the two above species for the three heavy metals. Pretreatment of live cells of Aspergillus strain was carried out .This dried biomass was then used for optimization of various parameters like concentration of metals, biomass concentration, pH, temperature of incubation and contact time. The filtrate was then analyzed after proper digestion and dilution by Atomic Absorption Spectrophotometer. The availability of variety of biomass and their metal binding potential makes it economical and sustainable option for developing effluent treatment process for removal and recovery of heavy metals.