Uptake of heavy metals

Microorganisms including fungi and bacteria have been reported to extract heavy metals from wastewater through bioaccumulation and biosorption.

Introduction

The highly heavy metal tolerant fungal isolates were evaluated for the uptake of heavy metals in potato dextrose broth medium containing 50 ppm concentration of different heavy metals Pb, Cd, and Cr individually in triplicate. Potato dextrose broth containing 50 ppm of one of the heavy metals was dispensed in100 ml lots to 250 ml conical flasks and sterilized at 15 lbs/psi for 15 min. These flasks were inoculated with 1 ml of freshly prepared spore suspension (106 to107 spores/ml) of each fungal isolate and put on a shaker at 150 rpm at 28°C for 96 h. Un-inoculated flasks containing PD broth of 50 ppm concentration of different heavy metals served as control. Fungal growth was harvested after 96 h through filtration using Whatman filter No. 42. The harvested fungal biomass was rinsed with double distilled water 3-4 times and dried in a hot air oven at 80°C for 18 h.

The dried fungal biomass was weighed and heavy metal concentration in it was estimated by digestion with nitric acid and perchloric acid (ratio = 3:1). The digested fungal biomass was filtered through Whatman filter No. 42 and made the volume of the filtrate to 50 ml in the volumetric flask. Similarly, in case of highly efficient bacterial isolates, 1 ml of freshly prepared cell suspension (108 to109 cells/ml) of each bacterial isolate inoculated into sterilized Nutrient broth containing 50 ppm of one of the heavy metals (Pb, Cd, Cr) and put on the shaker at 150 rpm at 37°C for 48 h. Un-inoculated flasks containing Nutrient broth of 50 ppm concentration of different heavy metals served as control.

The bacterial growth was harvested by centrifugation at 5000 rpm for 10 minutes after 48 h and washed with phosphate buffer saline (PBS). The harvested bacterial biomass was dried in a hot air oven at 80°C for 18 h and digested in the same way as mentioned above. The heavy metals concentration in digested fungal and bacterial biomass was estimated [11] by Atomic Absorption Spectrophotometer (GBC932, Semi-automatic). All the experiments were conducted in triplicate and average values are expressed for analysis. The uptake of heavy metal by fungal and bacterial biomass was calculated using the equation:

where q_e is the concentration of heavy metal accumulated by fungal/bacterial biomass in (mg/g), C is a concentration of heavy metal (ppm); V (ml) is the volume of the aqueous medium, and W is the dry weight (g) of the fungal/bacterial biomass.

Article Source: Some Fungal and Bacterial Species

Raman Kumar
Department of Biotechnology, M.M. University, Mullana-133203, Haryana, India
Prem Singh
Department of Physics, S.D. College, Ambala Cantt.-133001, Haryana, India
Bhupinder Dhir
Department of Genetics, South Campus, Delhi University, New Delhi-110021, India
Anil K Sharma
Department of Biotechnology, M.M. University, Mullana-133203, Haryana, India
Devinder Mehta
Department of Physics, Panjab University, Chandigarh-160014, India
DOI: DOI
Keywords: Heavy metals, Biosorption, Wastewater, Fungi, Bacteria

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