Myco-agro sorbents: novel heavy metal sequesters

The potential application of biosorption and biosorbents has evoked tremendous interest to prepare cheap and commercial biosorbents through manipulation of indigenous microbial resources along with abundantly available low cost natural plant by-products. In the present study, rice straw was used to cultivate five indigenous fungal species viz., Aspergillus niger Van Tieghem, Aspergillus terreus Thom, Aspergillus. flavus Link ex Gray, Rhizopus arrhizus Fischer and Trichoderma harzianum Rifai. Substrate colonized by fungi was utilized as adsorbent. Batch adsorption trials were accomplished by taking 0.1 g of powdered biomass of colonized substrate in 100 mL of solution comprised of 10 different concentrations of Ni(II) in the range of 50-500 mg L^-1. Results showed that colonized substrate exhibited significantly greater metal removal efficiency (50%) than uncolonized substrate (30%). Substrates colonized with T. harzianum and R. arrhizus demonstrated a significantly higher biosorption efficiency (20-50%) and capacity (20-250 mg g^-1) at metal concentration range of 50-500 mg L^-1 than the substrate colonized by rest of the fungal species. It was concluded that these two indigenous fungal species can be used as low cost biosorbents by growing their mycelia on rice straw for Ni(II) removal on pilot scale.