Development of microbial biosorbents -a need for standardization experimental protocols

摘要

An exhaustive culture isolation and screening program was undertaken in laboratory to obtain highly efficient metal sorbing microorganisms. The isolates belonged to diverse groups viz. i) Gram positive bacteria, ii) Gram negative bacteria, iii) yeasts, iv) fungi and v) algae. It was found that all the microbial cultures tested possessed ability to adsorb metals like lead, cadmium, chromium, copper, zinc and silver from solutions. Bacteria and algae showed higher metal uptake than fungi and yeasts. Some difficulties arose when an attempt was made to compare the data obtained with those reported in the literature. These difficulties were mainly because of the differences in experimental set-up, protocols and evaluation criteria used as well as the method of expressing results. Such aspects need to be standardized before data from different laboratories is compared. Our studies indicated that (a) there is a need for an exhaustive culture screening for obtaining good metal sorbing cultures and (b) there is an urgent requirement for standardizing the metal biosorption protocols with respect to the experimental parameters used. These parameters could include metal concentration, solution pH, biomass to volume ratio, etc. A standard experimental protocol for metal sorbing microorganisms I biomass in proposed.