In this work, we examined the possibility of improving ion-exchange adsorbent performance by nanoscale structuring of ligands into clusters of fixed size rather than a random distribution of individual charges. The calcium-depleted form of the protein alpha-lactalbumin, which displays a cluster of acidic amino acid residues, showed enhanced adsorption affinity and capacity on clustered-charge pentalysinamide and pentaargininamide adsorbents as compared to single-charge lysinamide and argininamide adsorbents of matched total charge. Two differently charge-clustered mutants of rat microsomal cytochrome b(5), E11Q and E44Q, with the same total charge also were well differentiated by clustered-charge adsorbents. Thus, an organized rather than random distribution of charges may produce adsorbents with higher capacity and selectivity, especially for biomolecules with inherent charge clustering.

The biodegradation of phenol by Pseudomonas putida (NICM 2174), a potential biodegradent of phenol has been investigated for its degrading potential under different operating conditions. Box-Behnken design has been employed to study the effect of different experimental variables. Four variables of maltose (0.25, 0.5, 0.75 g/l), phosphate (3, 12.5, 22 g/l), pH (7,8,9) and temperature (30°C, 32°C, 34°C) were used to identify the signi®cant effects and interactions in the batch studies. A second order polynomial regression model, has been developed using the experimental data. It was found that the degrading potential of Pseudomonas putida (NICM 2174) was strongly affected by the variations in maltose, phosphate, pH and temperature. The experimental values were in good agreement with the predicted values, the correlation coef®cient was found to be 0.9980. Optimum conditions of the variables for the growth of Pseudomonas putida (NICM 2174) and for maximum biodegradation of phenol are maltose (0.052 g/l), phosphate (8.97 g/l), pH (7.9) and temperature (31.5°C).

Pseudomonas pictorum (NICM-2077) immobilized on various matrices are used to protect the microbes from confronting shock loads of concentrated phenol. The cells were immobilized in activated carbon and were used in biodegradation of phenol. Biodegradation of phenol using immobilized Activated Carbon matrix played an important role in reducing the toxicity of phenol. The degradation was carried and using the Box-Behnken model and analysis of variance have been applied to the experimental degradation studies. Response surface method with three levels of phenol concentration (0.200, 0.400, 0.600 g/l), activated carbon (0.5, 1.0, 1.5 g/l) and pH (7,8,9) were used in the identi®cation of signi®cant effects and interactions in the biodegradation studies. Phenol removal rate increases especially when the degradation medium was supplemented with utilizable carbon sources. A ®rst-order polynomial regression model, which was used at ®rst for analysis of the experiment had a signi®cant lack of ®t. Therefore, linear and quadratic terms were incorporated into the regression model through variable selection procedures. Effect of incubation phenol concentration, activated carbon and pH were signi®cant. The predicted values using Box-Behnken model was found to be in close agreement with the experimental values, as indicated by the correlation coef®cient values of 0.9463.