Nano-bio hybrid system for enhanced degradation of cefdinir using Candida sp. SMN04 coated with zero-valent iron nanoparticles.

The present study evaluates the effect of integrated nano-bio hybrid system involving nanoscale zero-valent iron (nFe0) and yeast Candida sp. SMN04 on degradation of cefdinir in aqueous medium. The nanoparticle was chemically synthesised and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), EDAX analysis and particle size analyser. Nano-bio hybrid system was prepared using optimal concentration (50 mg/mL) of chemically synthesized nFe0, which were coated on the surface of yeast cells without causing any lethal effects to the cell. The survival and viability of the yeast cells were monitored by AFM and SEM images. Cefdinir (250 mg/L) degradation was studied, in both, the individual and hybrid system. The nano-bio hybrid system showed more effective cefdinir degradation compared to native yeast cell and nano zero-valent iron solely. The adherence of nanoparticles on the surface of the yeast cells increased the permeability of the cell membrane, thereby enhancing the entry of cefdinir into the cell. The kinetic data showed the half-life of cefdinir as 1.34 days for nano-bio hybrid system, 3.99 days for nFe0 and 2.96 days for native yeast, Candida sp. SMN04 confirming that nano-bio hybrid system reduced the half-life to less than half of the time taken by the yeast alone. This study signifies the potential efficacy of the nano-bio hybrid system to serve as an effective remedial tool for the treatment of pharmaceutical wastewater.

Degradation of cefdinir from pharmaceutical waste water using immobilized Candida sp. SMN04 and biofilm formed on gravels.

Cefdinir being a semi-synthetic third generation cephalosporin antibiotic is considered as an emerging pollutant which demands removal from environment. Degradation of cefdinir by yeast Candida sp. SMN04 immobilized on various single and hybrid matrices was investigated using entrapment method. The biofilm forming ability of Candida sp. was evaluated by crystal violet staining assay and the formed biofilm was monitored by SEM and AFM analysis. The amount of exopolysaccharides (EPS) produced by Candida sp. was quantified and characterized by FTIR, HPLC and TGA analysis respectively. Cefdinir degradation from pharmaceutical wastewater was found to be 96.6% and 92.2% by PVA-alginate immobilized yeas tand yeast biofilm formed on gravels over a period of 48 h in batch mode. Effectiveness of the process was also tested involving continuous-flow column studies. This is the first successful attempt on cefdinir degradation using immobilized yeast cells and yeast biofilm on solid substrate.