ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Caffeine (1, 3, 7-trimethylxanthine), a natural alkaloid present mainly in tea and coffee products has been suggested as an environmental pollutant. Decaffeination is an important process for the removal of caffeine from coffee industrial wastes. In the present study, caffeine removal (through degradation) by yeast isolate, Trichosporon asahii immobilized on various conventional matrices (sodium alginate, carboxymethyl cellulose, chitosan, agar and agarose) was investigated using the method of entrapment. The biofilm forming ability of T. asahii was monitored by atomic force microscopy and scanning electron microscopy. Exopolysaccharide produced by T. asahii biofilm was characterized by FT-IR spectroscopy and HPLC analysis. Caffeine removal from coffee processing industrial effluent was found to be 75 and 80 % by alginate immobilized yeast and yeast biofilm formed on gravels over a period of 48 hr in batch mode. Effectiveness of the process was also tested involving the continuous - flow column studies.
ABSTRACT
A novel yeast strain, Atz-EN-01 isolated from contaminated-agricultural soil was found to be highly effective in degrading atrazine in liquid culture and soil. The molecular characterization based upon partial 18S rDNA and ITS regions identified the strain Atz-EN-01 as Pichia kudriavzevii. The yeast could degrade atrazine completely within 7 days with a rate constant of 0.31 per day following the first order kinetic model. The time in which initial atrazine concentration (500 mg/L) was reduced by 50% (half-life) was 2.2 days under optimal conditions (pH 7.0, temperature 30˚ C, inoculum size 3% (v/v) and shaking speed 120 rpm). The analysis of the metabolites using GC-MS identified the formation of 3 intermediates viz. hydroxyatrazine, N-isopropylammelide and cyanuric acid. The enzyme atrazine chlorohydrolase exhibited maximum activity during degradation. Based upon the intermediates identified by GC-MS and FT-IR analysis, the sequential process of atrazine degradation was proposed. In soil bioremediation experiment, inoculation of soil with Atz-EN-01 promoted effective degradation than did the control. To the best of our knowledge, this is the first report on Pichia kudriavzevii strain Atz-EN-01 which can serve as a potential agent for in-situ bioremediation of atrazine contaminated environment.