Copper resistant bacterial biosorbents from food waste origin: efficiency, isothermal and kinetic studies
Vijay Rajendran, Chavan Priyanka Yashwanth, Srinivasan Krishnamoorthy, Arunkumar Anandaraj, Ashish Rawson, Baskaran Nagarathinam, Vignesh SivanandhamAbstract
Copper (Cu(II)) gets ionised easily, leaches into food, and becomes environmentally toxic. Hence, Cu(II) tolerant bacterial strains with high biosorption potential were screened from fruit, dairy and flour mill waste by in vitro antimicrobial susceptibility testing methods. Based on high tolerance capabilities (>250 mM Cu(II) ions), two strains, Klebsiella pneumonia (V1) and Cronobacter sakazakii (V2), were identified through genetic characterisation. The Cu(II) biosorption mechanism (V1, V2, V1 + V2) was further evaluated through the viable/dead cell method. The maximum biosorption of Cu(II) (91.3 %) was achieved in optimised conditions (pH 5–6, 30 °C and 30 min contact time) through V1 + V2 and well-fitting with Freundlich (R 2 = 0.9764) and Langmuir (R 2 = 0.9834) isotherm plots. Further, the exopolysaccharides from food waste were produced through a fed-batch fermentation process, where the V2 strain produced a maximum of 224.52 mg/L. The bacterial biosorbents reported in this study could benefit industrial applications.