Immobilization of Mycoplana sp. MVMB2 Isolated from Petroleum Contaminated Soil onto Papaya Stem (Carica papaya L.) and Its Application on Degradation of Phenanthrene

This study presents the degradation of phenanthrene using immobilized Mycoplana sp. MVMB2 isolated from contaminated soil. Papaya stem pretreated by two stage processes, treating with acid or alkali and drying, was used for the immobilization of Mycoplana sp. Alkali pretreated papaya stem was found to be most effective in cell uptake compared to acid treated one. The maximum immobilization capacity at various physiochemical conditions for the alkali pretreated papaya stem was found to be at 320 min time, pH 6.5, 30°C temperature, and 18.6 × 10⁶ cells/mL initial concentrations. The adsorption mechanism of Mycoplana sp. MVMB2 on pretreated papaya stem was assessed using various kinetic and isotherm models. The immobilization of Mycoplana sp. MVMB2 on to pretreated papaya stem was corroborated by scanning electron microscopy and Fourier transformed IR spectroscopy analysis. The performance of immobilized cells in batch reactor showed more than 95% phenanthrene degradation within 72 h, whereas, free cells were found to require 120 h. The immobilized cells also showed better degradation performance in the packed column study.     

Optimization of Minimal Salt Medium for Efficient Phenanthrene Biodegradation by Mycoplana sp. MVMB2 Isolated from Petroleum Contaminated Soil Using Factorial Design Experiments

This study presents the degradation of phenanthrene by Mycoplana sp. MVMB2 isolated from petroleum contaminated soil and the media optimization by factorial design experiments. The Plackett–Burman design was used to evaluate the effects of eight variables (potassium dihydrogen phosphate, disodium hydrogen phosphate, magnesium sulfate, calcium chloride, ferrous sulfate, glucose, inoculum concentration, and phenanthrene concentration) on phenanthrene degradation. Based on the results, the critical medium components having significant influence on the degradation were found to be disodium hydrogen phosphate, magnesium sulfate, ferrous sulfate, and phenanthrene. Furthermore, these four variables were used as central composite design parameters. The optimum minimal salt medium composition obtained by conventional and factorial design experiments for the degradation of phenanthrene by Mycoplana sp. MVMB2 at pH 6.5 and 30°C were found to be, potassium 2.5 g/L dihydrogen phosphate, 0.3505 g/L disodium hydrogen phosphate, 0.5501 g/L magnesium sulfate, 0.02 g/L calcium chloride, 0.0261 g/L ferrous sulfate, 0.6756 g/L phenanthrene, 0.5 g/L glucose, 0.5 g/L ammonium sulfate, and inoculum 5% v/v. The phenanthrene degradation was confirmed by analyzing the metabolites formed.