Biodegradation of toluene in the contaminated soil by Mycoplana sp. MVMB2

Toluene is one of toxic pollutant which occurs in the nature during the release of aromatic hydrocarbons through spillages and leakage from underground tanks. It has caused extensive contamination of surface soil, sea and groundwater environment. Toluene has been considered as a model monocyclic aromatic compound because of its relative toxicity. This study has focused on toluene biodegradation in the contaminated soil using isolated Mycoplana sp. MVMB2. The soil used was artificially spiked with toluene. Soil properties were studied by standard methods. The organism growth was studied by standard plate technique and the toluene concentration by extracting and quantifying in High Performance Liquid Chromatography. The strain was acclimatized for more than 17 weeks at concomitant changes in the nutrient level with increased toluene concentration. Growth studies were performed for non-acclimatized culture, non-acclimatized culture with toluene and acclimatized culture with toluene. The growth of acclimated strain was found to be better with an exponential phase of 15-45 h and stationary phase of 45-80 h. The physio-chemical parameters such as pH, C: N and C: N: P ratio was studied in the range of 5-8, 100:10-100: 50 and 100:20:1- 100:20:5 respectively. The result showed a maximum degradation of 87.99% at the optimum conditions of pH 7.0 and C: N: P ratio of 100:20:2. The study to enhance degradation using surfactant lead to choose non-ionic surfactant Triton X-100 among the five different surfactants tested. A maximum of 95% degradation was obtained by adding non-ionic surfactant Triton X-100 at CMC2. The optimized conditions were adjusted in the originally contaminated soil and a maximum of 97% toluene degradation was obtained. Thus, Mycoplana sp. may be used for the monocyclic aromatic hydrocarbon degradation and can be utilized for bioremediation purpose