Bioremediation of marine environmental pollution using marine microorganism

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Lignin-degrading enzyme possesses a unique system that can degrade not only lignin, a naturally occurring substrate, but also synthetic compounds such as xenobiotics. Lignin-degrading microorganisms show much promise in the remediation of heavily polluted environments. However, because they usually exist on land, there is little or no research on their use in remediating marine environmental pollution, although they may be used to treat contaminated soils. Given this background, we searched for lignin-degrading microorganisms originating in the marine environment with the objective of developing bioremediation technology for the marine environment, which utilizes enzymes produced by such degrading microorganisms or the degrading microorganisms themselves. As a result, we found a halotolerant microorganism that produces laccase, a type of lignin-degrading enzyme. Based on examinations of the optimal conditions for the production of laccase by this microorganism, the microorganism was id … More entified as a filamentous fungus of genus Pestalotiopsis. Because this microorganism can produce laccase in the presence of 3% NaC1 solution, it showed much potential for bioremediation in the presence of salt. The results of a dye decolorization test indicated that 7 of 11 Pestalotiopsis species decolorized dyes in the presence of 1.5% or 3% NaC1 solution. When the degrading activity against organotin compounds [tributyltin (TBT) and triphenyltin (TPT)], which are endocrine-disrupting chemicals and are toxic substances present in the environment, was examined in the presence of salt, Pestalotiopsis at the initial concentration of 0.1 ppm was found to degrade the two compounds by approximately 50% and 40% in the presence of 1.5% and 3% NaC1 solution, respectively (6-day culture). After culture for 2 weeks, TBT and TPT were almost completely degraded. Furthermore, to test the applicability of this microorganism to marine environmental cleanup, we evaluated its toxicity using mouse experiments, but found no acute toxic effects. Taken together, the results demonstrate the possibility of using this microorganism for the remediation of marine environment. Less