Culturable actinomycetes in dioxin-contaminated soil, laccase-producing ability and potential for application in bioremediation

Abstract

Actinomycetes play an important role in microbial community in contaminated soil, they are one of the dominant groups. Actinomycetes have the ability to metabolise and degrade persistent organic pollutants such as pesticides, polycyclic aromatic hydrocarbons (PAHs) and decolour textile dyes... In this study, phenanthrene and textile dyes were used as subjects to determine the degradation and decolourisation ability of actinomycetes which were isolated from dioxin-contaminated soil at A So airbase, Thua Thien Hue province. The results of quantifying culturable actinomycetes in dioxin-contaminated soil showed that at a depth of 20-30 cm the number of actinomycetes was greater than at a depth of 150-180 cm. Among the 26 tested actinomycete strains, there were 5 laccase-producing strains with laccase activity greater than 20 U/l, of which the highest was Streptomyces sp. XAS3 reached 468.06 U/l. Streptomyces sp. XAS3 degraded 42.04% phenanthrene after 3 weeks of incubation; and decoloured 16 out of 18 surveyed textile dyes, the highest decolourisation efficiency reaching 26.72±0.94% with an anthraquinone dye acid blue 62 after 20 minutes of reaction. The results show the potential of the actinomycete isolated from dioxin-contaminated soil at A So airport for application in bioremediation of pollutants.