Preliminary study regarding microbial diversity in landfarm soil by PCR-DGGE and prospection of surfactant and dibenzothiophene degradation activities

摘要

Soil microorganisms have a high metabolic diversity, which allows them to inhabitdifferent environments and interact with all kinds of substrates present in the middle part ofthe soil profle. The study of microbial communities that play a role in the biodegradationof the soil has been a challenge for microbiologists since less than 1% of these microorganisms are capable of cultivation. In view of this bias, the metagenomic tool has been usedto understand the profle of the soil microorganisms and has enabled us to assess their biotechnological potential. The goal of this study was to evaluate the effects of oil-enrichmenton diversity and functional structures of microorganisms from landfarm soil (Lf). For thispurpose, metagenomic DNA was extracted from Lf and Lf enriched with petroleum (Lf+).The PCR/DGGE technique was used to compare the electrophoretic profles of 16S rDNAamplicons for bacterial and archaeal communities, and 28S rDNA amplicons for yeast. Twometagenomic libraries of high molecular weight DNA were built using PCC2 fosmid vectors to perform the search for genes involved in the synthesis of biosurfactants and thedegradation of dibenzothiophene (DBT). The clones were cultivated on standard medium,and screening of biosurfactant-producing colonies was performed based on the qualitativedrop-collapse test, using mineral oil, diesel and petroleum as substrates. DBT biodegradation was verifed by growing the clones for 72 h on enriched mineral medium with DBT as asole sulfur source. The electrophoretic patterns have shown that the oil has a great in?uenceon the diversity of archaeal communities, but only a minor in?uence on the bacteria andyeast in the Lf soil. The two libraries totalized 8700 fosmid clones. None of the clones couldmineralize the DBT.