Metatranscriptomic Analysis of Metal Contaminated Soils for Isolation of Metal Tolerant Genes

Abstract

Environmental pollution due to accumulation of potentially toxic metals is an imminent universal problem that uncompromisingly endangers human health, biodiversity and ecosystems. Accumulation of heavy metals into the soil environment results into deterioration of soil and water quality, thus affecting the soil environment and its biotic as well as abiotic factors. Soil is also known as a hot spot for flourishing microbial communities and for countless phenomenon and mechanisms actively combating the heavy metal toxicity. Many of members of these microbial communities cannot be easily isolated or cultured in vitro under traditional microbiological methods, hence to appreciate their true functional diversity and their activities expressed in situ in response to various adverse environments, a new omic approach i.e., metatranscriptomics is developed which involves the use of pool of mRNA directly extracted from environmental samples. Here in this work, the potential of metal polluted agro-forestry soil from Pierrelaye (PL), France, was exploited through metatranscriptomic approach to mine the novel genes responsible for metal tolerance/resistance and to know the diversity of polluted soil at the time of sampling. To achieve this, a pilot scale sequence-based and function-based metatranscriptomic analysis on soil samples from polluted site PL was done. In the present investigation, three size fractionated cDNA libraries from total RNA of metal contaminated soil was synthesized and screened for Cd tolerant genes by yeast complementation system using Cd sensitive ycf1and#916; mutant. Here, a total of 35 cDNAs identified as unique good quality sequences are reported out of which four cDNAs with full length ORFs are further characterised for bioinformatic analysis, expression studies and multi-metal tolerance profiling.