Microbial communities in pesticide-contaminated soils in Kyrgyzstan and bioremediation possibilities

Environmental Science and Pollution Research, Sep 2017

In Kyrgyzstan, many former storehouses and dump sites for obsolete pesticides exist. In 2009/2010, an inventory and assessment of these sites including risks of environmental hazard has been conducted by FAO and the World Bank. Monitoring revealed high concentration of pesticides listed as persistent organic pollutants (POPs). The purpose of this research was to study the microbial structural complexes of the pesticide-contaminated soils in these dumping zones, and to search for and select microorganism’s destructors with cytochrome P450 genes for pesticide degradation. Culture-dependent and culture-independent approaches were used to determine the taxonomic composition of these bacterial communities. The universal primer set for the 16S ribosomal RNA (rRNA) gene and the specific primer set P450R were used to amplify the cytochrome P450 hydroxylase gene. In soils from Suzak A and B and soils from Balykchy dumping sites, the bacteria from the Actinobacteria phylum (Micrococcus genus) were dominant. These bacteria made up 32–47% of the indigenous local microflora; bacteria species from the Pseudomonas genus (Gammaproteobacteria phylum) made up 23% in Suzak, 12% in Balykchy soils. Bacillus species from the Firmicutes phylum were found only in Suzak soils. The 16S rRNA analyses and the specific primer set P450R have revealed bacteria with cytochrome genes which are directly involved in the degradation process of organic carbon compounds. Experiments were carried out to help select active degraders from the bacterial populations isolated and used to degrade Aldrin in laboratory. Active bacterial strains from the Pseudomonas fluorescens and Bacillus polymyxa population were selected which demonstrated high rates of degradation activity on Aldrin.

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Microbial communities in pesticide-contaminated soils in Kyrgyzstan and bioremediation possibilities

Microbial communities in pesticide-contaminated soils in Kyrgyzstan and bioremediation possibilities Tinatin Doolotkeldieva 0 1 Maxabat Konurbaeva 0 1 Saykal Bobusheva 0 1 0 Plant Protection Department, Kyrgyz-Turkish Manas University , 56 Prospect Mira, Bishkek , Kyrgyzstan 1 Responsible editor: Robert Duran 2 Tinatin Doolotkeldieva In Kyrgyzstan, many former storehouses and dump sites for obsolete pesticides exist. In 2009/2010, an inventory and assessment of these sites including risks of environmental hazard has been conducted by FAO and the World Bank. Monitoring revealed high concentration of pesticides listed as persistent organic pollutants (POPs). The purpose of this research was to study the microbial structural complexes of the pesticide-contaminated soils in these dumping zones, and to search for and select microorganism's destructors with cytochrome P450 genes for pesticide degradation. Culturedependent and culture-independent approaches were used to determine the taxonomic composition of these bacterial communities. The universal primer set for the 16S ribosomal RNA (rRNA) gene and the specific primer set P450R were used to amplify the cytochrome P450 hydroxylase gene. In soils from Suzak A and B and soils from Balykchy dumping sites, the bacteria from the Actinobacteria phylum (Micrococcus genus) were dominant. These bacteria made up 32-47% of the indigenous local mic roflora; bacteria spec ies from the Pseudomonas genus (Gammaproteobacteria phylum) made up 23% in Suzak, 12% in Balykchy soils. Bacillus species from the Firmicutes phylum were found only in Suzak soils. The 16S rRNA analyses and the specific primer set P450R have revealed bacteria with cytochrome genes which are directly involved in the degradation process of organic carbon compounds. Experiments were carried out to help select active degraders from the bacterial populations isolated and used to Obsolete pesticide dump; Contaminated soil; Microbial consortia; Bacterial populations with P450 cytochrome genes; active bacteria for aerobic bioremediation of pesticides - degrade Aldrin in laboratory. Active bacterial strains from the Pseudomonas fluorescens and Bacillus polymyxa population were selected which demonstrated high rates of degradation activity on Aldrin. Introduction Pesticides are widely used in agricultural production to prevent or reduce losses caused by pests. Over 1 billion pounds of pesticides are used in the USA each year, and approximately 5.6 billion pounds are used worldwide (United States Environmental Protection Agency 2011) . Estimates concerning the number of obsolete stocks around the world range from 300,000 to 500,000 t (FAO 2014, Pieterse et al. 2015) . Classes of organic pesticides include organochlorines, organophosphates, organometallic compounds, pyrethroids, and carbamates, among others (Gilden et al. 2010) . However, their chemical structures, along with their incorrect preparation, application, and storage, may pose a serious toxicity risk to other organisms, both environmental and human (Fantke et al. 2012; Pieterse et al. 2015; Torres et al. 2013) . In the present age, more than 500 different formulations of pesticides are used, mainly in agricultural tricks. These formulations are in general artificially synthesized substances that are nonbiodegradable and enhance environmental toxicity. These non-biodegradable compounds persist in agricultural fields after application. About three million people are intoxicated per annum as a result of pesticide usage, as reported by the World Health Organization (WHO) (Veiga et al. 2006) . Kyrgyzstan is a unique country with a rich natural and agricultural biodiversity in almost every region. However, there is a large legacy of former storehouses and dumping zones for obsolete pesticides and wastes from pesticide production, as is often observed in former Soviet countries (Toichuev et al. 2017a, b; Vijgen et al. 2013; Amirova and Weber 2015) but also occurs in other regions (Jit et al. 2010; Wycisk et al. 2013) . In recent years in Kyrgyzstan (2009, 2010), an inventory and assessment of these dumping zones, and the risk of environmental hazard that they pose, has been performed by international organizations (FAO, World Bank) and related international experts. In the territory of Kyrgyzstan, 50 storage facilities of obsolete pesticides exist, which store about 5000 t of these hazardous chemicals. In many places, the local populations try to dig out obsolete pesticides for reuse. They pose a serious threat to the people living there, to livestock, and to the environment (World Bank 2010; Toichuev et al. 2017b) . The pesticide level in the environment determines the dose and time at which an organism is exposed. Due to the mobility and persistence of these semi-volatile compounds, they can represent a hazard for the wider environment and can travel to remote locations. Hence, their persistence in the environment leads to a risk for (...truncated)


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Tinatin Doolotkeldieva, Maxabat Konurbaeva, Saykal Bobusheva. Microbial communities in pesticide-contaminated soils in Kyrgyzstan and bioremediation possibilities, Environmental Science and Pollution Research, 2017, pp. 1-15, DOI: 10.1007/s11356-017-0048-5