Phylogenetic And Diversity Analysis Of Genes Involved In Soil Sulfur Cycle Under Atrazine Stress And Factors Affecting Soil Microbial Biomass And DNA

Sulfur cycle is very important in soil biogeochemical cycles. This cycle play a critical role in biological processes of soil sediments, aquatic sediments and in air. In soil many sulfate reducing and sulfur oxidizing bacteria performing their functions. Among all reactions sulfate reduction is main anaerobic reaction in conversion of carbon compounds into simpler compounds. Almost half of sulfate conversion into sulfides done by sulfate reducing bacteria in aquatic environment. Sulfate reducing prokaryotes are responsible for sulfur oxidation in presence of inorganic sulfur in abiotic environment.Currently, many researchers reported sulfi de production and removal in sediments due to sulfur oxidation process. On other hand, only few studies focused on microbial community involved in sulfur cycle in soil and fresh water, where concentration of sulfates is relatively lower than marine sediments. Although in low availability of sulfates, sulfate reducing bacteria cannot perform well and sulfate reduction process become slower but still they convert carbon compounds into simpler forms.Chemolithotrophic are sulfur oxidizing prokaryotes which a re competent for oxidizing sulfur compounds and utilize as energy source for development. Almost all prokaryotes have this aptitude. Basically three main sulfur oxidizing phyla( Firmicutes, Proteobacteria and Aquificae) linked with bacteria while some are linked with Archaea; but most of the SRBs belong to Proteobacteria. So, we used apr A gene in current study to determine atrazine impact.; that atrazine may have positive or negative impact on soil sulfur bacteria.The present study was divided in two main parts. First one was diversity analysis of genes involved in soil sulfur cycle under atrazine stress. Results demonstrated that all sequences derived in this study were much analogous to apr A genes. Maximum similarity level(99%) was found in all samples h aving 0 mg/kg of atrazine concentration during all experiment from day 1 to 28 while sample taken from soil containing 20mg/kg of atrazine concentration illustrated maximum similarity only at day first of testing. General tendency in similarity sequences resulted that apr A gene sequences in soil samples having highest the atrazine concentration represented the lowest matching rate while apr A gene sequence from the soil with low atrazine concentration from 0, 20 and 50 mg/kg showed higher matching rate with other gene sequences in BLASTN tool. Results concluded that higher atrazine concentration influenced the genes regulating soil sulfur cycle.Second part was aimed to calculate environmental and anthropogenic factors affecting soil microbial biomass and DNA. For this reason organic and inorganic fertilizers were selected to see their impact on soil microbial biomass and DNA both in spring and summer season; also aimed to observe the correlation between soil microbial biomass and soil DNA. The Results concluded that type of fertilizer may alter the soil microbial biomass and DNA contents. In soil treated with organic fertilizers resulted in higher concentrations of microbial biomass and DNA contents in summers as compared to spring season dute to increase in temperature. Correspondingly, in case of inorganic fertilizer, concentrations of soil microbial biomass and DNA detected higher in summer season instead of spring. The statistical correlation between soil microbial biomass, DNA and ODR in spring and summer seasons along with organic and inorganic fertilizers were calculated highly significant(p>0.01). This study demonstrated the impact of fertilizers and seasonal variations on soil microbial biomass and also revealed significant correlation between soil mi crobial biomass and soil DNA.