Study On Soil Bacterial Heterogeneity And Distribution Along A Depth Gradient At Industrial Site In Tianjin,China

Soil pollution has transformed into a worldwide issue.Entry of petroleum byproducts and other contaminants into the soil environment is one of the key reasons for universal pollution.Such expanded organic and in-organic contaminants show serious consideration to human health as well as to the soil environment.Researchers around the world have used successive mitigation practices to overcome this hazard from the soil setting.Remediation techniques like bioremediation is widely applicable eco-friendly and cost-effective.Soil is the microbial setting with the most complex of species richness and group size.The coexistence of inorganic and organic contaminants may adversely affect the heterogeneity and distribution of soil bacteria.Earlier research concentrated primarily on surface soils,while little was specifically known about the depth gradient heterogeneity and distribution in soils contaminated with petroleum at industrial sites.Here,depth gradient community composition and distribution of soil bacteria through16 Sr DNA gene sequencing was investigated.Soil samples along different depths,A(120-240cm),B(360-480cm),C(600-720cm),D(960-1080cm)were also analyzed for co-influence of heavy metals and total petroleum hydrocarbons in soil bacterial heterogeneity and distribution.Results showed that the heterogeneity and distribution of soil bacterial communities changed significantly across the depth gradient.Greater community diversity was observed in the order of A>C>D>B(1.01,1.0,0.46,0.28 Shannon index).The relative abundance at the phylum level was higher for Firmicutes(87.87%)in the first layer followed by Proteobacteria which were dominating second(99.99%),third(99.99%)and fourth layers(99.98%)respectively.However,Pseudomonas,Lysinibacillus,and Enterobacter were the dominant genera.Redundancy analysis demonstrated that total petroleum hydrocarbons,chromium,zinc,cation exchange capacity,and lead were the important environmental drivers in structuring distribution and abundance of Proteobacteria and Firmicutes.Arsenic,Organic Matter,& Organic Carbon also influenced the distribution of bacterial species.Pearson’s correlation of bacterial diversity and richness with environmental gradient also indicated that total petroleum hydrocarbons,chromium,zinc,cation exchange capacity,and lead were the key environmental variables shaping community composition.The study offers substantial background information on depth gradient dynamics in the diversity,distribution,and application of these identified auspicious hydrocarbon degraders in bioremediation of petroleum-contaminated soils.