Quantification of Plasmid Isolated Resistant Pseudomonas Aeruginosa Present in Heavy Metal Soil as Biomarkers

Microorganisms have chromosomal, transposon,
and plasmid-mediated resistance systems to survive in
contaminated environments. Therefore, this study aimed to isolate Pseudomonas aeruginosa from heavy metal-contaminated
environments and investigate whether their plasmid's DNA are
responsible for the metal resistances, which could be used as biomarkers of heavy metal pollution. Plasmid detection was carried out to confirm whether the genes for resistance were encoded by plasmid DNA or not. Inductively coupled plasma-mass spectrometry (ICP-MS) and Energy X-Ray Fluorescence (EXRF) were used to analyse the heavy metal concentrations in the collected soil. A CHN analyser was used for TC, TOC, and TIC estimates. Procedural blanks, standard solutions and certified reference materials were used to verify precision and accuracy. A total of 28 isolates of P. aeruginosa resist to cadmium (P.
aeruginosa Cd5), lead (P. aeruginosa Pb2.3), mercury (P.
aeruginosa Hg30) and arsenic (P. aeruginosa As3.3) were isolated. Their minimum inhibitory concentration (MIC) of Cd, Pb, Hg and As were 5 mM Cd, 30 µM Hg, 2.3 mM Pb and 3.3 mM As, respectively. The concentration of heavy metals collected soil were 93 Pb, 19 As, 1.3 Cd and 0.0 Hg, 16 Mo, 56 Zr, 37 Sr, 13 U, 63 Rb, 17 Th, 78 Zn, 61Mn, 0.0 Cr, 59 V, 76 Sc, 11530 Fe, 532 Ca, 765 K and 2134 S (µg/g soil). There were relationships between MIC abilities of all isolated P. aeruginosa apart from three isolates were resist to 30 µM Hg which isolated from soil did not have any concentration of Hg. It is concluded that P. aeruginosa isolated
from heavy metal-contaminated environments were mainly
contained plasmid DNA responsible for resistances and thus can be used as a biomarker for any environmental contamination and monitoring environments.