Assessment of Physico-Chemical Properties of Sewage Sludge and Unlocking Its Prospect as a Powerhouse of Antibiotic-Resistant Bacteria

Sewage sludge is a reservoir of pharmaceutically active compounds (Antibiotics), antibiotic-resistant genes and antibiotic-resistant bacteria, a potential risk to mankind and the environment. This study unravels the physicochemical aspects of sewage sludge and its valorization using bio-remediation. Assessment of physico-chemical parameters was conclusive of the fact that sludge samples were enriched with inorganic components (Chloride, Phosphate and Sulfate) and organic constituents. Sludge samples were found to be contaminated with heavy metals Cr (12.69 mg.kg-1), As (1.23 mg.kg-1), Se (0.86 mg.kg-1), Hg (1.49 mg.kg-1), and Pb (30.32 mg.kg-1), with non-adherence to prescribed limits (Haryana State Pollution Control Board). Screening for bacterial isolates capable of utilizing Cephalosporin (Cefixime:200mg) as their sole source of carbon and energy was carried out. 5 isolates exhibiting fastidious growth were characterized as Bacillus sp., Escherichia sp., Pseudomonas sp., Streptococcus sp. and Enterobacter sp. Noteworthy is the fact, isolates exhibited a broad range of tolerance as reflected by Minimum Inhibitory Concentration (MIC). This was carried out by the Agar dilution method using cefixime (10-100 mg.L-1). 0.03, 0.05, 0.07, 0.06 and 0.09% w/v were the respective Minimum Inhibitory Concentration (MIC) range. The isolate with maximum tolerance to cefixime was subjected to 16S rDNA sequencing and characterized as Enterobacter SCef1.