GC-MS analysis of hospital waste soil and isolation of antimicrobial agent producing bacteria

Abstract

The current study, deals with the GC-Mass analysis of soil and antibiosis activity of soil bacteria, isolated from district hospital at Kabir Chaura, Varanasi, India. Standard serial dilution plate procedures were used to isolate the bacteria. Gram staining was used to identify the isolates morphologically. Strain KC14 was Gram-negative and all other isolates were Gram-positive. Isolated bacteria were tested against six human pathogens viz., Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus, Shigella flexneri and Bacillus subtilis. Primary and secondary screening were done by perpendicular streaking and seed overlay techniques. Based on the results most potential isolates were selected for tertiary screening. The GC-MS of soil samples revealed some major medical pollutants such as para-hydroxy acetanilide, 2-methyl-5-nitro-imidazole and 2-acetoxybenzoic acid. The KC14 isolate was chosen for further studies after demonstrating positive results against S. aureus with a maximum antagonistic activity of 17.3 ± 0.5 zone of inhibition. The molecular identification of KC14 isolate was determined by using 16S rRNA sequencing. The obtained nucleotide sequences were subjected to BLASTN in NCBI, and found similar to the available sequence of Acinetobacter junii. The nucleotide sequences have been deposited in GenBank with accession no. OP265396. The active compound was partially purified by ethyl acetate and tested its activity against S. aureus. This study defines the composition of hospital waste soil and identified a Gram-negative bacterium producing antibacterial activity against important human pathogens.