Antimicrobial Potential of Bacteria Isolated from Cockroaches in Polluted Environments

Abstract

The emergence of antimicrobial resistance (AMR) has posed an imminent threat to the discovery of new antimicrobial agents with alternative biological origins. The microbiota associated with insects is now of considerable interest for its role in producing bioactive metabolites, given that insects are exposed to diverse microbial communities in their habitats. This study examined the antimicrobial activity of cockroach bacteria, which survive in polluted environments (sewage systems, refuse dumps, and waste disposal sites). The cockroaches were dissected, bacterial isolates were collected from the gut, cultured and then screened against Enterococcus faecium, Klebsiella pneumoniae and Acinetobacter baumannii. Seven bacterial isolates were identified using 16S rRNA gene sequences, most of which belonged to the genera Bacillus and Enterobacter. Antimicrobial screening revealed that some isolates were inhibitory, and their ethyl acetate extracts showed high antimicrobial activity. Isolate WP2 ethyl extract, which was identified as Bacillus altitudinis, exhibited a 24 mm inhibition zone against E. faecium, 20 mm against A. baumannii, and 16 mm against K. pneumoniae. LC-MS identified bioactive compounds, including celastramycin A, cefditoren pivoxil, meclocycline, and sericetin, which exhibit antibacterial, antiviral, and antioxidant effects. Such findings demonstrate that bacteria coevolved with cockroaches, can serve as an alternative source of new antimicrobial drugs, and that insect microbiomes can be drug-discovery-worthy.