Citrobacter freundii SRS1, Gram-negative bacteria, were isolated from Savar, Bangladesh. The strain could tolerate up to 80 mM sodium arsenite, 400 mM sodium arsenate, 5 mM manganese sulfate, 3 mM lead nitrate, 2.5 mM cobalt chloride, 2.5 mM cadmium acetate, and 2.5 mM chromium chloride. The whole-genome sequencing revealed that the genome size of C. freundii SRS1 is estimated to be 5.4 Mbp long, and the G+C content is 51.7%. The genome of C. freundii SRS1 contains arsA. arsB, arsC, arsD, arsH, arsR and acr3 genes for arsenic resistance; czcA, czcD, cbiN, and cbiM genes for cobalt; chrA, and chrB genes for chromium; mntH, sitA, sitB, sitC, and sitD genes for manganese; and zntA genes for lead and cadmium resistance. This novel acr3 gene has never previously been reported in any C. freundii strain except SRS1. A set of 130 completely sequenced strains of C. freundii were selected for phylogenomic analysis. The phylogenetic tree showed that the SRS1 strain is closely related to the C. freundii 62 strain. Further analyses of the genes involved in metal and metalloid resistance might facilitate identifying the mechanisms and pathways involved in high metal resistance in the C. freundii SRS1 strain.
Multidrug-resistant P. aeruginosa has potential to cause nosocomial infections. In this study, whole-genome sequencing was performed of two extremely drug-resistant novel strains SRS1 and SRS4 isolated from Bangladesh. The size of draft genome of SRS1 is 6.8 Mbp, and 7.0 Mbp for SRS4. In silico analysis predicted that the genome of SRS1 has 82 and SRS4 has 75 antibiotic-resistant genes (ARGs). Antibiogram results revealed that both SRS1 and SRS4 were resistant to multiple members of the antibiotic groups of β−lactam, quinolones, and aminoglycosides families. In addition, the genomes of both SRS1 and SRS4 were predicted to have multiple mobile elements like prophages and plasmids. Comparative genome analysis with wildtype PAO1 and another drug-resistant P. aeruginosa strain JNQH-PA57 revealed that SRS1 and SRS4 contain more antibiotic resistance genes like AAC (6´)-II, ANT (2´´)-Ia, ANT (3´´)-IIa, OXA-395, PME-1, qacEΔ1, tet(A), tet(D), VEB-9 than PAO1 and JNQH-PA57. This study shows the importance of the genomic study to understand the distribution of ARGs in Bangladeshi P. aeruginosa strains to demonstrate the mechanisms responsible for multi drug resistance.
Bioresearch Commu. 9(1): 1208-1214, 2023 (January)
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