Impairment of novel non-coding small RNA00203 inhibits biofilm formation and reduces biofilm-specific antibiotic resistance in Acinetobacter baumannii

Abstract

Small RNAs (sRNAs) are post-transcriptional regulators of many biological processes in bacteria, including biofilm formation and antibiotic resistance. The mechanisms by which sRNA regulates the biofilm-specific antibiotic resistance in Acinetobacter baumannii have not yet been reported. This study aimed to investigate the influence of sRNA00203 (53 nucleotides) on biofilm formation, antibiotic susceptibility, and expression of genes associated with biofilm formation and antibiotic resistance. Our results showed that deletion of the sRNA00203-encoding gene substantially decreased the biomass of biofilm by 85%. Deletion of the sRNA00203-encoding gene also reduced the minimum biofilm inhibitory concentration for imipenem and ciprofloxacin by 1,024 and 128 folds, respectively. Besides, knocking out of sRNA00203 significantly downregulated genes involved in biofilm matrix synthesis (pgaB), efflux pump production (novel00738), lipopolysaccharide biosynthesis (novel00626), preprotein translocase subunit (secA), and the CRP transcriptional regulator. Overall, we found that suppression of sRNA00203 in an A. baumannii ST1894 strain impaired biofilm formation and sensitized the biofilm cells to imipenem and ciprofloxacin. As sRNA00203 was found to be conserved in A. baumannii, a therapeutic strategy targeting sRNA00203 may be a potential solution to the treatment of biofilm-associated infections caused by A. baumannii. To the best of our knowledge, this is the first study to show the impact of sRNA00203 on biofilm formation and biofilm-specific antibiotic resistance in A. baumannii.