Quorum sensing molecules production by nosocomial and soil isolates Acinetobacter baumannii

Abstract

Acinetobacter species remain alive in hospitals on various surfaces, both dry and moist, forming an important source of hospital infections. These bacteria are naturally resistant to many antibiotic classes. Although the role of the quorum sensing system in regulating the virulence factors of Acinetobacter species has not been fully elucidated, it has been reported that they play a role in bacterial biofilm formation. The biofilm formation helps them to survive under unfavorable growth conditions and antimicrobial treatments. It is based on the accumulation of bacterial communication signal molecules in the area. In this study, we compared the bacterial signal molecules of 50 nosocomial Acinetobacter baumannii strain and 20 A. baumannii strain isolated from soil. The signal molecules were detected by the biosensor bacteria (Chromobacterium violaceum 026, Agrobacterium tumefaciens A136, and Agrobacterium tumefaciens NTL1) and their separation was determined by thin-layer chromatography. As a result, it has been found that soil-borne isolates can produce 3-oxo-C8-AHL and C8-AHL, whereas nosocomial-derived isolates can produce long-chain signals such as C10-AHL, C12-AHL, C14-AHL and C16-AHL. According to these results, it is possible to understand that these signal molecules are found in the infection caused by A. baumannii. The inhibition of this signaling molecules in a communication could use to prevent multiple antibiotic resistance of these bacteria.

Unsaturated Fatty Acids Affect Quorum Sensing Communication System and Inhibit Motility and Biofilm Formation of Acinetobacter baumannii

“…In agreement with previous studies [ 13 , 14 ], we only detected the production of long-AHLs by A. baumannii ATCC 17978 ( Figure S2 ). To further examine the activity of UFAs and virstatin on AHLs production, we evaluated the activity of these compounds on the A. baumannii biofilm formation in presence of 500 nM of the main AHLs already described, i.e., OH-C 12 -HSL or N-C 10 -HSL [ 13 , 14 , 15 ] ( Figure 2 b). If OH-C 12 -HSL addition completely restored the biofilm formation when A. baumannii was treated by MoA, it only partially counteracted the activity of virstatin and PoA (recovery of 54 and 38% of the phenotype, respectively).…”

“…In most gram-negative bacteria, signal molecules, called acyl-homoserine lactones (AHLs), are diffusible autoinducers that are characterized by a length variable acyl-chain coupled with a homoserine lactone ring [ 11 ]. In A. baumannii , different type of AHLs have been described [ 12 ], the most commonly described ones are long chain AHLs with C 10 or C 12 acyl chains [ 13 , 14 , 15 ]. When considering its crucial involvement in biofilm development, QS is an interesting target for the development of antibiofilm strategies that can act either by inhibiting the signal molecule synthesis, or by degrading or quenching this signal in the external environment [ 12 ].…”

Synthesis and Biological Evaluation of Azamacrolide Comprising the Triazole Moiety as Quorum Sensing Inhibitors

“…The compounds were dissolved in DMSO and diluted at a final concentration of 12.5 mg/L in the AB minimal medium [ 21 , 22 ]. The results of the bacterial incubated with the compounds which showed QS Inhibitory activity was shown in Table 1 .…”

“…The Agrobacterium was cultured in AB minimal medium, when it grew to OD600 > 0.6. Taking 0.3 mL of bacterial suspension into a 1.5 mL microcentrifuge tube, both the test compound (soluble in DMSO) and AHL were added in, cultured at 28 °C for 3 h. The β-galactosidase activity was measured as described previously [ 21 , 22 , 23 ].…”

Cross-kingdom signalling regulates spore germination in the moss Physcomitrella patens

“…The bacteria isolated from mosses are generally different from those isolated from Ulva: predominantly Alpha-proteobacteria and Bacteroidetes, although Microbacterium has been isolated from all three species [82][83][84] . Most of the genera of Gamma-proteobacteria isolated (Pseudomonas, Serratia, Acinetobacter, Aeromonas) are AHL producers 26,[85][86][87][88] . However, it is important to note that only a small fraction (<1%) of all bacteria that exist in a particular environment can be grown in the lab on standard growth media 89 so there may be many other AHL-producing bacteria associated with Physcomitrella in the wild.…”