TABLE 1

Mechanisms of bacterial tolerance to chlorhexidine in strain Ab-2_clon_2010-CHLX, revealed by transcriptomic studiesa

GenBankb protein accession no.Gene expression fold change determined by:Functional descriptionDefense mechanism (reference no.)Tolerome type (reference no.)
DESeq2EdgeR
ODA53993.16.9337534756.982635042AdeA proteinAdeABC system (RND-type) (10)Transporter/efflux pump (5)
ODA53994.16.1499078926.175526694AdeB protein
ODA53995.14.2571535664.270842036AdeC protein
ODA55718.16.1193216476.133494454Tetracycline resistance proteinMFS system
ODA54617.15.3772924577.227172031Arsenite efflux pumpACR3 system (13)
ODA56577.13.4980981863.528728206Aminoglycoside phosphotransferaseAPT family
ODA54814.13.6057813313.649808635Chlorexidine efflux pumpAceI system (16)
ODA56167.15.2655506687.054151044MFS transporterMFS system
ODA53764.112.1676357514.92175121OXA 24/40 β-lactamaseAbATCC329p/pMMCU3Plasmid (5)
ODA53763.18.97563387311.30715263DNA replication protein A
ODA53762.15.2739850665.329333593RepB family plasmid replication initiator
ODA54084.13.5110199753.547062538CsuA proteinCsuABCDE (17, 18)Biofilm (14)
ODA54083.13.1997493783.259685195CsuB protein
ODA54082.12.5750949742.584527435CsuC protein
ODA54081.12.8106133412.819199271CsuD protein
ODA54080.12.7825527912.791313686CsuE protein
ODA53940.12.0377345232.053934504Cytochrome bCytochrome operon (1921)Stress oxidative (ROS) (21)
ODA57053.12.1730496912.184371809Cytochrome bd biosynthesis protein
ODA56663.12.4051018732.428897655Sodium/proline symporter
ODA56171.110.7570844413.32903693Cytochrome bd biosynthesis protein
ODA56172.110.3509343812.86380541Cytochrome d ubiquinol oxidase subunit
ODA54604.110.0765282312.56398102Taurine ABC transporter substrate-bindingTaurine transporter (22, 23)Electron transport
ODA54605.19.75831631212.21616998Taurine transporter-binding subunit (TauB)
ODA54606.18.96690800811.30350134Taurine ABC transporter permease (TauC)
ODA54607.110.8532468613.44475271Taurine dioxygenase (TauD)
ODA55153.1−6.486154998−6.530626555Hypothetical proteinReplicationppGpp network (28)c
ODA54592.10.9324752180.929842277DNA polymerase I
ODA54625.10.9316885770.929428817DNA polymerase III subunit alpha
ODA54730.1−1.77207536−1.816317901Response regulator
ODA55878.10.5000781840.50614067550S ribosomal protein L17
ODA55763.10.4382410110.436148678RNA polymerase subunit omega
ODA55654.10.5825231780.58092126350S ribosomal protein L7/L12
ODA55933.1−0.523115918−0.531876133ATP synthase subunit betaATP metabolismEnergy production (31, 32)c
ODA55935.1−0.570647356−0.579254835ATP synthase subunit alpha
ODA54585.10.4223904830.418615357Transcription termination factor rho
  • a The relative expression (expressed as fold change [FC]) of abaI (3.05) and abaR (2.88) genes, determined by RT-PCR, indicated activation of the quorum-sensing system.

  • b Sanger sequencing of these genes from the Ab-2_clon_2010-CHLX strain, as well as of the regulatory genes adeR and adeS, did not show mutations with respect to the sequence of strain Ab-2_clon_2010.

  • c Genes that belonged to the ppGpp network and energy production categories showed downregulation (FC, <1).