VIII Congreso Internacional de Investigación REDU
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| http://doi.org/10.5867/Medwave.2022.S1.CI17
Interacciones entre Rhodococcus sp. BH4 y bacterias del lodo: nuevos conocimientos sobre la extinción del quórum
Interactions between Rhodococcus sp. BH4 and Sludge Bacteria: New insights over Quorum Quenching
Naga Raju Maddela
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Palabras clave
Antibiofilm strategy, Bacterial infections, Biofilms, Quorum sensing
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Introducción
Bacterial communication through signalling molecules is familiar as “quorum sensing” (QS) which regulates several pathogenic activities in bacteria such as biofilm formation, antibiotic resistance, sporulation, and bacterial virulence (e.g. proteases, toxins, and adhesins). Breaking of quorum sensing signals is feasible by a mechanism known as “quorum quenching” (QQ). However, behaviour of QQ against different environmental isolates is not fully understood. This is the major hindrance for the emergence of QQ strategy as an alternative to antibiotic therapy for the control of bacterial infections.
Objetivos
The aim of this work was to understand the relationship of QQ bacterium (e.g. Rhodococcus sp. BH4) with twenty-three different biofilm forming bacteria.
Método
Mono- and dual-species biofilms were determined on 96-well polystyrene plates (Corning® Product No. 3370), finally biofilm biomass was quantified using plate reader (MultiskanTM FC Microplate Photometer) at 590 nm. Plate count method was used to quantify the amount of living cells present at the bottom of the microtiter plate well (i.e. in the biofilm) and expressed as colony forming units per cm2 of biofilm. Amount of polysaccharide and protein present in the exopolymeric substances (EPSs) of biofilms were measured by phenol-sulfuric acid and modified Lowry assays, respectively. Biofilm forming bacteria were identified by using 16S rDNA sequence analysis and nucleotide sequences were deposited in NCBI GenBank. GraphPad Prism 7 software was used to analyse the data statistically and P≤0.05 considered significant, unless otherwise stated.
Principales Resultados
Molecular identification studies (16S rDNA sequence analysis) revealed that biofilm forming bacteria were belonging to the genera such as Aeromonas, Bacillus, Klebsiella, Paenochrobactrum, Proteus, Serratia and Vagococcus. Biofilm biomass of 23 bacterial strains was in the range of 0.15-3.65 (n=3), and biofilm formation potential was strictly strain-dependent (P<0.005). Presence of Proteus vulgaris JSB20 led to a decrease in the biofilm biomass by 35-40% (n=3, P<0.005) of a mixed culture containing either Bacillus sp. JSB10 or Vagococcus sp. JSB21. Biofilm biomass was higher at 24h (A590 0.4815) than at short time (6h, A590 0.3212; 12h, A590 0.3645) or long-time incubations (48h, A590 0.2915) with significant (P<0.05) differences between the biofilm biomass of single-species and dual-species (containing strain BH4) cultures. Strain BH4 showed 74% of inhibition and 26% of stimulation interactions in dual-species biofilms with different biofilm forming bacteria, implying that strain BH4 supported the competitive interactions in dual-species biofilms.
Conclusiones
Strain BH4 did not show similar effects against all biofilm forming bacteria tested in this study, though inhibitory effects were predominant. Though majority dual-species biofilms exhibited similar effects in 48h biofilm dynamic study, other species showed significantly different interactions between early (6-24h) and late-stage (24-48h) biofilms. In order to understand completely about QQ, it is greatly warranted that future studies should be focused on interaction effects of BH4 with several different bacterial species.
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