Transcriptomic Analysis of Pseudomonas aeruginosa Response to Pine Honey via RNA Sequencing Indicates Multiple Mechanisms of Antibacterial Activity

Abstract

Pine honey is a unique type of honeydew honey produced exclusively in Eastern Mediterranean countries like Greece and Turkey. Although the antioxidant and anti-inflammatory properties of pine honey are well documented, few studies have investigated so far its antibacterial activity. This study investigates the antibacterial effects of pine honey against P. aeruginosa PA14 at the molecular level using a global transcriptome approach via RNA-sequencing. Pine honey treatment was applied at sub-inhibitory concentration and short exposure time (0.5× of minimum inhibitory concentration –MIC- for 45 min). Pine honey induced the differential expression (>two-fold change and p ≤ 0.05) of 463 genes, with 274 of them being down-regulated and 189 being up-regulated. Gene ontology (GO) analysis revealed that pine honey affected a wide range of biological processes (BP). The most affected down-regulated BP GO terms were oxidation-reduction process, transmembrane transport, proteolysis, signal transduction, biosynthetic process, phenazine biosynthetic process, bacterial chemotaxis, and antibiotic biosynthetic process. The up-regulated BP terms, affected by pine honey treatment, were those related to the regulation of DNA-templated transcription, siderophore transport, and phosphorylation. Pathway analysis revealed that pine honey treatment significantly affected two-component regulatory systems, ABC transporter systems, quorum sensing, bacterial chemotaxis, biofilm formation and SOS response. These data collectively indicate that multiple mechanisms of action are implicated in antibacterial activity exerted by pine honey against P. aeruginosa.

Physicochemical Characterization and Biological Properties of Pine Honey Produced across Greece

“…Overall, our data indicate multiple mechanisms of antibacterial activity exerted by pine honey. This is further supported by our recent study, whereas RNA−sequencing analysis revealed that pine honey affected the transcriptomic profile of P. aeruginosa by inducing the expression of 189 genes and by suppressing the expression of 274 genes [ 90 ]. Pine honey treatment exerted a broad range of action on several pathways and biological processes, including oxidative stress, transmembrane transport and regulation of DNA-templated transcription, two-component regulatory systems, ABC transporters and SOS response.…”

“…Pine honey treatment exerted a broad range of action on several pathways and biological processes, including oxidative stress, transmembrane transport and regulation of DNA-templated transcription, two-component regulatory systems, ABC transporters and SOS response. Interestingly, pine honey downregulates key physiological responses in P. aeruginosa such as quorum sensing, bacterial chemotaxis and biofilm formation [ 90 ].…”

In Vitro Antibacterial and Antibiofilm Activity of Hungarian Honeys against Respiratory Tract Bacteria

“…In the latter study, linden honey was one of the most effective honey samples against this bacterium, similarly to our findings. Another recent study revealed that multiple mechanisms of actions are responsible for the antibacterial activity of pine honey against P. aeruginosa , exerting an inhibitory effect on quorum sensing, bacterial chemotaxis and biofilm formation [ 76 ].…”

Combined Inhibitory Effect of Fir (Abies alba Mill.) Honeydew Honey and Probiotic Bacteria Lactiplantibacillus plantarum on the Growth of Salmonella enterica Serotype Typhimurium

“…Studies on the antibacterial activity of honeydew honeys reported superior antibacterial efficacy compared to nectar honeys, even stronger than manuka honey [ 2 , 3 , 4 , 5 ]. The antibacterial activity of honeydew honeys could be largely attributed to hydrogen peroxide formation [ 2 , 3 , 4 ].…”

“…Studies on the antibacterial activity of honeydew honeys reported superior antibacterial efficacy compared to nectar honeys, even stronger than manuka honey [ 2 , 3 , 4 , 5 ]. The antibacterial activity of honeydew honeys could be largely attributed to hydrogen peroxide formation [ 2 , 3 , 4 ]. However, results of recent research indicated that although hydrogen peroxide plays an important role in the inhibition of bacterial growth, phenolics and their interaction with hydrogen peroxide might be the key factors for the antibacterial activity of honeydew honeys [ 6 ].…”