RGCs co-cultured with hNP or hNPTD exhibited similar survival rates

ing a given threshold, binds to the receptor RhlR and activates certain target genes, including the genes responsible for the production of pyocyanin, elastases, siderophores, and rhamnolipids. DHA biofilm formation is an additional QS-controlled activity in P. aeruginosa, even though biofilm formation in P. aeruginosa requires supplemental environmental signals along with QSregulated factors, such as rhamnolipids and siderophores, and swarming motility. Bacteria growing in biofilm mode exhibit altered phenotypes that safeguard them from therapeutic treatment. The rampant use of antibiotics to treat illnesses involving biofilms has resulted in the evolution of antibiotic-resistant microorganisms. Because of this microbial antibiotic resistance, effective treatments are scarce, and there is a need to identify new treatment strategies. In this regard, QS is an exemplary target because it regulates assorted virulence factors. Most QS inhibitors, both natural and PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19722344 synthetic, belong to a family of secondary metabolites known as furanones, which are structurally similar to AHLs PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19724269 and therefore bind to AHL receptors. However, QS inhibitors are incapable of activating AHL receptors. India has a wealth of ayurvedic medicines, and Indian people have long used ayurvedic herbs to treat contagions. Cinnamon is a dietary phytochemical that shows antimicrobial properties and is particularly significant given that dietary chemicals are deemed trustworthy and used habitually in daily life. Cinnamon is conventionally endorsed for treating digestive problems, including nausea, vomiting, and diarrhea. Cinnamon oil is also used in several toothpastes as an antimicrobial substitute. The objective of this study was to investigate the ability of cinnamon oil to inhibit QS-mediated virulence factors and biofilm formation in P. aeruginosa PAO1. Materials and Methods Bacterial strains and culture conditions This investigation used the bacterial strain Chromobacterium violaceum CV026, a double mini-Tn5 mutant derived from ATCC31352 containing KanR, which has been previously used to detect QS inhibitory activity. The strain was obtained from CECT, Spain. P. aeruginosa PAO1 was obtained from the MTCC, IMTECH, Chandigarh. GFP-tagged P. aeruginosa PAO1 and E. coli pJN105L pSC11 were kindly provided by Dr. Peter Greenberg of the University of Washington. Cinnamon oil, hexanoyl homoserine lactone, kanamycin, gentamycin, ampicillin, L-arabinose, and 3-oxo-C12HSL were purchased from Sigma Aldrich, India. AHL was dissolved in DMSO to obtain a stock solution of 0.5 mg/ml, and kanamycin was dissolved in MilliQ water to obtain a stock solution of 20 mg/ml. All strains were cultivated in Luria-Bertani medium and maintained at 37C, except for C. violaceum CV026, which was grown at 30C, and all strains were sub-cultured when the OD of the culture reached 1 at 600 nm. Tween-20 was used as a surfactant for the uniform distribution of oil. PVC coupons were sterilized using the method described by Borucki et al.. Determination of the Minimum Inhibitory Concentration of Cinnamon Oil The MIC of cinnamon oil against P. aeruginosa PAO1 was determined following the guidelines of the NCCLS, USA . Briefly, an overnight culture of P. aeruginosa PAO1 was grown for 24 h in LB medium mixed with different concentrations of cinnamon oil, ranging from 0.01 l/ml to 1.5 l/ml, in microcentrifuge tubes. The lowest concentration that completely inhibited growth was recorded as the MIC for cinnamon oil. Furth