Robusta coffee extracts inhibit quorum sensing activity in Chromobacterium violaceum and reduce biofilms against Bacillus cereus and Staphylococcus aureus

Abstract

Background and Aim: Bacillus cereus and Staphylococcus aureus cause foodborne intoxication in humans and animals. Pathogens can produce biofilms controlled by the quorum sensing system. The study aimed to investigate the antibacterial, antibiofilm, and anti-quorum sensing activities of Coffea canephora P. ex Fr. (Robusta coffee) extracts against B. cereus and S. aureus. Materials and Methods: Ethanol extracts of fruit peels and seeds of Robusta coffee were tested for antibacterial activity against B. cereus and S. aureus using a broth microdilution assay. Reduction of the biofilm formation and elimination of the viability of mature biofilm-grown cells of B. cereus and S. aureus were determined. Inhibition of quorum sensing activity in Chromobacterium violaceum by the extracts was investigated using the disk diffusion method and flask incubation assay. Results: Fresh fruit peel extract showed the strongest antibacterial activity against B. cereus and S. aureus with minimum inhibitory concentration (MIC) values of 2 and 4 mg/mL, respectively. However, the extracts did not inhibit Escherichia coli, avian pathogenic E. coli, and Pseudomonas aeruginosa at 8 mg/mL. Significant inhibition of biofilm formation at 1/2 × MIC of the fresh peel extract was detected in B. cereus (56.37%) and S. aureus (39.69 %), respectively. At 8 × MIC of the fresh peel extract, a significant elimination of the mature biofilm viability was detected in B. cereus (92.48%) and S. aureus (74.49%), respectively. The results showed that fresh and dried peel fruit extracts at 1/2 × MIC significantly reduced violacein production with the highest percentage inhibition ranging from 44.53 to 47.48% at 24 h (p ≤ 0.05). Conclusion: The results of the present study suggest the potential therapeutic benefits of Robusta coffee extracts in inhibiting the growth, biofilm, and quorum sensing of both B. cereus and S. aureus. The results put forward an alternative strategy to control the foodborne intoxications caused by both pathogens.

Antibacterial and antivirulence factor activities of protein hydrolysates from Phatthalung Sangyod rice (Oryza sativa L.) seeds against zoonotic and foodborne pathogens

“…We determined the inhibitory effect of SYPs against the QS activity of C. violaceum, a biomonitoring strain, using agar well diffusion and microtube incubation assay as described previously. The QS ability is indicated by the production of the violacein Available at www.veterinaryworld.org/Vol.16/October-2023/1.pdf pigment by the bacteria, resulting in violet-colored colonies [30].…”

“…The diameters of the anti-C. violaceum and QS inhibition zones were measured in mm and their mean and standard deviation (SD) were calculated. Each test was performed in three duplicates [30].…”

“…As the SYPs exhibited potent antibacterial efficacy, we evaluated their antibiofilm activity using the crystal violet test described by Tritripmongkol et al [30] with slight modifications. Briefly, bacteria were grown in TSB enriched with 1% glucose, incubated at 37°C for 12-18 h, and diluted to 2 × 10 6 CFU/mL.…”

“…The inhibitory activity of the SYPs was assessed by measuring the biofilm growth at an OD of 570 nm using a microtiter plate reader (Thermo Scientific, Singapore). The formula used to determine the relative percentage of biofilm formation is ([mean OD 570 nm of treatment well-OD 570 nm of negative control]/[mean OD 570 nm of growth control well-OD 570 nm of nega tive control]) × 100 [30]. The experiments were performed in triplicate.…”

Anatomical, pathological, and histological features of experimental respiratory infection of birds by biofilm-forming bacteria Staphylococcus aureus

“…The incidence of methicillin-resistant S. aureus (MRSA)-associated surgical infections is associated with long-term catheter use [5]. The pathogenesis of staphylococcal infections is mediated by virulence factors, such as enzymes, toxins, and biofilms, which increase the resistance of microorganisms that evade the host immune system [6].…”