OBJECTIVES: In the present study, an endophyte was isolated from the leaves of T. indica and screened for its antimicrobial potential.
METHODS: The selected endophyte was identified by 16s rRNA partial genome sequencing and investigated for their antimicrobial potency. The preliminary phytochemical tests were conducted for the affirmation of phytoconstituents in the endophytic crude ethyl acetate extract of T. indica (TIM) and total phenolic content was performed. The antimicrobial potential of TIM was evaluated against human pathogenic ATCC gram-positive and gram-negative bacterial strains.
RESULTS: TIM exhibited an appreciable amount of gallic acid equivalent phenolic content (21.6 ± 0.04 mg GAE/g of crude extract). TIM showed the Minimum Inhibitory Concentration (MIC) at 250 μg/mL and Minimum Bactericidal Concentration (MBC) at 500 μg/mL among the selected human pathogenic ATCC strains. At MIC of 500 μg/mL, TIM displayed a significant zone of inhibition against P. aeruginosa and N. gonorrhoeae.
CONCLUSION: The results from our study highlighted for the first time the antimicrobial potential of endophytic bacterial strain Bacillus velezensis in T. indica leaves and it could be further explored as a source of natural antimicrobial agents.
OBJECTIVES: Here, the efficacy of graphene oxide (GO), a carbon-based nanomaterial, was tested against the biofilms and intracellular S. aureus invitro. Following that, the mechanism for the intracellular antimicrobial activities and GO toxicities was elucidated.
METHODS: GO antibiofilm properties were evaluated based on the disruption of biofilm structure, and the intracellular antimicrobial activities were determined by the survival of S. aureus in infected bovine mammary cells following GO exposure. The mechanism for GO intracellular antimicrobial activities was investigated using endocytosis inhibitors. GO toxicity towards the host cells was assessed using a resazurin assay.
RESULTS: At 100 ug/mL, GO reduced between 30 and 70% of S. aureus biofilm mass, suggesting GO's ability to disrupt the biofilm structure. At 200 ug/mL, GO killed almost 80% of intracellular S. aureus, and the antimicrobial activities were inhibited when cells were pre-treated with cytochalasin D, suggesting GO intracellular antimicrobial activities were dependent on the actin-polymerization of the cell membrane. At
METHODS: The antimicrobial activity was tested against the planktonic S. aureus cells using the microdilution broth assay, while the antibiofilm activity were evaluated using the crystal violet and resazurin assays. The cytotoxicity of the SBDs was assessed on MRC5 (normal lung tissue), using the MTT assay.
RESULTS: The individual SBDs showed significant reduction of biomass and metabolic activity in both S. aureus strains. Combinations of the SBDs with OXA and VAN were mainly additive against the planktonic cells and cells in the biofilm. Both the compounds showed moderate toxicity against the MRC5 cell line. The selectivity index suggested that the compounds were more cytotoxic to S. aureus than the normal cells.
CONCLUSION: Both the SBD compounds demonstrated promising antimicrobial and antibiofilm activities and have the potential to be further developed as an antimicrobial agent against infections caused by MRSA.