RESULTS: P. acidilactici Kp10 was moderately tolerant to phenol and adhere to mammalian epithelial cells (Vero cells and ileal mucosal epithelium). The bacterium also exhibited antimicrobial activity against several gram-positive and gram-negative food-spoilage and food-borne pathogens such as Listeria monocytgenes ATCC 15313, Salmonella enterica ATCC 13311, Shigella sonnei ATCC 9290, Klebsiella oxytoca ATCC 13182, Enterobacter cloaca ATCC 35030 and Streptococcus pyogenes ATCC 12378. The absence of haemolytic activity and proteinase (trypsin) and the presence of a strong peptidase (leucine-arylamidase) and esterase-lipase (C4 and C8) were observed in this LAB strain. P. acidilactici Kp10 also produced acid, coagulated milk and has demonstrated proteolytic and amylolactic activities.
CONCLUSION: The properties exhibited by P. acidilactici Kp10 suggested its potential application as probiotic and starter culture in the food industry.
RESULTS: The resazurin-based TB assay demonstrated that the L. cuprina larval extract was inhibitory against all tested bacteria, whilst the larval extract of S. peregrina and M. domestica were only inhibitory against the MRSA, with a MIC of 100 mg ml(-1). Subsequent sub-culture of aliquots revealed that the larval extract of L. cuprina was bactericidal against MRSA whilst the larval extracts of S. peregrina and M. domestica were bacteriostatic against MRSA. The GC-MS analysis had quantitatively identified 20 organic compounds (fatty acids or their derivatives, aromatic acid esters, glycosides and phenol) from the larval extract of L. cuprina; and 5 fatty acid derivatives with known antimicrobial activities from S. peregrina and M. domestica.
CONCLUSION: The resazurin-based turbidometric assay is a simple, reliable and feasible screening assay which evidently demonstrated the antibacterial activity of all fly larval extracts, primarily against the MRSA. The larval extract of L. cuprina exerted a broad spectrum antibacterial activity against all tested bacteria. The present study revealed probable development and use of novel and effective natural disinfectant(s) and antibacterial agent(s) from flies and efforts to screen more fly species for antibacterial activity using resazurin-based TB assay should be undertaken for initial screening for subsequent discovery and isolation of potential novel antimicrobial substances, particularly against the multi-drug resistant strains.
METHODOLOGY: Qualitative phytochemical analysis was firstly carried out to determine the possible active compounds in P. betle leaves methanolic extract. The antibacterial activities of major compounds from this extract against nine fish pathogenic bacteria were then assessed using TLC-bioautography agar overlay assay and their quantity were determined simultaneously by HPLC method.
RESULTS: The use of methanol has proved to be successful in extracting numerous bioactive compounds including antibacterial compounds. The TLC-bioautography assay revealed the inhibitory action of two compounds which were identified as hydroxychavicol and eugenol. The $-caryophyllene however was totally inactive against all the tested bacterial species. In this study, the concentration of hydroxychavicol in extract was found to be 374.72±2.79 mg g-1, while eugenol was 49.67±0.16 mg g-1.
CONCLUSION: Based on these findings, it could be concluded that hydroxychavicol and eugenol were the responsible compounds for the promising antibacterial activity of P. betle leaves methanolic extract. This inhibitory action has significantly correlated with the amount of the compounds in extract. Due to its potential, the extract of P. betle leaves or it compounds can be alternative source of potent natural antibacterial agents for aquaculture disease management.