Preliminary biochemical investigation of bioactive compounds and antibiofilm activity of Ocimum gratissimum against food-borne microorganisms

ABSTRACT The present study was aimed to investigate the antibiofilm activity and bioactive compounds in Ocimum gratissimum on bacterial strains of Staphylococcus aureus and Pseudomonas aeruginosa. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum biofilm inhibitory concentration (MBIC) was carried out on the aqueous, ethanol and methanol extracts. The bioactive components of plant extracts were investigated using Gas Chromatography-Mass Spectrometry (GC-MS). S. aureus was more susceptible to the extracts than P. aeruginosa. The biofilm of S. aureus showed more susceptibility to the extracts of Ocimum gratissimum compared to that of P. aeruginosa. The ethanol extract exhibited greater activities against all test organisms than the methanol and aqueous extracts with MIC and MBC values <1 mg/ml; and MBIC values > 1 mg/ml with a biofilm inhibition of 61.70% and 43.14% for S. aureus and P. aeruginosa, respectively. None of the extracts was able to disrupt the growth of preformed biofilm by at least 50%. The ethanol and aqueous extracts inhibited biofilm formation in S. aureus but not P. aeruginosa. The methanol and aqueous extracts enhanced biofilm growth in P. aeruginosa while ethanol extract showed negligible activity against biofilm of P. aeruginosa. GC-MS analysis of ethanol extract of Ocimum gratissimum revealed the presence of fourteen compounds with oleic acid (21.11%) as the dominant compound, followed by n-Hexadecanoic acid (20.13%), squalene (16.82%) and z-2-Octadecen-1-ol acetate (11.53%). The antibiofilm activity of the plant could be used for the extension of the shelf-life in processed foods and against microorganisms both in locally made foods.