Authors

Jeselle R. Kiroquero

Author

College of Science and Environment, Mindanao State University at Naawan, 9023 Naawan, Misamis Oriental

*Corresponding author: [email protected]

ABSTRACT

The search for alternative sources of antibiotics from marine organisms has been motivated by the exhaustion of traditional sources which are mostly terrestrial plants. This study focuses on analyzing crude extract from Padina japonica, a brown seaweed, for any bioactive compounds that can inhibit bacterial growth. Crude extracts were prepared separately from blade and holdfast parts of Padina using four types of solvents, namely, acetone, methanol, ethanol and seawater. These extracts were added to each of the clinical strains of bacteria, namely, Escherichia coli and Staphylococcus aureus grown on nutrient agar plates, incubated overnight and the zone of bacterial inhibition measured. Crude extract obtained using acetone showed a higher bacterial activity (mean MI = 0.372) than those using other solvents, although differences were not significant (P>0.05). Antimicrobial activity of the acetone extract was higher on E. coli (MI= 0.472) than on S. aureus (MI = 0.271). Crude extract from Padina blades exhibited higher microbial activity than holdfast extract. The strength of antibacterial activity of the crude blade extract was compared with that of a commercial antibiotic, chloramphenicol, as control. Results showed that the minimum inhibitory concentration (MIC) of the blade extract has a breakpoint of 250 μl for E. coli and 500 μl for S. aureus, while chloramphenicol has a breakpoint of 10 μg ml-1 and 30 μg ml-1, respectively for the two test bacteria. Despite the difference in concentrations, there is no significant difference (P>0.05) between the antibiotic and the crude extract in terms of inhibiting the two test bacteria. Thus, either the commercial antibiotic or the crude extract of P. japonica can be used to inhibit bacterial growth.