Antimicrobial activities of certain seaweeds from muddy shore places of kerala

Abstract

A study was carried out to reveal the growth inhibitory effect of methanol crude extract (MCE) and methanol supernatant extract (MSE) of sea weeds: 1) Gracillaria corticata, 2) Hypnea musciforms, 3) Gelidium micropterum and 4) Hypnea valentiae  against six bacterial pathogens, 1) Pseudomonas aeruginosa, 2) Bacillus licheniformis, 3) Serratia marcescens, 4) Aeromonas hydrophila, 5) Acinetobacter baumanii, 6) Escherichia coli and two fungal strains, 1) Aspergillus niger and 2) Candida albicans respectively. Well diffusion method using zone of inhibition as indicator for growth inhibition was adopted. The results showed that methanol extracts of seaweeds viz., Gracillaria corticata, Hypnea musciforms, and Hypnea valentiae prevented the growth of pathogenic bacteria and fungi. The effect on growth was observed as zone of inhibition, the diameter of which was indicated in the units of a millimeter. The growth of the bacterium, Serratia marcescens was affected by methanol supernatant extract of the three types of seaweeds, Gracillaria corticata, Hypnea musciforms, and Hypnea valentiae, and by the methanolic crude extract of Hypnea musciforms and Hypnea valentiae. However, the growths of other species of bacteria were not controlled by either of the extracts of the seaweeds except, Bacillus licheniformis which was controlled by only Gracillaria corticata. The growth of fungi: Aspergillus niger and Candida albicans were inhibited by the methanol extracts of Gracillaria corticata. Between the two forms of methanolic extracts i.e., supernatant and crude, the efficiency of the supernatant extract was greater than that of crude one. Further, among the three types of seaweeds which showed an effect on the growth of microbes, the level of the zone of inhibition caused by Gracillaria corticata was statistically higher than that of the other two, Hypnea musciforms, and Hypnea valentiae.