Antimicrobial Effects of Crude Bromelain Extracted from Pineapple Fruit (Ananas comosus (Linn.) Merr.).

Abstract

The study assessed the antimicrobial activity of crude bromelain extracted from pineapple fruit (Ananas comosus L.) on some microorganisms isolated from fresh and overnight meat at different temperatures and pH. Bromelain was extracted from pineapple fruit by homogenizing in cold phosphate buffer solution. Crude bromelain was estimated by Bradford method and the enzyme was assayed by the casein digestion method. Six bacteria namely, Proteus spp, Corynebacterium spp, B. subtilis, S. pyogenes and two different strains of E. coli., were isolated and identified by the conventional methods. The antimicrobial activity of crude bromelain was determined by the disc diffusion method. One strain of E. coli had the highest zone of inhibition (24.00±1.53mm) at 25°C, but the other strain was resistant. Corynebacterium spp was the least inhibited of all the organisms with 8.33±0.33mm zone of inhibition at 37°C and 45°C. Proteus spp was inhibited, but the effect was not temperature dependent. B. subtilis and S. pyogenes were resistant to the crude extract at all temperatures tested in neutral pH media. B. subtilis, S. pyogenes, and E. coli were totally inhibited at pH 10.0. The crude enzyme exhibited better activity against Proteus spp. at pH 10.0, but failed to inhibit the growth of Corynebacterium spp. Crude bromelain seems to be more effective in inhibiting gram positive bacteria than gram negative. Crude bromelain may be an effective antimicrobial agent against E. coli and Proteus spp.