A scanning electron microscopic method for the study of bacterial growth inhibition by the paper disc method

We previously found an inverse correlation between the number of bacteria and the number of fungi collected throughout the year from tatami mats in judo halls. Antibacterial substances produced by the fungi are presumably responsible for the decline in bacterial populations. Culture extracts from fungi isolated from the tatami mats were prepared and their antibacterial activity against Micrococcus luteus, Staphylococcus warneri, and Bacillus subtilis isolated from the mats was determined by the paper disc method. For all 3 bacteria, clear inhibitory zones were obtained indicative of the presence of a growth inhibitory compound in the fungal culture extract. A sampling method was developed for the scanning electron microscopic observation of bacteria around the inhibitory zones produced by the fungal culture extract. Using this method, changes in the surface microstructures of bacteria existing inside the inhibitory zone and growth region were successfully compared by scanning electron microscopy. © 2011 The Japan Mendel Society