Effects Of Rare Earth On Structure Of Cell Wall In Bacillus Subtilis

This research investigates the effect of rare earth ion on spore wall structure of bacillus subtilis using infrared spectrometry (IR), atomic force microscopy (AFM), scanning electron microscope(SEM), amino acid analysis and HR-MAS. The experimental results were achieved as following.1. The minimum bacteria-inhibiting concentration and minimum bactericidal concen- tration were measured for four salts.2. The IR tests showed that rare earth ions in the concetration higher than the minimum bacteria-inhibiting concentration destroyed a majority of peptide bond of the spore wall. Such damage effect wass proportional to the concentrate of the rare earth ions. The higher the concentrate was, the stronger the damage was.3. The SEM observation also revealed that the rare earth ion in the concetration higher than the minimum bacteria-inhibiting could rupture the structure of the spore. The spore wall was broken and the inner substances overflew. The higher concentration was, the more seriously spoiled the structure of the spore wall was.4. There was Er element in the inclusion of cell wall and spillage of spore according to the SEM observation.5. When the rare earth below the bacteria-inhibiting concetration was added, it made the amino acid content in the peptide polyose to increase which can promote to synthesize the spore wall. When the rare earths at the the bacteria-inhibiting and bactericidal concetrations were added, the content of peptide in the spore wall decreased, about 2-3 times fall.6. The roughness of spore surface was observed using AFM. The rare earth below the bacteria-inhibiting concetration made the spore surface rougher, while the rare earth at the bacteria-inhibiting concetration made the spore surface flater.7. The ~1H,HR-MAS spectrum measurement proved that The rare earth below the bacteria-inhibiting concetration made the net structure of peptidoglycan in spore deanser and the molecule bigger, while the rare earth at the bacteria-inhibiting concetration made the peptidoglycan to be broken to small pieces.We conclude that the rare earth ion in the concetration higher than the minimum bacteria-inhibiting could rupture the structure of the spore wall. The higher concentration was, more damage was. The rare earth can enter the spore and participate in the metabolized process of spore. All results from amino acid measurement, AFM and HR-MAS test show that the rare earth in lower concentration can promote the synthesis of the spore wall, while rare earth in higher concentration can inhibit the synthesis of the spore wall;The higher the concentration is, the stronger the inhibiting effect is. The one of inhibiting mechanism of rare earth iron on the bacillus subtilis is that rare earth iron can inhibit and destroy the spore wall.