Antibacterial effects of the Cu(II)-exchanged montmorillonite on Escherichia coli K88 and Salmonella choleraesuis.
The aim of this research was to determine the antibacterial properties and mechanisms of Cu(II)-exchanged montmorillonite (MMT-Cu) in vitro. Escherichia coli ATCC K88 and Salmonella choleraesuis ATCC 50020 were chosen as indicators of intestinal tract pathogenic bacteria in weanling pigs. The antibacterial activity of MMT-Cu and MMT were evaluated by determining the minimum inhibitory concentrations (MICs) using two-fold serial dilutions in MH broth, and the amount of Cu2+ released into the broth was measured by an atomic absorption technique. The rate of oxygen consumption was measured using a SP-II-type oxygen electrode analyzer; the structural integrity of cell walls of bacteria was observed by transmission electron microscope (TEM); enzymatic activity of bacteria was examined with a semi-automatic biochemical analyzer. The results showed that MMT-Cu inhibited the growth of E. coli K88 and S. choleraesuis, and the MICs were 1024 and 2048 microg/ml, respectively. The amount of Cu2+ released into the broth was in the range 6.51-45.65 microg/ml. Nevertheless, both tested bacteria still grew in broth containing 32,768 microg/ml of MMT. Treatment with MMT-Cu could lead to significant release of intracellular enzymes from the tested bacteria. Data from oxygen consumption of bacteria showed that MMT-Cu could inhibit the TCA pathway of the bacterial respiration metabolism. These results show that MMT-Cu has an antibacterial activity.
Tong
Guo
G
College of Aqua-life Science & Technology, Shanghai Fisheries University, Shanghai 200090, China. sxgtong@163.com
Yulong
Ma
M
Peng
Guo
G
Zirong
Xu
X
D000410:Alanine Transaminase / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001546:Bentonite / Q000493:pharmacokinetics / Q000494:pharmacology*; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D003300:Copper / Q000493:pharmacokinetics / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D012475:Salmonella / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D013054:Spectrophotometry, Atomic
D000900:Anti-Bacterial Agents; D001546:Bentonite; D003300:Copper; D007770:L-Lactate Dehydrogenase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase