Antibacterial Effects of the Cu(II)-exchanged Montmorillonite on Escherichia Coli K88 and Salmonella Choleraesuis

Vet Microbiol. 2005 Jan 31;105(2):113-22. doi: 10.1016/j.vetmic.2004.11.003. Epub 2004 Dec 19.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine Transaminase / metabolism
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / pharmacology*
  • Aspartate Aminotransferases / metabolism
  • Bentonite / pharmacokinetics
  • Bentonite / pharmacology*
  • Cell Wall / drug effects
  • Cell Wall / metabolism
  • Copper / pharmacokinetics
  • Copper / pharmacology*
  • Escherichia coli / drug effects*
  • Escherichia coli / enzymology
  • Escherichia coli / metabolism
  • L-Lactate Dehydrogenase / metabolism
  • Microbial Sensitivity Tests
  • Microscopy, Electron, Transmission
  • Oxygen Consumption / drug effects
  • Oxygen Consumption / physiology
  • Salmonella / drug effects*
  • Salmonella / enzymology
  • Salmonella / metabolism
  • Spectrophotometry, Atomic

Substances

  • Anti-Bacterial Agents
  • Bentonite
  • Copper
  • L-Lactate Dehydrogenase
  • Aspartate Aminotransferases
  • Alanine Transaminase