Effects of garlic extract on cell wall of Corynebacterium glutamicum

The Corynebacterineae represent a distinct group within Gram-positive bacteria, with prominent members being the human pathogens Mycobacterium tuberculosis, Mycobacterium leprae, and Corynebacterium diphtheriae. A common feature of the Corynebacterineae is that they possess an unusual cell wall architecture rich in mycolic acids that is responsible for host pathogenesis and antibiotic resistance. The present study was carried out to evaluate the effects ofgarlic extract (GE) on the viability, cell wall ultrastructure and fatty acid composition of extractible lipids of Corynebacterium glutamicum. We found that C. glutamicum is inhibited by 44.25 mg ml(-1) GE. Observations by electron microscopy revealed that GE alters the cell wall. In addition, GE-treated bacteria (23.6 mg ml-1) showed an increase (from 6.9% to 18.8%) in the extractible lipids released. The fatty acid composition of these lipids was also significantly perturbed, especially C16:0, C18:0, C18:1 and C18:2. These data indicate that the integrity of the cell wall, the most effective target of antimycobacterial drugs, is affected by GE. This knowledge could contribute to improving the treatment of pathogenic Corynebacterineae.