Abstract
The in vitro effect of L-ascorbic acid on bacteria was investigated using a wide variety of bacteria (30 strains). In the presence of a trace level of Cu^<2+>, L-ascorbic acid exerted a strong killing effect on Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Proteus morganii, Proteus vulgaris, Pseudomonas phaseolicola, Salmonella typhimurium, Serratia marcescens and Staphylococcus aureus. It excerted a moderate effect on Brevibacterium lactofermentum and Lactobacillus plantarum. On the other hand, it excerted no effect on Bacillus cereus, Corynebacterium glutamicus, Lactobacillus casei, Micrococcus flavus and Sarcina lutea. Also, the effect of L-ascorbic acid on yeasts was investigated using selected yeasts (8 strains ). It excerted no effect on Hansenula anomala, Pichia membranaefaciens, Rhodotorula rubra, Saccharomyces cerevisiae, Saccharomyces rouxii, Schizosaccharomyces octospolus and Sporobolomyces salmonicolor. The results indicate that L-ascorbic acid exerts a killing effect on a number of bacteria, procaryotic cells, but do not exert a killing effect on yeasts, eucaryotic cells. There were little differences in the killing effect between L-ascorbic acid and D-isoascorbic acid. This indicates that the effect is independent of the stereoisomerism with inversion of the hydroxyl group at C-5 of ascorbic acids.
