Antagonistic Effects of Lactobacillus against Helicobacter pylori in a Gel Stabilized Glucose - Gradient System

Helicobacter pylori is a gram-negative bacterium inhabits the gastric mucosa and may remains there for a long period. It causes gastritis and ulcer. Recently, antibiotics are widely used to treat the infections caused by Helicobacter pylori but other means of treatment such as Probiotic (using live organisms such as Lactobacilli) can be considered. Therefore in this study antagonistic effects of two species of Lactobacillus against Helicobacter pylori under the laboratory condition are investigated. In this study a gel stabilized system was used. This system consisted of two phases solid layer (10 ml peptone yeast extract salt solution plus 1.5% agar and 2% glucose) at the bottom and a semi layer (10 ml PYES plus 0.75% agar and 1.5 × 107 washed bacterial cell /ml) at the top in 30 ml screw test tubes. Lactobacilli and Helicobacter pylori were used as pure and mixed in the upper phase of the above system. After incubation at 37 ºC for different time intervals, samples were withdrawn from the semisolid layer using sterilized steel corkscrew and sectioned. The bacterial population, optical density, pH and glucose concentration of the medium were measured at the various depths. All bacteria had a condensed band of growth in the special places of semisolid. Growth appearance (growth band) viable count, optical density, pH in the mixed culture of Lactobacillus plantarum and Helicobacter pylori were like the pure culture of Lactobacillus plantarum. However, mixed culture of Lactobacillus casei and Helicobacter pylori was similar to that of pure culture of Helicobacter pylori. Regarding the results of this study Lactobacillus plantarum inhibited the growth of Helicobacter pylori in the mixed culture. This may be due to possible production of organic acids like lactic acid and bacteriocins, but Lactobacillus casei could not inhibit the Helicobacter pylori’s growth. Therefore, Lactobacillus plantarum has antagonistic effect against Helicobacter pylori under in vitro condition and it can be a good choice for the probiotic purposes against Helicobacter pylori infections for in vivo investigations.