The Effect Allium sativum (Garlic Extract) as Prebiotic Substance on the Activity of Probiotic Bacteria Lactobacillus acidophilus against Some Locally Isolates of Pathogenic Bacteria

Abstract

The aim of this study was to improve the growth and inhibitory activity of the selected Lactobacillus isolate. A total of twenty samples of dairy products (fresh yogurt) were collected. Seven isolates of Lactobacillus species. were obtained, and identified as three Lactobacillus fermentum, three Lactobacillus acidophilus and one of Lactobacillus brevis. The growth of lactobacillus acidophilus was counted, also inhibitory activity of Lactobacillus acidophilus against some pathogenic bacteria such as (Salmonella typhimurium and Pseudomonas aeruginosa) was tested on solid medium (nutrient agar) for two different incubation periods before the addition of Allium sativum (garlic extract) as prebiotic substances. To improve the growth and inhibitory activity of the selected isolate (Lactobacillus acidophilus), three different concentrations (10, 20, 30 %) v/v of it were used by addition of it to De Man, Rogosa and Sharpe agar (MRS) medium as prebiotic substances, and two incubation periods (24, 48) hour. The effect of Allium sativum (garlic extract) on the growth of probiotic bacteria was evaluated, measurement of Lactobacillus acidophilus growth curve was done after and before adding garlic extract. For analyzing inhibitory activity of Lactobacillus acidophilus with the Allium, results showed that Lactobacillus acidophilus propagated in MRS fortified with 20% and 30% v/v garlic extract with incubation period 24 hr compared to propagating of Lactobacillus acidophilus in MRS alone, by giving the highest inhibition zone. It was concluded that Lactobacillus acidophilus isolate can grow well and exhibit good effect against Gram-negative bacteria in a medium containing garlic extract (that is added as a substrate supporting probiotic growth and activity). also it was clear that filtrate of Lactobacillus acidophilus isolate that propagating in spesific broth fortified with 20% garlic extract at 48 hr incubation period produce antibacterial effect better than 10% but as same effect as in 30% against pathogenic bacteria, From above results it was concluded that prebiotic treatment enhance the growth of Lactobacillus acidophilus especially at 24 hr. this may due to fructooligosaccharide content in garlic have the best effect on the growth of Lactobacillus. acidophilus bacteria, but less effect was observed after 48 hr incubation period, and also when propagated in MRS without prebiotic treatment, and which may due to highly decrease in pH (less than 3) and this may cause inhibition the growth of Lactobacillus acidophillus cells and hydrolysis of its cells.