Investigation of the probiotic properties of bacterial strains from two probiotic drinks and their survivability in artificial gastric juice ABSTRACT: Two probiotic drinks were investigated in vitro to test their ability to survive acidic conditions and their probiotic factors. Both the products: Actimel and Yakult contain gram-positive bacteria, but Actimel also has a gram-negative bacteria. The ability to survive was investigated by adding artificial gastric juice to the products and incubating at different times. Actimel and Yakult were both able to survive the gastric juice. Actimel produced more colonies than Yakult but they both lost the same percentage of viability. The longer the time incubated the more the loss of viability. Introduction:
In recent years health promoting functional foods has entered the global market as a result of increased prevalence of lifestyle related diseases (A. A. Aramide et al, 2009). People use functional foods and diet to maintain optimal health. Consumption of probiotics is one of the ways someone could reach and maintain their optimal health. A probiotic is “living microorganisms, which upon ingestion in certain numbers, exert health benefits beyond inherent basic nutrition” (Todd R. Klaenhammer, 2000). According to the WHO/FAO report 2001 these probiotics can help prevent disorders associated with the gastrointestinal tract, diarrhoea caused by certain pathogenic bacteria and viruses, inflammatory diseases, allergies and a lot more. Actimel and Yakult is a couple of the said probiotic drinks. They claim to increase your body’s natural defences by fighting off the “bad” bacteria. Actimel is a yogurt-type drink produced by a company called Danone™. It has three strains of bacteria, two traditional yoghurt cultures: Lactobacillus bulgaricus and Streptococcus thermophiles and a third one called L. casei Imunitass® (http://www.actimel.co.uk/About/-WhatIsActimel.aspx, Accessed Feb, 28, 2010). Lactobacillus is a genus of bacteria that aid in the conversion of lactose to lactic acid hence increasing acidity in the stomach making it hard for harmful bacteria to survive (http://en.wikipedia.org/wiki/Lactobacillus, Accessed Feb 28, 2010). Actimel contains 10 billion L. casei Imunitass® bacteria per 100ml bottle. This bacterial strain works under a wide range of pH and temperature hence able to survive the acidic conditions in the stomach. This ensures that the bacteria reach the gut alive and active. It helps by topping up the good bacteria in the stomach and making it hard for the germs to survive. The bacteria also aids in strengthening the gut wall so that only certain nutrients can pass. In 2004 a trial carried out to find the effect of Actimel on the immune response of subjects under academic examination stress showed that Actimel was able to control the number of lymphocytes and CD56 cells in subjects under academic examination stress. Other studies also show that the Actimel bacterial strains can be used in treating allergic rhinitis, prevention of diarrhoea and induce immune responses. On the other hand Yakult is milk based probiotic and contains only one strain of bacteria: Lactobacillus casei Shirota. It is produced and distributed by Yakult Honsha Co. Ltd. It contains 6.5 billion L.casei Shirota per 65ml bottle. A variety of scientific studies have shown that Yakult has an effect on the human NK-cell activity, intestinal micro flora and immune parameters in humans. As a guideline a probiotic microorganisms should be resistant to gastric juices and be able to grow in the presence of bile under conditions in the intestines. The aim of this experiment is to measure the survivability of the strains in artificial gastric juice and to identify the bacterial strains said to be in the product. MATERIALS AND METHODS:
Firstly the bacteria were heat fixed according to the instruction in the lab manual. After heat fixing, crystal violet stain was added to the bacteria for 2...
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