Investigating the effect of ‘probiotic’ yoghurt drinks on intestinal health - page 2
Keywords: probiotic stomach conditions bacteria dillution and plating series experiment bifidobacteria
By xbryonyx on 13/02/2007
Level: A Level (Year 12) / AS Level
Page Number: 2 of 3 pages: 1 2 3acidic environment kills most bacteria that enter the digestive tract through the mouth (4) and bearing in mind ingested material remains in the stomach for 2-6 hours it would seem unlikely that any of the 6.5 billion per bottle (3) ‘Bifidus Digestivum’ could survive or at least too few to make any significant difference.
References
(1) www.wikipedia.com
(2) www.bifidusdigestivum.com
(3) www.yakult.co.uk
(4) www.healthline.com
Hypothesis
My hypothesis would be that due to the highly acidic conditions in the stomach evolved to prevent the passage of bacteria through it, very little, if any ‘Bifidus Digestivum’ would pass into the intestine and so no significant improvement to health would be apparent.
Materials and Methods
For the investigation I will attempt to artificially replicate the stomach conditions. I will use a container with a volume of roughly 2 litres as this is the average size of an adult stomach with about 700 mls Hydrochloric Acid (HCl) as this is the amount of gastric juice normally secreted per meal. This container will be kept at a temperature of 37 degrees Celsius and a PH of 2-3 so replicating the natural environment. I will use a varied number of ‘bifidus digestivum’ and place these into the container, ensuring no other bacteria contaminate the experiment. I would then leave the container for 4 hours as this is the average time the bacterial solution would spend in the stomach. I would then use the method of dilution and plating to obtain a manageable amount of bacteria in order to count how many bacteria remained. In order to do this I will use a clean, sterile, dry pipet to remove 0.1 ml from the bacteria sample and blow it into the 9.9 ml of dilution fluid in tube #1 and mix thoroughly by blowing lots of bubbles with the pipet for a couple seconds. (giving 1/100 the concentration of bacteria in the original sample because 0.1 ml is 1/100 of 10 ml.) I will then use another clean, sterile, dry pipet to remove 0.1 ml from Tube 1, wipe pipet, blow contents of pipet into Tube 2, continue blowing bubbles for a second or two for good mixing. Then, using another clean, sterile, dry pipet remove 0.1 ml from Tube 2, wipe, blow contents of pipet into Tube 3, continue blowing bubbles for a second or two for mixing. I will then plate 0.1ml from Tube 3. Then, however many bacteria colonies grow in the petri plate
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