In vitro study of probiotic bacteria in lowering serum cholesterol level by bile salt hydrolase activity
Thailand (IFMSA-Thailand) - Faculty of Medicine, Srinakharinwirot University, Bangkok
Assistant Professor Dr. Malai Taweechotipatr
Assistant Professor Dr. Malai Taweechotipatr
English, Thai
4 weeks
Cities/Months Jan Feb Mar Apr May Jun Jul Augt Sep Oct Nov Dec
No No No No No No Yes Yes Yes No No No
Type of Research Project
- Basic science
What is the background of the project?
Probiotics are live microorganisms which confer a health benefit on the host. One of the most significant groups of probiotic organisms are the lactic acid bacteria, such as Lactobacillus, Bifidobacterium, Enterococcus, which are commonly used in fermented foods and probiotic products. Hypercholesterolemia is one of the risk factors of atherosclerosis, a chronic disease with more than 400,000 cases annually in Thailand. Some lactic acid bacteria are beneficial bacteria as they can reduce cholesterol level by producing the bile salt hydrolase enzyme. This enzyme cannot be produced by human but can be produced in some bacteria. Deconjugation of bile acid has been related to the reduction of serum cholesterol levels. The objective of this study is to isolate and characterize the production of bile salt hydrolase enzyme of lactic acid bacteria in order to analyze their activity in lowering the serum cholesterol level. The candidate strains, isolated from Thai fermented food products, will be studied on their probiotic properties and molecular identification.
What is the aim of the project?
To isolate lactic acid bacteria from Thai fermented food products and investigate their bile salt hydrolase activity. The candidate strains will be studied on their probiotic properties and molecular identification.
What techniques and methods are used?
The techniques that will be used in this study include Bacteriological technique, Biochemical technique, Tissue culture technique and Molecular technique. The tools that will be used are Autoclave, Laminar flow, Spectrophotometer, Incubator, Centrifuge, Microscope, PCR (Polymerase Chain Reaction) and Gel electrophoresis. Steps and stages are as described below. 1. Bacterial isolation by using streak or spread plate technique in order to see the colonies and be able to select the lactic acid bacteria ones out. 2. Gram staining to find the gram-positive bacilli. 3. Characterization by using catalase to make sure that the selected bacteria are truly gram-positive lactic acid bacteria. 4. Bile salt hydrolase test to see if the selected bacteria can produce the enzyme or not by using spot method and TDCA (taurodeoxycholate) as substrate for the enzyme. 5. Genotypic identification to detect 16SrRNA gene sequence which will help to identify the species of bacteria.
What is the role of the student?
- The student will observe the practical experiments but will be highly involved in the analysis of the results
- If the project includes “lab work”
- the student will take active part in the practical aspect of the project
- The tasks of the student will be performed on his/her own
- The tasks will be done under supervision
What are the tasks expected to be accomplished by the student?
The student will both observe and learn all the processes, as described in steps/stages, under supervision from the project advisor and PhDs students. Following the techniques and tools that are used in this project, as mentioned above, the student should gain the basic knowledge of how to use the machines and be able to do bacterial culture, gram staining and microscope, molecular technique, and bioinformatics. The student will be expected to do lab work which are bacterial media preparation, gram staining, bacterial isolation, sterilize technique, bacterial characterization technique, bacterial preservation technique, bacterial DNA extraction, PCR, 16S rRNA sequence, BLAST (Basic Local Alignment Search Tool) sequence analysis, species identification, phylogenetic tree construction and write lab report. Moreover, the student will be taught how to design and conduct an experiment by themselves. However, the scientific report and poster will not be necessary unless he/ she wants to have one in order to give a presentation about their work.
Will there be any theoretical teaching provided (preliminary readings, lectures, courses, seminars etc)
The student will learn and practice through the processes, and also will be given some teachings by project advisor and PhD students.
What is expected from the student at the end of the research exchange? What will be the general outcome of the student?
- The student’s name will be mentioned in a future publication
- The student will have the opportunity to present the results together with the supervisor at a conference
- No specific outcome is expected
What skills are required of the student? Is there any special knowledge or a certain level of studies needed?
Cell culture, Gram staining, PCR
Are there any legal limitations in the student’s involvement
Type of students accepted
This project accepts:
- Medical students
- Graduated students (less than 6 months)
- Pre-Medical students from the American-British system
- Students in biomedical fields
- 1. Sirichotinun N; Pachekrepapol U; Nantavisai K; Taweechotipatr M; Nilwarangkoon S. Probiotic characterization and in vitro cholesterol lowering effects of lactic acid bacteria isolated from Thai healthy infants. Songklanakarin Journal of Science and Technology [Internet]. 2018 [cited 2019 Oct 5]. Available from:
- 2. Jones ML; Tomaro-Duchesneau C; Martoni CJ; Prakash S. Cholesterol lowering with bile salt hydrolase-active probiotic bacteria; mechanism of action; clinical evidence; and future direction for heart health applications. Expert Opinion on Biological Therapy. 2013 May; 13(5): 631-42. doi: 10.1517/14712598.2013.758706.