In vitro growth-inhibitory effect of stimulant beverages against intestinal bacteria associated with colorectal cancer

Kateřina Čerňanská

Bachelor's thesis

Abstract:

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. Its development depends on individual attributes such as age, healthy diet, habits, and lifestyle. Recently, there is rising evidence that specific bacteria play a significant role in the colorectal tumour microenvironment. Although currently available treatments such as chemotherapy, surgery, radiotherapy, and faecal microbiota transplantation are quite effective, further research in the area of prevention of the disease is still needed. Since stimulant beverages are largely consumed worldwide (coffee and tea consumption of all non-alcoholic beverages was 4.38% in 2022) and their antibacterial effects are already proven by some studies, we decided to evaluate the in vitro effects of these beverages on the growth of representatives of bacterial pathogens associated with CRC risk. In this thesis 6 representatives of stimulant beverages, namely Aspalathus linearis, Camellia sinensis var. sinensis, C. sinensis var. asamica, Coffea arabica, C. canephora and Ilex paraguariensis were tested against 6 pathogenic bacteria by broth microdilution method. As a result, all samples of stimulant beverages produced no inhibitory activity (MIC > 512 µg/ml) against Bacteroides fragilis, Clostridium septicum, Escherichia coli, Fusobacterium necrophorum, Peptostreptococcus anaerobius and Streptococcus bovis. For this reason, we decided to use bacterial growth kinetics but only E. coli and S. bovis were used for this method. From the growth lag phase duration measurement, it was found that the concentration 512 µg/ml of I. paraguariensis significantly inhibited the growth of E. coli ATCC 25922. On the other hand, A. linearis, C. arabica and C. canephora showed significant supportive growth effect of E. coli at concentrations 64, 128 and 256 µg/ml respectively. In general, the effects of stimulant beverages were much more significant on E. coli growth than on S. bovis. These results represent experimental background for future studies focused on monitoring of the effect of foods and beverages on growth of bacteria associated with CRC.

Keywords

colorectal cancer, stimulant beverages, intestinal bacteria

Language used: English

Date on which the thesis was submitted / produced: 17. 4. 2023

Thesis defence

• Date of defence: 26. 5. 2023
• Supervisor: prof. Ing. Ladislav Kokoška, Ph.D.
• Reader: Matěj Božik, Ing.

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Bachelor programme:
Tropical Agriculture