Utilizing Nordic Forest Plant and Fungi Extracts: Bioactivity assessment with bacterial whole-cell biosensors
|Tila||Julkaistu - 29 huhtikuuta 2020|
|Nimi||Tampere University Dissertations|
Efficient methods are needed in the search for novel biologically active components from natural sources. Bacterial whole-cell biosensors offer a less-examined alternative with high sensitivity. In this thesis, forest-derived extracts were screened for their bioactivity with bacterial whole-cell biosensors and complementary measures, such as antioxidant microplate tests. The main metabolites were also identified from endophytic fungi extracts using liquid chromatography-mass spectrometry (LC-MS). Two novel applications of biosensors are described for Escherichia coli whole-cell biosensors. The first application provides an improved antioxidant method via increased high-throughput screening potential and the other describes a method for measuring the UV protection capacity for both the biological and absorbance-based shield. There is also an opportunity to obtain simultaneous information of the genotoxicity of the sample. The methodologies were validated using reference compounds and were found to be usable in the field of forest-derived extracts with certain limitations. The bacterial biosensors were used in an activity/inactivity type of screening. By using small concentrations of forest-derived extracts or fractionated samples, the limitations, such as possible sample matrix masking effect and induction delay phenomenon, can be reduced. Endophytic fungi live asymptomatically inside a plant host and are often beneficial for the host plant growth and stress resistance. They comprise a large untapped source of potential bioactive compounds to be utilized for different purposes. Many metabolites (318) were discovered using an LC-MS methodology from Acephala applanata, Phialocephala fortinii and Humicolopsis cephalosporioides/ Coniochaeta mutabilis isolated from the roots of Scots pine seedlings. Out of the metabolites, 220 were identified with varying degree of certainty. The antioxidant and antimicrobial potential of the extracts and fractions were screened with the biosensors and complementary methods and various bioactivities were discovered. In conclusion, endophytic fungi are a rich source of potential functional metabolites and whole-cell biosensor methodologies are usable for nature-based samples and provide valuable insights into both the bioactivity and bioavailability of the material, if their limitations are also considered.