Cinnabarin Production in Pycnoporus Cinnabarinus in Dependence of Medium Composition, Temperature and Light Conditions
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Cinnabarin production in Pycnoporus cinnabarinus in dependence of medium composition, temperature and light conditions To obtain the academic degree Master of Science (MSc) Presented at the Leopold Franzens University of Innsbruck, Institute of Microbiology Under supervision of Mag. Dr. Pamela Vrabl and Dr. Bianka Siewert Submitted by Gaja Spes, BSc Innsbruck, Juni 2021 Abstract Fungal secondary metabolites are considered as a significant part of scientific studies since decades. They possess a multitude of functions, i.e. antibacterial, antifungal or/and antitumor effects, which may play an important role in pharmacy and biotechnology. Due to the negative effect of conventional forms of cancer therapy (chemo – and radiotherapy), the alternative, photodynamic therapy could be an opportunity to selectively remove malignant tissue by the effects of reactive oxygen species (ROS). PDT as treatment form requires a light-activated drug, which under irradiation produces ROS and thus induces cell death in the malignant tissue. Several light-activated natural drugs are known, and recently it was proposed that fungal pigments could be a yet unexplored source for new light-activated drug-like compounds. One pigment of potential interest is cinnabarin, the orange-red colour of the fruiting bodies by all members of the genus Pycnoporus. Cinnabarin belongs to the phenoxazone alkaloids, which in turn are characterized by interesting photochemical activities. In preliminary studies, an extract of P. cinnabarinus was shown to be photo-active. Thus the hypothesis was established that cinnabarin could be a biotechnologically produced light-activated drug-candidate from a wood-decaying fungus. The aim of this master thesis was the extraction and isolation of the secondary metabolite –cinnabarin from the agar media grown P. cinnabarinus. To trigger fungal secondary metabolite production, it is of vital importance to investigate the fungal morphology and physiology, which is affected by the cultivation factors – i.e. cultivation media, incubation temperature, and light. Consequently, another aim was to find the optimal conditions for cinnabarin production, and to study the influence of nutritional media, temperature and light on a smaller scale . Firstly the preliminary testing of three P. cinnabarinus strains and three various solid agar media - PDA, MEA, 2% SDA in dark and light conditions was performed. The results led to the selection of one strain and two media for further investigation with various LED lights (blue, red, white). Moreover, a successful morphological and physiological characterisation of all studied P. cinnabarinus strains was conducted. The results showed a great dependence of cinnabarin production on media composition, temperature and light. The cinnabarin production was triggered mostly on PDA and MEA agar media under constant radiation at wavelengths around 464 nm (blue light) and under daylight irradiation conditions (white light). A clear inhibitory effect in the cinnabarin production was noted with red light and in darkness, as well as with a higher incubation temperature of 30 °C. Table of content Abstract ..................................................................................................................................................... Table of content ....................................................................................................................................... i List of abbreviations ................................................................................................................................ iii List of figures ............................................................................................................................................ v List of tables ........................................................................................................................................... vii 1. Introduction ....................................................................................................................................... 1 1.1 Basidiomycota of genus Pycnoporus .......................................................................................... 1 1.1.1 The genus Pycnoporus .......................................................................................................... 2 1.2 Photodynamic therapy ................................................................................................................ 4 1.3 Photosensitizers – bioactive molecules with a hidden photoactive potential ........................ 5 1.3.1. Photophysical background of PS ........................................................................................ 6 1.3.2 Cinnabarin – a natural photosensitizer with antibiotic and antimicrobial properties ... 7 1.4 Secondary metabolites – regulation and role in filamentous fungi ......................................... 9 1.4.1 Functions ............................................................................................................................... 9 1.4.2 Biosynthesis and regulation ................................................................................................ 9 1.4.3 Influencing factors .............................................................................................................. 10 2. Aims of this study............................................................................................................................. 17 3. Materials & Methods......................................................................................................................... 18 3.1 Organism and strains ................................................................................................................... 18 3.2. Materials and Instruments ......................................................................................................... 18 3.2.1. General Instrumentation ..................................................................................................... 18 3.2.2. Reagents and materials ....................................................................................................... 19 3.3. Preparation of solid media ......................................................................................................... 19 3.4 Inoculation and incubation of agar plates ................................................................................... 20 3.5. Irradiation conditions ................................................................................................................. 22 3.5.1. Irradiation setup mimicking daylight ................................................................................... 22 3.5.2. LED boxes with defined wavelengths .................................................................................. 22 3.6. Extraction and isolation of cinnabarin........................................................................................ 25 3.6.1. Phytochemical materials and instruments .......................................................................... 25 3.6.2. Sample preparation and extraction process ....................................................................... 26 i 3.6.3. Additional extraction process using petroleum ether, dichloromethane, and acetone as solvents.......................................................................................................................................... 27 3.6.4. Isolation process .................................................................................................................. 28 3.6.5. Analytics .............................................................................................................................. 29 4. Results ............................................................................................................................................... 31 4.1 Preselection study ....................................................................................................................... 31 4.1.1 Growth at 25°C ..................................................................................................................... 31 4.1.2. Growth at 30°C .................................................................................................................... 39 4.1.3 Growth at 4°C ....................................................................................................................... 45 4.1.4 Selected strain ...................................................................................................................... 47 4.2 Irradiation setup .......................................................................................................................... 48 4.2.1 Influence of illumination conditions and medium composition on the morphology and pigmentation of P. cinnabarinus 2018/12 ..................................................................................... 48 4.3 Development of calibration curve for cinnabarin quantification ................................................ 59 4.4 Optimisation of an HPLC method for the quantification of cinnabarin ...................................... 60 4.5 HPLC-analysis of the Petroleum ether extract (PE), dichloromethane extract (DCM) and acetone extract with the optimized method .................................................................................................. 62 4.6 HPLC – analysis of agar plate cultures ........................................................................................