Natural Thallus Research Articles

Mycobiont and Whole Thallus Cultures of Roccella Montagnei Bél. For the Biosynthesis of Secondary Compounds

<p>The mycobiont and whole thallus cultures of Roccella montagnei Bel. were established using soredia as an inoculum.The mycobiont<br />cultures showed optimum growth, biomass and biosynthesis of compounds in Lilly and Barnett medium with glucose as a carbon source,<br />micronutrients and vitamins. After the incubation period of 180 days, the cultures were harvested, and their biomass and secondary<br />compound profiles were analysed. The HPTLC chromatogram of the acetone extract of the NT and mycobiont cultures revealed erythrin<br />as the major biosynthesized compound in both and identified as a key biosynthate by R. montagnei. Further, the NT biosynthesized 5<br />additional compounds and the mycobiont cultures biosynthesized 6 additional compounds. The molecular identity of the cultured<br />mycobiont was confirmed using nuclear ribosomal Internal Transcribed Spacer (ITS) as well as the secondary chemistry. Lichen<br />compound erythrin was identified as a key biosynthate by the cultures.<br />Key word:-Roccella montagnei, Mycobiont, Whole thallus culture, Soredia, Erythrin.<br />Abbreviation: - NT, Natural thallus; MYC, Mycobiont culture; WTC, Whole thallus culture; UV, Ultra violet wave length; HPTLC,<br />High performance thin layer chromatography; ITS, Internal transcribed spacer.</p><p> </p><p><a id="pub-id::doi" href="http://dx.doi.org/10.21756/cba.v0i.11014">http://dx.doi.org/10.21756/cba.v0i.11014</a></p>

Developmental stages and secondary compound biosynthesis of mycobiont and whole thallus cultures of Buellia subsororioides

Lichen species have unique culture media preferences, and established cultures are known for the synthesis of secondary metabolites. This paper reports observations on the developmental stages and secondary compound biosynthesis by the mycobiont and whole thallus cultures of Buellia subsororioides. It also investigates the suitable media compositions for the culture growth, the role (nutrient or stressor) of sucrose concentrations on the growth stages, biomass, secondary compound profiles, and the quantity of biosynthesized known compounds/g of culture biomass for each treatment using mycobiont cultures. The ascospore-derived mycobiont cultures and thallus macerate-derived whole thallus cultures of B. subsororioides were established and grown using malt yeast extract (MY) medium. Mycobiont cultures were subcultured in MY medium supplemented with sucrose and its concentrations ranging from 0 to 30 % (with 2 % increment between treatments) for 120 days. The molecular identity of cultures was confirmed using nuclear ribosomal Internal transcribed spacer (ITS) DNA sequences obtained from the cultured mycobiont and from the natural thallus. The ITS DNA sequences of the mycobiont showed 99 % similarity with the sequences of the natural thallus. The mycobiont cultures under varying sucrose concentrations initiated as white cottony stages and transformed to brown compact mycelia, with optimum biomass and biosynthesis of nine secondary compounds in MY 10 %. The number of compounds (1–9) varies according to treatments. The whole thallus cultures (MY 0 %) showed a profile of secondary compounds similar to that of the natural thalli along with a trace of one unknown compound. The obtained results are encouraging for the synthesis of the desired quantities of lichen secondary compounds through cultures for relevant applications.

Radical scavenging, prolyl endopeptidase inhibitory, and antimicrobial potential of a cultured Himalayan lichen Cetrelia olivetorum

Context: Lichens are source of natural bioactive compounds which are traditionally used to cure a variety of ailments.Objective: The objective of this study is to assess free radical scavenging, prolyl endopeptidase inhibitory (PEPI), and antimicrobial potential of a high altitude lichen species Cetrelia olivetorum (Nyl.) W. L. Culb. & C. F. Culb (Parmeliaceae).Materials and methods: Lichen C. olivetorum has been cultured in vitro, and optimized culture conditions were implemented in bioreactor to obtain high quantity of biomass for the study of radical scavenging, PEPI, and antimicrobial activities. Radical scavenging activity of methanol extract of Cetrelia olivetorum (MECO) was tested at 100 µg/mL, PEPI activity at 25 and 50 µg/mL, and antimicrobial activity at 5, 25, 50, and 100 µg/mL conc. All the biological activities of natural thallus extract and its derived culture extract were evaluated spectrophotometrically.Results: Murashige and Skoog medium supplemented with 3% glucose and 100 ppb indole-3-butyric acid (IBA) supported biomass growth at flask level and yielded 5.095 g biomass in bioreactor. MECO of both the cultured and the natural lichen exhibited half inhibiting concentration (IC50) for radical scavenging activities in the range of 50–60 µg/mL, whereas the IC50 value of standard antioxidants was found to be in the range of 12–29 µg/mL. The IC50 value of lichen extract for PEPI activity was 144–288 µg/mL, whereas the IC50 value of standard prolyl endopeptidase inhibitor, Z-pro-prolinal, was 57.73 µg/mL. As far as the antimicrobial activity of MECO is concerned, minimum inhibitory concentration (MIC) value of lichen extracts against tested microorganisms was obtained in the range of 50–104 µg/mL and found to be more effective than commercially available standard erythromycin.Discussion: Murashige and Skoog medium containing IBA was found to be suitable for maximum biomass production of C. olivetorum under bioreactor conditions. The cultured lichen biomass extract also showed antioxidant, PEPI, and antimicrobial potential.Conclusion: The present study indicates therapeutic potential of Himalayan lichen C. olivetorum against neurodegenerative diseases owing to its radical scavenging, PEPI, and antimicrobial activities. Further, the result encourages its commercial exploitation through mass culture for production of its bioactive components and their use in pharmaceutical and nutraceutical industries.

Tyrosinase-Inhibitory Activity in Some Species of the Lichen Family Graphidaceae

Twenty-five species of the lichen family Graphidaceae have been investigated for tyrosinase-inhibitory activity. Tyrosinase-inhibiting material was extracted with solvents methanol, acetone, ethanol, dimethyl sulphoxide in water, and with water only. Methanol has been found to be suitable for extracting adequate amounts of tyrosinase-inhibiting component from the natural thallus. The lichen species such as Graphina glaucorufa, Graphina multistriata, Graphina salacinilabiata, Graphis assamensis, Graphis nakanishiana, and Phaeographopsis indica, have shown inhibition of tyrosinase over a range of 30-78%. Half-inhibiting concentration (IC(50), microg/ml) has been found to be much lower than the standard tyrosinase inhibitors and thus can compete with other commercially available tyrosinase inhibitors. The extracts of these species have been found to be stable at 4 degrees C.

Zoosporogenesis In Trebouxia Gelatinosa: Ultrastructure Potential For Zoospore Release And Implications For The Lichen Association

AbstractZoosporogenesis was observed in the algal symbiont (Trebouxia gelatinosa) of Parmelia caperata. This is the first detailed report of this phenomenon in a Trebouxia species and, more importantly, in lichens, where zoosporogenesis in this alga is usually suppressed and the arrested zoospores form aplanospores. Observations of zoospore formation by algal cells within the natural thallus and in thallus fragments incubated on a mineral medium suggest that zoospores are released within thalli and may escape from the thallus to form free-living microcolonies. These colonies potentially could unite with hyphae derived from spores of either the same, or genetically different mycobionts (fungal symbionts) to establish new lichen associations, as has been shown in laboratory studies. Such natural resyntheses could be one cause for the observed heterogeneity characterizing fungi in many lichen populations. Other implications of free-living Trebouxia populations are discussed.