Malt-yeast Extract Medium Research Articles

Biosynthetic origin of alkylated decaline-type polyketides and induction of a new metabolite by addition of benzoate in cultured mycobionts of Pyrenula sp.

The assembly pattern of acetate units and methyl groups in the biosynthesis of a polyketide, pyrenulic acid C (1), in cultured mycobionts of a Vietnamese Pyrenula sp. was verified by administration of sodium [1-13C]-acetate, sodium [1,2-13C2]-acetate, and L-[methyl-13C]-methionine. The cultured mycobionts were induced to produce a new polyketide, pyrenulic acid I (2), by addition of sodium benzoate to malt-yeast extract medium supplemented with 5% sucrose. Its structure was determined by spectroscopic methods.

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.

Sesquiterpene derivatives from cultured lichen mycobionts of Diorygma sp.

Lichens are distinctive organisms resulting from a symbiosis between algae and fungi. Lichens are well known for their production of unique lichen substances, some of which are potentially useful and biologically active compounds. Although the cooperative mechanisms for the biosyntheses of lichen substances are not fully understood, they are thought to be produced by the fungal portion (mycobiont) of the symbiotic system. However, our previous studies demonstrated that isolated lichen mycobionts are, in some cases, capable of producing new compounds, which are not detected in the natural lichen thalli [1,2]. These findings suggested that laboratory cultures of isolated lichen mycobionts could provide a potential source of novel secondary metabolites. In continuing our chemical studies on the cultured lichen mycobionts [3], we have cultivated the spore-derived mycobionts of Diorygma sp. collected in Vietnam on conventional malt-yeast extract medium supplemented with 10% sucrose at 18 °C in the dark. Purification of their metabolites afforded four new sesquiterpene derivatives 1-4 related to cameroonanol (5) and presilphiperfol-7-ene (6) [4]. Their structures were elucidated by spectroscopic and chemical means. This is the first instance of isolation of this type of metabolites from cultured mycobionts of lichen.

Polyketides from the cultured lichen mycobiont of a Vietnamese Pyrenula sp.

A spore-derived mycobiont of a crustose Pyrenula sp. lichen collected in Vietnam was cultivated on a malt-yeast extract medium supplemented with 10% sucrose. Chemical investigation of the cultivated colonies led to the isolation of eight new alkylated decalin-type polyketides (1-8) along with three known compounds. The structures of these compounds were elucidated by spectroscopic and chemical means. This is the first instance of this type of polyketide being isolated from a cultured lichen mycobiont. The isolated polyketides 1 and 7 exhibited inhibitory activities against mammalian DNA polymerases α and β with IC50 values ranging from 8.1 to 19.5 μM. Compound 1 showed cytotoxic effects against the HCT116 human colon carcinoma cultured cell line with an IC50 value of 6.4 ± 0.7 μM.

Degradation of polycyclic aromatic hydrocarbons by microbial consortia enriched from three soils using two different culture media

A consortium composed of many different bacterial species is required to efficiently degrade polycyclic aromatic hydrocarbons (PAH) in oil-contaminated soil. We obtained six PAH-degrading microbial consortia from three oil-contaminated soils using two different isolation culture media. Denaturing gradient gel electrophoresis (DGGE) and sequence analyses of amplified 16s rRNA genes confirmed the bacterial community was greatly affected by both the culture medium and the soil from which the consortia were enriched. Three bacterial consortia enriched using malt yeast extract (MYE) medium showed higher degradation rates of PAHs than consortia enriched using Luria broth (LB) medium. Consortia obtained from a soil and then added back to that same soil was more effective in degrading PAHs than adding, to the same soil, consortia isolated from other, unrelated soils. This suggests that inoculum used for bioremediation should be from the same, or very similar nearby soils, as the soil that is actually being bioremediated.

NAPHTHOQUINONES AND PHENALENONE DERIVATIVES FROM THE CULTURED LICHEN MYCOBIONTS OF TRYPETHELIUM SP.

Spore-derived mycobionts of the crustose lichen Trypethelium sp. collected in Vietnam were cultivated on a malt-yeast extract medium supplemented with 10% sucrose. The investigation of their metabolites resulted in isolation of a new naphthoquinone and a new phenalenone derivative, together with (+)-trypethelone methyl ether and (+)-sclerodin. Their structures were determined by spectroscopic methods. Lichens are symbiotic organisms of fungi (mycobionts) and photoautotrophic algal partners, namely, green algae and/or cyanobacteria. Lichens produce many unique compounds, which are considered to have important biological and ecological functions, such as antimicrobial activity. Most of these metabolites are produced by the fungal partner, in symbiosis or in the aposymbiotic state. Cultures of isolated lichen mycobionts, however, often exhibit the ability under osmotically stressed conditions to produce substances that have never been detected in the lichenized state. These findings suggested that cultures of lichen mycobionts could be a new source of bioactive compounds. In the course of our studies on cultured mycobionts of Vietnamese lichens, we cultivated the spore-derived mycobiont Trypethelium sp. and isolated a novel naphthoquinone and a new phenalenone derivative along with two known compounds from its cultures. In this paper, we report the isolation and characterization of the new compounds. Specimens of Trypethelium sp. were collected from tree bark in Ba Ria-Vung Tau Province, Vietnam in 2009. The polyspore-derived mycobionts were cultivated on a malt-yeast extract medium supplemented HETEROCYCLES, Vol. 87, No. 9, 2013 1897

A 14-Membered Macrolide and Isocoumarin Derivatives from the Cultured Lichen Mycobionts of <i>Graphis vestitoides</i>

Spore-derived mycobionts of the crustose lichen Graphis vestitoides collected in Vietnam were cultivated on a malt-yeast extract medium supplemented with 10% sucrose. The investigation of their metabolites resulted in isolation of a novel 14-membered macrolide and a new isocoumarin, together with five known isocoumarin derivatives. Their structures were determined by spectroscopic and chemical means. This is the first instance of isolation of a 14-membered macrolide from a lichen mycobiont.

Eremophilane-type sesquiterpenes from cultured lichen mycobionts of Sarcographa tricosa

Spore-derived mycobionts of the crustose lichen Sarcographa tricosa were cultivated on a malt-yeast extract medium supplemented with 10% sucrose. Chemical investigation of the cultivated colonies led to isolation of three eremophilane-type sesquiterpenes, 3-epi-petasol (1), dihydropetasol (2) and sarcographol (3), together with six known eremophilanes and ergosterol peroxide. These structures were elucidated by spectroscopic and chemical methods. This is the first report of eremophilane-type sesquiterpenes from the cultured mycobionts of lichen.

Phenolic compounds from the cultured mycobionts of Graphis proserpens

Spore-derived mycobionts of the lichen Graphis proserpens were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Isocoumarin derivatives 1–3 and 7-oxo-5,7-dihydrooxepino[4,3,2-de]isochromene derivatives, proserins A–C (4–6), were isolated along with three known isocoumarin derivatives and three benzoic acid derivatives. Their structures were determined by spectroscopic methods.

Studies on cytochromes of lichenized fungi under optimized culture conditions

Cytochromes are membrane-bound hemoproteins responsible for the generation of ATP via the electron transport system to fuel the metabolic processes of the organism for their growth. This study reports the properties of cytochromes present in the isolated lichenized fungi of the cultured lichen Usnea ghattensis under optimized conditions. The fungal partner of the cultured lichen Usnea ghattensis contains a, b and c types of cytochromes. The concentrations of a, b and c type cytochromes were found to be significantly high (0.0967, 0.0900, and 0.1030 mM/ mg protein, respectively) in the isolated fungal symbiont of cultured lichen grown in malt-yeast extract medium supplemented with 0.01 mol/l sucrose and 0.01 mol/l polyethylglycol. The results suggest that supplementation of additional carbon sources may play a role in optimizing the growth via activating the cytochrome respiratory system in lichenized fungi.

Studies on cytochromes of lichenized fungi under optimized culture conditions

Cytochromes are membrane-bound hemoproteins responsible for the generation of ATP via the electron transport system to fuel the metabolic processes of the organism for their growth. This study reports the properties of cytochromes present in the isolated lichenized fungi of the cultured lichen Usnea ghattensis under optimized conditions. The fungal partner of the cultured lichen Usnea ghattensis contains a, b and c types of cytochromes. The concentrations of a, b and c type cytochromes were found to be significantly high (0.0967, 0.0900, and 0.1030mM/ mg protein, respectively) in the isolated fungal symbiont of cultured lichen grown in malt-yeast extract medium supplemented with 0.01mol/l sucrose and 0.01mol/l polyethylglycol. The results suggest that supplementation of additional carbon sources may play a role in optimizing the growth via activating the cytochrome respiratory system in lichenized fungi.

Naphthopyrones from Cultured Lichen Mycobionts of Pyrenula sp.

Spore-derived mycobionts of the lichen Pyrenula sp. were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. A new naphthopyrone derivative, pyrenulin, as well as toralactone were isolated. Their structures were determined by spectroscopic methods. This is the first instance of the isolation of naphthalene derivatives from lichen mycobionts.

Effect of Ribitol and Plant Hormones on Aposymbiotical Growth of the Lichenforming Fungi of Ramalina farinacea and Ramalina fastigiata

This study was aimed at evaluating the growth promoting effect of symbiotic algal polyol (ribitol) and plant hormones on the lichen-forming fungi (LFF), Ramalina farinacea (CH050010 and 40403) and Ramalina fastigiata. The addition of ribitol to basal (malt-yeast extract) medium enhanced the relative growth rates of all three LFF. R. farinacea (CH050010), R. farinacea (40403) and R. fastigiata (H06127) showed 35.3%, 29.0% and 29.3% higher growth rates, respectively, compared to the control. I BA (indole-3-butyrie acid) and TTBA (2,3,5-tridobcnzoic acid) also increased growth rates of the LFF by 34 to 64% and 7 to 28%, respectively, compared to the control. The combination of ribitol with I BA or TTBA synergistieally increased the growth of all LFF. For example, ribitol and I BA treatments increased growth rates of R. farinacea (CH050010), R. farinacea (40403) and R. fastigiata (H06127) by 79.4%, 40.3% and 72.8% in, respectively, compared to those grown on the basal medium. The stimulating effect of ribitol and I BA on the LFF growth induced vertical development of the fungal mass in culture. We suggest that lichen-forming fungal growth of Ramalina lichens can be stimulated aposymbiotieally by-supplementing polyols and plant hormones to the basal medium in the mass production of lichen secondary metabolites under large scale culture conditions.

Experimental studies on the growth and usnic acid production in “lichen” Usnea ghattensis in vitro

The study was aimed to optimize the culture conditions for the production of usnic acid in the cultured cell aggregates composed of symbionts in lichen Usnea ghattensis in vitro. The cultured lichen tissue composed of symbionts appeared after about 2-3 weeks of inoculation in water-agar and malt-yeast extract (MYE) media and shown the production of usnic acid after 2-3 months of inoculation. However, the growth of symbionts was strongly affected by different culture conditions. The addition of excess carbon and nitrogen sources in the media has significantly enhanced the growth as well as usnic acid content. The cultured symbionts in MYE medium having 4% sucrose, 4% polyethyl glycol (PEG) gave 7.63 g dry biomass with 3.9 microg usnic acid/g dry biomass. In water-agar medium having 4% sucrose and 4% PEG gave 3.08 g dry biomass with 1.11 microg usnic acid/g dry biomass. The positive effects of medium on the growth of symbionts and the production of usnic acid are seemed to be due to nutritional factors.

Monomeric and dimeric dibenzofurans from cultured mycobionts of Lecanora iseana

Spore-derived mycobionts of the lichen Lecanora iseana were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Four 3,7-dihydroxy-1,9-dimethyldibenzofuran derivatives along with the known 3,7-dihydroxy-1,9-dimethyldibenzofuran and five norlichexanthone derivatives were isolated. Their structures were determined by spectroscopic methods.

Three isocoumarins and a benzofuran from the cultured lichen mycobionts of Pyrenula sp.

The spore-derived mycobionts of the lichen Pyrenula sp. were cultivated on a malt–yeast extract medium supplemented with 10% sucrose. The investigation of their metabolites resulted in isolation of four compounds, three isocoumarins and a biogenetically related benzofuran; their structures were determined by spectroscopic methods.

Elucidation of polysaccharide origin inRamalina peruvianasymbiosis

A structural elucidation of polysaccharides extracted from the aposymbiotically cultured mycobiont of the lichen Ramalina peruviana was carried out in order to determine whether the polysaccharides found previously in the symbiotic thalli are produced by the mycobiont or photobiont or both. The mycobiont isolate was cultivated on a solid malt-yeast extract-medium and the freeze-dried colonies were defatted and the polysaccharides extracted successively with hot water and aq. 2% KOH, each at 100 degrees C. The alkaline extract was obtained in much higher yield (31.5%) and submitted to a freeze-thawing treatment, giving rise to a precipitate (PK2) of a mixture of (1-->3),(1-->4)-alpha-glucan (1.2:1 ratio, nigeran) and a (1-->3)-beta-glucan (laminaran). The mother liquor was treated with Fehling solution to give a precipitate (galactomannan). This had a (1-->6)-linked alpha-d-mannopyranosyl main chain, substituted at O-4 and in small proportion at O-2,4 by beta-Galp units. All three polysaccharides have previously been found in the symbiotic thalli of R. peruviana, showing that these are produced by the fungus, without the participation of the Trebouxia photobiont. Surprisingly, isolichenan, a cold-water soluble (1-->3),(1-->4)-alpha-linked-glucan (3:1 ratio) was not found in the isolated mycobiont, despite being the main polysaccharide found in the thalli.

Elucidation of polysaccharide origin in Ramalina peruviana symbiosis

A structural elucidation of polysaccharides extracted from the aposymbiotically cultured mycobiont of the lichen Ramalina peruviana was carried out in order to determine whether the polysaccharides found previously in the symbiotic thalli are produced by the mycobiont or photobiont or both. The mycobiont isolate was cultivated on a solid malt-yeast extract-medium and the freeze-dried colonies were defatted and the polysaccharides extracted successively with hot water and aq. 2% KOH, each at 100 °C. The alkaline extract was obtained in much higher yield (31.5%) and submitted to a freeze-thawing treatment, giving rise to a precipitate (PK2) of a mixture of (1 → 3),(1 → 4)-α-glucan (1.2:1 ratio, nigeran) and a (1 → 3)-β-glucan (laminaran). The mother liquor was treated with Fehling solution to give a precipitate (galactomannan). This had a (1 → 6)-linked α- d-mannopyranosyl main chain, substituted at O-4 and in small proportion at O-2,4 by β-Gal p units. All three polysaccharides have previously been found in the symbiotic thalli of R. peruviana, showing that these are produced by the fungus, without the participation of the Trebouxia photobiont. Surprisingly, isolichenan, a cold-water soluble (1 → 3),(1 → 4)-α-linked-glucan (3:1 ratio) was not found in the isolated mycobiont, despite being the main polysaccharide found in the thalli.

Phenyl Ethers from Cultured Lichen Mycobionts of Graphis scripta var. serpentina and G. rikuzensis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Phenyl ethers from cultured lichen mycobionts of Graphis scripta var. serpentina and G. rikuzensis.

Spore-derived mycobionts of the lichen Graphis scripta var. serpentina and G. rikuzensis were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. 3,3'-Dihydroxy-5,5'-dimethyldiphenyl ether was isolated from the cultures of the mycobionts of G. scripta var. serpentina, while a new phenyl ether, rikuzenol, along with two known diphenyl ethers, violaceol-I and violaceol-II, were isolated from those of G. rikuzensis. The structure of the new compound was determined by spectroscopic methods. Violaceol-I was chemically synthesized and interconversion between violaceol-I and violaceol-II was proven.