Lanostane triterpenoids from cultivated fruiting bodies of the basidiomycete Ganoderma australe

A new lanostane triterpene (1), together with three known compounds (2–4), were isolated from cultivated fruiting bodies of the basidiomycete Ganoderma australe. The structure was elucidated on the basis of NMR spectroscopic and mass spectrometry data. The olefinic geometry of methyl australate (2) was revised from 20(22)Z to 20(22)E. These compounds (1–4) were different from the lanostanes isolated from mycelial cultures of the same strain source.     

Efficient production of arachidonic acid of <Emphasis Type="Italic">Mortierella</Emphasis> sp. by solid-state fermentation using combinatorial medium with spent mushroom substrate

Solid-state fermentation (SSF) is a bioconversion process for turning cheap agro-industrial materials to added-value products. For enrichment of agro-industrial materials with arachidonic acid (ARA; C20:4 n-6), SSF process of Mortierella sp. was developed by optimizing cultivation medium and parameters. The results showed that the fungal cultivation on the medium with optimal ratio of selected agricultural materials provided the fermented mass containing high ARA proportion of total fatty acid. Inclusion of the optimal medium with suitable amount of spent mushroom substrate, which was used as an internal support, significantly promoted the ARA production yield. Using the predicted quadratic model generated by Box–Behnken design, the maximal ARA production yield was achieved, thereby the fermentation parameter set for ARA production was experimentally validated using the developed medium formula. Of variables studied, the culture temperature and initial moisture content were important for the ARA production. The developed SSF process would provide a prospect for larger scale production of ARA by this fungal strain.     

Enhancing the production of gamma-linolenic acid in <Emphasis Type="Italic">Hansenula polymorpha</Emphasis> by fed-batch fermentation using response surface methodology

Gamma-linolenic acid (GLA, C18:3Δ^6,9,12) is an n-6 polyunsaturated fatty acid (PUFA) that has been used for the alleviation and treatment of a number of symptoms and diseases. Increasing GLA demand has led to a search for alternative producers and potential strategies for GLA production. Based on the successful performance of Hansenula polymorpha, a methylotrophic yeast, as a “cell factory” for the production of valuable bioproducts, a bioprocess development approach was implemented for GLA production in the recombinant yeast carrying the mutated Δ⁶-desaturase gene of Mucor rouxii. Using a substrate-feeding strategy under glycerol-limited conditions, the physical-chemical variables during the fed-batch fermentation of the recombinant H. polymorpha were optimised for GLA production through response surface methodology using a Box-Behnken design. The medium composition, including yeast extract and trace elements, and dissolved oxygen tension (DOT) were targeted. We found that DOT was the most effective variable for enhancing GLA yield. These results also suggest that the optimum conditions for GLA production are 28 % saturation of DOT, 1 g L⁻¹ of yeast extract and 3.6 mL L⁻¹ of the Pichia trace metals 1 (PTM1).