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- Feng, Xin Mei, et al.
(författare)
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Production of volatile compounds by Rhizopus oligosporus during soybean and barley tempeh fermentation
- 2007
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Ingår i: International Journal of Food Microbiology. - Amsterdam, Netherlands : Elsevier. - 0168-1605 .- 1879-3460. ; 113:2, s. 133-141
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Tidskriftsartikel (refereegranskat)abstract
- Rhizopus oligosporus Saito can ferment soybeans or cereal grains to tempeh, a sliceable cake with improved nutritional properties. Volatiles produced by different R. oligosporus strains grown on malt extract agar (MEA), barley and soybean were investigated. The effect of co-cultivation with Lactobacillus plantarum on the production of volatiles was also studied. Volatile compounds were collected in situ by headspace diffusion and identified by GC-MS. The ten R. oligosporus strains that had different colony morphologies on MEA produced very similar volatile profiles, except for slight variations among the minor volatile compounds (e.g. sesquiterpenes). Likewise, practically no differences in volatile profiles were observed between three of the strains grown on soybeans. In contrast, the R. oligosporus volatile profile on soybean was different from that on barley from the same strain. Co-cultivation with L. plantarum did not influence volatile production by R. oligosporus. The dominant compounds produced on all three Substrates were ethanol, acetone, ethyl acetate, 2-butanone, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol. Acetaldehyde and 2-methyl-propanal were also produced on MEA and barley, while 2-pentanone, methyl acetate, 2-butanol and 3-methyl-3-buten-1-ol were observed on soybeans. Ethanol, 2-methyl-1-butanol and 3-methyl-1-butanol were the most abundant volatile compounds produced on MEA and barley, while 2-butanone was the dominant volatile metabolite on soybean. The mushroom odour compounds, 3-octanone and 1-octen-3-ol, were only detected from soybean and soybean tempeh.
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| 2. |
- Grijseels, S., et al.
(författare)
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Identification of the decumbenone biosynthetic gene cluster in penicillium decumbens and the importance for production of calbistrin
- 2018
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Ingår i: Fungal Biology and Biotechnology. - : Springer Science and Business Media LLC. - 2054-3085. ; 5:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Filamentous fungi are important producers of secondary metabolites, low molecular weight molecules that often have bioactive properties. Calbistrin A is a secondary metabolite with an interesting structure that was recently found to have bioactivity against leukemia cells. It consists of two polyketides linked by an ester bond: a bicy-clic decalin containing polyketide with structural similarities to lovastatin, and a linear 12 carbon dioic acid structure. Calbistrin A is known to be produced by several uniseriate black Aspergilli, Aspergillus versicolor-related species, and Penicillia. Penicillium decumbens produces calbistrin A and B as well as several putative intermediates of the calbistrin pathway, such as decumbenone A-B and versiol. Results: A comparative genomics study focused on the polyketide synthase (PKS) sets found in three full genome sequence calbistrin producing fungal species, P. decumbens, A. aculeatus and A. versicolor, resulted in the identification of a novel, putative 13-membered calbistrin producing gene cluster (calA to calM). Implementation of the CRISPR/ Cas9 technology in P. decumbens allowed the targeted deletion of genes encoding a polyketide synthase (calA), a major facilitator pump (calB) and a binuclear zinc cluster transcription factor (calC). Detailed metabolic profiling, using UHPLC-MS, of the ∆calA (PKS) and ∆calC ( TF) strains confirmed the suspected involvement in calbistrin productions as neither strains produced calbistrin nor any of the putative intermediates in the pathway. Similarly analysis of the excreted metabolites in the ∆calB (MFC-pump) strain showed that the encoded pump was required for efficient export of calbistrin A and B. Conclusion: Here we report the discovery of a gene cluster (calA-M) involved in the biosynthesis of the polyketide calbistrin in P. decumbens. Targeted gene deletions proved the involvement of CalA (polyketide synthase) in the biosynthesis of calbistrin, CalB (major facilitator pump) for the export of calbistrin A and B and CalC for the transcriptional regulation of the cal-cluster. This study lays the foundation for further characterization of the calbistrin biosynthetic pathway in multiple species and the development of an efficient calbistrin producing cell factory.
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