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Characterization of a Newly Isolated Marine Fungus Aspergillus dimorphicus for Optimized Production of the Anti-Tumor Agent Wentilactones.

Xu R, Xu GM, Li XM, Li CS, Wang BG - Mar Drugs (2015)

Bottom Line: The result was further verified by fermentation scale-up for wentilactone production.Moreover, some small-molecule elicitors were found to have capacity of stimulating wentilactone production.The present study might be valuable for efficient production of wentilactones and fundamental investigation of the anti-tumor mechanism of norditerpenoids.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Nanhai Road 7, Qingdao 266071, China. xrxurui@yeah.net.

ABSTRACT
The potential anti-tumor agent wentilactones were produced by a newly isolated marine fungus Aspergillus dimorphicus. This fungus was derived from deep-sea sediment and identified by polyphasic approach, combining phenotypic, molecular, and extrolite profiles. However, wentilactone production was detected only under static cultures with very low yields. In order to improve wentilactone production, culture conditions were optimized using the response surface methodology. Under the optimal static fermentation conditions, the experimental values were closely consistent with the prediction model. The yields of wentilactone A and B were increased about 11-fold to 13.4 and 6.5 mg/L, respectively. The result was further verified by fermentation scale-up for wentilactone production. Moreover, some small-molecule elicitors were found to have capacity of stimulating wentilactone production. To our knowledge, this is first report of optimized production of tetranorlabdane diterpenoids by a deep-sea derived marine fungus. The present study might be valuable for efficient production of wentilactones and fundamental investigation of the anti-tumor mechanism of norditerpenoids.

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Related in: MedlinePlus

Phylogenetic trees of the fungal strain SD317 and related Aspergillus spp. (A) Neighbor-joining tree based on the fungal ITS rDNA sequence; (B) Neighbor-joining tree based on the beta-tubulin gene sequence. The Kimura two-parameter method was used, with the evolutionary distances bar illustrated and the bootstrap values above the branches.
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marinedrugs-13-07040-f002: Phylogenetic trees of the fungal strain SD317 and related Aspergillus spp. (A) Neighbor-joining tree based on the fungal ITS rDNA sequence; (B) Neighbor-joining tree based on the beta-tubulin gene sequence. The Kimura two-parameter method was used, with the evolutionary distances bar illustrated and the bootstrap values above the branches.

Mentions: The fungal strain SD317 was recently isolated from deep-sea sediment of the South China Sea. The taxonomic status of this fungus was determined using the polyphasic approach, combining morphological, molecular, and extrolite characteristics. Morphological analysis of the strain indicated that the colonies grown on CYA, MEA, and YES plates have the main characteristics of Aspergillus (Figure 1A–F). The colonies reached 2~4 cm diameter in seven days, at first yellowish but later brownish. The mycelia and spores were closely similar to the morphological descriptions of Aspergillus section Cremei. Genotypic identification of the strain was authenticated by the fungal ITS and beta-tubulin gene partial sequences. After BLAST search in the GenBank database and some of the closely related species selected, the phylogenetic trees were constructed using the MEGA6.0 software [20]. The neighbor-joining tree based on fungal ITS sequence (Figure 2A) showed the clustering of strain SD317 within the A. dimorphicus and A. wentii, which could not be distinguished separately [21]. However, the phylogenetic tree based on beta-tubulin gene sequence (Figure 2B) showed that strain SD317 was assigned to the A. dimorphicus, which is a distinct species [22]. The beta-tubulin gene sequence of strain SD317 has the highest identity value (99%) with several A. dimorphicus strains. Strains of A. wentii have been reported to produce important metabolites, like aflatoxin, emodin, and wentilactone [11,23]. Extrolite analysis showed that strain SD317 could also produce wentilactones and emodin related derivatives (Figure 3). Based on these combined morphological, molecular, and extrolite porfiles, this marine fungus from deep-sea sediment was identified as Aspergillus dimorphicus.


Characterization of a Newly Isolated Marine Fungus Aspergillus dimorphicus for Optimized Production of the Anti-Tumor Agent Wentilactones.

Xu R, Xu GM, Li XM, Li CS, Wang BG - Mar Drugs (2015)

Phylogenetic trees of the fungal strain SD317 and related Aspergillus spp. (A) Neighbor-joining tree based on the fungal ITS rDNA sequence; (B) Neighbor-joining tree based on the beta-tubulin gene sequence. The Kimura two-parameter method was used, with the evolutionary distances bar illustrated and the bootstrap values above the branches.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663565&req=5

marinedrugs-13-07040-f002: Phylogenetic trees of the fungal strain SD317 and related Aspergillus spp. (A) Neighbor-joining tree based on the fungal ITS rDNA sequence; (B) Neighbor-joining tree based on the beta-tubulin gene sequence. The Kimura two-parameter method was used, with the evolutionary distances bar illustrated and the bootstrap values above the branches.
Mentions: The fungal strain SD317 was recently isolated from deep-sea sediment of the South China Sea. The taxonomic status of this fungus was determined using the polyphasic approach, combining morphological, molecular, and extrolite characteristics. Morphological analysis of the strain indicated that the colonies grown on CYA, MEA, and YES plates have the main characteristics of Aspergillus (Figure 1A–F). The colonies reached 2~4 cm diameter in seven days, at first yellowish but later brownish. The mycelia and spores were closely similar to the morphological descriptions of Aspergillus section Cremei. Genotypic identification of the strain was authenticated by the fungal ITS and beta-tubulin gene partial sequences. After BLAST search in the GenBank database and some of the closely related species selected, the phylogenetic trees were constructed using the MEGA6.0 software [20]. The neighbor-joining tree based on fungal ITS sequence (Figure 2A) showed the clustering of strain SD317 within the A. dimorphicus and A. wentii, which could not be distinguished separately [21]. However, the phylogenetic tree based on beta-tubulin gene sequence (Figure 2B) showed that strain SD317 was assigned to the A. dimorphicus, which is a distinct species [22]. The beta-tubulin gene sequence of strain SD317 has the highest identity value (99%) with several A. dimorphicus strains. Strains of A. wentii have been reported to produce important metabolites, like aflatoxin, emodin, and wentilactone [11,23]. Extrolite analysis showed that strain SD317 could also produce wentilactones and emodin related derivatives (Figure 3). Based on these combined morphological, molecular, and extrolite porfiles, this marine fungus from deep-sea sediment was identified as Aspergillus dimorphicus.

Bottom Line: The result was further verified by fermentation scale-up for wentilactone production.Moreover, some small-molecule elicitors were found to have capacity of stimulating wentilactone production.The present study might be valuable for efficient production of wentilactones and fundamental investigation of the anti-tumor mechanism of norditerpenoids.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Nanhai Road 7, Qingdao 266071, China. xrxurui@yeah.net.

ABSTRACT
The potential anti-tumor agent wentilactones were produced by a newly isolated marine fungus Aspergillus dimorphicus. This fungus was derived from deep-sea sediment and identified by polyphasic approach, combining phenotypic, molecular, and extrolite profiles. However, wentilactone production was detected only under static cultures with very low yields. In order to improve wentilactone production, culture conditions were optimized using the response surface methodology. Under the optimal static fermentation conditions, the experimental values were closely consistent with the prediction model. The yields of wentilactone A and B were increased about 11-fold to 13.4 and 6.5 mg/L, respectively. The result was further verified by fermentation scale-up for wentilactone production. Moreover, some small-molecule elicitors were found to have capacity of stimulating wentilactone production. To our knowledge, this is first report of optimized production of tetranorlabdane diterpenoids by a deep-sea derived marine fungus. The present study might be valuable for efficient production of wentilactones and fundamental investigation of the anti-tumor mechanism of norditerpenoids.

Show MeSH
Related in: MedlinePlus