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Phomopsin A production by Phomopsis leptostromiformis in liquid media
Abstract:
Phomopsis leptostromiformis WA1515 produced 75 to 150 mg of phomopsin A per liter in stationary cultures in a Czapek-Dox medium supplemented with 5 to 10 g of yeast extract per liter. pH and temperature optima were approximately 6.0 and 25 degrees C, respectively. A commercial tryptic digest of casein was a satisfactory alternative to the yeast extract, but poor growth and very little phomopsin were obtained when the yeast was replaced by vitamin-free Casamino Acids or a mixture of 18 amino acids. Approximately 95% of the phomopsin A produced was found in the cutlure liquid. No phomopsin was detected in shaken cultures. No phomopsin B was found in any culture. Methods are described for recovery and estimation of phomopsin A from culture liquids.
Insights
Phomopsis leptostromiformis WA1515 efficiently produces phomopsin A in stationary cultures using yeast extract. Optimal conditions and alternative nutrient sources were identified for phomopsin A production.
Area of Science:
- Mycology
- Natural Product Chemistry
- Biotechnology
Background:
- Phomopsis leptostromiformis is a fungal species known to produce mycotoxins.
- Phomopsin A is a significant toxin produced by this fungus, posing potential risks.
Purpose of the Study:
- To optimize the culture conditions for maximizing phomopsin A production by Phomopsis leptostromiformis WA1515.
- To identify suitable nutrient sources and culture parameters for efficient phomopsin A biosynthesis.
Main Methods:
- Culturing Phomopsis leptostromiformis WA1515 in Czapek-Dox medium with varying yeast extract concentrations.
- Investigating the effects of pH and temperature on fungal growth and phomopsin A yield.
- Evaluating alternative nutrient sources, including casein digest and amino acid mixtures.
- Analyzing phomopsin A localization within the culture (intra- or extracellular) and presence of phomopsin B.
Main Results:
- Stationary cultures yielded 75–150 mg/L of phomopsin A with 5–10 g/L yeast extract.
- Optimal pH was ~6.0 and optimal temperature was ~25°C.
- A commercial tryptic casein digest supported good production, while amino acid mixtures did not.
- Approximately 95% of phomopsin A was extracellular; phomopsin B was not detected.
Conclusions:
- Yeast extract or a tryptic casein digest are effective nutrient sources for phomopsin A production.
- Stationary culture conditions at pH 6.0 and 25°C are optimal for maximizing phomopsin A yield.
- Phomopsin A is primarily found in the culture filtrate, and phomopsin B is not produced under these conditions.