Abstract
Heat-stable antifungal factor (HSAF) is produced by the fermentation of Lysobacter enzymogenes, which is known for its broad-spectrum antifungal activity and novel mode of action. However, studies on the separation of HSAF have rarely been reported. Herein, alteramide B (the main byproduct) was removed firstly from the fermentation broth by photodegradation to improve the purity of HSAF. Then, the separation of HSAF via adsorption by macroporous adsorption resins (MARs) was evaluated and NKA resin showed highest static adsorption and desorption performances. After optimizing the static and dynamic adsorption characteristics, the content of HSAF in the purified product increased from 8.67 ± 0.32% (ethyl acetate extraction) to 31.07 ± 1.12% by 3.58-fold. These results suggest that the developed strategy via photodegradation and macroporous resin adsorption is an effective process for the separation of HSAF, and it is also a promising method for the large-scale preparation of HSAF for agricultural applications.
Highlights
The Gram-negative Lysobacter bacteria, belonging to the Xanthomonadaceae family of Gammaproteobacteria, are ubiquitous soil and freshwater environmental microorganisms
The Heat-stable antifungal factor (HSAF) fermentation broth was produced by L. enzymogenesOH11, reported in a previous study (Tang et al, 2018a)
It can be seen from the high-performance liquid chromatography (HPLC) chromatogram that the alteramide B (ATB) in the fermentation broth was found to decrease with increasing time, and no residual ATB was detected in the fermentation broth after exposure to 2 days of light (Figure 1)
Summary
The Gram-negative Lysobacter bacteria, belonging to the Xanthomonadaceae family of Gammaproteobacteria, are ubiquitous soil and freshwater environmental microorganisms Members of this genus have been regarded as promising biological control agents against crop fungal and bacterial diseases because of their characteristics of fast growth, easy maintenance, and genetic amenability to bioengineering (Chen et al, 2018). Regarding its distinct structure and novel mode of action, HSAF has great potential for being used as biological pesticides for green and safe agricultural production. At present, it is an attractive subject, and much progress has been made in investigating its biosynthesis mechanism, identifying regulatory factors, and improving its yield. Studies on the separation and purification of HSAF from the fermentation broth have rarely been reported
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