由于储存不当,马铃薯块茎会产生有毒的糖苷生物碱(glycoalkaloids, GAs),对人类健康构成严重威胁。生物降解是有效去除马铃薯中GAs首选技术。该文从发芽绿化的马铃薯块茎中分离内生菌,采用以GAs为唯一碳源的无机盐培养基进行筛选,通过菌落形态观察、生理生化测定和16S rDNA测序进行菌株鉴定,并进行体外安全性评价,最后采用HPLC和液相色谱-离子阱-飞行时间串联质谱检测菌株对GAs的降解特性和降解产物。筛选出1株可高效降解GAs菌株C11,经鉴定为Bacillus velezensis。该菌株对部分抗生素具有抗性但不含质粒,不产生有害代谢产物,不具有溶血性,菌株具有一定的安全性。该菌株最适降解条件为30 ℃、pH 6.0。Mn2+能增加菌株C11的降解能力,而Cu2+较强地抑制降解。菌株C11可能在胞内将GAs降解为胆固醇后进一步代谢利用。菌株C11具有高效的GAs降解能力和良好的环境适应性,在菌剂开发中具有较高的应用前景。
Improper storage of potatoes produces toxic glycoalkaloids (GAs), posing a severe threat to human health. Biodegradation is the first-choice technology to effectively degrade GAs from potato. In this study, endophytic bacteria were isolated from sprouted and green potato tubers. The inorganic salt medium with GAs as the sole carbon source was used for screening GA degrading bacteria. The strains were identified by physiological and biochemical determination and 16S rDNA sequencing. Then the safety of GA degrading bacteria was studied. Finally, the degradation characteristics and products of GAs were detected by HPLC and liquid chromatography-ion trap-time of flight mass spectrometry (LC-IT-TOF-MS). The results showed that strain C11, which could efficiently degrade GAs, was screened and identified as Bacillus velezensis. The strain C11 was resistant to some antibiotics but did not contain plasmid, did not produce harmful metabolites, and had no hemolytic activity. So, strain C11 had certain safety. The optimum degradation conditions of the strain C11 were 30 ℃ and pH 6.0. Mn2+ could increase the degradation ability, while Cu2+ could strongly inhibit the degradation. Additionally, strain C11 may degrade GAs into cholesterol and further metabolize and utilize them in the cell. The strain C11 has high efficiency of GAs degradation and excellent environmental adaptability, which has a high application prospect in the development of bacterial agents.
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