Abstract

Several microorganisms are currently being used as production platform for glycolipid biosurfactants, providing a greener alternative to chemical biosurfactants. One of the reasons why these processes are commercially competitive is the fact that microbial producers can efficiently export their product to the extracellular environment, reaching high product titers. Glycolipid biosynthetic genes are often found in a dedicated cluster, amidst which genes encoding a dedicated transporter committed to shuttle the glycolipid to the extracellular environment are often found, as is the case for many other secondary metabolites. Knowing this, one can rely on gene clustering features to screen for novel putative transporters, as described and performed in this review. The above strategy proves to be very powerful to identify glycolipid transporters in fungi but is less valid for bacterial systems. Indeed, the genetics of these export systems are currently largely unknown, but some hints are given. Apart from the direct export of the glycolipid, several other transport systems have an indirect effect on glycolipid production. Specific importers dictate which hydrophilic and hydrophobic substrates can be used for production and influence the final yields. In eukaryotes, cellular compartmentalization allows the assembly of glycolipid building blocks in a highly specialized and efficient way. Yet, this requires controlled transport across intracellular membranes. Next to the direct export of glycolipids, the current state of the art regarding this indirect involvement of transporter systems in microbial glycolipid synthesis is summarized in this review.

Key points

• Transporters are directly and indirectly involved in microbial glycolipid synthesis.

• Yeast glycolipid transporters are found in their biosynthetic gene cluster.

• Hydrophilic and hydrophobic substrate uptake influence microbial glycolipid synthesis.

Graphical abstract

中文翻译：

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转运蛋白在微生物糖脂生物表面活性剂生产中的作用

摘要

目前有几种微生物被用作糖脂生物表面活性剂的生产平台，为化学生物表面活性剂提供了更绿色的替代品。这些方法之所以具有商业竞争力，原因之一是微生物生产商可以将其产品有效地出口到细胞外环境，从而达到较高的产品滴度。通常在专用簇中发现糖脂生物合成基因，其中经常发现编码致力于将糖脂穿梭到细胞外环境的专用转运蛋白的基因，许多其他次级代谢产物就是这种情况。知道这一点，就可以依靠基因聚类特征来筛选新颖的假定转运蛋白，如本综述中所述和进行的。上述策略被证明对鉴定真菌中的糖脂转运蛋白非常有效，但对细菌系统却不太有效。确实，这些出口系统的遗传学目前在很大程度上尚不清楚，但给出了一些提示。除了糖脂的直接出口外，其他几种运输系统对糖脂的生产也有间接影响。具体的进口商规定哪些亲水性和疏水性底物可用于生产并影响最终产量。在真核生物中，细胞分隔可以高度专业化和高效地组装糖脂结构单元。然而，这需要跨细胞内膜的受控运输。在直接出口糖脂的旁边，

关键点

•转运蛋白直接和间接参与微生物糖脂的合成。

•酵母糖脂转运蛋白存在于其生物合成基因簇中。

•亲水性和疏水性底物的吸收会影响微生物糖脂的合成。

图形概要