PDF(Pubmed)
Abstract：
Astaxanthin, a versatile C40 carotenoid prized for its applications in food, cosmetics, and health, is a bright red pigment with powerful antioxidant properties. To enhance astaxanthin production in Corynebacterium glutamicum, we employed rational pathway engineering strategies, focused on improving precursor availability and optimizing terminal oxy-functionalized C40 carotenoid biosynthesis. Our efforts resulted in an increased astaxanthin precursor supply with 1.5-fold higher β-carotene production with strain BETA6 (18 mg g-1 CDW). Further advancements in astaxanthin production were made by fine-tuning the expression of the β-carotene hydroxylase gene crtZ and β-carotene ketolase gene crtW, yielding a nearly fivefold increase in astaxanthin (strain ASTA**), with astaxanthin constituting 72% of total carotenoids. ASTA** was successfully transferred to a 2 L fed-batch fermentation with an enhanced titer of 103 mg L-1 astaxanthin with a volumetric productivity of 1.5 mg L-1 h-1. Based on this strain a pathway expansion was achieved towards glycosylated C40 carotenoids under heterologous expression of the glycosyltransferase gene crtX. To the best of our knowledge, this is the first time astaxanthin-β-D-diglucoside was produced with C. glutamicum achieving high titers of microbial C40 glucosides of 39 mg L-1. This study showcases the potential of pathway engineering to unlock novel C40 carotenoid variants for diverse industrial applications.
摘要：
虾青素,一种多功能的C40类胡萝卜素因其在食品中的应用而备受赞誉，化妆品,和健康，是一种具有强大抗氧化性能的鲜红色颜料。为了提高谷氨酸棒杆菌的虾青素产量，我们采用了合理的道路工程策略，专注于提高前体的可用性和优化末端氧官能化C40类胡萝卜素的生物合成。我们的努力导致虾青素前体的供应增加，而菌株BETA6（18mgg-1CDW）的β-胡萝卜素产量提高了1.5倍。通过微调β-胡萝卜素羟化酶基因crtZ和β-胡萝卜素酮酶基因crtW的表达，进一步促进了虾青素的生产。虾青素(菌株ASTA**)增加近五倍，虾青素占总类胡萝卜素的72%。ASTA**已成功转移到2L补料分批发酵中，滴度提高了103mgL-1虾青素，体积生产率为1.5mgL-1h-1。基于该菌株,在糖基转移酶基因crtX的异源表达下,实现了针对糖基化C40类胡萝卜素的途径扩展。据我们所知,这是第一次用谷氨酸棒杆菌生产虾青素-β-D-二葡萄糖苷，达到39mgL-1的高滴度的微生物C40葡萄糖苷。这项研究展示了途径工程解锁新的C40类胡萝卜素变体用于各种工业应用的潜力。
