竹黄伴生真菌对竹红菌甲素合成的调控作用

Shiraia fruiting body-associated fungi regulate the biosynthesis of hypocrellin A

摘要:

竹黄是一种传统中药，来源于寄生在竹子上的竹黄属(Shiraia)真菌子实体。竹红菌甲素(hypocrellin A, HA)是竹黄中的活性苝醌成分，是一种具有抗肿瘤、抗菌作用的非卟啉类新型光敏剂。目的 探讨竹黄菌子实体伴生真菌对宿主竹红菌甲素合成的影响，并构建伴生菌-竹黄菌共培养方法以生产竹红菌甲素。方法 从竹黄菌子实体中分离得到伴生真菌，采用平板对峙法筛选能够影响竹黄菌竹红菌甲素合成的伴生菌株，比较活性菌株胞内及胞外成分对竹红菌甲素的诱导作用，并建立与优化伴生菌-竹黄菌共培养技术。结果 从竹黄菌子实体中分离得到34株真菌，包括6株竹黄菌和28株伴生真菌。镰孢菌(Fusarium sp.) SF12及其胞外多糖具有促进竹红菌甲素合成的能力。镰孢菌SF12对竹黄菌(Shiraia sp.) S9的生长无显著影响，但可通过上调竹黄菌中竹红菌甲素合成的关键酶基因转录水平，促进竹红菌甲素的合成。在竹黄菌培养24 h后加入镰孢菌SF12孢子(100个/mL)，竹红菌甲素的总产量在第8天达到209.46 mg/L，是对照组的1.93倍。结论 竹黄菌子实体中存在丰富的伴生真菌，伴生镰孢菌SF12与宿主竹黄菌的共培养是一种提高竹红菌甲素生物技术生产的新型诱导技术。

关键词:竹黄菌;子实体;伴生真菌;竹红菌甲素;共培养

Abstract:

The fruiting bodies of fungi of genus Shiraia inhabiting bamboo have a medicinal use in traditional Chinese medicine. Hypocrellin A (HA), the main bioactive perylenequinone pigment from S. bambusicola fruiting bodies is a novel non-porphyrin photosensitizer with antitumor and antimicrobial properties.Objective To investigate the effects of Shiraia fruiting body-associated fungi on HA biosynthesis and develop a co-culture method for enhancing HA production.Methods Shiraia fruiting body-associated fungi were isolated and the strains influencing HA biosynthesis were screened by a plate confrontation assay. The effects of intracellular and extracellular metabolites of the strains on HA production were evaluated. A co-culture system for Shiraia sp. S9 and associated fungi was established and optimized for enhancing HA production.Results There were 34 fungal strains including 6 host Shiraia strains isolated from the fruiting bodies. Among them, Fusarium sp. SF12 and its extracellular polysaccharides significantly promoted HA biosynthesis. Fusarium sp. SF12 did not noticeably affect the growth of Shiraia sp. S9 but regulated HA synthesis by upregulating the transcription levels of key enzyme genes involved in HA biosynthesis. The total HA yield was enhanced to 209.46 mg/L on day 8 after adding spores (100 cell/mL) from Fusarium sp. SF12 to the Shiraia culture at the time point of 24 h, which was 1.93 times that of the control.Conclusion There are diverse fungi in Shiraia fruiting bodies. The co-culture of the associated fungus Fusarium sp. SF12 and the host Shiraia sp. S9 is a new technique to improve HA production.

Key words:Shiraia;fruiting bodies;associated fungi;hypocrellin A;co-culture