College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, China.
Department of Horticultural Sciences, Soochow University, Suzhou, 215123, China.
Microb Cell Fact. 2019 Jul 5;18(1):121. doi: 10.1186/s12934-019-1170-5.
Fungal perylenequinonoid (PQ) pigments from Shiraia fruiting body have been well known as excellent photosensitizers for medical and agricultural uses. The fruiting bodies are colonized by a diverse bacterial community of unknown function. We screened the companion bacteria from the fruiting body of Shiraia sp. S9 and explored the bacterial elicitation on fungal PQ production.
A bacterium Pseudomonas fulva SB1 isolated from the fruiting body was found to stimulate the production of fungal PQs including hypocrellins A, C (HA and HC), and elsinochromes A-C (EA, EB and EC). After 2 days of co-cultures, Shiraia mycelium cultures presented the highest production of HA (325.87 mg/L), about 3.20-fold of that in axenic culture. The co-culture resulted in the induction of fungal conidiation and the formation of more compact fungal pellets. Furthermore, the bacterial treatment up-regulated the expression of polyketide synthase gene (PKS), and activated transporter genes of ATP-binding cassette (ABC) and major facilitator superfamily transporter (MFS) for PQ exudation.
We have established a bacterial co-culture with a host Shiraia fungus to induce PQ biosynthesis. Our results provide a basis for understanding bacterial-fungal interaction in fruiting bodies and a practical co-culture process to enhance PQ production for photodynamic therapy medicine.
来自 Shiraia 子实体的真菌聚对醌（PQ）色素已被广泛认为是医学和农业用途的优秀光敏剂。子实体被功能未知的多样化细菌群落定植。我们从 Shiraia sp. S9 的子实体中筛选出伴生细菌，并探索了细菌对真菌 PQ 产生的诱导作用。
从子实体中分离到的假单胞菌 SB1 被发现能刺激真菌 PQ 的产生，包括 Hypocrellin A、C（HA 和 HC）和 Elsinochrome A-C（EA、EB 和 EC）。共培养 2 天后， Shiraia 菌丝体培养物中 HA 的产量最高（325.87mg/L），约为无菌培养物的 3.20 倍。共培养导致真菌产孢和更紧凑的真菌球形成。此外，细菌处理上调了聚酮合酶基因（PKS）的表达，并激活了 ABC 和 MFS 转运体基因以促进 PQ 外排。
我们建立了一个与宿主 Shiraia 真菌的细菌共培养体系来诱导 PQ 生物合成。我们的结果为理解子实体中细菌-真菌相互作用提供了基础，并为增强光动力治疗药物中 PQ 生产的实际共培养过程提供了依据。
