Abstract
Hypocrellin A (HA) is a natural red perylenequinone pigment from Shiraia fruiting body, which was used clinically on various skin diseases and developed as a photodynamic therapy agent against cancers. The fruiting bodies may harbor a diverse but poorly understood microbial community. In this study, we characterized the bacterial community of Shiraia fruiting body using a combination of culture-based method and Illumina high-throughput sequencing, and tested the involvement of some companion bacteria in fungal HA production using the fungal–bacterial confrontation assay. Our results revealed that the bacterial community in the fruiting body was dominated by Bacillus and Pseudomonas. Some Pseudomonas isolates such as P. fulva, P. putida, and P. parafulva could stimulate fungal HA accumulation by Shiraia sp. S9. The bacterial treatment of P. fulva SB1 up-regulated the expression of polyketide synthase (PKS) for HA biosynthesis and transporter genes including ATP-binding cassette (ABC) and major facilitator superfamily transporter (MFS) for HA exudation. After the addition of live P. fulva SB1, the mycelium cultures of Shiraia sp. S9 presented a higher HA production (225.34 mg/L), about 3.25-fold over the mono-culture. On the other hand, B. cereus was capable of alleviating fungal self-toxicity from HA via down-regulation of HA biosynthetic genes or possible biodegradation on HA. To our knowledge, this is the first report on the diversified species of bacteria associated with Shiraia fruiting bodies and the regulation roles of the companion bacteria on fungal HA biosynthesis. Furthermore, the bacterial co-culture provided a good strategy for the enhanced HA production by Shiraia.
Highlights
The observation based on SEM revealed that the fruiting body of S. bambusicola was mainly composed of pseudoparenchyma and prosenchyma, and the latter was only distributed around the ascocarp (Figures 1A–C)
This study presented the first assessment of the diversity of bacteria communities inhabiting in the fruiting body of S. bambusicola by using culture-dependent and -independent approaches
It is an interesting finding that the associated bacteria from some Pseudomonas strains exhibited the capacity to stimulate hypocrellin A (HA) biosynthesis in host Shiraia fungus, whereas some Bacillus strains suppressed fungal HA production significantly
Summary
Hennings is a pathogenic fungus of bamboos, and its fruiting body has been used in traditional Chinese medicine for the treatment of vitiligo, stomachache, psoriasis, and rheumatic pain (Zhen and Di, 1995). The red perylenequinone pigments isolated from the fruiting body including hypocrellin A (HA), B, and C have attracted intense interest as new non-porphyrin photosensitizers in photodynamic therapy (PDT) for cancers and human immunodeficiency virus (Di et al, 1990; Mulrooney et al, 2012). Due to the difficulty in their chemical synthesis (O’Brien et al, 2010), the fruiting bodies are the main resources for hypocrellin supply in medical application (Liang et al, 2009). The fungal fruiting bodies grow and develop in association with various endophytic bacteria. The predominant aerobic bacteria Pseudomonas fluorescens were found in fruiting body
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
