Study On QSMs Influencing Dimorphic Transition Of Tremella Fuciformis

Tremella fuciformis is a kind of edible and medicinal fungus, which has been planted for a long time in China. It is a dimorphic fungus with multi-transformation mode that contains spore-pseudohyphae mode, pseudohyphae-spore mode and polarity-matching spore-hyphae mode. Up to date, researches on dimorphic transition of Tremella fuciformis are mainly focused on environment factors and differences of dimorphic cells, which are absent of further exploration. Quorum sensing is an extensively existed phenomenon in bacteria and fungi. It is a phenomenon that quorum-sensing cells secrete some chemical molecules during growth, detect the chemical molecules of certain threshold and synchronize the cell-population behavior by altering gene expression. Researchers had deeply studied quorum sensing in a plenty of bacteria, while less exploration was conducted in fungi. Candida albicans is the only fungus which was comprehensively explored on quorum sensing. There is still a large gap to fill on quorum sensing in fungi.According to the characteristics of QSMs summarized by Paul William, this paper screened possible QSMs with GC/HPLC and UV spectrum, and identified QSMs produced by Tremella fuciformis as farnesol and tyrosol using GC-MS and LC-MS. During the experiments, effect of short time and long time was compared, and drew the conclusion that action speed of QSMs was proportional to the growth rate. Adding QSMs of different concentration at different stages and calculating correspondant yeast rate or pseudohyphae rate, we manifested the threshold of farnesol was 25 μmol/L, which suppressed the formation of pseudohyphae in the early of exponential phase and promoted the pseudohypae-yeast transition in the stationary phase. The threshold of tyrosol was 50 μmol/L, and it favored the transition from yeast to pseudohyphae in the exponential phase, which didn’t work when farnesol was present in the liquid medium. Compared the effect of liquid-culturing with solid-culturing environment, it was suggested that environmental change took some effect on QSMs functioning. Thereinto, the working threshold of farnesol in solid medium was much higher than that in liquid medium, and farnesol had the strongest suppression effect on yeast-pseudohyphae transition of Tremella fuciformis in liquid medium. On the other hand, β-phenyl ethyl alcohol showed stronger restriction effect on morphological transition than other QSMs in solid medium, which displayed the repression as a QSM that was not produced by Tremella fuciformis. It indicated that there may be a cross-communication between Tremella fuciformis spore and other fungi or bacteria, which needs further exploration from other researchers in the future.