Preliminary Research On The Quorum-sensing Of Nematode-trapping Fungi Arthrobotrys Oligospora

Quorum sensing(QS)is a mechanism of microbial communication that regulates population behavior and adapts to environmental changes,this phenomenon is mediated by QS molecules(QSM).Model species of filamentous nematophagous fungi A.oligospora produce three-dimensional trap to prey nematode.Research on the QS phenomenon of A.oligospora will improve its ability to kill nematodes and reveal the role of QS in filamentous fungi.Therefore,in this paper we studied the inoculum size effect on A.oligospora morphologies and preliminary isolated its QSMs from A.oligospora solid culture medium.Research achievements are as follows:(1)Cultured on the medium supplemented with ammonia,different initial spore densities have a significant effect on the mycelial growth rate,germinating time and number of traps in A.oligospora.As the initial spore density increases,the mycelium growth rate accelerates and the germination time advances,while the number of A.oligospora traps start increase and then decrease.A.oligospora produces the most traps when its initial spore density was 10~2cells/plate.A.oligospora did not produce trap when its initial spore density was 10~6cells/plate.The results indicate that there is a QS phenomenon in A.oligospora.(2)Addition litmus reagent to the culture medium to observe the medium pH changes during the A.oligospora growth with different initial spore densities.The results show that A.oligospora produce acid substances during its growth.The decreasing of A.oligospora trap numbers with the different initial spore densities don't be caused by its acid production,but is regulated by QSMs produced by A.oligospora.(3)Cultured on methol extracts from A.oligospora medium with initial spore densities of 10~2cells/plate,A.oligospora with initial spore densities of 10~4-10~6cells/plate produce more traps than control.Cultured on methol extracts from A.oligospora medium with initial spore densities of 10~6 cells/plate,A.oligospora with initial spore densities of 10~1-10~2cells/plate produce less traps than control.The results prove that A.oligospora with initial spore densities of 10~2 cells/plate produced QSMs that can promote trap formation in A.oligospora.A.oligospora with initial spore densities of 10~6cells/plate produced QSMs that can inhibit trap formation in A.oligospora.(4)QSMs produced respectively by A.oligospora with initial spore densities of 10~2and 10~6cells/plate were purified preliminarily.Highlights of this paper:(1)The study proved that there is a QS phenomenon in A.oligospora;(2)Our results demonstrate that A.oligospora with initial spore densities of 10~2and 10~6cells/plate produce QSMs.