Inhibitory effect of biosurfactant rhamnolipid on Saprolegnia parasitica in vitro

doi:10.16535/j.cnki.dlhyxb.2021-048

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Journal of Dalian Fisheries University ›› 2022, Vol. 37 ›› Issue (1) : 95-103. DOI: 10.16535/j.cnki.dlhyxb.2021-048

Inhibitory effect of biosurfactant rhamnolipid on Saprolegnia parasitica in vitro

LIU Yunyi,QI Jianhua,WANG Nian,YU Xiaojuan,HE Xuanhao,LIU Xuanming,SONG Zengfu

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Abstract

The inhibitory effect of rhamnolipid against Saprolegnia parasitica in vitro were investigated for the development of ecological prevention and control agent of saprolegniasis of aquatic animals.The inhibitory activity of rhamnolipid on S.parasitica was detected by multiple dilution method,mycelial growth rate method,mycelial dry weight method and spore germination assay,and the effect of rhamnolipid on membrane permeability of S.parasitica was studied by measuring the conductivity of the S.parasitica.Finally,the morphological alteration of mycelium was observed in the S.parasitica exposed to rhamnolipid by a light microscope,and electron microscope.It was found that the minimum inhibitory concentration (MIC)of rhamnolipid was 125 mg/L on mycelium and 15.625 mg/L on spore of the S.parasitica.The inhibition rate was shown to be 59.84% on mycelial growth and 85.70% on spore germination at 15.625 mg/L of rhamnolipid,with increase in the inhibition rates with the increase in the dosage.The conductivity test revealed that rhamnolipid led to increase the membrane permeability of the mycelia of the S.parasitica,conductivity being increased by 39.57% in the S.parasitica exposed to 15.625 mg/L of rhamnolipid for 10 h,and the conductivity being increased by 68.10% in the S.parasitica exposed to 125 mg/L of rhamnolipid for 6 h.The morphological observation showed that rhamnolipid had a certain destructive effect on the mycelium of the S.parasitica.Rhamnolipid had a good inhibitory effect on the S.parasitica,which provided a new idea for the development of new ecological protection,prevention and control agents for saprolegniasis of aquatic animals.

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rhamnolipid / Saprolegnia parasitica / ecological prevention and control / inhibition effect

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LIU Yunyi, QI Jianhua, WANG Nian, YU Xiaojuan, HE Xuanhao, LIU Xuanming, SONG Zengfu. Inhibitory effect of biosurfactant rhamnolipid on Saprolegnia parasitica in vitro[J]. Journal of Dalian Fisheries University, 2022, 37(1): 95-103 https://doi.org/10.16535/j.cnki.dlhyxb.2021-048