两株抑制烟草疫霉的海洋源木霉的分离、鉴定及发酵条件优化

Isolation, identification, and fermentation condition optimization of two marine Trichoderma strains antagonizing Phytophthora parasitica

摘要:

【背景】 红树林作为一种生长在热带与亚热带潮间带的特殊植物群落，其沉积物中微生物种类繁多，是筛选植病生防菌株的潜在来源。【目的】 从红树林沉积物中筛选抑制烟草黑胫病病原真菌烟草疫霉(Phytophthora parasitica)的活性菌株。【方法】 对厦门五缘湾红树林沉积物中的真菌进行分离培养，通过ITS序列测序鉴定，采用平板对峙法筛选能显著抑制烟草疫霉的真菌，并确定发酵条件对候选生防真菌产孢量的影响。【结果】 从厦门五缘湾红树林沉积物分离得到2门15属真菌，其中对烟草疫霉抑制效果显著的菌株为哈茨木霉(Trichoderma harzianum) M312和绿木霉(Trichoderma virens) M552，发酵温度分别为25 ℃和31 ℃，pH 7.0且低盐度时产孢量最高。【结论】 从厦门五缘湾红树林沉积物中筛选出的哈茨木霉M312和绿木霉M552可作为防治烟草黑胫病的候选功能菌，但其发酵条件仍需进一步优化以满足商业化应用。

关键词:烟草疫霉;红树林沉积物;真菌多样性;木霉;发酵条件

Abstract:

[Background] A mangrove forest is a special plant community distributed in the intertidal zone of tropical and sub-tropical regions, where a large number of microorganisms exist in the sediments, serving as potential sources for screening agents for the control of plant diseases. [Objective] To screen fungal strains antagonizing Phytophthora parasitica from the microorganisms isolated from mangrove sediments. [Methods] Fungal strains were isolated from the sediments of Xiamen Wuyuan Bay mangrove wetland and then identified based on the similarity of ITS sequences. The dual culture method was employed to select the Trichoderma strains with high activities of inhibiting P.parasitica. The effects of different fermentation conditions on the sporulation of selected strains were examined. [Results] The fungi isolated from the sediments of Xiamen Wuyuan Bay mangrove wetland belonged to 15 genera of 2 phyla. The inhibitory activities of Trichoderma harzianum M312 and Trichoderma virens M552 against P.parasitica were higher than those of other Trichoderma strains. The two strains (M312 and M552) should be cultured at 25 ℃ and 31 ℃, respectively, pH 7.0, and low salinity for high sporulation. [Conclusion] T. harzianum M312 and T.virens M552 screened from the sediments of Xiamen Wuyuan Bay mangrove wetland could be used as candidate fungi for the biocontrol against tobacco black shank, while the fermentation conditions need to be optimized before commercial application.

Key words:Phytophthora parasitica;mangrove sediment;fungal diversity;Trichoderma;fermentation conditions