广西夹竹桃内生真菌的多样性和抑制几种水产病原菌活性筛选

Diversity of endophytic fungi isolated from Nerium oleander in Guangxi and activity screening of inhibiting several aquatic pathogens

关键词:  夹竹桃, 内生真菌, ITS序列分析, 弧菌, 抑菌活性

Key words:  Nerium oleander, endophytic fungi, analysis of ITS sequence, Vibrio, antibacterial activities

摘要:

为研究夹竹桃(Nerium oleander)内生真菌的多样性并评价其次生代谢产物的活性,该研究对广西夹竹桃(Nerium oleander)的内生真菌进行分离纯化,采用形态学和ITS序列分析结合的方法进行鉴定,以5种指示菌(其中有3种弧菌)对内生真菌提取物进行抑菌活性筛选。结果表明:(1)从广西夹竹桃中共得到19株内生真菌,这19株内生真菌都属于子囊菌门,涵盖5个目7个属,包括炭疽菌属(Colletotrichum)、球座菌属(Guignardia)、叶点霉属(Phyllosticta)、新壳梭孢属(Neofusicoccum)、曲霉属(Aspergillus)、隔孢壳科新属(Nothophoma)和间座壳属(Diaporthe),优势属为炭疽菌属(分离率为36.85%)和球座菌属(分离率为21.05%),其中炭疽菌属主要分布于茎,球座菌属全部来源于叶。(2)jing-117(Neofusicoccum sp.)和ye-130(Guignardia sp.)对坎氏弧菌有较为特异的抑菌效果,ye-136(Aspergillus sp.)能同时抑制蜡样芽孢杆菌和坎氏弧菌,ye-135(Aspergillus sp.)和jing-116(Colletotrichum sp.)仅能抑制蜡样芽孢杆菌,ye-134(Guignardia sp.)对溶藻弧菌有抑制作用。该研究首次基于ITS序列揭示了广西夹竹桃内生真菌存在较为丰富的多样性,并筛选到一些有抑菌活性的菌株,其提取物可以抑制水产病原弧菌的生长,具有较好的开发潜力。

Abstract:

Nerium oleander is an important medicinal plant. In order to study the diversity of endophytic fungi from N. oleander and evaluate the activity of its secondary metabolites, the endophytic fungi of N. oleander in Guangxi were isolated and purified, and identified by a combination of morphology and ITS sequence analysis. Then the antibacterial activities of endophytic fungus extracts were screened with five indicator bacteria(including three Vibrio species). The results were as follows:(1)A total of 19 endophytic fungi were obtained from Guangxi N. oleander. The ITS sequence analysis showed that these 19 endophytic fungi all belonged to the Ascomycota, and covered five orders and seven genera, which including Colletotrichum, Guignardia, Phyllosticta, Neofusicoccum, Aspergillus, Nothophoma and Diaporthe. Among them, the dominant genera were Colletotrichum(the separation rate was 36.85%)and Guignardia(the isolation rate was 21.05%). Colletotrichum was mainly distributed on stems, and Guignardia all originated from leaves.(2)Antibacterial experiments showed that jing-117(Neofusicoccum sp.)and ye-130(Guignardia sp.)had specific antibacterial effects on Vibrio campbellii, ye-136(Aspergillus sp.)could simultaneously inhibit Bacillus cereus and Vibrio campbellii. ye-135(Aspergillus sp.)and jing-116(Colletotrichum sp.)could only inhibit B. cereus, and ye-134(Guignardia sp.)had an inhibitory activity to Vibrio alginolyticus. The study revealed for the first time that endophytic fungi of N. oleander in Guangxi has a relatively rich diversity based on the ITS sequence. Some antibacterial active strains could be screened, and their extracts could inhibit the growth of aquatic pathogen Vibrio, which will has good development value in the future.