Kejela Tekalign, Thakkar Vasudev R, Thakor Parth
Department of Biology, Faculty of Natural and Computational Sciences, Mettu University, Mettu, Ethiopia.
Present Address: BRD school of Biosciences, Sardar Patel University, Vallabh Vidyanagar, 388120, India.
BMC Microbiol. 2016 Nov 18;16(1):277. doi: 10.1186/s12866-016-0897-y.
Colletotrichum and Fusarium species are among pathogenic fungi widely affecting Coffea arabica L., resulting in major yield loss. In the present study, we aimed to isolate bacteria from root rhizosphere of the same plant that is capable of antagonizing Colletotrichum gloeosporioides and Fusarium oxysporum as well as promotes plant growth.
A total of 42 Bacillus species were isolated, one of the isolates named BT42 showed maximum radial mycelial growth inhibition against Colletotrichum gloeosporioides (78%) and Fusarium oxysporum (86%). BT42 increased germination of Coffee arabica L. seeds by 38.89%, decreased disease incidence due to infection of Colletotrichum gloeosporioides to 2.77% and due to infection of Fusarium oxysporum to 0 (p < 0.001). The isolate BT42 showed multiple growth-promoting traits. The isolate showed maximum similarity with Bacillus amyloliquefaciens.
Bacillus species (BT42), isolated in the present work was found to be capable of antagonizing the pathogenic effects of Colletotrichum gloeosporioides and Fusarium oxysporum. The mechanism of action of inhibition of the pathogenic fungi found to be synergistic effects of secondary metabolites, lytic enzymes, and siderophores. The major inhibitory secondary metabolite identified as harmine (β-carboline alkaloids).
炭疽菌属和镰刀菌属是广泛影响阿拉伯咖啡的致病真菌，会导致严重的产量损失。在本研究中，我们旨在从同一植物的根际土壤中分离出能够拮抗胶孢炭疽菌和尖孢镰刀菌并促进植物生长的细菌。
共分离出42种芽孢杆菌，其中一种名为BT42的分离株对胶孢炭疽菌（78%）和尖孢镰刀菌（86%）的径向菌丝生长抑制作用最大。BT42使阿拉伯咖啡种子的发芽率提高了38.89%，将胶孢炭疽菌感染导致的发病率降至2.77%，将尖孢镰刀菌感染导致的发病率降至0（p < 0.001）。分离株BT42表现出多种促进生长的特性。该分离株与解淀粉芽孢杆菌的相似度最高。
在本研究中分离出的芽孢杆菌（BT42）能够拮抗胶孢炭疽菌和尖孢镰刀菌的致病作用。发现抑制致病真菌的作用机制是次生代谢产物、裂解酶和铁载体的协同作用。鉴定出的主要抑制性次生代谢产物为哈尔明碱（β-咔啉生物碱）。
