香草兰酚酸类自毒物质降解菌的筛选和鉴定及其抑菌效果

为了探讨利用有益微生物降解根系自毒物质、缓解香草兰连作生物障碍，并储备有益菌种资源，采用传统分离培养方法筛选香草兰根际土壤酚酸类自毒物质降解菌株，并测定其在液体培养基和连作土壤中对酚酸类物质的降解效果及其对病原菌的平板抑制能力。结果表明:从香草兰连作种植园根际土壤筛选到6株可降解酚酸类自毒物质的菌株，分别为真菌BM-5、FD-21、BD-8和细菌ZD-4、ZH-19、ZH-20。菌株FD-21在摇瓶培养72 h时对苯甲酸、对羟基苯甲酸和水杨酸的降解率分别为78.87%、89.5%和93.62%；但在香草兰连作土壤中接种该菌株恒温培养7 d后降解率分别为43.5%、34.2%和67.28%。平板抑菌效果试验表明，该6株菌对香草兰土传枯萎病致病菌尖孢镰刀菌（Fusarium oxysporum f. sp. vanillae ）具有一定拮抗作用，其中菌株ZH-19、ZH-20对尖孢镰刀菌的抑制率最高，分别达82.87%和82.94%；FD-21对尖孢镰刀菌的抑制率为45.49%。16S rRNA 和ITS序列比对结果表明，ZD-4为枯草芽孢杆菌(Bacillus subtilis)、ZH-19为炭疽芽孢杆菌（Bacillus anthracis）、ZH-20为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)、BM-5为黄丝曲霉（Talaromyces sp.）、FD-21为青霉（Penicillium sp.）、BD-8为桔青霉（Penicillium citrinum）。说明筛选到的微生物菌株可降解香草兰根系酚酸类自毒物质且对尖孢镰刀菌具有拮抗作用。

Screening,identification and antimicrobial activity of microbial strains degrading autotoxic phenolic acids in the rhizosphere of vanilla

In order to explore the use of beneficial microorganisms to degrade root autotoxic substances, alleviate the biological obstacles of continuous cropping of vanilla (Vanilla planifolia Andr.), and reserve beneficial microbial resources, microbial strains degrading phenolic acids which are autotoxic substances in the rhizosphere of vanilla plantations were screened by using the traditional isolation and culture method. Degrading activity of the isolated microbial strains against the phenolic acids in culture medium and continuous cropping soil and their plate inhibition ability against pathogenic agents were determined, and 6 microbial strains were isolated from the rhizosphere of vanilla plantations with continuous cropping, which were labelled fungi BM-5, FD-21 and BD-8, and bacteria ZD-4, ZH-19 and ZH-20. The fungal strain FD-21 when cultured in shake flasks for 72 h, had degradation rates of 78.87%, 89.5% and 93.62% for p-benzoic acid, p-hydroxybenzoic acid and salicylic acid, respectively, but it had degradation rates of 43.5%, 34.2% and 67.28%, respectively, when thermostatically cultured for 7 days after its inoculation of the continuous cropping soil. The plate bacteriostatic effect test showed that the 6 strains had a certain antagonistic effect on Fusarium oxysporum f. sp. vanillae, a pathogen of vanilla soil-borne Fusarium wilt disease. The bacterial strains ZH-19 and ZH-20 had the highest inhibition rates against F. oxysporum f. sp. vanillae, which were 82.87% and 82.94%, respectively, and the fungal strain FD-21 had an inhibition rate of 45.49% against F. oxysporum f. sp. vanillae. 16S rRNA and ITS sequence alignment showed that the bacterial strain ZD-4 was identified as Bacillus subtilis, the bacterial strain ZH-19 as Bacillus anthracis, the bacterial strain ZH-20 as Bacillus amyloliquefaciens, the fungal strain BM-5 as Talaromyces sp., the fungal strain FD-21 as Penicillium sp., the fungal strain BD-8 as Penicillium citrinum. This indicates that the screened microbial strains can degrade autotoxic phenolic acids secreted by the vanilla roots and have an antagonistic effect on F. oxysporum f. sp. vanillae.