有益细菌是指引入根区或生长介质后，能积极改善植物健康、养分有效性和抗病性的微生物。水培法中研究最多的属包括枯草芽孢杆菌（抑制腐霉和其他根部病原体）、木霉（一种有益真菌，可在根部定殖并胜过有害真菌）和菌根真菌（形成共生网络，显着扩大根部的养分吸收表面积）。
关键事实
- Bacillus subtilis: produces antifungal compounds that suppress Pythium root rot
- Trichoderma: colonises root surfaces and outcompetes harmful pathogens for space and nutrients
- Mycorrhizae: form symbiotic networks extending effective root surface area up to 1000×
- Beneficial microbes are incompatible with hydrogen peroxide, bleach, and strong oxidising treatments
- Most effective in media-based systems (coco, rockwool, perlite) — harder to maintain in DWC
- Products: Great White, Tarantula, Hydroguard (Bacillus amyloliquefaciens) — apply at transplant