Plant Growth-Promoting Bacteria: A Potential Tool for Arid Mangrove Reforestation

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Microbes (bacteria and fungi) play a crucial role in nutrient recycling in mangrove systems, which are nutrient deficient. Microbes make nutrients, especially nitrogen and phosphorous, available to mangroves, while mangroves may improve soil conditions for microbes (for example, by oxidizing the soil). PGPB may be nitrogen fixers, phosphate solubilizers, mineral uptake enhancers, and phytopathogen controllers.

Research Goals & Methods

This article reviews recent work on the relationship between plant growth-promoting bacteria (PGPB) and mangroves and suggests that PGPB can be used in mangrove restoration, especially for arid mangroves.

Conclusions & Takeaways

Several studies have found mangrove pneumatophores (aerial roots) to be heavily colonized by microbes, including nitrogen-fixing bacteria. Others have demonstrated that inoculation with cyanobactera significantly increases nitrogen-fixation by mangroves. Little research has been done on phosphate-solubilizing or photosynthetic anoxygenic bacteria, but their presence in high concentrations on mangrove roots suggest that they are important to mangrove productivity. One model for microbial transformation in mangrove sediments describes microbially generated detrital particles as the major substrate for bacterial growth, carrying nutrients throughout the system; another focuses on the mutualistic relationship between microbes and mangroves that effectively recycles nutrients. The author suggests that in reforestation efforts, mangrove seedlings could be inoculated with PGPB. Inoculating with a combination of multiple rather than single-species PGPB may be more effective, as evidenced in numerous studies. The author suggests that commercially-available mixes of PGPB used for crop inoculations may be used, but that care must be taken when introducing non-native PGPB into a system.