Plant-cyanobacteria interactions: Beneficial and harmful effects of cyanobacterial bioactive compounds on soil-plant systems and subsequent risk to animal and human health

Plant-cyanobacteria interactions occur in different ways and at many different levels, both beneficial and harmful. Plant-cyanobacteria interactions, as a beneficial symbiosis, have long been demonstrated in ricegrowing areas (Poaceae) where the most efficient nitrogen-fixing cyanobacteria are present in paddies. Moreover, cyanobacteria may in turn produce and/or secrete numerous bioactive compounds that have plant growthpromoting abilities or that may make the plant more resistant to abiotic or biotic stress. In recent years, there has been a growing worldwide interest in the use of cyanobacterial biomass as biofertilizers to replace chemical fertilizers, in part to overcome increasing organic-farming demands. However, the potential presence of harmful cyanotoxins has delayed the use of such cyanobacterial biomass, which can be found in large quantities in freshwater ecosystems around the world. In this review, we describe the existing evidence for the positive benefit of plant-cyanobacteria interactions and discuss the use of cyanobacterial biomass as biofertilizers and its growing worldwide interest. Although mass cyanobacterial blooms and scums are a current and emerging threat to the degradation of ecosystems and to animal and human health, they may serve as a source of numerous bioactive compounds with multiple positive effects that could be of use as an alternative to chemical fertilizers in the context of sustainable development.

Automated summary

Plant-cyanobacteria interactions can be beneficial, with cyanobacteria producing compounds that promote plant growth and resistance to stress. However, the presence of harmful cyanotoxins has hindered the widespread use of cyanobacterial biomass as biofertilizers. Despite the threat of cyanobacterial blooms, their bioactive compounds may offer a sustainable alternative to chemical fertilizers.