The optimization of high-protein duckweed cultivation in eutrophicated water with mutualistic bacteria

The exponential increase in the human population is the leading cause of food crises in Thailand and Southeast Asia, and it is affecting global food security while increasing humanity’s carbon footprint. One approach to resolving these issues is the cultivation of the aquatic plant, duckweed (Wolffia globosa) for consumption in the Northern and Northeastern provinces of Thailand. Duckweed has drawn increasing attention due to its rapid growth rate, adaptability to extreme conditions, and potential as an alternative protein; however, due to the difficulty in achieving these properties, they could potentially be greatly enhanced. Our research investigates two optimizations for the cultivation of duckweed: (1) the use of phosphorus- and nitrogen-rich growing media and (2) the use of plant growth–promoting bacteria (PGPB). Based on evidence from past research on the biochemical and metabolic functions of nitrogen and phosphorus, the absorption rates for duckweed, and the nitrogen-fixing properties of PGPB, we hypothesized that using phosphorus-rich water and PGPB would significantly increase duckweed biomass production, while nitrogen-rich water would increase protein content. We found that using a phosphorus-rich medium boosted duckweed biomass greatly, while using a nitrogen-rich medium significantly enhanced the protein value of the duckweed. Furthermore, PGPB yielded the highest increase in duckweed biomass but had an insignificant impact on protein content. Based on our results, we recommend the use of nitrogen- and phosphorus-rich water and PGPB to optimize duckweed cultivation and help address the global food crisis and reduce the environmental impact from meat production.