Performance of a biocrust cyanobacteria-indigenous bacteria (BCIB) co- culture system for nutrient capture and transfer in municipal wastewater

This study aimed to explore the potential for transferring nutrients from municipal wastewater through the cultivation of biocrust cyanobacteria, since little is known regarding the growth and bioremediation performance of biocrust cyanobacteria in actual wastewater, especially their interaction with indigenous bacteria. Therefore, in this study, the biocrust cyanobacterium, Scytonema hyaliowas cultivated in municipal wastewater under different light inten-sities, to establish a biocrust cyanobacteria-indigenous bacteria (BCIB) co-culture system, in order to investigate its nu-trient removal efficiency. Our results revealed that the cyanobacteria-bacteria consortium could remove up to 91.37 % and 98.86 % of dissolved nitrogen and phosphorus from the wastewater, respectively. The highest biomass accumula-tion (max. 6.31 mg chlorophyll-a L-1) and exopolysaccharide secretion (max. 21.90 mg L-1) were achieved under re-spective optimized light intensity (60 and 80 mu mol m-2 s-1). High light intensity was found to increase exopolysaccharide secretion, but negatively impacted cyanobacterial growth and nutrient removal. Overall, in the es-tablished cultivation system, cyanobacteria accounted for 26-47 % of the total bacterial abundance, while proteobacteria consisted up to 50 % of the mixture. The composition and ratio of cyanobacteria to indigenous bacteria were shown to be altered by adjusting the light intensity of the system. Altogether, our results clearly illustrate the potential of the biocrust cyanobacterium S. hyalinum in establishing a BCIB cultivation system under different light in-tensity for wastewater treatment and other end-applications (e.g., biomass accumulation and exopolysaccharide secre-tion). This study presents an innovative strategy for transferring nutrients from wastewater to drylands through cyanobacterial cultivation and subsequent biocrust induction.

Automated summary

This study aimed to explore the potential of transferring nutrients from municipal wastewater through the cultivation of biocrust cyanobacteria. The results showed that the cyanobacteria-bacteria consortium could remove a high percentage of dissolved nitrogen and phosphorus from the wastewater. The composition and ratio of cyanobacteria to indigenous bacteria were altered by adjusting the light intensity, indicating the potential for establishing a BCIB cultivation system for wastewater treatment and other applications.