Changes in Microbial Population during Piggery Wastewater Treatment Process using Microalgae

초록

Monitoring pathogenic microbial populations in an emerging wastewater treatment system is recommended for public health. This study piloted piggery wastewater treatment by growing microalgae and traced changes in microbial population with amplicon sequencing. The sequencing results showed that heterotrophic microalgal cultivation barely changed the bacterial community, however, mixotrophic microalgal cultivation induced a drastic change. Assessment of the risk group (RGs) bacterial population resulted in that the untreated piggery wastewater included abundant RG2 pathogens, and the microalgal treatment decreased the pathogens by 63%. A microbial interaction network was constructed to elucidate algae-bacteria interrelationships based on Spearman rank correlation, and the decrease of the most abundance RG (Oligella) was correlated indirectly with microalgal growth in the model, having Brevundimonas, Sphingopyxis, and Stenotrophomonas as mediators. In a validation test, 3 among 4 connecting bacterial strains exhibited inhibition zones against Oligella. This study found that the microalgal wastewater treatment caused a decrease in RG2, and the statistical analysis predicted potential mediator bacteria at a false-discovery rate (FDR) of 0.25. Further study on adjusting the FDR of microbial association is required.