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¹ College of Environmental & Resource, Zhejiang A & F University, Hangzhou, 311300, China
² College of Food and Health, Zhejiang A & F University, Hangzhou, 311300, China
³ Zhejiang Shangda Public Utilities Group Co., LTD, Hangzhou, 310000, China DOI : 10.4194/TRJFAS28645 Viewed : 147 - Downloaded : 157 In this study, two highly active functional bacterial strains, identified as Bacillus sp. BS-K1 and Pseudomonas sp. CN-B1, were isolated and applied in combination within a perch (Maccullochella peelii) recirculating aquaculture system (RAS) to improve water quality and enhance disease resistance against pathogenic bacteria. Experimental results revealed that the combined probiotics K1+B1 achieved inhibitory rates of 65.0% and 52.3% against Staphylococcus aureus and Vibrio parahaemolyticus, respectively. Remarkably, it exhibited removal efficiencies of 81.9%, 62.4%, and 68.8% for ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen under controlled conditions. Practical application in RAS demonstrated enhanced performance with ammonia and nitrite removal rates reaching 63.8% and 60.5%, respectively, significantly higher than those observed with individual strains. Metagenomic analysis showed altered microbial community structure after K1+B1 addition, with ACE and Chao1 indices increasing by 5%, indicating higher species richness. Notably, the relative abundance of functional genera involved in nitrogen cycling (Novosphingobium and Aquabacterium) carrying nitrifying and denitrifying capabilities increased significantly. Concurrently, pathogenic Staphylococcus aureus exhibited a dramatic reduction (>98%) compared to the control group. These results suggest that the K1+B1 consortium enhances water purification efficiency through strategic modulation of microbial community structure, promoting beneficial nitrogen-cycling populations while suppressing pathogenic microorganisms. Keywords : Combined probiotics Nitrogen removal Bacteriostasis Metagenomic analysis Microbial community structure