Abstract：Aquaculture and Product Processing in Dongting Lake Area, Hunan Provincial Key Laboratory for Molecular Immunity Technology of Aquatic Animal Diseases, Hunan Engineering Research Center of Aquatic Organism Resources and Environmental Ecology, School of Life and Environmental Sciences, Hunan University of Arts and Science, Changde 415000, China; 2. School of Life and Health Sciences, Hunan University of Science and Technology, Xiangtan 411201, China; 3. Hengyang Medical School, University of South China, Hengyang 421009, China)
Abstract: Aeromonas spp. are highly pathogenic bacteria that can infect various aquatic animals, their infection risk can be increased under ammonia nitrogen and nitrite stress. The use of probiotics for water quality regulation and biocontrol is highly recommended for its non-toxic, residue free, and non-drug resistant properties. The antagonistic Bacillus spp. was screened using fish pathogenic Aeromonas spp. as indicator and their degradation effect on the water samples with excessive ammonia nitrogen and nitrite was tested. Morphological observation, physiological and biochemical identification, and molecular biology were used to identify the species. The skin sensitivity test and the immersion attack and infection method were used to detect its biosafety. The single factor and orthogonal experimental methods were used to optimize the sporulation medium and fermentation conditions. In addition, the fish pathogen toxicity protection test and the in-situ pond water quality regulation test were also used to evaluate the potential of the strain in aquaculture. In this study, a strain of Bacillus D34 with obvious inhibitory effect on Aeromonas spp. was identified as Bacillus velezensis, which could effectively degrade ammonia nitrogen and nitrite from different sources of pond water. Moreover, D34 had no infectious effect on the skin of mammals and was safe for the grass carp fry, its optimized sporulation medium and fermentation conditions were as follows: yeast maceration powder 5.0 g/L, raw soybean meal 15.0 g/L, sodium chloride 10.0 g/L, magnesium sulfate 8.0 g/L, fermentation time 48 h, temperature 30℃, inoculum amount 5%, rotational speed 220 r/min, under these conditions, its spore production rate and spore quantity reached 96.5% and 2.03×109 CFU/mL respectively. D34 microbial agent had significant protective effect against Aeromonas veronii infection on the summer fry of grass carp and good in-situ regulation effect on the pond water quality with serious nitrite overload, the nitrite degradation rate reached 91.7% in 24 h. Our results showed that Bacillus velezensis D34 has the potential for both biocontrol and water quality regulation as well as good biosafety, providing new microbial resources for the research and development of green and environmentally friendly aquatic microecological agents.
Key words: Bacillus velezensis; pathogenic Aeromonas spp.; biocontrol; water quality regulation; probiotics
（Acta Laser Biology Sinica, 2025, 34(2): 165-175）
引用本文:
寻 晴，周芳颖，罗玉双，程 万，陈海琳，卢 颖，俞 涛，邹万生，陈中元，王荣华. 一株兼具生物防治和水质调节功能的贝莱斯芽孢杆菌D34新菌株的筛选与应用[J]. 激光生物学报, 2025, 34(2): 165-175.
XUN Qing, ZHOU Fangying, LUO Yushuang, CHENG Wan, CHEN Hailin, LU Ying, YU Tao, ZOU Wansheng, CHEN Zhongyuan, WANG Ronghua. Screening and Application of a Bacillus velezensis New Strain D34 with both Biocontrol and Water Quality Regulating Functions#br#. journal1, 2025, 34(2): 165-175.
