Isolation and selection of bacteria inhibiting Streptococcus agalactiae causing dark-body disease on snakeskin gourami fish (Trichogaster pectoralis)

Le Thi Anh Hong, Pham Thi Minh Ngoc, Duong Khanh, Vo Van Tuan, Nguyen Hoang Dung
Author affiliations


  • Le Thi Anh Hong
  • Pham Thi Minh Ngoc
  • Duong Khanh
  • Vo Van Tuan
  • Nguyen Hoang Dung



Streptococcus agalactiae is one of the microbial pathogens causing the dark-body disease on
snakeskin gourami fish (Trichogaster pectoralis) that affects the growth and quality of fish. This research aimed to isolate and select bacteria inhibiting S. agalactiae which are able to use for controling pathogenic bacteria instead of antibiotics. Fourteen bacteria strains were isolated and screened from healthy fishes, sediment and water samples at fish ponds in Dong Thap province. Among these strains, L7 strain showed the highest inhibition ability with the clear zone diameter was 9,3 mm. The results of the 16S rRNA sequence analysis indicated that the L7 strain belonged to Bacillus subtilis. The experiment to evaluate the inhibition capacity and fish disease control of selected B. subtilis in experimental conditions was conducted by challenging fish with S. agalactiae. Fishes in the control treatment was infected with S. agalactiae at 106 CFU/mL had survival rate 41,7%. The experimental treatments NT1, NT2, NT3 which were treated with B. subtilis at concentrations of 105 CFU/mL, 106 CFU/mL, and 107 CFU/mL gave higher survival rates compared with the non-treated control, with the rates of 60%, 76,7%, and 81,7%, respectively. These results revealed that the isolated B. subtilis is potential used in control dark-body disease on snakeskin gourami fish.


Download data is not yet available.


Chuanzhong Zhu, Lijuan Yu , Wei Liu , Ming Jiang , Shan He , Ganfeng Yi , Hua Wen (2019) Dietary supplementation with Bacillus subtilis LT3‐1 enhance the growth, immunity and disease resistance against Streptococcus agalactiae infection in genetically improved farmed tilapia, Oreochromis niloticus. Aquaculture Nutrition 25 (6): 1241-1249.

FAO (2020) Species fact sheets Trichogaster pectoralis (Regan, 1910)., truy cập ngày 12/04/2020., truy cập ngày 12/04/2020.">

Galindo AB (2004). Lactobacillus plantarum 44A as a live feed supplement for freshwater fish. Ph.D. Thesis, Wageningen University, The Netherlands: 131.

Iman MK, Wafaa T Abbas, Elham S Awaad, Mohammad MN Authman, Kawther El- Shafei, Osama M Sharaf, Gamal A Ibrahim, Zeinab I Sadek, Hoda SEl- Sayed (2013). Evaluation of Lactobacillus plantarum as a probiotic in aquaculture: Emphasis on growth performance and innate immunity. Journal of Applied Sciences Research 9(1): 572-582.

Lê Thị Hải Yến và Nguyễn Đức Hiền (2016) Khảo sát đặc tính probiotic các chủng vi khuẩn Bacillus subtilis phân lập tại các tỉnh Đồng bằng sông Cửu Long. Tạp chí khoa học Trường Đại học Cần Thơ 2: 26-32.

Minas K, McEwan NR, Newbold CJ, Scott KP (2011) Optimization of a high-throughput CTAB-based protocol for the extraction of qPCR-grade DNA from rumen fluid, plant and bacterial pure cultures. FEMS Microbiology Letters 325(2): 162–169

Nazmul Hossain Md and Mahbubur Rahman Md (2014). Antagonistic Activity of Antibiotic Producing Streptomyces sp. against Fish and Human Pathogenic Bacteria. Braz. Arch. Biol. Technol. 57 (2): 233 – 237.

Ngô Thị Ngọc Trân, Nguyễn Trọng Nghĩa và Đặng Thị Hoàng Oanh (2016). Xác định tính kháng khuẩn của vi khuẩn lactic với vi khuẩn (Streptococcus agalactiae) phân lập từ cá rô phi (Oreochromis niloticus) bệnh phù mắt và xuất huyết. Tạp chí khoa học Trường Đại học Cần Thơ 42: 48-55.

Phan Thị Lệ Hoa và Từ Thanh Dung (2014) Nghiên cứu bệnh thân đen trên cá Sặc rằn (Trichogaster pectoralis) nuôi thâm canh của tỉnh Đồng Tháp. Trường Đại học Cần Thơ

Tu Thanh Dung, Haesebrouck F, Tuan NA, Sorgeloos P, Baele M and Decostere A (2008). Antimicrobial Susceptibility Pattern of Edwardsiella ictaluri isolates from natural outbreaks of Bacillary Necrosis of Pangasianodon hypophthalmus in Vietnam. Microb. Drug Res 14: 311-316.

Vaseeharan B and Ramasamy P (2003) Control of pathogenic Vibrio spp. by Bacillus subtilis BT23, a possible probiotic treatment for black tiger shrimp Penaeus monodon. In The society for Applied Microbiology 36: 83-87.

Wing-Keong Ng, Young-Chul Kim, Nicholas Romano, Chik-Boon Koh & Si-Yong Yang (2014) Effects of Dietary Probiotics on the Growth and Feeding Efficiency of Red Hybrid Tilapia, Oreochromis sp., and Subsequent Resistance to Streptococcus agalactiae. Journal of Applied Aquaculture 26 (1): 22-31 DOI: 10.1080/10454438.2013.874961




How to Cite

Anh Hong, L. T., Minh Ngoc, P. T., Khanh, D., Tuan, V. V., & Hoang Dung, N. (2021). Isolation and selection of bacteria inhibiting Streptococcus agalactiae causing dark-body disease on snakeskin gourami fish (Trichogaster pectoralis). Vietnam Journal of Biotechnology, 19(3), 547–555.