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QUACH VAN CAO THI
Faculty of Applied Biological Sciences, Vinh Long University of Technology Education. 73 Nguyen Hue Street, Vinh Long City 89000, Vietnam
Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology

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Antibacterial activity of lactic acid bacteria from various freshwater fish species against pathogenic bacteria in caged red tilapia (Oreochromis sp.) QUACH VAN CAO THI; TRAN QUOC DUNG; HA NGỌC HIEN; NGUYEN BAO TRUNG; TU THANH DUNG; NGUYEN PHUONG THUY
Biodiversitas Journal of Biological Diversity Vol. 24 No. 6 (2023)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d240633

Abstract

Abstract. Quach VCT, Tran QD, Ha NH, Nguyen BT, Tu TD, Nguyen PT. 2023. Antibacterial activity of lactic acid bacteria from various freshwater fish species against pathogenic bacteria in caged red tilapia (Oreochromis sp.). Biodiversitas 24: 3373-3383. Antibiotic-resistant bacteria are a big challenge for many aquaculture countries around the world. The search for new solutions, such as probiotics to replace antibiotics in aquaculture, attracts the interest of many scientists. The investigation was accomplished by isolating Lactic Acid Bacteria (LAB) inhibiting Streptococcus agalactiae and Aeromonas hydrophila, which cause swollen eyes and hemorrhagic skin disease in caged red tilapia (Oreochromis sp.) in Vinh Long province. The findings isolated 37 isolates of LAB from the intestines of catfish, red tilapia, and tilapia. Using the diffusion well method, the results showed that 13/37 (35.14%) and 18/37 (48.65%) isolates were inhibitory against S. agalactiae and A. hydrophila, respectively. The research found that eight isolates were inhibitory to two species of S. agalactiae and A. hydrophila, especially isolate CT6.2, which has the strongest inhibition (10.5 mm inhibition zone diameter). Our finding revealed that the isolates CT6.2 and RP6 demonstrate the highest antagonistic activity against S. agalactiae and A. hydrophila at a density of 108 CFU/mL after incubation at 35°C, pH = 5-6 for 48-60 h. Using PCR techniques and 16S rRNA gene sequencing combined with morphological and biochemical characteristics, the LAB isolates in the findings belong to the genera Lactobacillus and Pediococcus, being 99.35% and 99.02% similar to Lactobacillus plantarum and Pediococcus pentosaceus, respectively. This is the first report on the antimicrobial activity of LAB against S. agalactiae and A. hydrophila in caged red tilapia in the Mekong Delta.
Isolation of Trichoderma strains from rhizospheric soil and assessment of their potential for biofertilizer from freshwater aquaculture pond sediment QUACH VAN CAO THI; TRAN HOANG NHAN; NGUYEN VIET KHANH HUNG; NGUYEN PHUONG THUY
Biodiversitas Journal of Biological Diversity Vol. 25 No. 7 (2024)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d250708

Abstract

Abstract. Thi QVC, Nhan TH, Hung NVK, Thuy NP. 2024. Isolation of Trichoderma strains from rhizospheric soil and assessment of their potential for biofertilizer from freshwater aquaculture pond sediment. Biodiversitas 25: 2866-2876. Trichoderma spp. are filamentous fungi found in almost all soils and can synthesize massive quantities of cellulase enzymes which can simply break down cellulose polysaccharides. Freshwater water aquaculture pond sediment has caused some environmental pollution which is required to be properly dealt with. The objective of this study was to isolate Trichoderma strains from rhizosphere soil and to evaluate their potential for biofertilizer from freshwater aquaculture pond sediments. Twenty-six strains of Trichoderma spp. were isolated from soil. The Carboxymethyl Cellulose (CMC) degrading ability of the S25 strain was extremely strong, with a halo diameter zone measuring 8.9±3.8 cm. According to the BLAST result, there was 99.11% similarity between S25 strains and Trichoderma asperelloides, with a max score of 1011 and an E-value of 0.0. The T. asperelloides S25 was selected for bioproduct production. The use of T. asperelloides S25 bioproduct passively enhanced the efficient decomposition of organic fertilizers. After just 30 days of incubation, total organic matter content was ? 30% and material had a spongy, soft, and brown-black in color. According to the Government of Vietnam’s Decree No. 14/2019/ND-CP on fertilizer management, dated September 14, 2019, all treatments were chosen for the production of granular bio-compost. These findings highlight the potential of bioproduct T. asperelloides S25 for sustainable aquaculture practices and organic waste management.
Characterization of endophytic bacteria isolated from wild rice plants in the Mekong Delta, Vietnam QUACH VAN CAO THI; NGUYEN LU KHOI MINH; NGUYEN PHUONG THUY; TRUONG QUOC TAT; THANH TRAN
Biodiversitas Journal of Biological Diversity Vol. 25 No. 6 (2024)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d250628

Abstract

Abstract. Thi QVC, Minh NLK, Thuy NP, Tat TQ, Tran T. 2024. Characterization of endophytic bacteria isolated from wild rice plants in the Mekong Delta, Vietnam. Biodiversitas 25: 2576-2585. Endophytic bacteria bring many benefits to plants, such as stimulating plant growth and inhibiting many microbial pathogens that cause plant diseases. Hence, this investigation aimed to evaluate the association of endophytic bacteria with wild rice (Oryza rufipogon) that can fix nitrogen, solubilize phosphorus and produce indole-3-acetic acid (IAA). Twelve-five bacterial strains were recovered from wild rice stems and roots collected from Vinh Long and Tien Giang provinces of the Mekong Delta. Among these strains, six had phosphorus solubilizing and seven had nitrogen-fixing activity. Strain BR3.5 fixed the highest nitrogen, i.e. ammonia (NH4+) content of 0.109 ± 0.002 mg/L after eight-day incubation. However, the highest phosphorus solubilization was recorded in two isolates, RR3.7 and RR1.1, with clear zone diameters of 0.800 ± 0.020 mm and 0.800 ± 0.030 mm, respectively. In addition, bacterial strains could synthesize IAA, and BR2.5 produced the highest, i.e., 0.067 ± 0.002 ?g/mL, IAA after eight-day incubation. Notably, strain BR3.5 exhibited multiple activities like nitrogen fixation (0.109 ± 0.002 mg/L), phosphorus solubilization (1.02 ± 0.002 mm), and IAA synthesis (0.056 ± 0.00 ?g/mL). Strain BR3.5 was identified as Pantoea sp. based on 16S rRNA gene sequencing (92.69% similarity) together with morpho-physiological and biochemical characteristics. The findings indicate that strain BR3.5 may be used for the production of biofertilizers for rice farming.
Investigation of streptococcosis (Streptococcus iniae) as a cause of popeye and hemorrhagic disease in tilapia (Oreochromis niloticus) in the Mekong Delta, Vietnam NGUYEN BAO TRUNG; TU THANH DUNG; QUACH VAN CAO THI
Biodiversitas Journal of Biological Diversity Vol. 25 No. 9 (2024)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d250924

Abstract

Abstract. Trung NB, Dung TT, Thi QVC. 2024. Investigation of streptococcosis (Streptococcus iniae) as a cause of popeye and hemorrhagic disease in tilapia (Oreochromis niloticus) in the Mekong Delta, Vietnam. Biodiversitas 25: 3032-3040. Streptococcus iniae, is a dangerous pathogen that causes serious harm to several aquatic animals around the world. The current study aimed to isolate, characterize, and assess the pathogenicity of the Streptococcus iniae that causes popeye and hemorrhagic diseased nile tilapia (Oreochromis niloticus Linnaeus, 1758) in the Mekong Delta, Vietnam. Infected tilapia showed disorienting or lethargic swimming, exophthalmia (unilateral or bilateral), corneal opacity, and hemorrhages on the body, the operculum, and the abdomen of the fish. Upon internal examination, the diseased fish were found to have a pale liver, swollen kidney, and white or yellow fluid accumulation in the abdominal cavity. With the use of the API 20Strep Kit, conventional techniques, and 16S rRNA gene sequencing, a total of 16 isolates were determined to be S. iniae. They are Gram-positive bacteria, cocci or streptococci, with ?-hemolysis and small, white, opalescent colonies on BHIA medium after 24-36 hours of incubation at 28ºC. The obtained challenge tests showed that both isolates of RPBT02 and RPHG36 were highly virulent to fish, with LD50 values determined to be 2.34×104 and 1.81×104 CFU/mL, respectively. Interestingly, the two isolates of RPHG36 and RPBT02 in this study contained the virulence gene phosphoglucomutase (pgm), one of the factors that make S. iniae enhance antibiotic resistance and phagocytosis of the immune system by the host. These results of the study are important information for finding effective ways to control this bacterium in tilapia in the future.
Co-Authors HA NGỌC HIEN NGUYEN BAO TRUNG NGUYEN BAO TRUNG NGUYEN LU KHOI MINH NGUYEN PHUONG THUY NGUYEN PHUONG THUY NGUYEN PHUONG THUY NGUYEN VIET KHANH HUNG THANH TRAN TRAN HOANG NHAN TRAN QUOC DUNG TRUONG QUOC TAT TU THANH DUNG TU THANH DUNG