Khả năng gây độc và liều vi khuẩn gây chết 50% trên cá tra của vi khuẩn Aeromonas veronii

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Tác giả: Thị Mai Nguyễn, Đình Hoài Trương, Thị Thanh Hương Vũ

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Tạp chí Khoa học Đại học Hạ Long, 2023

Mô tả vật lý: tr.108

Bộ sưu tập: Metadata

ID: 359104

Thêm vào giỏ Liên kết toàn văn

Aeromonas veronii-related illnesses in aquatic animals have been studied recently, but no research on striped catfish has been documented. The current study was carried out to determine the toxicity and median lethal dose (LD50) of A. veronii in striped catfish Pangasianodon hypophthalmus. Experimental fish (size of 15 – 20 g) were injected with bacterial solution after 20 hours of culture at 28oC and diluted at a series of concentrations: 108, 107, 106, 105, 104 CFU/mL (in triplicate). The fish injected with physiological saline water were used as a control batch. The results showed that, after 20 hours of bacterial culture, the bacterial density reached 1.1 ´ 109 CFU/mL, the 50% lethal dose of A. veronii in common carp was 6.2 ´ 107 CFU/mL. The skin, fins, and abdomen of the fish may bleed
the gallbladder and spleen may swell
there may be internal bleeding
and the intestine may swell and bleed. After bacterial infection, mortality was highest between 1 and 3 days
after day 4, no dead fish were discovered. Fresh microscopic examination of the bacteria using the results of bacterial re-isolation and tissue staining revealed that the bacteria were gram-negative bacilli with rounded, ivory-white colonies.Bệnh do vi khuẩn Aeromonas veronii gây ra trên động vật thủy sản mới được nghiên cứu trong những năm gần đây nhưng chưa có nghiên cứu nào trên cá tra được báo cáo. Nghiên cứu được thực hiện để xác định khả năng gây độc và liều gây chết 50% (LD50) do vi khuẩn A. veronii gây ra ở cá tra Pangasianodon hypophthalmus. Cá thí nghiệm (cỡ 15 – 20 g) được tiêm với dịch vi khuẩn A.veronii nuôi sinh khối sau 20 giờ ở 28oC và pha loãng ở các nồng độ 108, 107, 106, 105, 104 CFU/mL, mỗi nồng độ lặp lại thí nghiệm 3 lần. Một lô cá được tiêm với nước muối sinh lí được sử dụng làm lô đối chứng. Kết quả cho thấy, sau 20 giờ nuôi sinh khối vi khuẩn, mật độ vi khuẩn thực tế đạt 1,1 ´ 109 CFU/mL, liều gây chết 50 % của A. veronii trên cá tra là 6,2 ´ 107 CFU/mL. Cá bị bệnh có dấu hiệu xuất huyết trên da, gốc vây, vùng bụng
mật và lách sưng to
nội tạng xuất huyết
ruột sưng to và xuất huyết. Cá chết nhiều trong khoảng 1 – 3 ngày đầu sau cảm nhiễm, từ ngày thứ 4 thì không thấy có cá chết. Kết quả tái phân lập vi khuẩn và nhuộm mô, soi tươi vi khuẩn cho thấy, vi khuẩn A. veronii có dạng trực khuẩn, gram âm, khuẩn lạc có dạng tròn, lồi, màu trắng ngà.

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