光合细菌对鱼病原细菌生长的影响

Influence of photosynthetic bacteria on pathogenic bacteria isolated from two freshwater fish

从发病的棒花鱼(Abbottina rivularis)和鲫鱼(Carassius auratus)分离得到7株菌,经人工感染证实其中的B3、J1和J2等3株菌均为病原细菌。B3和J1鉴定为嗜水气单胞菌(Aeromonas hydrophila),J2鉴定为豚鼠气单胞菌(Aeromonas caviae)。采用平板扩散法测定了光合细菌嗜酸红假单胞菌Y7(Rhodopseudomonas aci-dophila Y7)、球形红假单胞菌X3(R.spheroids X3)和桃红荚硫菌S(Tniocapsa roseopersicina S)对病原细菌B3和J2生长的影响。结果表明:在营养琼脂平板上3种光合细菌对两种病原细菌(B3和J2)无明显拮抗作用,但光合细菌能覆盖在病原细菌上生长;3种光合细菌对病原细菌生长有明显的抑制作用,其中球形红假单胞菌X3抑制作用最大,但X3代谢产物对病原细菌生长无明显抑制作用,说明X3对病原细菌的抑制作用来自菌体细胞。X3还能明显抑制水体中的病原菌B3和J2的生长。

Seven strains of bacteria were isolated from the diseased Abbottina rivularis and Carassius auratus, and three of them, B3, J1 and J2, were proved to be pathogenic bacteria by artificial infection. B3 and J1 were identified as Aeromonas hydrophila, J2 as Aeromonas caviae by physiological and biochemical test. The plates pervasion tests show that the photosynthetic bacteria （PSB） , Rhodopseudomonas acidophila Y7, R. spheroids X3 and Tniocapsa roseopersicina S, present no significant antagonistic action on the pathogenic bacteria, B3 and J2, cultured on nutrient agar culture. But PSB could grow over the pathogenic bacteria on the plates. PSB, especially R. spheroids X3, alters the growth curve of pathogenic bacteria, inhibiting their growth. However, the metabolic product of R. spheroids X3 shows no inhibiting effect, indicating that bacteria ceils are key role of the inhibiting effect. Meantime, R. spheroids X3 inhibits J2 and B3 growth in water apparently.