| The related researches of CZBC1(Bacillus cereus) were studied in this article. The CZBC1 is a strain of algicidal bacteria for cyanobacteria which was isolated by researchers in laboratory early. In this article, the methods of experiment ecology and pond aquaculture experiment were used to analyze the effect of CZBC1 on eliminating the ecological dominance of harmful cyanobacteria, promoting the growth of beneficial microalgae, in shrimp cultured water. Meanwhile, the effect of CZBC1 on the regulation of microalgae community can be definited, which provide reference for productive applicationof the CZBC1.1. The regulation of algicidal bacteria to the Oscillatoria chlorine dominance inmicroalgae community.The experiments were conducted in several 20 L aquarium systems, in which were poured into the shrimp aquaculture water. The pure Oscillatoria chlorine was added to regulate its dominance in the experiment water. According to the amount of algicidal bacteria, Group HC0, Group HC3 and Group HC5 were set with three parallels, which the dosages were 0 CFU/m L, 3.0×103 CFU/m L and 3.0×105 CFU/m L, respectively. The results showed that :The Oscillatoria chlorine dominance and quantity of Group HC0 were significantly higher than that in Group HC3 and Group HC5 after 15 d of culture(P<0.01).The Oocystis borgei dominance and quantity of Group HC0 were significantly lower than that in Group HC3 and Group HC5(P<0.01), at 15 th d.The experiments were conducted in several 20 L aquarium systems, in which were poured into the shrimp aquaculture water. The pure Oscillatoria chlorine was added to regulate its different dominance. According to the amount of algicidal bacteria and dominance, Group LC0, Group LC3, Group HC0 and Group HC3 were set. The results showed that : ①The Oscillatoria chlorine and Oocystis borgei dominance and quantity of Group LC0 and Group LC3 were basically stable. There is no significantly difference between groups(P>0.05). ②The Oscillatoria chlorine dominance and quantity of Group HC3 were significantly lower than that in Group HC0 after 15 d of culture(P<0.01). The Oocystis borgei quantity of Group HC3 were significantly higher than that in Group HC0 after 15 d of culture(P<0.01).The results indicated that algicidal bacteria CZBC1 could effectively inhibit the growth of Oscillatoria chlorine, reduce its dominance. This was favor to occupying the ecological advantage for O. borgei(Chlorophyta), and optimizing the microalgae community structure. With CZBC1 amount’s increasing, its optimization effect was more prominent.2. The regulation of algicidal bacteria to the Microcystis floslutea dominance in microalgae community.The experiments were conducted in several 20 L aquarium systems, in which were poured into the shrimp aquaculture water. The pure Microcystis floslutea was added to regulate its dominance in the experiment water. According to the amount of algicidal bacteria, Group LW0, Group LW3 and Group LW5 were set with three parallels. The results showed that :①The Microcystis floslutea dominance of Group LW3 and Group LW5 were significantly lower than that in Group LW0(P<0.01). The Microcystis floslutea quantity of Group LW3 and Group LW5 were significantly lower than that in Group LW0(P<0.01). ②The Chlorella pyrenoidosa dominance of Group LW3 and Group LW5 were significantly higher than that of Group LW0, when there is no different between their quantities.The experiments were conducted in several 20 L aquarium systems, in which were poured into the shrimp aquaculture water. The pure Microcystis floslutea was added to regulate its dominance in the experiment water. According to the amount of algicidal bacteria, Group HW0, Group HW3 and Group HW5 were set with three parallels. The results showed that:① The Microcystis floslutea dominance of Group HW3 and Group HW5 were lower than that of Group HW0(P<0.01). The Microcystis floslutea dominance of Group HW5 was also lower than that of Group HW3(P<0.05). The Microcystis floslutea quantity of Group HW3 and Group HW5 were lower than that of Group HW0(P<0.01). The Microcystis floslutea quantity of Group HW5 was also lower than that of Group HW3(P<0.05). ② The Chlorella pyrenoidosa dominance of Group HW5 was significantly higher than that of Group HW0(P<0.01).3. The effects of applying algicidal bacteria CZBC1 on microalgae community structure in shrimp cultured pondThe ponds experiment was conducted in 5 shrimp cultured ponds with similar conditions. T1, T2, T3 were used with algicidal bacteria CZBC1 in 6×103 CFU/m L once the seven day, while C1 and C2 were not used. The results were as follows:The cyanophyta microalgae biomasses of T1 pond, T2 pond and T3 pond were maintained at 104μg/m L magnitude, when those of C1 pond and C2 pond were maintained at 105μg/m L magnitude. The cyanophyta microalgae biomasses of ponds with no use of CZBC1 were higher than that of ponds using CZBC1 about one level of magnitude.After the use of aligicidal bacteria CZBC1, the quantity of Microcystis floslutea in T1 pond decreased dramatically with the quantity dominant species turned into Oocystis borgei; Oocystis borgei turned to be the quantity and biomass dominant specie in T2 pond. The quantity dominant species of T3 pond was Melosira islandica. In the subsequent phase of experiment, the dominant species turned into chlorophyta microalgae, including Chlamydomonas libonica, Scenedesmus quadricauda and so on. With the variation of microalgae community structure, the quantity and biomass dominant specie of C1 pond became Oocystis borgei. In the subsequent phase of experiment, Microcystis floslutea bloom occurred, whose quantity, quantity dominance and biomass dominance reached to 1.59×107 cell/m L, 64.91% and 64.65%, respectively. Microcystis floslutea bloom occurred again, two days later, after using of copper compounds. The quantity and biomass dominant specie in C2 pond were Planktolyngbya subtilis, Oscillatoria angustissima.The results indicated that the using of algicidal bacteria CZBC1 in the shrimp cultured ponds could effectively inhibit the harmful cyanophyta to be dominant species. This was favor to excellent microalgae to be dominant species, in 6×103CFU/ml once in 7 days. CZBC1 was also favor to keep good water environment for cultured shrimp, with optimizing the microalgae community structure. Key wordsalgicidal bacteria; aquaculture; microalgae community; Oscillatoria sp.;... |
PDF Full Text Request