| Bdellovibrio-and-like-organisms (BALOS) is a class of gram-negative bacteria that cancleavage variety of parasitic bacteria, that makes it has dual characteristics with probiotics andantibiotics. And different strains of Bdellovibrio have different cracking spectrum capacity.There has also been a problem that Bdellovibrio cost much in preparation processcumbersome and preservation of decreased activity. In transportation and preservation process,Bdellovibrio’s cracking activity affects by temperature. Therefore to prefer a kind ofBdellovibrio which has better pathogens cracking effect on the environment and in vivoshould be very important.In this study, firstly DNB double-plate was used to separate Bdellovibrio from brackishwhich had been collected in Haikou. The Bdellovibrio-and-like-organisms was named BDS02.Then15‰salinity brackish double-plate was used to purification BDS02. The diameter ofthese plaques were changed from0.90mm to3.50mm in24h~48h and they had same size.The cell morphology of BDS02was1.28μm×0.57μm and it had a flagellum almost3.17μm. Then these Bdellovibrio had been used to do the experiment in the effect of cracking hostbacteria. BDS02was found that it could live with five kinds of common beneficial bacterialike Bacillus subtilis and cleavage ten strains like E.coli rapidly within24h. Theconcentration of Bdellovibrio preparations made by BDS02was about1010~1011pfu/mL.Selected sodium glutamate, glycerol and sucrose to be the protectant, by means of thethermostat classic accelerated test the optimized concentration of three kinds of protectantwere5%(w/v) sodium glutamate,15%(w/v)glycerol and5%(w/v)sucrose. The shelf-life of theBdellovibrio preparation added when the final activity ratio was to reach1%in4℃and10℃were63.3d and27.3d,63.6d and27.9d,62.7d and27.3d. Compared with the controlgroup the shelf-life of Bdellovibrio formulations containing protectant was33percent higherthan it. Then used orthogonal test to elect the composition of best protectant, it was found thatthe Bdellovibrio formulation which containing protectants of3%(w/v) sodium glutamate,13%(w/v)glycerol and5%(w/v)sucrose had the best effect on its shelf-life. when the finalactivity ratio was to reach1%,0.1%and0.01%in4℃and10℃the shelf-life could be95.5d,143.3d,191.0d and40.2d,60.3d,80.4d. Three kinds of protectant all had significantimpact on the formulation of Bdellovibrio shelf-life, the degree of the protectant above wassucrose>glycerol> glutamate. By means of the constant temperature storage test to verifyaccurateness of thermostat classic accelerated test and orthogonal experimental, the results shown that the the error values of Bdellovibrio’s shelf-life are within±0.59%and itcorresponded the requirements.Finally used Bdellovibrio(BDS02) formulations in aquaculture water, compared thecontrol of bacteria between the new cultured Bdellovibrio formulation and Bdellovibrioformulation added the best protectant combination which kept one month in water and rotifer.The result indicated that there was no significant difference (P>0.05) between two kinds ofBdellovibrio formulation, both of them could decrease the total bacterial rapidly in24h andup to4lg. When the concentration of Bdellovibrio formulation in aquaculture water was keptat105pfu/mL, it could effectively reduce the growing speed of bacteria. And the aquaculturewater that contained Bdellovibrio formulation had significantly better effect in inhibit bacteriathan which without Bdellovibrio. The protectant had no harm to the aquaculture water. Theconcentration of Bdellovibrio formulation and bacteria in the aquaculture water wereimportant factors. And the effect shown Bdellovibrio formulations contained protectant inlong-term storage had no effect on its lytic activity. |
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