Biological Characterization And Application Of Bdellovibrio Sp. HKM

Bdellovibrio sp. is a kind of parasitic microorganism which can lead the host cracking. It has a good effect on eliminating the pathogens which can cause human food poisoning disease and fish farming. In our investigation, seawater was obtained from salinity environment of Hainan Pro vice, one bacteria which could prey on E.coil was isolated through DNB double layer agar plating technique. The strain was identified, according to "Bergey's manual identification of bacteria" (ninth edition), as Bdellovibrio sp. through observing the plaques formed in the DNB double layer agar plate and their morphological properties by transmission electron microscopy and named HKM. The amplification, sequencing and phylogenetic analysis of 16S rRNA gene was utilized to further identify the Evolutionary position of this strain.At last, applied research of Bdellovibrio-and-like organism in the aquaculture of Scophthlmus maxims was done.Combining 20d water exchange cycle, one group as the control (B group) and one group as the adding Bdellovibrio-and-like organism (C group), while with the ponds of production as reference(A group).Then, determination was carried out on survival rate, weight gain, average daily weight increment, body length growth rate, average daily growth rate in body length and fat factor. Besides, the number of vibrios in seawater of each group was detected during the period of experiment (the moment before changing seawater). The results showed that the values of growth indexes of the group of adding Bdellovibrio-and-like organism were obviously higher than that of the production and the control groups (P<0.05).Compared to the production group, the survival rate increased by 13.23%, while, weight gain, average daily weight increment, body length growth rate, average daily growth rate in body length and fat factor increased by 663%, 130.35mg,28.09%,31.82μm and 4.99, respectively. Vibrios were reduced obviously in the group of adding Bdellovibrio-and-like organism.The conclusion showed that Bdellovibrio-and-like organism has the effect on the growth and the survival rate of the Scophthlmus maxims, also can eliminate the vibrio aquaculture.