Vibrio vulnificus phagocytophilus acts on pathogenic bacteria in the " penetration, stabilization, lysis" model, i.e., Vibrio vulnificus phagocytophilus firstly recognizes and adsorbs the host bacterium (the causative organism), and then enters into the interior of the bacterium through a series of reactions such as enzymolytic digestion and mechanical drilling, and ultimately lyses and kills the pathogenic bacterium to form a zygote Vibrio vulnificus!
The unique effect of Vibrio vulnificus in shrimp and crab aquaculture
Vibrio vulnificus mainly destroys the pathogenic bacteria by mechanical drilling and enzymolysis, so as to achieve the effect of sterilization. This mode of action of Vibrio phagocytophilus also determines that its bactericidal range is more extensive than that of other biocontrol bacteria.
A large number of research results show that the bacteriophage Vibrio vulnificus is almost able to cleave common shrimp and crab pathogenic bacteria species, Vibrio harveyi, Vibrio parahaemolyticus, Vibrio eel, Vibrio melitensis, Vibrio alginolyticus, Vibrio rivericus, Aeromonas aeruginosa, and other***25 strains of common shrimp and crab pathogenic bacteria have good bacteriophagic activity. Therefore, by splashing Vibrio phagocytophilus into the water body, the species and number of shrimp and crab pathogenic bacteria in the water body can be widely reduced, thus reducing the incidence of bacterial diseases of shrimp and crab.
In addition, the experiments proved that Vibrio phagocytophilus decreased the content of Aeromonas hydrophila by 103cfu/mL in 5 days, and decreased the content of Aeromonas hydrophila by 107cfu/mL in 9 days, which demonstrated that Vibrio phagocytophilus was highly efficient in eliminating the pathogenic bacteria, and it provided an important basis for the further popularization of the application in the control of shrimp and crab bacterial diseases in the clinical trials.
As a parasitic bacterium, Vibrio vulnificus, in addition to good phagocytosis, has been proven to have the triple effect of water quality improvement, enhancement of immunity and resistance to bacterial infections, which is any kind of probiotic and chemical disinfectants (e.g., chlorine dioxide, povidone-iodine, etc.) can not be compared. Vibrio phagocytophilus can significantly improve the main chemical indicators in the aquaculture environment, as shown in the following: after sprinkling Vibrio phagocytophilus preparation with the content of 5×104PFU/L into the water, the COD, ammonia nitrogen and sulfide content of the aquaculture water body decreased by 29.95%, 33.87% and 34.38%, respectively, and the dissolved oxygen content increased by 12.43%; the study further pointed out that Vibrio phagocytophilus can inhibit the infection of Vibrio. Vibrio vulnificus inhibited Vibrio vulnificus significantly better than sodium dichloroisocyanurate (0.3 mg/L) and quaternary ammonium complex iodine (0.3 mg/L).
In addition, Vibrio vulnificus phagocytophilus was able to significantly promote the growth of Chinese shrimp and increase the activity of non-specific immune factors. After adding Vibrio phagocytophilus at 1% to the basal feed of Chinese shrimp for 25 days, the growth rate, weight gain rate, and survival rate of shrimp were increased by 49.07%, 74.61%, and 50%, respectively; the lysozyme activity and superoxide dismutase activity were increased by about 500% and 100%, respectively, and the relative protection rate of shrimp against Vibrio eel infections was also up to 52.9%. All these findings showed the superiority of Vibrio vulnificus phagocytophilus in preventing shrimp and crab pathogenic infections.
The reasons for the occurrence of bacterial diseases in rearing aquatic animals are, firstly, due to the large number of Vibrio proliferation in the nursery pool, the content is too high; secondly, the aquatic animals in the poor water environment of their own immunity and resistance to decline, by a large number of germs invasion and triggering all kinds of diseases.
In the aquatic animal nursery and aquaculture process, we must adhere to the principle of prevention is more important than cure, regular testing of water quality and total amount of Vibrio bacteria, and daily pond inspection. Especially in the middle and late stages of aquaculture, with the continuous growth of aquatic animals, residual bait, feces is also gradually increased, a variety of pathogens, especially Vibrio content increased. Practice shows that once found in the water Vibrio content of more than 1000 / ml, are required to use aquaculture water biocides for prevention as soon as possible. Otherwise, there is a high possibility of outbreaks of various types of bacterial infections, resulting in large-scale deaths of aquatic animals.
Shelf life: 3 months
Non-stimulating, non-oxygen depletion, rain or shine,
can also be used during the shedding period.
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