Encapsulated Powder as a Potential Bio-Disinfectant against Whiteleg Shrimp-Pathogenic Vibrios.

Liquid preparations of bdellovibrios are currently commercialized as water quality improvers to control bacterial pathogens in whiteleg shrimp . However, the efficacy of these liquid preparations is significantly impaired due to a dramatic loss of viable cells during long-term room temperature storage. Thus, new formulations of bdellovibrios are greatly needed for high-stablility room-temperature storage. In the present study, the encapsulated powder of sp. strain F16 was prepared using spray drying with 20 g L gelatin as the coating material under a spray flow of 750 L h, a feed rate of 12 mL min, and an air inlet temperature of 140 °C. It was found to have a cell density of 5.4 × 10 PFU g and to have spherical microparticles with a wrinkled surface and a diameter of 3 μm to 12 μm. In addition, the encapsulated powder presented good storage stability with its cell density still remaining at 3.5 × 10 PFU g after 120 days of room-temperature storage; it was safe for freshwater-farmed whiteleg shrimp with an LD over 1200 mg L, and it exhibited significant antibacterial and protective effects at 0.8 mg L against shrimp-pathogenic vibrios. To our knowledge, this is the first report on a promising powder against shrimp vibrios with high stable room-temperature storage.