Spirulina Boosts Immunity, Fights Bacterial Infection

KEELUNG, TaiwanTaiwanese researchers found white shrimp Litopenaeus vannamei injected with a hot-water extract of Spirulina platensis enhanced innate immunity and increased resistance against Vibrio alginolyticus infection, which can cause ear infections or inflammation or wound infection (Fish Shellfish Immunol. 2010;28(5-6):764-73). L. vannamei was injected with a hot-water extract of S. platensis at 6, 10 and 20 mcg g(-1) or immersed in aerated seawater containing 200, 400 and 600 mg L(-1) of the extract and were challenged with V. alginolyticus at 1.5 x 10(6) or 1.4 x 10(6) colony-forming units (CFUs) shrimp, and then placed in seawater.

Survival rates of shrimp receiving the extract of S. platensis at 6to 20 mcg g(-1), and those of shrimp immersed in seawater containing the extract at 400 and 600 mg L(-1) were significantly higher than those of control shrimp after 24 to 96 and 48 to 96 hours, respectively. In a separate experiment, the hyaline cell (HC) count, granular cell (GC, including semi-granular cell) count, total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity and lysozyme activity were measured when shrimp were injected with the extract at 6, 10 and 20 mcg g(-1) and immersed in seawater containing the extract at 200, 400 and 600 mg L(-1). These parameters directly increased with the concentration and significantly increased when shrimp were immersed in the seawater containing the extract at 0.5 to 4 hours. L. vannamei received all doses of the extract via injection or via immersion all had increased phagocytic activity and clearance efficiency to V. alginolyticus at 12 to 72 hours and 3 to 4 hours, respectively.