Isolation and partial characterization of bacteriophages infecting Vibrio harveyi from shrimp farm effluent water

Bacteriophage isolated from the semi-intensive culture of Pacific white leg shrimp Litopenaeus vannamei infects the luminous bacteria Vibrio harveyi. Lytic activity and lytic spectrum results revealed that the isolated phage had strong lytic activity in V. harveyi, V. parahaemolyticus, and V. vulnificus. Biofilm inhibition activity was performed against different pathogenic vibrios on high-density polyethylene (HDPE) template and the result revealed that the phage effectively inhibited the biofilm formation in V. harveyi. Spectrophotometric assay performed for lytic activity of the isolated phage in V. harveyi liquid culture showed that the phage significantly decreased the V. harveyi cell densities at different time intervals (P?<?0.05). To study the stability of phage at different temperature and pH revealed that the phage withstands the temperature ranged between 40 and 70 °C and the pH of 4 and 9 at a significant level (P?<?0.001). One-step growth curve depicted that the burst size gradually increased to a significant level and reached the maximum of 90% at 180 min (P?<?0.05). This study concluded that the isolated phage had specific activity against pathogenic V. harveyi infections.

     

Herbal biomedicines: a new opportunity for aquaculture industry

Hormones, antibiotics, vitamins and several other chemicals have been tested in aquaculture operations for various remedies. Even though they give positive effects, they cannot be recommended due to their residual and other side effects. The alternative herbal bio-medicinal products in the aquacultural operations, that have the characteristics of growth promoting ability and tonic to improve the immune system, act as appetite stimulators. They increase consumption, induce maturation, and have antimicrobial capability and also antistress characteristics that will be of immense use in the culture of shrimps and other fin fishes without any environmental and hazardous problems. Herbal compounds such as phenolics, polyphenols, alkaloids, quinones, terpenoids, lectines and polypeptides have been shown to be very effective alternatives to antibiotics and other synthetic compounds. The present paper is presented after a careful review of more than 50 herbal plants for their biological effects such as growth promotion, immunostimulation, antistress, antibacterial, antifungal, antivirals, appetite stimulators and aphrodisiac.