EFEKTIVITAS INDIGEN BAKTERIOFAG TERHADAP RESPON IMUN NONSPESIFIK Litopenaeus vannamei SEBAGAI AGEN BIOKONTROL PREVENTIF WHITE FECES DISEASE MELALUI TEKNOLOGI FREEZE-DRYING

White Feces Disease (WFD) attacks shrimp ponds, causing stunted growth of whiteleg shrimp and mortality of up to 30% within 1-3 days. Current prevention efforts include the use of antibiotics, which can induce pathogen resistance and reduce microbial activity, resulting in decreased water quality. Bacteriophages, or phages, are an alternative to address the problem of pathogenic bacterial infections that cause WFD, with their use being more beneficial than antibiotics and herbal remedies. However, as free virions, phages are sensitive to various environmental factors. Therefore, an appropriate phage preservation method is needed, namely a preservation method using freeze-drying technology that can increase virus survival during storage. The purpose of this study was to determine whether phages can be preserved and can become a product with potential to overcome WFD. This research method used a RAL design consisting of 5 treatments and 4 replications. The observed parameters were phage isolation, purification, and propagation, SEM, and in vivo laboratory-scale tests. Data analysis used ANOVA. The results of the phage study can infect V. alginolyticus bacteria, as indicated by the appearance of plaques on double-layer agar, a decrease in the number of V. alginolyticus bacterial colonies, and the occurrence of bacterial cell lysis in SEM tests. In vivo laboratory-scale tests showed that the administration of phage was able to overcome WFD with an increase in the phagocytosis index and THC value. Based on these results, the use of intestinal phage can overcome WFD and thus increase shrimp survival.