Cyanobacteria Desertifilum tharense NIOF17/006 as a Novel Aquafeed Additive: Effect on Growth, Immunity, Digestive Function, and Genes Expression of Whiteleg Shrimp Postlarvae

Mohamed Ashour ^1* Ahmed AlSooti ^2* Ahmed Mamoon ³ Fawzia S Ali ¹ Mostafa Elshobary ⁴ Mohamed M Mabrouk ⁵ Ahmed I A Mansour ¹ Abdallah Tageldein Mansour ⁶ Ehab El-Haroun ⁷ Ahmed F Abdelhamid ^3,5

• ¹ National Institute of Oceanography and Fisheries (NIOF), Alexandria, Egypt
• ² Sultan Qaboos University, Muscat, Oman
• ³ Faculty of Science, Al Azhar University, Cairo, Beni Suef, Egypt
• ⁴ Faculty of Science, Tanta University, Tanta, Gharbia, Egypt
• ⁵ Faculty of Agriculture, Al-Azhar University, Cairo, Beni Suef, Egypt
• ⁶ King Faisal University, Al-Ahsa, Eastern Province, Saudi Arabia
• ⁷ Cairo University, Giza, Giza, Egypt

This work investigated the molecular identification and potential application of the cyanobacteria strain, Desertifilum tharense, NIOF17/006 as a novel aquafeed additive for whiteleg shrimp (Litopenaeus vannamei) postlarvae (PLs). Morphological and molecular characterization confirmed the isolate as D. tharense, with 16S rRNA sequence analysis showing high similarity (98.01-98.53%) to the known strains of D. tharense. Biochemical analysis revealed that the isolate contained 37.74% protein, 5.52% lipid, and 21.25% carbohydrate, based on a dry weight basis. An eight-week feeding trial for L. vannamei PLs evaluated the effects of dietary supplementation with D. tharense NIOF17/006 at doses of 0, 1, 2.5, and 5 g kg -1 diet.Compared to the control group, shrimp-fed D. tharense diets had significantly higher feed utilization, growth performance, survival rate, and whole-body composition. Nonspecific immunity parameters (lysozyme, superoxide dismutase, catalase), as well as the digestive enzymes´ activities of amylase and lipase, were significantly enhanced in shrimp-fed diets supplemented with cyanobacteria, while Malondialdehyde (MDA) levels decreased. The gene expression analysis revealed upregulation of growth-related genes (Growth Hormone, Insulin-like Growth Factor-I, and Insulin-like Growth Factor-II) and immune-related genes of prophenoloxidase (proPO), superoxide dismutase (SOD), and lysozyme) in shrimp muscles with increasing cyanobacteria supplementation, particularly at doses of 2.5-5 g kg -1 diet.Moreover, the polynomial regression machine learning model predicts that the ideal supplementation level of probiotic cyanobacteria D. tharense NIOF17/006 ranges from 3.4 to 4.2 g/kg diet. This study demonstrates the potential of D. tharense NIOF17/006 as a promising aquafeed additive for improving the growth, immunity, and overall health of L. vannamei PLs, opening new avenues for sustainable aquaculture practices.