On October 21, at the VNUHCM-University of Science (HCMUS), Researcher Lê Hồng Linh successfully defended the doctoral thesis titled ‘Study on the Preparation and Testing of a Biological Product Using Yeast Cell Surface Technology (Saccharomyces cerevisiae) for the Prevention of White Spot Syndrome Virus (WSSV) in Whiteleg Shrimp (Litopenaeus vannamei),’ under the supervision of Prof. Đặng Thị Phương Thảo.

The dissertation substantiated the significant biological efficacy of the Saccharomyces cerevisiae W303::vp28 extract in stimulating immune responses and enhancing resistance against white spot disease in whiteleg shrimp. Supplementation of 10 g of yeast extract per kilogram of feed resulted in a protection rate against WSSV of 87.19 ± 2.15% after 14 days.

Based on these findings, the researcher developed an optimized formulation combining 50% yeast extract containing VP28 and 50% beneficial microorganisms (density 109 cfu/g). The study determined the optimal application method as a daily feed supplement of 10 g of biological product per kilogram of feed, a protocol that improved both shrimp growth and disease resistance.

Laboratory trials confirmed that the completed formulation achieved a protection rate of 77.8 ± 1.9% against WSSV and enhanced shrimp immunity. Enzyme activity levels of SOP reached 61 ± 1 and PO reached 2.2 ± 0.1—markedly higher than treatments using only probiotic supplements (SOP: 34 ± 1.2; PO: 1.5 ± 0.1) or industrial feed alone (SOP: 25 ±1; PO: 1.1 ± 0.1).

Field trials conducted at commercial shrimp ponds in Binh Dinh Province demonstrated the most significant impact of the study. The product exhibited a dual effect: boosting shrimp immune system activity throughout the cultivation period and concurrently improving pond water quality by controlling H₂S gas, reducing NH₃ and COD concentrations, and inhibiting Vibrio spp. proliferation.

After 90 days of cultivation, shrimp raised in ponds treated with the new formulation achieved an average weight of 16.02 ± 0.37 g (an 18.2% increase) and a length of 12.54 ± 0.29 cm (a 6.6% increase) compared to the control group. From an economic perspective, the trial pond yielded a profit of VND 129.7 million, approximately 1.6 times higher than ponds utilizing existing commercial products. The yeast extract–probiotic formulation demonstrated strong potential for practical application in shrimp aquaculture by enhancing immune function, reducing disease incidence, and improving profitability for farmers.