42 DECEMBER • WORLD AQUACULTURE • WWW.WAS.ORG Thraustochytrids as a Promising Source of Omega-3 Fatty Acids and Functional Bioactives for Sustainable Aquaculture Kurapati Nagendrasai, Saurav Kumar, Chundru Sri Sai Venkat, Bhautik Savaliya and Rishikesh Venkatrao Kadam Aquaculture stands as a cornerstone of global food security, steadily expanding to meet the escalating demand for aquatic protein. With capture fisheries production stagnating since the 1980s, farmed aquatic species now contribute nearly half of the world’s total fish supply (Jaseera and Kaladharan 2019). However, this remarkable growth is not without its challenges. A primary concern revolves around the increasing reliance on finite marine resources, particularly fishmeal and fish oil, which are crucial components in aquafeeds due to their rich content of essential longchain polyunsaturated fatty acids (LC-PUFAs) like docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The dwindling supply and fluctuating prices of these traditional marine-derived ingredients pose significant sustainability and economic hurdles for the aquaculture industry. Furthermore, aquatic animals themselves have high dietary requirements for DHA and EPA to ensure optimal growth, health, and flesh quality, which in turn benefit human consumers (Parrish 2024). This creates an “omega-3 gap”, a growing disparity between the demand for these vital nutrients in aquafeeds and the sustainable availability of their primary sources. In response to this pressing need, marine heterotrophic protists known as thraustochytrids have emerged as a highly promising and sustainable alternative. These microorganisms possess a unique metabolic capacity to synthesize substantial quantities of LCPUFAs, particularly DHA, through controlled fermentation processes (Raghukumar 2008). Beyond their impressive omega-3 profile, thraustochytrids also produce a spectrum of functional bioactives, including beneficial carotenoids and antioxidants, offering additional health and performance advantages for aquaculture species (Table 1). This article briefs the multifaceted potential of thraustochytrids as a sustainable and bio-functionally rich ingredient for aquafeeds, addressing both the critical TABLE 1. Various applications of thraustochytrids in aquaculture. Application Target Species Extracted Product Observed Benefits References DHA Atlantic salmon Thraustochytrid oil Maintains growth rate and FCR; Jaseera and Kaladharan Supplementation (Salmo salar) DHA-rich fillet quality 2019 Fish Oil Tilapia Whole-cell biomass/oil Improved weight gain; better Jaseera and Kaladharan Replacement (O. niloticus) FCR; enhanced DHA in tissue 2019 Larval Nutrition Pacific white shrimp Schizochytrium meal Higher survival; better growth Marchan et al. 2018 (L. vannamei) in early life stages Pigmentation & Shrimp, Salmonids Astaxanthin-rich biomass Enhanced coloration; Parrish 2024; Antioxidants oxidative stress resistance Raghukumar 2008 Immunity Fish & Shellfish Functional lipids, squalene Improved immune response; Marchan et al. 2018 Enhancement disease resistance Gut Health & Multiple aquaculture Enzymes, phospholipids Enhanced digestion, better Parrish 2024 Nutrient Uptake species nutrient absorption Sustainable Feed All species Fermented biomass/oil Reduced reliance on fish oil; Raghukumar 2008; Ingredient lower ecological impact; Wang et al. 2024 alignment with the circular economy
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