Aurantiochytrium sp., a marine heterotrophic eukaryotic protist that inhabits tropical waters of the Indian and Pacific Oceans and temperate and cold waters of Australia, Arctica, and Antarctica, has attracted interest in the aquaculture industry due to its nutritional profile and ability to enrich fish and shrimp feeds with long-chain polyunsaturated fatty acids (arachidonic acid – ARA and large amounts of docosahexaenoic acid – DHA. Aurantiochytrium sp. also produces astaxanthin and β-carotene. Dietary intake of Aurantiochytrium sp. as a feed additive may improve zootechnical performance and pathogen resistance by enhancing the immune system of fish and shrimp.
To better understand the composition and potential of Aurantiochytrium sp., test samples were analysed by CSIRO at the Queensland Bioscience Precinct Analytical Laboratory using established best practice methods. Analyses were based on methods prescribed by the Association of Official Agricultural Chemists (AOAC, 2016). Results are shown in Table 1 and show enrichment of Aurantiochytrium sp. with lipids, compared to a benchmark ingredient – squid meal.
To explore possible anti-inflammatory activity of Aurantiochytrium flours, an in vitro assay was performed using the mouse macrophage-like cell line, RAW264.7. Bacterial lipopolysaccharide (LPS) was used to induce production of nitric oxide (NO), a signalling molecule that plays an important role in the development of inflammation. Quercetin, a well-known plant-derived anti-inflammatory molecule, was used as the positive control, and squid meal was also assayed for comparison. Decreases in LPS-stimulated NO production following treatment with quercetin, squid meal, or Aurantiochytrium flours indicated anti-inflammatory potential. To ensure anti-inflammatory activity was not related to cytotoxicity, cell viability was measured using the MTT assay and ranged from 80 to 100%. The samples explored in the anti-inflammatory assay are described in Table 2.