PROBLEM TO BE SOLVED: To provide a sports nutrition food which increases the remaining capacity of physical function of athletes, improves stress tolerance, and promptly recovers physical strength and psychological state after physical stress. A bioactive additive having a protective action, which is an acid-enucleating bacterial biomass of a strain of a methane-oxidizing bacterium Methylococcus capsulatus GBS-15. [Selection diagram] None【課題】スポーツ選手の身体機能の余力を大きくし、ストレス耐性を向上させ、肉体的負荷がかかった後の素早い体力および心理状態の回復をもたらすスポーツ栄養食品の提供。【解決手段】防御作用のある生物活性添加物であって、メタン酸化細菌Methylococcus capsulatus GBS-15の菌株の酸除核細菌バイオマスであることを特徴とする生物活性添加物。【選択図】なし