PROBLEM TO BE SOLVED: To provide: a microbial oil in which polyunsaturated fatty acids, and esters, acid salts, alcohols, and/or aldehydes thereof are highly concentrated； a composition comprising the highly concentrated microbial oil； and a method for producing and using the highly concentrated microbial oil.SOLUTION: A Schizochytrium species microorganism isolated from a sample taken from an intertidal habitat, a culture of said microorganism, a concentrated microbial oil comprising a combination of DHA and EPA obtained from said microorganism, and a pharmaceutical composition comprising said microbial oil are provided.SELECTED DRAWING: None【課題】多価不飽和脂肪酸、そのエステル、その酸性塩、そのアルコール、及び／又はそのアルデヒドが高濃度化された微生物油；高濃度化微生物油を含有する組成物；及び高濃度化微生物油の作製及び使用方法の提供。【解決手段】潮間生息地から採取した試料より単離したシゾキトリウム種（Ｓｃｈｉｚｏｃｈｙｔｒｉｕｍ ｓｐｅｃｉｅｓ）の微生物、該微生物の培養物、該微生物から得られるＤＨＡとＥＰＡとの組み合わせを含む高濃度化微生物油、該微生物油を含む医薬組成物。【選択図】なし
