University of the Ryukyus · Faculty of Agriculture · 准教授

Research keywordsdietary polysaccharides・Spirulina platensis・anti-obesity・adipogenesis・metabolic syndrome・anti-inflammatory compounds・Lactobacillus therapeutics・broiler nutrition

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• Exploring the advantages of Lactobacillus species from plants for future therapeutics and foods2026 · Wichiansri, S; Siripornadulsil, S; Iwasaki, H; Siripornadulsil, W
• Dietary polysaccharides extract from Spirulina platensis: a natural alternative for enhancing broiler performance and antioxidation status2026 · 1. The demand for natural alternatives to antibiotic growth promoters in poultry has led to growing interest in bioactive compounds, such as polysaccharides derived from algae. This study evaluated the effects of algae (Spirulina platensis)-derived polysaccharides (ADP) on growth performance, blood profiles, carcase characteristics, meat quality, amino acid composition and antioxidant status in broilers. 2. A total of 320, 1-d-old Ross 308 mixed-sex broilers were randomly allocated to one of the five dietary treatments; a control diet (0% ADP) and diets supplemented with 0.15%, 0.30%, 0.45% and 0.60% of ADP. Each treatment included four replicates containing 16 birds each. The feeding trial was conducted over 42 d and was divided into three phases, including starter (1–14 d), grower (15–28 d) and finisher (29–42 d). 3. Dietary inclusion of ADP at 0.30% significantly improved body weight gain and feed conversion ratio during the finisher (1.77 kg and 1.71, respectively) and overall (2.82 kg and 1.56, respectively) periods. There were no adverse effects observed on haematological, serum biochemistry or carcase characteristics. 4. Supplementation with 0.45–0.60% ADP reduced cooking loss to 34–40% and improved meat cohesiveness by about 5%. Its inclusion elevated the levels of key amino acids, such as threonine, histidine, isoleucine, arginine and glutamic acid in the breast muscle. Additionally, ADP linearly increased hepatic antioxidant enzyme activities, including total superoxide dismutase (317.60–337.12 U/mg protein), glutathione peroxidase (39.98–48.70 U/mg protein), catalase (7.09–7.71 U/mg protein) and decreased malondialdehyde concentrations (0.63–0.68 nmol/mg protein) demonstrating enhanced oxidative status. These improvements were attributed to the prebiotic and antioxidant properties of Spirulina-derived polysaccharides, which enhance nutrient utilisation, maintain gut integrity and strengthen redox balance. 5. This study provides preliminary evidence that polysaccharides derived from S. platensis, particularly at 0.30–0.45%, can be used as safe and effective feed additives in broiler diets. These compounds have the potential to enhance performance, oxidative stability and certain aspects of meat quality without adverse effects.
• Metabolomic changes and enhanced digestibility with algae (Spirulina platensis) derived polysaccharides supplementation in broilers2025 · The objective of this study was to investigate the effects of algae (Spirulina platensis)-derived polysaccharides (ADPs) on performance, digestibility, intestinal histomorphology, digestive enzyme activities, and metabolomic profiles in broiler chickens. A total of 320 one-day-old Ross 308 mixed-sex broilers were randomly allocated to 5 dietary treatments comprising 0 (Control), 1500, 3000, 4500, and 6000 mg ADPs/kg in a completely randomized design. Each treatment included 4 replications, with 16 birds per replicate. The feeding trial lasted 42 days, encompassing starter (1–10 days), grower (11–24 days), and finisher (25–42 days) phases. The results demonstrated that dietary ADPs supplementation at 3000 mg/kg significantly enhanced (P < 0.05) body weight gain and improved feed conversion ratio during the overall period (1–42 days). In addition, supplementation with 1500–4500 mg/kg ADPs significantly improved (P < 0.05) in vitro crude protein digestibility (period 2) and apparent metabolizable energy (periods 2 and 3). Meanwhile, in vivo digestibility was also enhanced by ADPs supplementation, with significant improvements (P < 0.05) in dry matter (period 2) and crude protein (periods 2 and 3) digestibility. Histomorphological analysis revealed that ADPs supplementation at 1500–6000 mg/kg significantly increased (P < 0.05) villus height, villus width, villus height-to-crypt depth ratio, and villus surface area throughout the small intestine. Additionally, digestive enzyme activities, including amylase, lipase, and protease, were significantly elevated (P < 0.05) in broilers supplemented 3000–4500 mg/kg ADPs. Metabolomic analysis identified significant alterations in liver and breast muscle metabolites, with 194 differentially expressed metabolites in the liver and 134 in the breast, primarily associated with amino acid metabolism pathways. In the liver, the most affected pathways included lysine degradation, glycine-serine-threonine metabolism, and arginine biosynthesis. In the breast muscle, key pathways included phenylalanine-tyrosine-tryptophan biosynthesis, glycine-serine-threonine metabolism, and valine-leucine-isoleucine biosynthesis. Regarding principal component analysis demonstrated distinct clustering between control and ADPs-treated groups, indicating notable metabolic shifts. These findings suggest that the supplementation of ADPs from S. platensis enhances nutrient digestibility, intestinal morphology, digestive enzyme activity, and key metabolic pathways, ultimately supporting broiler growth performance. Based on the comprehensive findings of this study, dietary supplementation with ADPs at 3000 mg/kg is recommended as the optimal level.
• Stress amelioration and anti-inflammatory potential of Shiikuwasha (Citrus depressa Hayata) essential oil, limonene, and γ-terpinene2022 · Y Asikin, K Shimizu, H Iwasaki, H Oku, K Wada

• 海藻の生育を支える海藻-微生物相互作用の全体像の解明2020 · オキナワモズク微生物叢の網羅的解析法の構築を試みた。16S rRNA遺伝子のアンプリコンシーケンシングによる微生物叢解析法をオキナワモズクに適用するにあたり、実際の微生物叢に近いと考えられるショットガンシーケンシングによるオキナワモズク微生物叢データと、高い相関を示すデータを得られるPCR条件を72通りの組み合わせから選抜した。次に、本研究で選抜したPCR条件を用いて、沖縄県内8地点から採取したオキナワモズクとオキナワモズク漁場の微生物叢を解析した。結果として、オキナワモズクとその周辺海水の微生物叢は明確に異なっており、オキナワモズクにはオキナワモズクの微生物叢が形成されていること、および、オキナワモズク微生物叢は産地ごとの特徴があることが判明した。また、沖縄県本部町備瀬の地先のオキナワモズク漁場にモズク微生物叢を時系列で追跡する野外実験を行い、モズクの採取時期によりオキナワモズク微生物叢に大きな差異が見出された。以上のオキナワモズク微生物叢データより、オキナワモズクの全サンプルに見出される１菌種を見出すことができた。 オキナワモズクのトランスクリプトーム解析を行う目的で市販の植物用キットを用いてRNA抽出を行ったところ、収量がきわめて低く、市販キットの標準プロトコルはオキナワモズクに適用できないことが判明した。そこで、独自のステップを追加するなど当該プロトコルを修正し、遺伝子発現解析に適用可能なオキナワモズクからのRNA抽出法を確立した。 オキナワモズクの藻体成分の解析の結果、オキナワモズク細胞壁多糖組成に生長段階ごとの差異が見出された。水溶成分を標的としたメタボローム解析では、脂肪酸が多く検出された一方、有機酸やビタミン類の検出には解析法の修正が必要であることが明らかとなった。
• マングローブのトリテルペノイド合成をとりまく耐塩性制御ネットワークの解明2011 · 基盤研究(C)
• 食品性植物由来の腫瘍細胞選択的細胞毒性成分の機能解析
• Tumor Selective Cytotoxicity and Functional Analysis of Medical Herb Extract

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