Sutthi Nantaporn, Wangkahart Eakapol, Panase Paiboon, Karirat Thipphiya, Deeseenthum Sirirat, Ma Nyuk Ling, Luang-In Vijitra
Department of Agricultural Technology, Faculty of Technology, Mahasarakham University, Maha Sarakham 44150, Thailand.
Applied Animal and Aquatic Sciences Research Unit, Division of Fisheries, Faculty of Technology, Mahasarakham University, Maha Sarakham 44150, Thailand.
Animals (Basel). 2023 Oct 19;13(20):3262. doi: 10.3390/ani13203262.
Overuse of antibiotics in aquaculture has generated bacterial resistance and altered the ecology. Aquacultural disease control requires an environmentally sustainable approach. Bacterial exopolysaccharides (EPSs) as bioimmunostimulants have not been extensively explored in aquaculture. This study investigated EPS produced from 5% / riceberry broken rice as a carbon source and 1% / soybean meal as a nitrogen source by PS21 from milk kefir grain for its immunomodulatory, antioxidant activities and resistance to pathogenic in Nile tilapia (). The FTIR spectrum of EPS confirmed the characteristic bonds of polysaccharides, while the HPLC chromatogram of EPS displayed only the glucose monomer subunit, indicating its homopolysaccharide feature. This EPS (20 mg/mL) exhibited DPPH scavenging activity of 65.50 ± 0.31%, an FRAP value of 2.07 ± 0.04 mg FeSO/g DW, and antimicrobial activity (14.17 ± 0.76 mm inhibition zone diameter) against EW1 using the agar disc diffusion method. Five groups of Nile tilapia were fed diets (T1 (Control) = 0.0, T2 = 0.1, T3 = 0.2, T4 = 1.0, and T5 = 2.0 g EPS/kg diet) for 90 days. Results showed that EPS did not affect growth performances or body composition, but EPS (T4 + T5) significantly stimulated neutrophil levels and serum lysozyme activity. EPS (T5) significantly induced myeloperoxidase activity, catalase activity, and liver superoxide dismutase activity. EPS (T5) also significantly increased the survival of fish at 80.00 ± 5.77% at 14 days post-challenge with EW1 compared to the control (T1) at 53.33 ± 10.00%. This study presents an efficient method for utilizing agro-industrial biowaste as a prospective source of value-added EPS via a microbial factory to produce a bio-circular green economy model that preserves a healthy environment while also promoting sustainable aquaculture.
水产养殖中抗生素的过度使用已产生细菌耐药性并改变了生态环境。水产养殖疾病控制需要一种环境可持续的方法。细菌胞外多糖（EPSs）作为生物免疫刺激剂在水产养殖中尚未得到广泛研究。本研究调查了以5%红米碎米为碳源、1%豆粕为氮源，由开菲尔粒中的PS21产生的EPS对尼罗罗非鱼的免疫调节、抗氧化活性及对病原体的抗性。EPS的傅里叶变换红外光谱（FTIR）证实了多糖的特征键，而EPS的高效液相色谱（HPLC）色谱图仅显示葡萄糖单体亚基，表明其为同多糖特征。这种EPS（20mg/mL）的DPPH清除活性为65.50±0.31%，铁还原抗氧化能力（FRAP）值为2.07±0.04mg FeSO/g干重，采用琼脂扩散法对嗜水气单胞菌EW1的抑菌活性（抑菌圈直径为14.17±0.76mm）。将五组尼罗罗非鱼投喂含不同剂量EPS的饲料（T1（对照）=0.0、T2=0.1、T3=0.2、T4=1.0和T5=2.0g EPS/kg饲料）90天。结果表明，EPS不影响生长性能或鱼体组成，但EPS（T4+T5）显著刺激中性粒细胞水平和血清溶菌酶活性。EPS（T5）显著诱导髓过氧化物酶活性、过氧化氢酶活性和肝脏超氧化物歧化酶活性。与对照（T1）在攻毒后14天的存活率53.33±10.00%相比，EPS（T5）还显著提高了尼罗罗非鱼在攻毒嗜水气单胞菌EW1后14天的存活率，达到80.00±5.77%。本研究提出了一种有效的方法，通过微生物工厂将农业工业生物废弃物作为增值EPS的潜在来源，以生产一种生物循环绿色经济模式，既能保护健康环境，又能促进可持续水产养殖。
