DataSheet1_An Eco-Friendly Conversion of Aquaculture Suspended Solid Wastes Into High-Quality Fish Food by Improving Poly-β-Hydroxybutyrate Production.docx

The aquaculture industry is vital in providing a valuable protein food source for humans, but generates a huge amount of solid and dissolved wastes that pose great risks to the environment and aquaculture sustainability. Suspended solids (in short SS), one of the aquaculture wastes, are very difficult to be treated due to their high organic contents. The bioconversion from wastewater, food effluents, and activated sludge into poly-β-hydroxybutyrate (PHB) is a sustainable alternative to generate an additional income and could be highly attractive to the agricultural and environmental management firms. However, little is known about its potential application in aquaculture wastes. In the present study, we first determined that 7.2% of SS was PHB. Then, the production of PHB was increased two-fold by the optimal fermentation conditions of wheat bran and microbial cocktails at a C/N ratio of 12. Also, the PHB-enriched SS showed a higher total ammonia nitrogen removal rate. Importantly, we further demonstrated that the PHB-enriched SS as a feed could promote fish growth and up-regulate the expression of the immune-related genes. Our study developed an eco-friendly and simple approach to transforming problematic SS wastes into PHB-enriched high-quality food for omnivorous fish, which will increase the usage efficiency of SS and provide a cheaper diet for aquatic animals.

水产养殖业对于为人类提供宝贵的蛋白质食物来源至关重要，然而它却产生了大量固体和溶解废物，这些废物对环境及水产养殖业的可持续性构成了巨大风险。悬浮固体（简称 SS）作为水产养殖废物之一，由于其高有机含量，处理难度极大。将废水、食物废液和活性污泥生物转化为聚-β-羟基丁酸（PHB）是一种可持续的替代方案，不仅能够创造额外收入，对农业和环境管理公司也极具吸引力。然而，关于其在水产养殖废物中潜在应用的知识却知之甚少。在本研究中，我们首先确定了悬浮固体中 7.2% 为 PHB。随后，通过小麦麸和微生物混合物的最优发酵条件，在碳氮比 12 的情况下，PHB 的产量提高了两倍。此外，富含 PHB 的悬浮固体表现出更高的总氨氮去除率。更重要的是，我们进一步证明了富含 PHB 的悬浮固体作为饲料能够促进鱼类生长并上调免疫相关基因的表达。本研究开发了一种环保且简便的方法，将问题悬浮固体废物转化为富含 PHB 的高品质鱼食，这将提高悬浮固体的利用效率，并为水生动物提供更经济的饲料。