ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar, Odisha, 751002, India.
BMC Microbiol. 2024 Oct 26;24(1):432. doi: 10.1186/s12866-024-03473-4.
The biofloc system (BFS) provides a sustainable aquaculture system through its efficient in situ water quality maintenance by the microbial biomass, besides continuous availability of these protein-rich microbes as feed to enhance growth and immunity of the reared organism. This study explores the gill architecture, growth performance, digestive enzyme activity, intestinal microbial composition, and histology of three freshwater fish species, Puntius gonionotus, Pangasianodon hypophthalmus, and Heteropneustus fossilis reared in biofloc based polyculture system.
The three species in T2 showed significantly higher WG and SGR, followed by T1 and T3. The wet mount of gill architecture showed smaller inter-filament gaps in gill arches of silver barb followed by stinging catfish and stripped catfish, but showed no correlation with the weight gain. However, silver barb being an omnivore and filter-feeder, accumulated a more diverse microbial community, both in T1 and BFS (T2 and T3), while the bottom feeder H. fossilis exhibited unique gut bacterial adaptability. The presence of floc in T2 and T3 enhanced bacterial abundance in water and fish gut, but their microbial diversities significantly reduced compared to T1 receiving only feed. Next-generation sequencing revealed that the Pseudomonas dominated in gut of P. gonionotus and P. hypophthalmus in T1, Enterobacterales and Fusobacterium prevailed in those of T2 and T3, respectively. In contrast, gut of H. fossilis had the highest proportion of Clostridium in T1, while Rhizobiaceae dominated in T3. Similarly in floc samples, Enterococcus dominated in T1 while Micrococcales and Rhizobiaceae dominated in T2 and T3, respectively. A positive correlation of enterobacteria, with the digestive enzyme activities and growth patterns was observed in all treatments.
The present study revealed feeding behaviour to play crucial role in distinguishing the gut microbial composition patterns in fishes reared in Biofloc System. Further it revealed the requirement of supplementary feed along with floc in these three species for higher growth in the biofloc system.
生物絮团系统（BFS）通过微生物生物量有效地原位维持水质，为可持续水产养殖系统提供了保障，同时这些富含蛋白质的微生物也可以作为饲料持续供应，从而增强养殖生物的生长和免疫力。本研究探讨了在生物絮团混养系统中养殖的三种淡水鱼类，金线鲃、杂交鲟和小口鲇的鳃结构、生长性能、消化酶活性、肠道微生物组成和组织学。
在 T2 组的三种鱼类的增重率和特定生长率均显著高于 T1 组和 T3 组。在 T2 组和 T3 组中，银鲃的鳃弓上的丝状间间隙较小，而 T1 组的黄颡鱼和大口鲇的鳃弓上的丝状间间隙较大，但这些差异与体重增加没有相关性。然而，银鲃是杂食性滤食性鱼类，在 T1 组（T2 组和 T3 组）积累了更多样的微生物群落，而底栖食性的小口鲇则表现出独特的肠道细菌适应性。T2 组和 T3 组中的絮团增加了水和鱼肠道中的细菌丰度，但与仅接受饲料的 T1 组相比，其微生物多样性显著降低。下一代测序结果表明，在 T1 组中，假单胞菌在金线鲃和杂交鲟的肠道中占优势，肠杆菌科和梭杆菌属在 T2 组和 T3 组中占优势。相比之下，在 T1 组中，小口鲇的肠道中梭菌属的比例最高，而在 T3 组中根瘤菌科占优势。同样，在絮团样本中，肠球菌在 T1 组中占优势，而微球菌科和根瘤菌科在 T2 组和 T3 组中占优势。在所有处理中，均观察到肠杆菌与消化酶活性和生长模式呈正相关。
本研究表明，摄食行为在区分鱼类在生物絮团系统中肠道微生物组成模式方面起着至关重要的作用。此外，它还表明，在这三种鱼类的生物絮团系统中，需要补充饲料和絮团以获得更高的生长。
