驯化硝化型生物絮体养殖南美白对虾的初步研究

尝试在养殖中期逐渐降低碳源添加量至零,探讨驯化硝化型生物絮体对生物絮凝高密度南美白对虾养殖系统的水质、生物絮体细菌群落动态变化和对虾生长性能的影响。实验在3个跑道式养殖系统中进行,放养密度均为685尾/m~3。水质结果表明养殖前1~45 d,每日按日投饵量的100%~150%添加葡萄糖,能很好地降低氨氮的浓度,但对亚硝酸盐氮处理效果不明显。投糖量下降至零后,氨氮仍能维持在较低水平,亚硝酸盐氮浓度明显下降。利用高通量测序技术对生物絮体的细菌群落结构进行分析。检测结果表明在门水平上,异养型和硝化型生物絮体的主要优势菌群都是Proteobacteria(变形菌门)和Bacteroidetes(拟杆菌门)。在纲水平上,异养型生物絮体的优势菌群是Alphaproteobacteria(α-变形菌纲),而硝化型生物絮体的优势菌群有Alphaproteobacteria(α-变形菌纲)、Flavobacteria(黄杆菌纲)和Gammaproteobacteria(γ-变形纲)。系统在65 d后不添加碳源情况下,生物絮体的异养细菌丰度减少,硝化螺旋菌属(Nitrospiral)开始快速增多并发展成为硝化细菌的优势菌群属,异养型生物絮体逐渐转变为硝化型生物絮体。实验结束时,总投糖量占总投饵量的41.03%±7.86%。南美白对虾的存活率和产量分别为43.35%±7.57%和(3.03±0.59)kg/m3。研究表明驯化硝化型生物絮体能优化高密度零水交换对虾养殖系统生物絮体的细菌群落结构和丰度,改善养殖水环境,保证对虾的生长和存活,节约成本。

Preliminary study on domesticating nitrifying bio-flocs to rear Litopenaeus vannamei

This study tries to gradually reduce the addition of carbon source to zero,and exploring the effect of domesticating nitrifying bio-flocs on water quality,bacterial community dynamics of bio-floc and the growth performance of shrimp in high-intensive culture system. Experiment was carried out in three runway aquaculture systems at stocking densities of 685 shrimp/m3.Water quality results showed that daily addition of glucose at 100~150% of feed,which can decrease the concentration of TAN,but the concentration of NO2--N was not decreased obviously.When the addition of glucose was dropped to zero,TAN can be maintained at lower level,and the NO2--N concentration decreased significantly.Respectively,the highest concentration of NO3--N and TSS are 207.13 ± 35.10 mg/L and 709.5 ± 95.46 mg/L.The bacterial community structure was analyzed by using High throughput sequencing technology.At the phylum level,experiment results showed that both the main advantage microflora of heterotrophic bioflocs and nitrifying bioflocs are Proteobacteria and Bacteroidetes.At the class level,dominant microflora of heterotrophic biofloc is Alphaproteobacteria,and dominant microflora of nitrifying bioflocs are Alphaproteobacteria,Flavobacteria and Gammaproteobacteria.After 65d,study founded that without adding carbon source,nitrifying bio-flocs can limit the abundance of heterotrophic bacteria,Nitrospira was rising ,and developing into dominant bacteria.At the end of the experiment,Glucose which is 41.03±7.86% of feed was added throughout the culture period.The survival rate and harvest of Litopenaeus vannamei respectively were 43.35±7.57% and 3.03±0.59 kg/m3.The domestication of nitrifying bio-flocs not only saved cost but also effectively optimized the structure of bacterial communities, and contributed toward better water environment which result in the higher growth and survival of shrimp.