Azim M E, Little D C, Bron J E
Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, United Kingdom.
Bioresour Technol. 2008 Jun;99(9):3590-9. doi: 10.1016/j.biortech.2007.07.063. Epub 2007 Sep 14.
The present experiment investigated the possibility of microbial protein production in 250 l indoor tanks by manipulating C:N ratio in fish feed applied. Two different levels of protein feed (35% and 22% CP) resulting in C:N ratio of 8.4 and 11.6, respectively, were applied at 25 g daily in each tank. Tanks were aerated and agitated continuously using a dome diffuser. The experiment was carried out for eight weeks. The biofloc development in terms of VSS and BOD5 was better in the low protein fed tanks than in the high protein fed tanks. An estimated biofloc productivity ranged 3-5 g Cm(-3)day(-1). A 3-D image stained with DAPI indicates that the biofloc is comprised of hundreds of bacterial nuclei, size being ranged from 100 to 200 microm. Biofloc quality was independent of the quality of feed applied and contained more than 50% crude protein, 2.5% crude lipid, 4% fibre, 7% ash and 22 kJ g(-1) energy on dry matter basis. The dietary composition and size of biofloc can be considered as appropriate for all omnivorous fish species. The underlying ecological processes are explained through factor analysis. The potential of using biofloc in fish culture is also discussed.
本实验通过控制投喂鱼饲料中的碳氮比，研究了在250升室内水箱中生产微生物蛋白的可能性。在每个水箱中，每天投喂25克两种不同蛋白质水平的饲料（粗蛋白含量分别为35%和22%），其碳氮比分别为8.4和11.6。使用穹顶式曝气器对水箱进行连续曝气和搅拌。实验持续了八周。就挥发性悬浮固体（VSS）和生化需氧量（BOD5）而言，低蛋白投喂水箱中的生物絮团发育情况优于高蛋白投喂水箱。估计生物絮团的生产力在3 - 5克碳每立方米每天之间。用4',6-二脒基-2-苯基吲哚（DAPI）染色的三维图像表明，生物絮团由数百个细菌核组成，大小在100至200微米之间。生物絮团的质量与所投喂饲料的质量无关，以干物质计，其含有超过50%的粗蛋白、2.5%的粗脂肪、4%的纤维、7%的灰分和22千焦每克的能量。生物絮团的饮食组成和大小可被认为适合所有杂食性鱼类。通过因子分析解释了潜在的生态过程。还讨论了在鱼类养殖中使用生物絮团的潜力。
