| In the face of the problem of water environment deterioration and low economic benefit to the aquaculture industry,on the one hand,the reform of culture technology and the new biological flocs technology can effectively improve the water quality,reduce the discharge of aquaculture waste water and improve the ecological benefits.On the other hand,adding microbial agents to the aquaculture water or feed can reduce the feed coefficient and promote the growth and immunity of the breeding objects,as well as the economic benefits.Since biofloc mainly a microbial assimilation and metabolism,the competitiveness of it outweighs that of the organic substances in the system.However,whether the addition of a microbial preparation to biofloc has an effect or not has not been observed.This paper studied the effects of pH,dissolved oxygen and temperature on the biofloc with Lactobacillus plantarum as an additive,and the effect of adding Lactobacillus plantarum on the nutrient composition and culture efficiency of flocs.1.A orthogonal experiment,which set 3 factors in 3 levels and lasted for 35 days,was conducted to study the culture of the biofloc when using the lactic acid bacteria as additive.By observing the situation of tristate nitrogen,dehydrogenase activity and microbial population structure,the best technology to get biofloc which utilizes lactic acid bacteria as additive was obtained.The results showed that the minimum time to get biofloc was 13 day at aerobic,pH 8.5 and 30 ?,and the bionitrogen removal efficiency was high.The temperature and dissolved oxygen had significant effect on dehydrogenase activity(DHA).And the activity of biofloc wasthe highest under anaerobic-aerobic alternation condition,pH7 and 25 ?.The analysis of microbial community structure showed that the biofloc was mainly consisted of metamorphoses(> 70 %),followed by Bacillus.The quantity of lactobacillus plant-arum is at highest level(1.8%)under aerobic condition,pH5.5 and 35?.2.The effects of Lactobacillus plantarum on the effect,activity and nutrient content of biological flocculating aquaculture water were studied under the conditions of pH5.5~6.5,5mg/L and 32?,with the feed of black eel as raw material.The results showed that adding Lactobacillus plantarum could improve the efficiency of floc treatment and shorten the acclimation time of floc.And no accumulation of STCNS and nitrite at the end of the test.Adding Lactobacillus plantarum can improve dehydrogenase activity in flocculation system but has no effect on flocculation performance.When system reaches stability,dehydrogenase activity is 49.22 mol.L-1H-1 while the other one without dehydrogenase,the activity is 18.12 mol.L-1.H-1,and FVI of the two groups of floc is 55mg/L.Adding Lactobacillus plantarum had a significant effect on the content of floc fatty acids.The polyunsaturated fatty acids(PUFA)in the experimental group were significantly higher than those in the control group.17 kinds of amino acids were detected in the two groups.The ratio of essential amino acids to total amino acids(EAA/TAA)was 34.61% and 36.92%,and the ratio of fresh amino acids to total amino acids(DAA/TAA)was 54.88% and 52.90%,respectively.The results showed that Lactobacillus plantarum could improve the efficiency of water treatment,dehydrogenase activity and polyunsaturated fatty acids,and floc nutrition was suitable for food intake of objects.3.The effects of Lactobacillus plantarum supplemented on Lactobacillus growth and blood biochemical parameters of tilapia were studied in this experiment.After bioflocs of tilapia 60 d,the addition of Lactobacillus plantarum resulted in the weight gain of fish,specific growth rate,and fatness of 43.21%,6.3% and 2.59g/cm3 were significantly higher than those of the control group,and the feed coefficient was1.44% lower than that of the non-added bacteria group.The two groups had no obvious influence on the biochemical indexes of fish serum.It is indicated that Lactobacillus plantarum can promote the growth of tilapia and not stimulate the fish. |
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