| Along with the scale,intensive development of aquaculture in China,the pond is easy to accumulate a large amount of animal waste and food residue,leading to eutrophication.The results show that ammonia compounds are the main pollutants of water eutrophication.Nitrogen would lead to high fish immunity decline,slow growth and other problems,bringing huge economic losses to the aquaculture industry.Ammonia can be removaled by physical,chemical and biological method.The biological method is widely favored by people,because of its simple process,low cost,easy popularization.Probiotics are environmentally friendly,safe and efficient.They are commonly used as additives in biological degradation.They can not only improve the environment of aquaculture water,but also reduce the occurrence of animal diseases.Therefore,in this study,the samples from waters around are placed in the high concentration of ammonia nitrogen,through continuous domestication and enrichment,separation and gain tolerance based strain.Screening 2 strains through simulation experiment which could degrade ammonia in water.The screened 2 ammonia nitrogen degrading bacteria were mixed into 1 kinds of protein removal bacteria preserved in our laboratory.Through cultivation experiments,to evaluated the effect of compound bacterium compared with the commonly used four kinds of aquatic microbial preparation.The specific regulation of water quality as follows:1.After the sample was collected,the strains were separated by directional enrichment and separation method.The sample is placed in high concentration ammonia processed medium enrichment and domestication cultivation of 6 generations,not eliminated by NH4.9 strains of high nitrogen tolerance based strain by streak plate method separation,numbered xh1-xh9.Through 20 L simulation water culture experiment,to evaluate the strain’s ability of ammonia degradation.Results showed that xh1 and xh7 two degradation strains were significantly higher than those of other strains.And the two degradation strains’ rate reached more than 90% when 24 h,when the xh7 degrading rate of up to 98.5% when 72 h.Respectively from the morphological,physiological,biochemical and molecular biology,three of the strains were identified.By identification,xh1 and xh7 strains were Bacillus coagulans.The Yellow River carp as the test materials.The test results showed that with thebacteria concentration increased from 105cfu/mL to 109cfu/mL,the Yellow River carp feeding ability and action are normal,the phenomenon of death did not occur in all groups.From pH value temperature,salinity and C/N the four aspects on growth conditions were optimized.The results show that the pH value is 7.5,the optimum growth conditions of the two strains of the temperature is 35 centigrade.And the xh1 optimum is 10;the xh7 optimum salinity was 5per thousand;the optimal C/N is 15,when C/N rose to 20 the xh7 growth slightly affected,while xh1 strains still grow well.2.The screened Bacillus coagulans xh1 and xh7 were made up of complex microbial inoculants with Bacillus subtilis B38 preserved in our laboratory with the ratio of 1:1:1.Selecting four kinds of aquaculture probiotics commonly used(photosynthetic bacteria,yeasts,potent EM bacteria,Bacillus)compared to breeding test.6 experimental groups and 2 control group in the test set,3 replicates in each group.One control group normal feeding,and the other control group no feeding.Experimental results show that :(1)A pond of adding ammonia nitrogen content of photosynthetic bacteria showed a downward trend after rising,in the 10 d the effect had significant difference(p<0.05)than the control group.The effect of adding ammonia degradation pond compound bacteria obviously,ammonia nitrogen content after 1d was significantly lower than that of normal control group for feed(p<0.05),indicating that the composite bacteria can quickly and effectively the degradation of ammonia nitrogen in aquaculture water.Other groups also showed different degrees of decline.At the end of the experiment,compared with other groups,add pond ammonia nitrogen content of compound bacteria has been at a low level,about 1mg/L fluctuated.Test group shows that the effect of adding ammonia degrading bacteria is better to continuity.(2)The nitrite contents were all increased after the 5d test.Two groups added potent EM bacteria and bacillus are higher in each time point than others,and in the 9d and 11 d their content were to 5mg/L.The groups added yeast and compound bacteria are relatively low,and the fluctuation amplitude is very small,which at each time point had no significant difference with the control group(p>0.05).(3)The normal control group for the feed in 0d-11 d nitrate content has been at a high level,the highest content is as high as the control group for 9mg/L.The control group,whichdid not feed,showed a trend of rising first and then decreasing,reaching the highest value at5 d.In the course of the experiment,the test group added nitrate content of compound bacteria was always lower than the normal investment control group feed.Adding compound bacteria is useful for degradation but will not cause the accumulation of nitrate in water.(4)The results from the beginning to 11 d,add change test group COD content of 5 kinds of probiotics are not obvious.The content of 18 d was increased in each group.In the course of the experiment,the normal control group for feed has gradually increased.At the start of the test,test group COD content the yeast was significantly lower than that of normal control group for feed(p<0.05),and shows good effect in a very short time.(5)The test group added algae content of photosynthetic bacteria was significantly lower than the control group(p<0.05),which indicates that the addition of photosynthetic bacteria and inhibit the growth of algae in ponds in a certain extent.Add yeast and potent EM bacteria in experimental group and control group had no significant difference(p>0.05).In the experiment 9d and 14 d,the test group the algae content of Bacillus and compound bacteria were significantly higher than the control group normal feed(p<0.05).The maximum content of up to the control group for two times.The evaluation of composite microbial water quality control effect research results show that the self-made composite agent has a good regulation of aquaculture water quality,especially ammonia nitrogen can effectively control water.But it will not cause the accumulation of nitrate in water.It also can contribute to the algae in the water to grow. |
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