| In recent years,Chinese Litopenaeus vannaeus aquaculture industry has been developing rapidly,and the high-density intensive factory aquaculture model has been developing vigorously in the north.Controllable breeding environment,high yield and high risk are its main characteristics.Farmers tend to ignore environmental issues while pursuing high efficiency,and the deterioration of aquaculture water body has seriously affected the sustainable development of litopenaeus aquaculture industry.Bioflocc technology is an emerging,green,energy-saving and efficient prawn culture technology.Organic carbon source is added to the culture environment to promote the growth and propagation of microorganisms in the aquaculture water,and effectively clean up toxic nitrogen such as ammonia nitrogen and nitrite in the water.Therefore,organic carbon source is an important factor in the construction of bioflocc.At present,the scheme of building bioflocks from simple dissolved carbon sources is increasingly mature,and there are few researches on the scheme of building bioflocks from composite solid carbon sources.In view of the imperfect construction scheme of bioflocks composite solid carbon sources,the following researches are carried out:1.Effect of particle size of peanut shell powder on culture system of penaeus prawn biofloccIn order to explore the influence of different particle sizes of peanut shell meal on the construction of bioflocc,this study started from the particle size of peanut shell meal,and selected 50 mesh,100 mesh,150 mesh and 200 mesh peanut shell meal to construct the culture system of shrimp bioflocc,and explored the influence of carbon source particle size on the water quality,microbial community and growth performance of prawn.The results showed that the removal efficiency of total ammonia nitrogen and nitrate concentration in 200 mesh and 150 mesh groups were significantly higher than those in other groups.The flora richness of biofloc treatment group was higher than that of control group,and the flora richness of 150 mesh and 200 mesh treatment groups was significantly higher than that of control group.In the water microbial community,Bacteroidetes(33.20%-41.86%),Proteobacteria(33.72%-44.17%)and actinomyces(8.54%-16.76%)were dominant,and the proportion of Ruggeella(4.15%-5.25%)in 150 and 200 orders was significantly higher than that in other groups.The survival rate and weight gain rate of prawn in 150 mesh and 200 mesh groups were significantly higher than those in 50 mesh and 100 mesh groups.Therefore,peanut shell powder with different particle sizes is an important factor affecting the construction of bioflocc,and peanut shell powder with smaller particle sizes is more conducive to the construction of bioflocc system of prawn.2.The Effect of Adding Peanut Shell Powder and Brown Sugar on the Biological Flocculation Culture System of ShrimpIn order to explore the optimal matching ratio between dissolved carbon sources and solid carbon sources in the construction of bioflocs of Penaeus vannamei,five different carbon source matching groups were set in this study: single peanut shell powder,single brown sugar,peanut shell powder: brown sugar(1:1),peanut shell powder: brown sugar(2:1),peanut shell powder:Brown sugar(1:2),to explore the effects of carbon source collocation ratio on water quality,microbial community and growth of prawn in bioflocc culture system.The results showed as follows: In terms of water quality control,the total ammonia nitrogen removal efficiency and nitrate concentration in the peanut shell powder: brown sugar(2:1)group were significantly higher than those in the other groups.In the Alpha analysis of microbial community,the diversity of bioflocc treatment group was significantly higher than that of water exchange control group.The richness index of peanut shell powder and brown sugar mixed and matched group was significantly higher than that of peanut shell powder and brown sugar alone group.In the analysis of microbial population in water environment of each group,the proportion of paraphylococcus and Microbacillus in mixed-match group was significantly higher than that in carbon source addition group.The GST-S transferase activity in mixed carbon source group was significantly higher than that in single carbon source group.The specific growth rate of prawn in peanut shell powder: brown sugar(2:1)group was significantly higher than that in other groups.Therefore,peanut shell powder: brown sugar(2:1)is the best ratio of biofloc formation in Litopenaeus vannamei culture.3.Effect of pretreatment of peanut shell powder on culture system of prawn bioflocculumIn order to explore the effects of enzymatic hydrolysis of peanut shell meal on the water quality,bioflocc composition,microbial community and growth of prawn,this study selected strains that could produce cellulase for fermentation and activation treatment.There were 8 groups including Bacillus amyloliticus fermentation(JF)and activation(JH)groups,Trichoderma viridis fermentation(LF)and activation(LH)groups,hemorporus thermophilus fermentation(SF)and activation(SH)groups,water exchange Control group(Control)and peanut shell powder treatment group(HSK).The results showed that the removal efficiency of total ammonia nitrogen in SH group was significantly higher than that in other groups,and the ammonia nitrogen concentration remained below 1mg/L.The nitrate concentration in JF group was significantly higher than that in other groups,and the nitrate concentration at the end of the experiment was 19.81±2.45mg/L.The cellulase activity in JF,JH,LF,LH,SF and SH groups was significantly higher than that in Control and HSK groups,and the enzyme activity in JF group was the highest(7.20±2.68U/mgprot).The content of biofloc active substance(PHB)in JF,LF and SF groups was significantly higher than that in JH,LH and SH groups,and the PHB content in JF group was the highest(90.21±3.45mg/L).The flora richness of JF,JH,LF,LH,SF and SH groups was higher than that of Control and HSK groups,and the richness of JF and LH groups was significantly higher than that of Control and HSK groups.In the analysis of microbial population in each group,Proteobacteria dominated(41.94%-52.78%),followed by Bacteroidetes(26.61-42.10%),actinobacteria(5.03%-13.55%),Firmicutes(0.00%-10.12%).The proportion of Firmicutes(10.12%)in JH group was significantly higher than that in other groups,and the proportion of erythrobacteriaceae(35.80%)in JF group was significantly higher than that in Control group and HSK group.The activity of GST-ST in the bioflocc treatment group was significantly higher than that in the Control group,and the activity of GST-ST in JF group was the highest(38.40±2.64U/mgprot).The weight gain rate and specific growth rate of the bioflocc treatment group were significantly higher than those of the Control group,and the growth rate and specific growth rate of the JF group were the highest.Therefore,the fermentation treatment of peanut shell powder by Bacillus amyloliticus is more conducive to the construction of shrimp bioflocculation system. |
