Preliminary Study On The Effects Of The Aquaculture Water Quality By Compound Bacillus

In recent years,China’s aquaculture has been growing rapidly,and the farming model is gradually moving towards industrialization and intensive farming model.As with the fast development of aquaculture,the problem of aquaculture water quality deterioration and aquatic animals diseases frequently occurred,they prouceded negative effects that have become the biggest stumbling blocks to the sustainable development of aquaculture industry in our country.Focus on reducing water pollution problems and solving the safety of aquatic products,an pollution problems and solving the safety of aquatic products,an environment-friendly water purification agent-microecological preparation,it has been widely used in aquaculture industry,the critical step is filtering out microecological strains which is suitable for using in aquaculture.This research was aimed to study the effects of four Bacillus on the aquaculture water quality of crucian carp,the feasibility of using them as a microbial water purification agent as follows:First,in order to investigate the effects of four Bacillus on the aquaculture water quality,the Bacillus lentus,Bacillus licheniformis,Bacillus subtilis and Bacillus coagulans were added into aquaculture water of crucian carp（they were numbered group BE,BL,BS and BC）,with the final concentration of bacteria in aquaculture water was 10⁷ cfu/mL,the experiment lasted for 19 days,continuous measurements of permanganate index(COD_Mn),ammonia nitrogen（NH₄⁺-N）,nitrite nitrogen（NO₂^--N）,dissolved oxygen（DO）and pH every 2 days.The results indicated that all four bacillus could be used to improve the water quality of crucian carp,group BS for removal of COD_Mn and NH₄⁺-N are the best,the removal rate of COD_Mn and NH₄⁺-N of Group BS were 54.55%and 55.44%;On the third day,the removal rate of NO₂^--N of Group BC was up to 51.63%;at the beginning of the experiment,the DO of Group BL declined sharply,and as low as 7.53 mg/L;the pH of the different groups in the range of 7.18 to 7.39,there was no significant difference.Therefore,the next experimental uses the Bacillus subtilis and Bacillus coagulans.Next,in order to find out the best concentration of Bacillus subtilis and Bacillus coagulans when used in aquaculture to improve the water quality,the concentration of two Bacillus are 10⁵ cfu/mL,10⁶ cfu/mL,10⁷ cfu/mL and 10⁸ cfu/mL,the experiment lasted for 19 days,continuous measurements of COD_Mn,NH₄⁺-N,NO₂^--N,DO and pH every 2 days.The results showed that at some extend,the removal efficiency of pollutants increase with the concentration of bacteria increasing,2Bacillus at the concentration of 10⁷ cfu/mL and 10⁸ cfu/mL had good efficiency,in view of the principle of effectiveness and economy,the next experimental uses the concentration of 10⁷ cfu/mL.Finally,to imitate the ecological environment of crucian carp aquaculture,Bacillus subtilis and Bacillus coagulans and compound Bacillus were added to the crucian carp aquaculture water with 10⁷ cfu/mL.The experiment lasted for 60 days,continuous measurements of COD_Mn,NH₄⁺-N,NO₂^--N,DO and pH every 3 days,after breeding 60 days,the weight,length and the activity of digestive enzyme of crucian carp were assayed.The results showed that compared with single Bacillus,the compound Bacillus have more significant effects on the growth performance and digestive enzyme activity of crucian carp,at the end of the experiment,the weight gain rates of crucian carp was 40.22%,the activities of protease and amylase in intestine of crucian carp were promoted by24.40%and 24.55%,the activities of protease and amylase in hepatopancrea of crucian carp were promoted 34.32%and 25.82%;the compound Bacillus had better effects in removing pollutants from aquaculture water,compound Bacillus could effectively reduced the content of COD_Mn,NH₄⁺-N and NO₂^--N（P<0.05）,the removal rate of COD_Mn,NH₄⁺-N and NO₂^--N were 53.62%,31.38%and 47.76%,to maintain the high level of DO and pH of the aquaculture water and fluctuates remarkably in the tiny range.