The Effect Of The Nitrifying Bacteria On The Water Quality And The Change Of Heterotrophic Bacterial Population In Freshwater Aquarium

With the expansion of intensive aquaculture, deterioration of culture environmentand abuse of antibiotic or chemicals, the aquatic environmental load increaseddramatically. Meanwhile, the acceleration of reproductions of bacteria in water lead tothe water eutrophication and destroyed the micro ecological environment. Thepathogenic bacteria would weaken the immunity and decreased the output of farmedanimals by forming a advantage flora. Oxygenation, water change or adding absorptionwere usually used in production to reduce the concentration of ammonia nitrogen andnitrite, which may make waste and increase the production cost. In our studies, amethod of biological control was performed to manage the concentration of ammonianitrogen, nitrite and sulfide, inhibit the pathogenic bacteria breeding and ensure thehealthy growth of farmed animals.Microecologics, which made by special processing utilizing normal microbes orpromote materials from animals, were productions or metabolite productions that couldadjust the micro ecological imbalance and develop the health of host. They were madeof microbial compounds including photosynthetic bacteria, yeasts, lactobacillus,nitrifying bacteria, filamentous bacteria and so on from10genera,80species.Microecologics were widely used in food, breeding and aquaculture industries. Theycould partly replaced the antibiotics, enzymes, amino acid and vitamins to improve theintestinal absorption, immunity, inhibition of pathogens and maintenance of microecosystem balance because of the safety and non-drug residues.Nitrifying bacteria was the major bacteria in biological denitrification and play animportant roles in natural nitrogen cycle and water purification. It is a kind ofnitrification and autotrophic bacteria that can activate ammonia oxidation and nitrate oxidation into nitrates. There were only a small amount of nitrifying bacteria due to thepoor growth and a long period of system establishment, and exogenous supplement isneeded to make sure the nitrification successfully.In this paper, four groups including a control group and three experimental groupswith different concentration of nitrifying bacteria were performed to investigate theheterotrophic bacterial population in freshwater aquarium and the effect of nitrobacteriaon the physicochemical index of water quality and the change of the bacteria floracomposition. After sampling water and attaching organism from the aquarium and filtercartridge respectively, the pH, NH₄⁺-N, NO₂^--N andNO₃^--N were determined accordingto the―Water and wasted water analysis testing method‖. The bacterial counts wasanalysed by a plate count. The bacteria flora composition was analysed by bothBIOLOG microorganism identification system and16S rDNA.1. The pH in experimental group A decreased at6d and changed significantly; pH inexperimental group B and C changed quit the same, kept steady before27d with pH＞8.0, and then, reduced gradually. The concentration of NH₄⁺-N and NO₂^--N inexperimental group A and control A were in a high level while the it decreased graduallyin experimental group B and C （nitrifying bacteria added）, and0.045mg·L^-1at6d andNO₂^--N cannot detected at11d.2. The increase of bacteria in control was significantly higher than experimental groups,with the bacteria amount about4.9×10⁶CFU·mL^-1at13d. At19d, the bacteria amountin experimental group B and C were2.05×10⁷CFU·mL^-1and3.75×10⁷CFU·mL^-1respectively. The heterotrophic bacteria amount increased by orders in control while thetotal bacteria amount reduced gradually in experimental group B and C.3. There was a significant difference about the attaching bacteria amount in filterchamber between control, experimental group A and experimental B plus experimentalC（P＜0.05）. The total bacteria amount in control were higher than that in water. On thecontrast, group B and C were lower.4. The establishment of a nitrifying system need approximately2weeks and the optimalconcentration of supplemental nitrifying bacteria was1.46×10⁸CFU·L^-1.5. The advantage flora in fresh water aquarium were Bacillus sp. and Pseudomonas sp.,and it turned to Bacillus subtilis, Pseudomonas stutzeri and Bacilllus marisflavi after theaddition of nitrifying bacteria.Our results showed that there was a significant effect of nitrobacteria to decreasethe concentration of NH₄⁺-N and NO₂^--N in freshwater aquarium. It could keep thecommunity structure of heterotrophic bacteria steady and adjust the balance of themicro-ecology in water.