| Two sections included in this research: Firstly, constructed a GFP-labeled strain of Bacillus subtilis B412. The coding sequence of gfp gene was amplified through PCR from pAD123, a plasmid which contained the full-length gfp gene fragment. Then the recombinant plasmid pAXc-gfp was constructed by ligating pAXc and gfp DNA fragments purified from PCR products. pAXc-gfp was linearized and transformed into Bacillus subtilis B411. The linearized plasmid was integrated into the chromosome of Bacillus subtilis B411 on lacA locus. Recombinant was selected by use of chloramphenicol resistance (5μg/mL) and named it Bacillus subtilis B412. It showed that GFP can be expressed stably even without the existence of antibiotic. Consequently, the dynamics of Bacillus subtilis B412 was studied with strain B412 released into aquatic environment and real-time tracked on the fluctuation in certain pond. It can be detected for more than 16 days in natural environment and the sum ranged from 5.5×103 cfu/ml~8.9×104 cfu/ml. Secondly, to study the influence of various factors such as organic matter, dissolved oxygen, temperature, pH, sediment and microorganisms (B411) on water quality, we carried out a series of simulation experiments at laboratory scale, and analyzed the effects of B411 on water bioremediation. Results showed that water quality deteriorated by the comprehensive actions of organic matter, temperature, dissolved oxygen, pH and sediment. Water rich with sugars or others, a lower temperature (< 20℃), higher dissolved oxygen (> 1.34 mg/L), or an unusual pH (> 9.0 or < 6.0) and sediment can alleviate or avoid water deteriorate; And water rich with protein, lower dissolved oxygen(< 0.10 mg/L) or moderate pH (7.0~7.5) can increase the worsen process. In low dissolved oxygen (≤0.10 mg/L), if the concentration of organic matter is less than 0.l‰,water didn't not deteriorate, once the organic matter is over certain value ((?) 0.2‰), water deterioration didn't avoid, the sequence of water deteriorate is 0.2‰ . 0.4‰, 0.6‰, 0.8‰ and 1.0‰ respectively; In higher dissolved oxygen (> 1.34 mg/L), if concentration of organic matter is not more than 0.4‰, water didn't deteriorate, if concentration of organic matter is not more than 0.4‰,water does not deteriorate, if more than or equal to 0.4‰ water will happen to deteriorate at differentextent and the sequence of water deteriorate is 1.0‰, 0.8‰, 0.6‰ and 0.4‰ respectively. Water degradation is easy in higher temperature (25℃ ,30 ℃) than in lower temperature (15 ℃ , 20℃), when the color of water became black at the forth day in high temperature (25 ℃ , 30 ℃), there was no obvious change in water in low temperature (15 ℃ , 20℃). COD removal efficiencies of water with sediment is higher than the water without sediment, in the water of sediment without autoclave, removal efficiency of COD can reach 60.1% in six days, over 18.6% than the water without sediment. Effects of wastewater bioremediation depends on the number of bacteria introduced and dissolved oxygen, COD removal efficiencies of water can reach 90.1% and 91.3% when the number of bacteria introduced was 104 cfu/ml and 105 cfu/ml respectively, dramatically higher than the other treatments and control. However the effects of water bioremediation was determined by dissolved oxygen, COD removal efficiencies of water was 75.9% in high dissolved oxygen, higher than control (55.1% in high dissolved oxygen and 42.1% in low dissolved oxygen respectively) and treatment 45.7% in low dissolved oxygen.
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