ISOLATION AND IDENTIFICATION OF AN AMMONIA-NITROGEN-DEGRADING BACTERIUM BACILLUS STERCORISL1 AND DEGRADATION CHARACTERISTICS
Keywords:
Ammonia-nitrogen degradation, Bacillus stercoris SL1, Biological denitrification, BacillusAbstract
This study aimed to screen efficient ammonia-nitrogen-degrading bacteria from natural environments and investigate their taxonomic status and degradation characteristics, thereby providing bacterial resources for the biological treatment of ammonia-nitrogen wastewater. Ammonia-nitrogen-degrading bacteria were enriched and isolated from soil samples collected around South Lake in Wuhan, using ammonium chloride as the primary nitrogen source. The bacterial strain was identified through morphological observation and 16S rDNA sequencing. The effects of initial ammonia-nitrogen concentration (40~120 mg/L), inoculum size (1%~10%, V/V), temperature (25~35 ℃), and initial pH (6.0~8.0) on the ammonia-nitrogen removal rate of the strain were investigated using single-factor experiments. A highly efficient ammonia-nitrogen-degrading bacterium, identified as Bacillus stercoris SL1 (16S rDNA similarity 99.65%), was isolated. The single-factor experiments revealed that under the conditions of an initial ammonia-nitrogen concentration of 60 mg/L, an inoculum size of 1%, and a pH of 7.0, the strain exhibited a removal rate of 61.50% at 30 ℃ over a 48-hour period. Notably, when the temperature was increased to 35 ℃, the removal rate significantly rose to 70.08% (P<0.05). Additionally, substrate inhibition was observed when the initial ammonia-nitrogen concentration was ≥80 mg/L. The highest removal rate (60.41%) was achieved with an inoculum size of 1% over a 48-hour period, while excessive inoculum (10%) reduced the rate to 50.03%. The strain exhibited high degradation activity within the pH range of 6.0~8.0. After culturing under optimal conditions for 48 hours, the nitrite nitrogen accumulation in the culture medium was only 0.016 mg/L, indicating minimal nitrite accumulation during the ammonia-nitrogen degradation process. The strain Bacillus stercoris SL1 has significant heat tolerance and efficient ammonia-nitrogen degradation ability, showing great potential in the biological treatment of medium and high temperature ammonia-nitrogen wastewater.References
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