Isolation of a Dissolved Organic Phosphorus-removing Strain and Its Biological Characteristics

Abstract:

The study was conducted to screen and isolate dissolved organic phosphorus removal bacteria in soils taken from the eutrophic pond by adopting sodium glycerophosphate (NaGly) as exogenous dissolved organic phosphate. By comparing dissolved organic phosphorus removing abilities between five isolated bacteria, the most effective dissolved organic phosphorus removal bacterium named D2 was chose. In liquid media contained 5 mg/L phosphorus glycerophosphate (GP-P), the phosphorus-removal ratio of the strain D2 could reach 99.0%. Based on the 16S rRNA analysis, the strain D2 exhibited high similarity (Almost 100%) with Enterococcus faecium KT4S13 (Accession number: AB481104) and CICC6078 (Accession number: DQ672262), so it was identified as Enterococcus sp.. The growth characteristics and phosphorus removing abilities of the strain D2 were measured. The growth curve of the strain D2 was as follows: lag phase was 0-4 h, log phase was 4-8 h, stationary phase was 8-28 h, decline phase was after 28 h. Additionally, the phosphate-removal ratio of the strain D2 increased gradually before decline phase, and it could maintain the phosphate removal effect stability for 4 hours after the decline phase. Results also exhibited that the strain D2 could grow normally with temperature ranging from 15°C to 40°C, pH from 4.0 to 9.0 and initial GP-P concentration from 5 mg/L to 40 mg/L, meanwhile the optimal temperature and pH for growth varied from 30°C-35°C and 6.0-7.0. Moreover, the GP-P could significantly promote the growth of the strain D2 when its concentration was from 20 mg/L to 30 mg/L. In addition, the 20 mg/L GP-P removing capability was found gradually increased with extension of action time before the coming of decline phase and keep stability from 28 h to 32 h after entry of decline phase. The D2 had the phosphorus removal ability at the condition of temperature of 15°C-40°C, pH of 4.0-9.0 and concentration of 5-40 mg/L. The optimal range of temperature, pH and initial GP-P concentration for the dissolved organic phosphorus removing capability ranged from 25°C-35°C, 6.0-7.0 and 5-10 mg/L , respectively.