Isolation and Identification of the Ammonium and Nitrite Oxidizing Bacterial Strains for Nitrogen Treatment in Shrimp Pond in Quang Ninh Province, Vietnam

The objective of this study was to isolate and identify the nitrifying bacteria from wastewater in the aquaculture system at Quang Ninh province and initially evaluate their ability to treat nitrogen in water and determine the strain of bacteria and identify the strain of bacteria. Nitrifying bacteria were isolated by serial dilution and agar plates and then purified by agar slant until axenic colonies were obtained. The study has successfully isolated 3 bacterial strains capable of ammonium oxidation (AOB-1, AOB-2, AOB-3) and 3 bacterial strains with nitrite oxidation ability (NOB-1, NOB-2, NOB-3) from shrimp farming wastewater in Quang Ninh province, Vietnam. These strains demonstrate potential for ammonium and nitrite oxidation, making them applicable for nitrogen treatment in sewage. Strains with nitrite oxidation ability showed a potential high capability for nitrogen removal from water. The decoding of the 16S rRNA gene sequences, compared using Blastn (NCBI) indicated similarities with Bacillus subtilis (AOB-1), Pantoea agglomerans strain JCM1236 16S RNA (AOB-2), Enterobacter hormaechei strain ES1 16S RNA (AOB-3), Arthrobacter nicotianae (NOB-1), Acinetobacter lactucae strain JVAP01 16S RNA (NOB-2) and Enterobacter asburiae (NOB-3). Therefore, the bacteria that contained 6 strains can be considered to apply for wastewater treatment in shrimp farming.