Potential of Bacillus sp. as a Nitrifying Agent in Coastal Ecosystems: Isolation and Characterization from Awur Bay Beach, Jepara, Indonesia

Coastal waters often experience nitrogen pollution, which can be harmful to aquaculture. One potential approach to mitigate this issue involves the use of biological agents that can transform nitrogen compounds through nitrification and denitrification. This study aimed to identify local nitrifying bacteria capable of adapting to marine environments and reducing the ammonia concentrations. Seawater and sediment samples were collected from the Awur Bay Beach in Jepara, Central Java, Indonesia.. Isolation and purification processes employed specific autotrophic media to cultivate ammonia-oxidizing bacteria (AOB). The measured parameters included the concentrations of nitrogen species, such as ammonia, nitrite, and nitrate, in the media before and after inoculation with the bacterial isolate. The incubation period was seven days. Nine pure isolates (four from seawater and five from sediment) were obtained and screened to identify bacteria that thrive at high ammonia concentrations. The results indicated that one potential isolate, S20-7, was identified as Bacillus sp. using 16S rRNA sequencing. Bacillus sp. demonstrated the ability to thrive in media with a salinity of 20‰ and reduced ammonia concentration by 37.19% from an initial concentration of 500 mg/L. This study highlights the potential of Bacillus sp. as a nitrogen waste degradation agent in coastal waters, particularly in wastewater treatment and aquaculture. Its ability to efficiently degrade ammonia nitrogen and nitrite, coupled with its tolerance to high concentrations of these compounds, makes it a valuable tool for improving water quality and mitigating the effects of nitrogen pollution in coastal ecosystems.