Anti-biofilm compound of 1, 4-diaza-2, 5-dioxo-3-isobutyl bicyclo[4.3.0]nonane from marine Nocardiopsis sp. DMS 2 (MH900226) against biofilm forming K. pneumoniae

In this study, the 16S rRNA of the marine endophytic actinomycete was characterized and identified as Nocardiopsis sp. strain DMS 2 (MH900226). Partial purification and spectroscopies data were interpreted and confirmed as 1, 4-diaza-2, 5-dioxo-3-isobutyl bicyclo[4.3.0]nonane. Anti-bacterial activity of the crude extract and partially purified compound were shown highest inhibition activity against biofilm forming K. pneumoniae. Minimum biofilm inhibition concentration of identified compound against K. pneumoniae was exhibited at the concentration of 300 µg/mL. Decreased metabolic activity and modified exopolysaccharide production of biofilm forming cells were observed at 350 µg/mL and 300 µg/mL concentration. At the same biofilm inhibition concentration, the intracellular architecture of the biofilm cells and extracellular shape modifications were clearly viewed by confocal laser scanning electron microscope and scanning electron microscope respectively. All the in-vitro inhibition results and microscopic images were strongly suggested that the identified compound was a potential anti-biofilm agent against tested K. pneumoniae.