Innovative Isolation of Nostoc minutum Protein for Antibacterial Applications

The study successfully identified a new Iraqi blue-green alga, Nostoc minutum HA-YJ, through both morphological and molecular diagnostics, and recorded it in the gene bank for the first time as a genus found in northern Nineveh (Ain Sifni). This cyanobacterium thrived in BG11 medium and is notable for its bioactive compounds, particularly its protein content. In this study, the protein was extracted, purified, and continuously monitored. Chromatography revealed a single peak, confirming the presence of pure protein. Both spectrophotometry and Fourier Transform Infrared (FTIR) spectroscopy were employed to identify the protein. UV absorption peaks were observed at 304 and 614nm in the protein extracts. FTIR analysis showed distinct features, such as an aromatic primary amine (N-H stretching) at 3202cm−1 and an amide I band at 1638cm−1 (C=O stretching vibration). Additionally, an absorption peak at 2891 cm−1 indicated the presence of carboxylic acids, and the amide II band appeared at 1437cm−1. The optimal concentrations of purified protein (10.0 and 7.5mg/ ml) were effective against all bacteria tested, with Gram-negative bacteria being particularly sensitive. The protein was tested against a variety of pathogenic bacteria, including both Gram-positive and Gram-negative species. At concentrations of 5.0mg/ ml, the protein exhibited moderate antibacterial activity, while 2.5mg/ ml showed no effect. Notably, E. coli displayed high sensitivity to the protein, whereas Staphylococcus aureus showed resistance.