In vitro antimicrobial, antioxidant and molecular study of Nostoc punctiforme isolated from the rice field

Cyanobacteria are photosynthetic prokaryotes and are reservoir of bioactive compounds having substantial antimicrobial and antioxidant activity. They serve as a rich source of structurally novel and biologically active metabolites, holding great potential for various pharmaceutical applications. The aim of this study is to investigate in vitro antimicrobial and antioxidant activities of the extracts of Nostoc punctiforme, a filamentous heterocystous cyanobacterium predominant in the rice fields of Lakhanpur (Bargarh District), Odisha. The heterocystous cyanobacteria was collected from rice field and identified by means of morphological and molecular approach (Nostoc punctiforme Jbr02). Subsequently, in vitro antimicrobial and antioxidant activity was assayed using acetone, methanol, and benzene extract. The cyanobacterial extracts established important antimicrobial actions against bacterial and fungal pathogens with significant MIC values from 62.5 to 500 μg/ml. The methanolic extract displayed better inhibitory activities against both V. Cholerae and P. verrucosun with the MIC value 62.5μg/ml while no such activity was recorded in benzene extract against B. subtilis, A. niger and F. oxysporum pathogens. The antioxidant study, depicted that the methanolic extract showed relatively higher antiradical activity of IC50 542±0.012 μg/ml among the three solvents. The Ferric reducing assay result was also maximum in methanolic extract (0.478±0.78) as compared to benzene and acetone extract. These findings infer that Nostoc punctiforme has potential antimicrobial and antioxidant activity, unveiling its potential as a valuable source of bioactive compounds. Thus, N. punctiforme in specific and cyanobacteria in general are one of the most promising candidates for commercial applications.