Antibacterial and Biopriming Effects of Nostocales Cyanobacteria on Tomato Plants Infected with Bacterial Spot Disease.

Abstract

A new generation of farming inputs is being developed, designed to be more environmentally friendly and have fewer negative impacts on consumer health. Bio-based antimicrobial compounds are one such example. These compounds are used against pathogens and stimulate plant immune systems, reducing disease severity. This study evaluated suspensions and hydro-alcoholic extracts of 55 cyanobacteria from the Nostocales order for their antimicrobial effects and growth-promoting activity on tomato plants. Suspensions and extracts of 0.5 and 1 mg mL^-1 of two cyanobacteria, Nostoc sp. G-4D and Calothrix sp. G-403 were selected for their disease control capabilities and growth enhancement effects on plants. The GC-MS technique was used to investigate the chemical compounds in the hydroalcoholic extracts of two cyanobacteria species. The analysis shows that the Nostoc sp. G-4D extract contained 28 compounds, accounting for 96.04% of the total composition, while the Calothrix sp. G-403 extract contained 27 compounds, making up 93.62% of the total composition. These findings highlight the rich chemical diversity in the extracts, which might be responsible for the observed bioactivities. The predominant components of the hydroalcoholic extracts of Nostoc sp G-4D and Calothrix sp. G-403 were Hexadecanoic acid, methyl ester (28.29%) and Octadecanoic acid, methyl ester (15.89%) for the former, and Hexadecanoic acid, methyl ester (27.95%) and phytol (10.82%) for the latter.