Cyanobacteria: A Promising Source of Antifungal Metabolites

Cyanobacteria are a rich source of secondary metabolites, and they have received a great deal of attention due to their applicability in different industrial sectors. Some of these substances are known for their notorious ability to inhibit fungal growth. Such metabolites are very chemically and biologically diverse. They can belong to different chemical classes, including peptides, fatty acids, alkaloids, polyketides, and macrolides. Moreover, they can also target different cell components. Filamentous cyanobacteria have been the main source of these compounds. This review aims to identify the key features of these antifungal agents, as well as the sources from which they are obtained, their major targets, and the environmental factors involved when they are being produced. For the preparation of this work, a total of 642 documents dating from 1980 to 2022 were consulted, including patents, original research, review articles, and theses.

Determination of Volatile Organic Compounds and Antibacterial Activity of the Amazonian Cyanobacterium Synechococcus sp. Strain GFB01

Cyanobacteria exhibit great biotechnological potential due to their capacity to produce compounds with various applicability. Volatile organic compounds (VOCs) possess low molecular weight and high vapor pressure. Many volatiles produced by microorganisms have biotechnological potential, including antimicrobial activity. This study aimed to investigate the VOCs synthesized by cyanobacterium Synechococcus sp. strain GFB01, and the influence of nitrate and phosphate on its antibacterial potential. The strain was isolated from the surface of the freshwater lagoon Lagoa dos Índios, Amapá state, in Northern Brazil. After cultivation, the VOCs were extracted by a simultaneous distillation-extraction process, using a Likens-Nickerson apparatus (2 h), and then identified by GC-MS. The extracts did not display inhibitory activity against the Gram-positive bacteria tested by the disk-diffusion agar method. However, the anti-Salmonella property in both extracts (methanol and aqueous) was detected. The main VOCs identified were heptadecane (81.32%) and octadecyl acetate (11.71%). To the best of our knowledge, this is the first study of VOCs emitted by a cyanobacterium from the Amazon that reports the occurrence of 6-pentadecanol and octadecyl acetate in cyanobacteria.