Evaluation of hydrolytic enzymes and antifungal activity of extracellular bioactive compounds of Desmonostoc alborizicum and Neowestiellopsis persica against plant pathogenic fungi

Agriculture requires the extensive use of chemical pesticides to protect crops against pests and diseases. An important mechanism for the biological control of pathogenic fungi is the breakdown of their cell walls. Cyanobacteria are found commonly growing as blooms which provides a competitive advantage to these organisms. This is one of the critical factors responsible for the production of several hydrolytic enzymes with antifungal activity. However, the role of the hydrolytic enzymes of Neowestiellopsis and Desmonostoc, which are implicated in the fungicidal activity of several biocontrol strains, has not been explored. Therefore in this study, hydrolytic enzymes (chitosanase, protease, FPase, carboxymethyl cellulose, xylanase, cellobiohydrolases and cellobiase) of two cyanobacteria strains were evaluated against a set of phytopathogenic fungi (Alternaria alternata, Fusarium solani, Fusarium oxysporum, Macrophomina phaseolina, Verticillium dahliae and Phytophthora). The results of statistical analysis showed that the level of protease, FPase and xylanase activity in Desmonostoc alborizicum cyanobacterial extract has been significantly higher than in Neowestiellopsis. Moreover, IAA hormone activity and soluble protein content were significantly higher in Desmonostoc alborizicum cyanobacterial extract. While CMCase, cellobiohydrolases, cellobiase, and chitosanase activity was significantly higher in Neowestiellopsis persica A1387 cyanobacterial extract in comparison to Desmonostoc alborizicum. Moreover, Neowestiellopsis persica was observed to be highly potent in terms of its fungicidal activity. Comparative evaluation of the activity of hydrolytic enzymes and antifungal activity revealed that such enzymes might contribute to the fungicidal activity of the cyanobacterial strains, besides other bioactive compounds, including IAA, which are established promising traits for biocontrol agents. This study is a first-time report on the production of hydrolytic enzymes by these two cyanobacteria strains, which can be potential candidates for the development of biocontrol agent(s) against selected phytopathogenic fungi.