Antifungal Activities of Streptomyces blastmyceticus Strain 12-6 Against Plant Pathogenic Fungi

Abstract

Streptomyces blastmyceticus strain 12-6 was isolated from a forest soil sample of Cheonan area on the basis of strong antifungal activities against plant pathogenic fungi. Butanol extracts of the cultural filtrates were active against C. acutatum, C. coccodes, C. gloeosporioides, F. oxysporum, and T. roseum. Active fractions were prepared by thin layer chromatography using silica gel plate; 12-6-2 (Rf 0.36), 12-6-3 (Rf 0.44). Scanning electron microscopy showed that the active fractions caused a change in surface texture of fungal spores from smooth surface to wrinkled surface. The lethal effect on the spores of the active fractions varied from 56% to 100%. It was shown that the spores of C. acutatum were more sensitive to the antifungal fractions than the spores of F. oxysporum. Fluorescence staining using TOTO-1 indicated that the antifungal fractions could make the spores more sensitive to the fluorescence dye. Thus, it was suggested that antifungal agents prepared in this study exhibited the antifungal activity by damaging the plasma membrane of both fungal spores and hyphae. Identification of antifungal agents in the active fraction using GC-MS analysis revealed the presence of cyclo-(Leu-Pro) and 9-octadecenamide as major components that have already been known as antifungal substances.

Deciphering the antagonistic effect of Streptomyces spp. and host-plant resistance induction against charcoal rot of sorghum

“…Often, these rhizospheric microbes individually or in consortia produce a wide variety of secondary metabolites that are known to aid in plant growth under stressful conditions (Musilova et al 2016). Inhibition of M. phaseolina growth by these Streptomyces strains is mainly attributed to their ability to produce anti-fungal compounds such as hydrolytic enzymes and acids (Alekhya and Gopalakrishnan 2017;Vijayabharathi et al 2018;Kim et al 2019). These PGPR strains are mainly regarded as bio-control agents as they potentially produce chitinase, siderophore and hydrocyanic acid (HCN) which confer disease resistance in crops such as wheat (Kumar et al 2018) and tomato (Abo-Elyousr et al in the present study were previously reported to produce chitinase, siderophore and HCN (Gopalakrishnan et al 2011a;Sreevidya et al 2016).…”

Identification and Characterization of a Streptomyces albus Strain and Its Secondary Metabolite Organophosphate against Charcoal Rot of Sorghum

“…This hypothesis was confirmed in the secondary metabolite production assay as the organic fraction of the culture filtrate of CAI-21 inhibited M. phaseolina by 73.8% (Table 1 and Figure 2). Inhibition of M. phaseolina growth by PGP microbial strains is mainly attributed to their ability to produce antifungal compounds such as hydrolytic enzymes (cellulase and chitinase) and hydrocyanic acids (HCN) [24,25]. Plant growth-promoting rhizobacteria (PGPR) strains are mainly regarded as biocontrol agents as they potentially produce siderophores, chitinase, and HCN, which induce disease resistance in agriculturally important crops [26,27].…”

Understanding the Evolution of Plant Growth-Promoting Rhizobacteria

“…PGPR especially, the For HCN production, the following rating scale was used: 0 ¼ no colour change; 1 ¼ light reddish brown; 2 ¼ medium reddish brown; and 3 ¼ dark reddish brown Streptomyces spp. produce various hydrolytic enzymes and acids that show antifungal ability against different agriculturally important fungal pathogens (Alekhya and Gopalakrishnan 2017;Vijayabharathi et al 2018;Kim et al 2019;. This PGPR-plant interaction also enhances the jasmonic acid, salicylic acid and ethylene production, which in turn activates the induced and systemic acquired resistance to subdue the disease (Vleesschauwer and Höfte 2009).…”

“…During recent years, several research studies have reported the significance of rhizosphere microbes in playing an important role in the plant growth promotion, in formation of important microbial consortia and disease resistance in host plants (Bhattacharyya and Jha 2012;Alekhya and Gopalakrishnan 2017;Vijayabharathi et al 2018;Anusha et al 2019;Gopalakrishnan and Vadlamudi 2019;Kim et al 2019). Also, they emerged as a potential alternative for chemical fertilizers and have shown promising crop yield outputs in agricultural fields (Laslo and Mara 2019).…”