Bioactive Products From Plant-Endophytic Gram-Positive Bacteria

Abstract

Endophytes constitute plant-colonizing microorganisms in a mutualistic symbiosis relationship. They are found in most ecosystems reducing plant crops’ biotic and abiotic stressors by stimulating immune responses, excluding plant pathogens by niche competition, and participating in antioxidant activities and phenylpropanoid metabolism, whose activation produces plant defense, structural support, and survival molecules. In fact, metabolomic studies have demonstrated that endophyte genes associated to specific metabolites are involved in plant growth promotion (PGP) by stimulating plant hormones production such as auxins and gibberellins or as plant protective agents against microbial pathogens, cancer, and insect pests, but eco-friendly and eco-safe. A number of metabolites of Gram-positive endophytes isolated from agriculture, forest, mangrove, and medicinal plants, mainly related to the Firmicutes phyla, possess distinctive biocontrol and plant growth-promoting activities. In general, Actinobacteria and Bacillus endophytes produce aromatic compounds, lipopeptides, plant hormones, polysaccharides, and several enzymes linked to phenylpropanoid metabolism, thus representing high potential for PGP and crop management strategies. Furthermore, Actinobacteria have been shown to produce metabolites with antimicrobial and antitumor activities, useful in agriculture, medicine, and veterinary areas. The great endophytes diversity, their metabolites production, and their adaptation to stress conditions make them a suitable and unlimited source of novel metabolites, whose application could reduce agrochemicals usage in food and drugs production.

Plant growth promoting and antifungal activity in endophytic Bacillus strains from pearl millet (Pennisetum glaucum)

“…subtilis (EPP65), and B. cereus (EPP5, EPP71, and EPP74) strains are highly promising and proficient antagonists showing ≥ 50% fungal mycelium growth inhibition against all the tested phytopathogenic fungi (RS, SR, and FS). One of the most significant characters of these endophytic bacterial strains reflecting strong antagonistic behavior may be explained by prevalence of structurally different antibiotics (surfactin, bacillomycin, and iturin) with manifold mode of action [14,21,26,[68][69][70]. PCR based screening of AMP gene(s) in the present study clearly reflected the presence srfA, bmyC, and ituD genes in all the endophytic Bacillus strains.…”

Phyllospheric Microbiomes: Diversity, Ecological Significance, and Biotechnological Applications

“…Endophytic Bacillus produces phytohormones such as abscisic acid, auxins, brassinosteroids, cytokinins, ethylene, gibberellins, jasmonates, and strigolactones, and increases nutrient (nitrogen and phosphorous) accessibility to the host (Reinhold-Hurek and Hurek 2011;Brader et al 2014;Santoyo et al 2016;Shahzad et al 2016;Ek-Ramos et al 2019). Zeiller et al (2015) reported that C. botulinum 2301 significantly produce PGPs in a field experiment of clover.…”

Isolasi, Seleksi, dan Uji Antagonis Bakteri Endofit diisolasi dari Salawaku (Falcataria mollucana) dalam Menekan Pertumbuhan Cendawan Patogen Cercospora spp

“…Endofit dari kelompok Streptomyces, Kenedia nigriscans strain NRRL 30562 dan Streptomyces caeruleatus dilaporkan efektif terhadap patogen kedelai Xanthomonas campestris pv. glisin [28] , sedangkan metabolit dari tanaman Azadirachta indica dan Nothofagus spp adalah endofit actinomycetes yang dapat menghambat jamur patogen tanaman Mycosphaerella fijiensis, Sclerotinia sclerotiorum, dan Rhizoctonia solani, dan Pythium sp dan Phytophthora [29] , juga metabolit sekunder yang dihasilkan oleh actinobacteria terbukti menghasilkan aktivitas antimikroba dan antitumor, berguna dalam bidang pertanian, kedokteran, dan kedokteran hewan [30] . Keanekaragaman endofit yang tinggi, produksi metabolit, dan adaptasinya terhadap kondisi stres sehingga dapat dijadikan sumber metabolit baru untuk mengurangi penggunaan bahan kimia pertanian dalam produksi makanan dan obatobatan maupun di bidang proteksi tanaman kehutanan.…”