Endophytic Bacillus spp. from medicinal plants inhibit mycelial growth of Sclerotinia sclerotiorum and promote plant growth

Plant growth promoting bacteria that are also capable of suppressing plant pathogenic fungi play an important role in sustainable agriculture. There is a critical need of conducting research to discover, characterize and evaluate efficacy of new strains of such bacteria in controlling highly aggressive plant pathogens. In this study, we isolated endophytic bacteria from medicinal plants of Bangladesh and evaluated their antagonistic capacity against an important phytopathogenic fungus Sclerotinia sclerotiorum. Growth promoting effects of those isolates on cucumber and rice seedlings also were assessed. Among 16 morphologically distinct isolates, BDR-2, BRtL-2, and BCL-1 significantly inhibited the growth of S. sclerotiorum through induction of characteristic morphological alterations in hyphae and reduction of mycelial dry weight. When cucumber and rice seeds were treated with these endophytic bacteria, seven isolates (BCL-1, BDL-1, BRtL-2, BRtL-3, BDR-1, BDR-2 and BBoS-1) enhanced seed germination, seedling vigor, seedling growth, and number of roots per plant at varying level compared to untreated controls. All isolates produced high levels of indole-3-acetic acid (6.3 to 63μg mL−1) in vitro. Two most potential isolates, BDR-2 and BRtL-2 were identified 34 as Bacillus amyloliquefaciens and B. subtilis, respectively based on the 16S rRNA gene sequencing. These results suggest that endophytic Bacillus species from native medicinal plants have great potential for using as natural plant growth promoter and biopesticides in sustainable crop production

Sea Cucumber Glycosides: Chemical Structures, Producing Species and Important Biological Properties

Sea cucumbers belonging to echinoderm are traditionally used as tonic food in China and other Asian countries. They produce abundant biologically active triterpene glycosides. More than 300 triterpene glycosides have been isolated and characterized from various species of sea cucumbers, which are classified as holostane and nonholostane depending on the presence or absence of a specific structural unit γ(18,20)-lactone in the aglycone. Triterpene glycosides contain a carbohydrate chain up to six monosaccharide units mainly consisting of d-xylose, 3-O-methy-d-xylose, d-glucose, 3-O-methyl-d-glucose, and d-quinovose. Cytotoxicity is the common biological property of triterpene glycosides isolated from sea cucumbers. Besides cytotoxicity, triterpene glycosides also exhibit antifungal, antiviral and hemolytic activities. This review updates and summarizes our understanding on diverse chemical structures of triterpene glycosides from various species of sea cucumbers and their important biological activities. Mechanisms of action and structural–activity relationships (SARs) of sea cucumber glycosides are also discussed briefly

Sea Cucumber Glycosides: Chemical Structures, Producing Species and Important Biological Properties

Sea cucumbers belonging to echinoderm are traditionally used as tonic food in China and other Asian countries. They produce abundant biologically active triterpene glycosides. More than 300 triterpene glycosides have been isolated and characterized from various species of sea cucumbers, which are classified as holostane and nonholostane depending on the presence or absence of a specific structural unit γ(18,20)-lactone in the aglycone. Triterpene glycosides contain a carbohydrate chain up to six monosaccharide units mainly consisting of d-xylose, 3-O-methy-d-xylose, d-glucose, 3-O-methyl-d-glucose, and d-quinovose. Cytotoxicity is the common biological property of triterpene glycosides isolated from sea cucumbers. Besides cytotoxicity, triterpene glycosides also exhibit antifungal, antiviral and hemolytic activities. This review updates and summarizes our understanding on diverse chemical structures of triterpene glycosides from various species of sea cucumbers and their important biological activities. Mechanisms of action and structural–activity relationships (SARs) of sea cucumber glycosides are also discussed briefly

Macrocyclic Trichothecenes from Myrothecium roridum Strain M10 with Motility Inhibitory and Zoosporicidal Activities against Phytophthora nicotianae

The cytotoxicity of the extract obtained from Myrothecium roridum M10 and a characteristic ¹H signal at δ_H ∼8 led to the assumption that verrucarin/roridin-type compounds were present. Upscaling on rice medium led to the isolation of four new metabolites: verrucarins Y (<b>1</b>) and Z (<b>6</b>) (macrocyclic trichothecenes), bilain D (<b>12</b>) (a diketopiperazine derivative), and hamavellone C (<b>14</b>) (an unusual cyclopropyl diketone). In addition, nine known trichothecenes [verrucarin A (<b>3</b>), 16-hydroxyverrucarin A (<b>5</b>), verrucarin B (<b>7</b>), 16-hydroxyverrucarin B (<b>8</b>), verrucarin J (<b>2</b>), verrucarin X (<b>4</b>), roridin A (<b>9</b>), roridin L-2 (<b>10</b>), and trichoverritone (<b>11</b>)] and a bicyclic lactone [myrotheciumone A (<b>15</b>)] were identified. Their structures and configurations were determined by spectroscopic methods, published data, Mosher’s method, and considering biosyntheses. Some trichothecenes showed motility inhibition followed by lysis of the zoospores against devastating Phytophthora nicotianae within 5 min. Compounds <b>2</b>, <b>3</b>, <b>7</b>, and <b>9</b> also exhibited potent activities against Candida albicans and Mucor miehei

Endophytic Bacillus spp. from medicinal plants inhibit mycelial growth of Sclerotinia sclerotiorum and promote plant growth

Plant growth-promoting bacteria that are also capable of suppressing plant pathogenic fungi play an important role in sustainable agriculture. There is a critical need for conducting research to discover, characterize and evaluate the efficacy of new strains of such bacteria in controlling highly aggressive plant pathogens. In this study, we isolated endophytic bacteria from medicinal plants of Bangladesh and evaluated their antagonistic capacity against an important phytopathogenic fungus Sclerotinia sclerotiorum. Growth-promoting effects of those isolates on cucumber and rice seedlings were also assessed. Among 16 morphologically distinct isolates, BDR-2, BRtL-2 and BCL-1 significantly inhibited the growth of S. sclerotiorum through induction of characteristic morphological alterations in hyphae and reduction of mycelial dry weight. When cucumber and rice seeds were treated with these endophytic bacteria, seven isolates (BCL-1, BDL-1, BRtL-2, BRtL-3, BDR-1, BDR-2 and BBoS-1) enhanced seed germination, seedling vigor, seedling growth and number of roots per plant at a varying level compared to untreated controls. All isolates produced high levels of indole-3-acetic acid (6 to 63 μg/mL) in vitro. Two most potential isolates, BDR-2 and BRtL-2, were identified as Bacillus amyloliquefaciens and B. subtilis, respectively, based on the 16S rRNA gene sequencing. These results suggest that endophytic Bacillus species from native medicinal plants have great potential for being used as natural plant growth promoter and biopesticides in sustainable crop production