Isolation and Identification of Antifungal Compounds from Bacillus subtilis C9 Inhibiting the Growth of Plant Pathogenic Fungi

Antagonistic microorganisms against Rhizoctonia solani were isolated and their antifungal activities were investigated. Two hundred sixteen bacterial isolates were isolated from various soil samples and 19 isolates were found to antagonize the selected plant pathogenic fungi with varying degrees. Among them, isolate C9 was selected as an antagonistic microorganism with potential for use in further studies. Treatment with the selected isolate C9 resulted in significantly reduced incidence of stem-segment colonization by R. solani AG2-2(IV) in Zoysia grass and enhanced growth of grass. Through its biochemical, physiological, and 16S rDNA characteristics, the selected bacterium was identified as Bacillus subtilis subsp. subtilis. Mannitol (1%) and soytone (1%) were found to be the best carbon and nitrogen sources, respectively, for use in antibiotic production. An antibiotic compound, designated as DG4, was separated and purified from ethyl acetate extract of the culture broth of isolate C9. On the basis of spectral data, including proton nuclear magneric resonance (1H NMR), carbon nuclear magneric resonance (13C NMR), and mass analyses, its chemical structure was established as a stereoisomer of acetylbutanediol. Application of the ethyl acetate extract of isolate C9 to several plant pathogens resulted in dose-dependent inhibition. Treatment with the purified compound (an isomer of acetylbuanediol) resulted in significantly inhibited growth of tested pathogens. The cell free culture supernatant of isolate C9 showed a chitinase effect on chitin medium. Results from the present study demonstrated the significant potential of the purified compound from isolate C9 for use as a biocontrol agent as well as a plant growth promoter with the ability to trigger induced systemic resistance of plants.

Isolation, Identification and Optimal Culture Conditions of Streptomyces albidoflavus C247 Producing Antifungal Agents against Rhizoctonia solani AG2-2

Streptomyces albidoflavus C247 was isolated from the soil of the Gyeongsan golf course in Korea. Physiological, biochemical and 16S rDNA gene sequence analysis strongly suggested that the isolate belonged to Streptomyces albidoflavus. Preliminary screening revealed that the isolate was active against fungi and bacteria. Self-directing optimization was employed to determine the best combination of parameters such as carbon and nitrogen source, pH and temperature. Nutritional and culture conditions for the production of antibiotics by this organism under shake-flask conditions were also optimized. Maltose (5%) and soytone (5%) were found to be the best carbon and nitrogen sources for the production of antibiotics by S. albidoflavus C247. Additionally, 62.89% mycelial growth inhibition was achieved when the organism was cultured at 30degrees C and pH 6.5. Ethyl acetate (EtOAc) was the best extraction solvent for the isolation of the antibiotics, and 100 microg/ml of EtOAc extract was found to inhibit 60.27% of the mycelial growth of Rhizoctonia solani AG2-2(IV) when the poison plate diffusion method was conducted.

Optimal Culture Conditions for Mycelial Growth and Exo-polymer Production of Ganoderma applanatum

The effect of fermentation parameters and medium composition on the simultaneous mycelial growth and exo-polymer production from submerged cultures of Ganoderma applanatum was investigated in shake-flask cultures. The optimum initial pH for mycelial growth and exo-polymer production was 5.0 and 6.0, respectively. The optimum temperature was 25degrees C and the optimum inoculum content was 3.0% (v/v). The optimal carbon and nitrogen sources were glucose and corn steep powder, respectively. After 12 days fermentation under these conditions, the highest mycelial growth was 18.0 g/l and the highest exo-polymer production was 3.9 g/l.

Anti-tumor Effects of Exo- and Endo-biopolymers Produced from Submerged Cultures of Three Different Mushrooms

The anti-tumor effects of exo- (EX) and endo-biopolymers (EN) produced from submerged mycelial cultures of Ganoderma applanatum (GA), Collybia confluens (CC), and Pleurotus eryngii (PE) were studied using Sarcoma 180 bearing mice. Solid tumor growth was inhibited most effectively when 40 mg/kg body weight (BW) of GA-EX or PE-EN was administered to the intraperitoneal (i.p.) cavity of BALB/c mice. The spleen and liver indexes were increased in mice following i.p. administration of GA-EX and PE-EN fractions. GA-EX and PE-EN reduced the tumor formation by 30.7% and 29.4%, respectively. GA-EX and PE-EN increased the natural killer (NK) cell activity of splenocytes by 41.3% and 28.9%, respectively.

Hypoglycemic Effects of Exo-biopolymers Produced by Five Different Medicinal Mushrooms in STZ-induced Diabetic Rats

Hypoglycemic effects of exo-biopolymers (EBP) produced by submerged mycelial cultures of Coriolus versicolor, Cordyceps sinensis, Paecilomyces japonica, Armillariella mellea, and Fomes fomentarius were investigated in streptozotocin (STZ)-induced diabetic rats. The rats from each experimental group were orally administered with EBPs (100 mg/kg BW) daily for 2 weeks. Though the hypoglycemic effect was achieved in all the cases, however, C. versicolor EBP proved as the most potent one. The administration of the C. versicolor EBP substantially reduced (29.9%) the plasma glucose level as compared to the saline administered group (control). It also reduced the plasma total cholesterol (TC), triglyceride (TG), aspartate aminotransferase (AST) and, alanine aminotransferase (ALT) levels by 9.22, 23.83, 16.93, and 27.31%, respectively. The sugar and amino acid compositions of this EBP were also analyzed in detail.

Hypolipidemic Effects of Biopolymers Extracted from Culture Broth, Mycelia, and Fruiting Bodies of Auricularia auricula-judae in Dietary-induced Hyperlipidemic Rats

Hypolipidemic effect of biopolymers extracted from culture broth (CP), mycelia (MP), and fruiting bodies (FP) of Auricularia auricula-judae was investigated in dietary-induced hyperlipidemic rats. The experimental animals were administrated (100 mg/kg body weight) with different biopolymers, daily for 4 weeks. Hypolipidemic effects were achieved in all the experimental groups, however, FP was proved to be the most potent one. The administration of the FP reduced the plasma triglyceride, total cholesterol, low-density lipoprotein cholesterol, and atherogenic index by 24.3, 28.5, 36.4, and 40.9%, respectively, while increased the high-density lipoprotein cholesterol level (9.0%), when compared to the saline (control) administered group.

Anti-complementary Activities of Exo- and Endo-biopolymer Produced by Submerged Mycelial Culture of Eight Different Mushrooms

The Elfvingia applanata (EA), Hericium erinaceum (HE),Grifola frondosa (GF), Pholiota nameko (PN), Pleurotus eryngii (PE), Trametes suaveolens (TS), Fomes fomentarius (FF), and Inonotus obliquus (IO) could produce the endo- (EN) and exo-biopolymer (EX) in submerged culture. The highest anti-complementary activity of the EN was exhibited by PN (49.1%), followed by HE (38.6%), TS (37.0%),and FF (33.0%),whereas the high activity of the EX was found with GF (59.8%),followed by HE (36.3%),TS (30.8%),and IO (28.8%). The EN of P. nameko (EN-PN) and EX of G. frondosa (EX-GF) were found to contain 78.6% and 41.2% carbohydrates, while 21.4% and 58.8% protein, respectively. The sugar and amino acid compositions of EN-PN and EX-GF were also analyzed in detail.