A total of 123 actinomycetes was isolated from 12 varieties of wild orchids and screened for potential antagonistic activity against Phytophthora, which causes black rot disease in orchids. In vitro and in vivo experimental results revealed that Streptomyces sp. strain 9X166 showed the highest antagonistic activity; its β-1,3-glucanase production ability was a key mechanism for growth inhibition of the pathogen. PCR amplification and DNA sequencing of the 16S ribosomal RNA gene allowed the identification of this strain, with high similarity (99.93%) to the novel species Streptomyces similaensis. The glucanase enzyme, purified to homogeneity by anion exchange and gel filtration chromatography, showed a specific activity of 58 U mg(-1) (a 3.9-fold increase) and yield of 6.4%. The molecular weight, as determined by SDS-PAGE and gel filtration, was approximately 99 and 80 kDa, respectively, suggesting that the enzyme was a monomer. The purified enzyme showed the highest substrate specificity to laminarin, indicating that it was β-1,3-glucanase. The hydrolyzed products of cello-oligosaccharides suggested that this enzyme was endo-type β-1,3-glucanase. Streptomyces sp. 9X166 culture filtrate, possessing β-1,3-glucanase activity, could degrade both freeze-dried and living mycelium. This is the first report on a β-1,3-glucanase-producing Streptomyces sp. that could be an effective biocontrol agent for black rot disease in orchids.

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Functional foods have received considerable attention due to their numerous health benefits. Lion's mane mushroom (Hericium erinaceus) is a functional food source that contains bioactive compounds of medicinal importance. The main aim of this study was to explore antimicrobial and anticancer activities and identify bioactive compounds of H. erinaceus mycelia cultivated on mixed red and white jasmine rice (HMR) with the aid of solid-state fermentation (SSF). The HMR extract and its fractions were analyzed for antibacterial activity via disc diffusion and minimum inhibitory concentration (MIC) assays and anticancer activity against cervical cancer (HeLa) examined with the [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay. Chemical profiles were analyzed using gas chromatography-mass spectrometry (GC-MS). Our results showed that the lipophilic fraction (LF2) had antibacterial activity against P. mirabilis (MIC = 250 µg/mL). LF2 is primarily composed of fatty acid derivatives with antibacterial components, including nonanoic acid, 2-dodecen-1-yl(-) succinic anhydride, linoleic acid ethyl ester, 3,4-dimethylbenzoic acid, and lauryl acetate. However, all HMR fractions displayed relatively weak anticancer activity (IC 50 > 100 µg/mL). Our collective findings support the potential utility of H. erinaceus mycelium cultivated on mixed red and white jasmine rice as an antibacterial agent.

Biofilm formation has become a serious health and environmental problem. Mushrooms are now considered a valuable source of bioactive compounds with antimicrobial properties. The lion's mane mushroom ( Hericium erinaceus [HE]) has been used as an antimicrobial for ulcers and gastritis in East Asian countries. However, studies on the antibiofilm activities of HE basidiome against biofilm-forming pathogenic bacteria and their bioactive compound profiles are still limited. The purpose of this study was to determine the antibiofilm activity of HE and to identify its phenolic compound profile. The HE inhibitory activities against bacterial growth and biofilm formation were performed against Pseudomonas aeruginosa, Salmonella Typhimurium, Proteus mirabilis, and Staphylococcus aureus. Remarkably, P. mirabilis was the most susceptible bacteria to HE. The total phenolic content (TPC) of HE was 1652 ± 1.06 µg/ml, with protocatechuic acid and p-coumaric acid being the most abundant phenolic compounds as determined by high-performance liquid chromatography-mass spectrophotometry (HPLC-MS). This research highlights the possibility of HE as an antibiofilm agent that can be developed as a nutraceutical and natural food preservative.