ABSTRACT
Streptomyces murinus strain SPC1, isolated from foxtail palm seeds, exhibited antimicrobial activity against fungal pathogens of palms. The assembled genome was 8.3 Mb, with 71.96% GC content, and contained 37 secondary metabolite clusters (SMCs). A complete SMC for antifungal metabolite pentamycin (fungichromin) biosynthesis was identified in SPC1 genome.
ABSTRACT
Damping-off caused by Pythium aphanidermatum (Pa) is one of the most destructive diseases for watermelon seedlings. Application of biological control agents against Pa has attracted the attention of many researchers for a long time. In this study, the actinomycetous isolate JKTJ-3 with strong and broad-spectrum antifungal activity was screened from 23 bacterial isolates. Based on the morphological, cultural, physiological, and biochemical characteristics as well as the feature of 16S rDNA sequence, isolate JKTJ-3 was identified as Streptomyces murinus. We investigated the biocontrol efficacy of isolate JKTJ-3 and its metabolites. The results revealed that seed and substrate treatments with JKTJ-3 cultures showed a significant inhibitory effect on watermelon damping-off disease. Seed treatment with the JKTJ-3 cultural filtrates (CF) displayed higher control efficacy compared to the fermentation cultures (FC). Treatment of the seeding substrate with the wheat grain cultures (WGC) of JKTJ-3 exhibited better control efficacy than that of the seeding substrate with the JKTJ-3 CF. Moreover, the JKTJ-3 WGC showed the preventive effect on suppression of the disease, and the efficacy increased with increase in the inoculation interval between the WGC and Pa. Production of the antifungal metabolite actinomycin D by isolate JKTJ-3 and cell-wall-degrading enzymes such as ß-1,3-glucanase and chitosanase were probably the mechanisms for effective control of watermelon damping-off. It was shown for the first time that S. murinus can produce anti-oomycete substances including chitinase and actinomycin D. This is the first report about S. murinus used as biocontrol agent against watermelon damping-off caused by Pa.
ABSTRACT
The food enzyme AMP deaminase (AMP aminohydrolase; EC 3.5.4.6) is produced with the non-genetically modified Streptomyces murinus strain AE-DNTS by Amano Enzyme Inc. The food enzyme is free from viable cells. It is intended to be used in yeast processing and the production of mushroom extracts. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.0004 mg TOS/kg body weight (bw) per day in European populations. The food enzyme batches, including the batch used in the toxicological studies, were not fully characterised. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic reactions by dietary exposure cannot be excluded, but the likelihood is low. In the absence of adequate toxicological data, the Panel could not conclude on the safety of the food enzyme AMP deaminase from the non-genetically modified Streptomyces murinus strain AE-DNTS.
ABSTRACT
The food enzyme is a glucose isomerase (d-xylose aldose-ketose-isomerase; EC 5.3.1.5) produced with a non-genetically modified Streptomyces murinus strain NZYM-GA by Novozymes A/S. The glucose isomerase is intended only to be used in an immobilised form in glucose isomerisation for the production of high fructose syrups. Residual amounts of total organic solids are removed by the purification steps applied during the production of high fructose syrups using the immobilised enzyme; consequently, dietary exposure was not calculated. Genotoxicity tests did not raise a safety concern. Similarity of the amino acid sequence to those of known allergens was searched and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood to occur is considered to be low. Based on the data provided, the immobilisation process and the removal of total organic solids during the production of high fructose syrups, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.