https://www.selleckchem.com/peptide/apamin.html 10.1007/s13205-020-02547-0) contains supplementary material, which is available to authorized users.In this study, nine strains of Pseudomonas aurantiaca and P. chlororaphis, and two isolates of Pseudomonas sp. At1RP4 and RS-1, were characterized for the in-vitro production of secondary metabolites in LB, DMB, and King's B media, and of the genes responsible for the production of antagonistic metabolites. Based on 16S rRNA gene sequence, isolates At1RP4 and RS-1 were identified as strains of P. aeruginosa and P. fluorescens. Five phenazine derivatives comprising phenazine, phenazine-1-carboxylic acid (PCA), 2-hydroxyphenazine-1-carboxylic acid (2-OH-Phz-1-COOH), phenazine-1,6-dicarboxylic acid (Phz-1,6-di-COOH), and 2-hydroxyphenazine (2-OH-Phz) were produced by all strains in all three culture media including DMB, King's B and LB. However, 2,8-dihydroxyphenazine, 6-methylphenazine-1-carboxylic acid, pyrrolnitrin, and the ortho-dialkyl-aromatic acids, were produced by the P. aurantiaca and P. chlororaphis strains. In addition, all strains produced 2-acetamidophenol, pyochelin, and diketopiperazine derivativ material available at 10.1007/s13205-020-02585-8. The online version contains supplementary material available at 10.1007/s13205-020-02585-8.The effects of alginate oligosaccharides (AOs) on the growth performance and non-specific immunity of juvenile grass carp (Ctenopharyngodon idella) were investigated by performing a 60-day feeding trial. Four trial diets were formulated and supplemented with different doses of AOs (0, 100, 200 and 400 mg/kg). Triplicate groups of grass carp were fed with one of the diets twice daily. The grass carps fed with diets containing an appropriate dose of AOs for 60 days exhibited higher survival rates; body weight gains; specific growth rates; resistance to Aeromonas hydrophila; superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities; and serum tota