Abstract
The study of antibiotic-free feed additives production by Acremonium terricola (A. terricola) solid-fermented Camellia oleifera meal (COM) has been carried out in this work. Firstly, the minimum inhibitory concentration (MIC, 10 mg/mL) and minimum bactericidal concentration (MBC, 15 mg/mL) of tea saponin on A. terricola were determined by double dilution method. Then, the tea saponin tolerance concentrations (≤5 mg/mL) for A. terricola to increase production of cordycepic acid and ergosterol has been determined according to the stress mechanism for homeostasis balance of cell and energy, and change in enzyme protection system. Lastly, the comparative analysis of production and accumulation of cordycepic acid and ergosterol in A. terricola cultures (ATCs), which solid-fermented desaponificated COM (tea saponin, 2.6 mg/100 g), rice bran (RB) and wheat bran (WB), has been conducted. All results demonstrated homeostasis of cell and energy has been balanced by increasing production of chitin and ergosterol, and the activity of POD and Na+/K+-ATPase, respectively. COM containing tea saponins (≤5 mg/mL) significantly promoted the production and accumulation of cordycepic acid and ergosterol compared to rice bran (RB) and wheat bran (WB). This work indicated that COM can partially replace food or food by-products to prepare antibiotic-free feed additives by A. terricola.