Strain Identification And Optimization Of Fermentation Conditions Of AmB Producing Strain

Amphotericin B?AmB?is one of the most efficient antimycotic agents and widely used in clinical practice.The preparation and biological properties of various AmB analogs and conjugates have been studied for a long time.Therefore,it is important to improve the production of AmB.In this study,Streptomyces nodosus ZJB15076 was used for AmB fermentation.The aim of this study was to optimize the fementation condition of AmB production and study on the influence of adding precursors.In addition,the effect of microparticles on morphology and AmB production,and the fermentation condition in fermentor were studied.First of all,through morphological,physiological and biochemical characteristics,ZJB15076 was identified as Streptomyces nodosus.The optimal carbon source,nitrogen source and fermentation conditions for the production of AmB were tested.The results showed that glucose and nitrogen beef extract is best for the fermentation of AmB,the optimal concentration is 45 g/L and 40 g/L,C/N ratio is 1:1.Under the above condition,the maximum AmB production reached to 1850.7 mg/L,which was 46%higher than that of the initial conditions?998.2 mg/L?.Secondly,the optimized fermenting conditions through single factor test were summed up as follows:culture temperature 28?,initial pH value 7.0,inoculation 2%,Mg²⁺0.2 g/L and liquid volume 40 mL/250mL.The AmB production could reach to 2183.5 mg/L,which improved by 118.7%.The influence of adding glass bead is significant.After adding glass bead,the production of AmB increased by 341.1%and reached4563.2 mg/L.Finally,the effects of ventilation?stirring speed and type of the agitator on the AmB production were studied in the fermenter.The optimum ventilation was 1.5 vvm,the agitation speed was controlled at400 rpm.It found that dissolved oxygen is always an important factor limiting the fermentation yield.