Effect of culture medium optimization on two methods of nisin detection

To improve efficiency of the agar diffusion method and spectrophotometry for nisin detection,the culture medium was optimized. The influence of the optimized medium on two methods of nisin detection was further investigated.The relative error and relative standard deviation was used to evaluate whether the precision and sensitivity of nisin quantification were enhanced after medium optimization.The results showed that culture medium optimization improved the precision and accuracy of nisin quantification by using spectrophotometry. On the contrary,in determining nisin concentration by agar diffusion method,the basic medium obtained the higher sensitivity and smaller relative error compared with the optimized culture medium.In addition,it was difficult to form a clear bacteriostatic circle at the low concentration of nisin with the optimized culture medium. Therefore,basic culture medium was a suitable choice when the agar diffusion method was used to determine nisin concentration.