Exploration on relative quality standard of Corynebacterium diphtheriae culture medium

Abstract

Objective To establish relative quality standards of Corynebacterium diphtheriae culture medium.Methods Corynebacterium diphtheriae culture media with ≥ 1.8 g/L and ＜ 1.8 g/L ammonia nitrogen were prepared respectively to use for Corynebacterium diphtheriae culture in large fermtor.The statistical analysis of the culture results were made by t test,and the optimal culture medium was identified.Fifteen batches of Corynebacterium diphtheriae culture media were prepared according to the identified formula and used to large fermentor culture.Quantities of diphtheria toxin harvested by culture were detected,and correlativity between ammonia nitrogen contents in Corynebacterium diphtheriae culture medium and diphtheria toxin produced by Corynebacterium diphtheriae was analysed.Fifteen batches of 15％-20％ maltose solutions were made up and fed into large fermentor as supplement during Corynebacterium diphtheriae culture.Quantities of diphtheria toxin harvested by culture were detected,and correlativity between concentrations of maltose solutions and diphtheria toxin produced by Corynebacterium diphtheriae was analysed.Results Quantities of diphtheria toxin harvested from Corynebacterium diphtheriae culture media with ≥ 1.8 g/L ammonia nitrogen were significantly higher than those harvested from Corynebacterium diphtheriae culture media with ＜ 1.8 g/L ammonia nitrogen(t =0.5635,P ＜ 0.05).Positive linear correlation (r =0.52) was showed between ammonia nitrogen contents in Corynebacterium diphtheriae culture medium and quantities of diphtheria toxin in ranges of identified ammonia nitrogen contents (1.8-2.0 g/L).When concentrations of maltose solutions ranged from 15％ to 20％,negative linear correlation (r =-0.53) was showed between concentrations of maltose solutions and quantities of diphtheria toxin.Conclusion When ammonia nitrogen contents in Corynebacterium diphtheriae culture medium and concentrations of maltose solutions for feeding into large fermentor are controlled in ranges of 1.8-2.0 g/L and 15％-20％,respectively,quantities of diphtheria toxin harvested by large fermentor culture can achieve requirements of the regulation. Key words: Culture media ; Corynebacterium diphtheriae ; Diphtheria toxin ; Maltose ; Ammonia nitrogen content ;