Composition optimization of medium for a syntrophic acetogen coculture

Abstract:

Hydrogen-producing acetogens,between acidogenes and methanogens in trophic niche,is very difficult to be separated and only few of the pure cultures have been obtained.This has restricted the development of new anaerobic organic wastewater treatment process with high efficiency based on enhancing their metabolic capability.A new syntrophic acetogen coculture named 7-m-2a which showed great capacity in degrading propionic acid was introduced in this paper.To optimize the culture medium,the influences on 7-m-2a’s growth and metabolism of propionic acid concentration,nitrogen sources,Fe2+,Mg2+,Ca2+ and pantothenic acid were investigated.The results indicated that the suitable concentration of propionic acid and Fe2+,Mg2+,pantothenic acid were 10 g/L and 88,38,30 mg/L,respectively.The optimum nitrogen source was the mixture of yeast extract,tryptone and NH4Cl with a concentration of 0.33 g/L respectively.With the optimization culture,a specific degradation rate of propionic acid and acetic acid yield of 998 mg/(L·d) and 3 947 mg/L,respectively,obtained after fermenting for 30 days at 38 ℃.