Hydrogen production by Escherichia coli depends on glucose concentration and its combination with glycerol at different pHs

摘要

Escherichia coli produces molecular hydrogen (H_2) during glucose or mixed carbon (glucose and glycerol) fermentation. Dependence of H_2 production rate (V_(h2) ) on glucose at different pHs was studied in a concentration dependent manner. During growth of wild-type on glucose, increasing glucose concentration from 0.05% to 0.2% resulted in the marked inhibition of V_(H2). Inhibitory effect of glucose was shown at pH 7.5 and 6.5 but not pH 5.5. However, glycerol added in the growth medium with 0.1% glucose significantly increased V_(h2) but different effects at different pHs were established upon glucose or glycerol assays. The results indicate that H_2 production is inhibited by glucose in a concentration dependent manner during glucose fermentation but glucose in combination with glycerol might enhance H_2 production during mixed carbon fermentation.