The effects of L-cysteine concentration on biohydrogen production by

Enterobacterium Bacterium

M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth

hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L

-1

while it had negative effects when its concentration was higher than 500 mg·L

-1

.The hydrogen production was the highest 1.29 mol·mol

-1

(H

2

/glucose) when 300 mg·L

-1

L-cysteine was added into the culture

and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP)

which was influenced by L-cysteine

also affected hydrogen production.The ORP values were in the range -300 mV to -150 mV when the L-cysteine concentration was higher than 500 mg·L

-1

.Although the ORP in this range was favorable for hydrogen production

it was not suitable for the biomass growth.Hence

less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L

-1

the ORP was more suitable for both biomass growth and hydrogen production.In addition

at least 91%glucose was consumed when L-cysteine was added to the culture media

compared to the 97.37% consumption without L-cysteine added.