Biomedical Engineering Reference
In-Depth Information
coordination among bacteria can stabilize the ecological system so that the value
of bio-producing hydrogen would be increased. Liu et al. [
83
] studied the ability
of hydrogen production of
Clostridium butyricum
D2,
Enterobacter aerogenes
C3,
and
Candida maltosa
M4. With a mixed culture of these three strains at 36
ı
Cfor
48 h, the volume of hydrogen production was 22.2 mL, and the average rate of
hydrogen production was 15.42 mL
L
1
, which showed that a mixed culture
of three strains had a synergistic effect on hydrogen production. Zhang and Xing
[
84
] analyzed a mixed culture consisting of gfp-harbored
Enterobacter aerogenes
and
Clostridium paraputrificum
for hydrogen production. The concentrations of the
respective strains in the mixed culture were calculated using aerobic fluorescence
recovery (AFR) technology. Fan et al. [
85
] treated the simulated organic wastewater
containing sucrose and starch with natural anaerobic microorganism bacteria from
cow dung compost. The biohydrogen was produced through anaerobic hydrogen
fermentation with synchronous purification of the wastewater.
h
1
H
2
(2) Mixed strain phototrophic hydrogen production
Mixed strain phototrophic hydrogen production has been little studied at present.
Han et al. [
86
] reported the most suitable conditions based on experiments of three
kinds of mixed strains of
Rhodopseudomonas
growing at different combinations of
carbon source, nitrogen source, pH value, and growth temperature. Miura et al. [
87
]
achieved stably sustained continuous production of hydrogen with high molar yield
through a combination of dark fermentive hydrogen evolution by
Chlamydomonas
sp. strain MGA161 and hydrogen photoevolution by a marine photosynthetic
bacterium W-1S in an alternating light-dark cycle as a model of the day-night cycle.
Zhang et al. [
82
,
88
] studied the main conditions of hydrogen production by mixed
cultivation of
Rhodobacter sphaeroides
. The result showed that the anaerobic and
illumination atmospheres were necessary for hydrogen production, and suitable
conditions were a temperature range from 32 to 40
ı
C, pH from 5 to 8, and
inoculation from 5 to 15 %. The highest hydrogen production with 1 % glucose
was 1.62 L
L
1
in the best condition.
(3) Mixed photosynthetic and dark fermentation hydrogen production
The substrates utilized by different kinds of microorganisms vary greatly. Dark
fermentation strains can utilize a variety of organic compounds, even some large
molecules, such as cellulose. The by-products include short-chain organic acids
generally, which cannot be further used by dark fermentation strains. These
organic acids decrease the pH value and reduce system stability. At the same
time, these short-chain organic acids happen to be suitable substrates for pho-
tosynthetic hydrogen-producing microorganisms. Therefore, coupling these two
methods together not only can increase hydrogen production but also can improve
the utilization of organic matter. The process has become a new direction in the
development for the biohydrogen production process.
Miyake et al. [
89
] immobilized
Clostridium butyricum
and
Rhodopseudomonas
sp
.
to produce hydrogen through glucose degradation; the yield was 7 mol H
2
mol
1
glucose. Yokoi et al. [
90
] used a mixed culture of
C. butyricum, Enterobacter
aerogenes,
and
Rhodobacter sphaeroides
to produce hydrogen from a sweet potato
