Effect of fermentation temperature on hydrogen production from xylose and the succession of hydrogen‐producing microflora

Abstract

BACKGROUND Hydrogen production through anaerobic dark fermentation is considered to be a potential biological process for xylose utilization. Temperature is one of the most important environmental factors, however, most studies have been carried out over a small temperature range. Batch tests were carried out to investigate the temperature effect on hydrogen production from xylose using a mixed culture over a wide temperature range (35–65°C). Hydrogen production, metabolite distribution and dynamics of microbial communities were investigated. RESULTS Hydrogen‐producing cultures were successfully enriched at each tested temperature. Two peaks of fermentation temperature for hydrogen production were observed at 35 and 55°C (1.11 and 1.30 mol‐H2 mol−1‐xyloseconsumed, respectively). Butyrate and acetate were the major liquid metabolites at 35–60°C. While at 65°C the main by‐product was ethanol. Polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) analysis indicated that Clostridium species were dominant at 35–40°C, while Thermoanaerobacterium dominated at 45–60°C. Both species were found at 65°C, but with lowest microbial community diversity. CONCLUSION Hydrogen production efficiency was mainly affected by the liquid metabolite distributions, which depended mainly upon the temperature. Several microbial community structures were formed at mesophilic, transition, thermophilic and extreme‐thermophilic conditions, resulting in different metabolic pathways of xylose and hydrogen production capacity. © 2017 Society of Chemical Industry

Optimization of Batch Dark Fermentation of Chlorella sp. Using Mixed-Cultures for Simultaneous Hydrogen and Butyric Acid Production

“…Two operating temperatures, mesophilic temperature (35 • C) and thermophilic temperature (55 • C), were employed for fermentative hydrogen production under acidogenic anaerobic dark fermentation in batch mode. Temperature is an essential factor for microbial biodegradation to produce hydrogen and VFAs [43,44]. As demonstrated in Figure 3, at initial pH 7, hydrogen production yields obtained from Chlorella sp.…”

“…Thus, the production of hydrogen depends on the microbes used as inoculum. In our research, as the anaerobic sludge used as inoculum was taken from mesophilic operation conditions, operating at higher thermophilic temperature could lead to some of the microorganisms being inhibited, resulting in decreased microbial community diversity and consequently reduced hydrogen productivity [43,45]. Two operating temperatures, mesophilic temperature (35 • C) and thermophilic temperature (55 • C), were employed for fermentative hydrogen production under acidogenic anaerobic dark fermentation in batch mode.…”

“…Although the inoculum was brought from the mesophilic condition, in a mixed culture, some bacteria can grow at high temperatures, in accordance with the research of Stein et al [12] and De la Rubia et al [26] who used inoculum from a mesophilic condition for fermentation at thermophilic or even hyperthermophilic temperature. However, Qui et al [43] studied the effect of temperature, finding that the mesophilic range of 35-40 • C yielded higher hydrogen production. They used active sludge from sewage treatment plant and the mesophilic range was familiar for microbes.…”

Impacts of short-term temperature fluctuations on biohydrogen production and resilience of thermophilic microbial communities

“…Studies on anaerobic biological processes have shown that even small changes in the operating temperature can cause significant changes in microbial community composition and H2 yields [14,19,20]. Temporal temperature fluctuations can also lead to changes in the enzymatic activities, growth rates and/or loss of microbial diversity, which directly affect H2 production [21].…”

Study on the hydrogen production ability of high-efficiency bacteria and synergistic fermentation of maize straw by a combination of strains

“…Noike and Mizuno 10 intermittently produced hydrogen by using rice husk with 1.73 mol H 2 /mol hexose, 2.54 mol H 2 /mol hexose, and rice shell with 1.29 mol H 2 /mol hexose. Qiu 11 conducted a batch test to study the effect of temperature on the hydrogen production of xylose using a mixed culture over a wide temperature range. The results showed that several microbial community structures were formed under different temperature conditions, resulting in different metabolic pathways for xylose and hydrogen production capacity.…”