Effects of Dilute Acid-intensified Hydrolysis on Fermentative Biohydrogen Production Capacity of Maize Stalk

[Objective] This study was to explore the effects of dilute acid hydrolysis on fermentative biohydrogen production capacity of maize stalk. [Method] Using maize stalks subjected to mechanical disintegration,steam explosion and dilute acid hydrolysis as experimental materials,we measured and analyzed the effects of different treatments and particle size of maize stalk were analyzed. [Result] The optimal fermentative biohydrogen production was found under following parameters：pretreatment of 0.8% dilute H2SO4 following steam explosion,particle size of maize stalk of 0.425-0.850 mm,liquid-solid ratio [0.8% H2SO4 （M）：stalk （W）] of 10：1. [Conclusion] Post steam explosion,dilute 0.8% dilute H2SO4 intensified hydrolysis on maize stalk could produce fermentative biohydrogen production capacity.

Characterization and phylogenetics of a new species of genus Lactobacillus from the activated sludge in biohydrogen production

Anaerobic process of biohydrogen production was developed. There is a great deal of Lactobacillus bacteria in the activated sludge of biohydrogen reactor. The isolation and identification of different anaerobic bacteria in the reactor is important for fermented biohydrogen production process by anaerobic digesting organic wastewater. Considering with the physiological and biochemical traits,morphological characteristics and 16SrDNA sequence,the isolated Rennanqilyf13 is a new species in Lactobacillus genus. And the temporary nomenclature of the species is Lactobacillus Strain Rennanqilyf13 sp. nov.

Fermentative Biohydrogen Production with Enteric Bacteria Isolated from the Intestine of Wild Common Carp Dwelling in Tarim River Basin

The biological hydrogen generating from fermentation of low-cost lignocellulosic feedstocks by hydrogen-producing bacteria has attracted many attentions in recent years. In the present investigation, ten hydrogen-producing bacteria were newly isolated from the intestine of wild common carp (Cyprinus carpio L.), and identified belonging to the genera of Enterobacter and Klebsiella based on analysis of the 16S rDNA gene sequence and examination of the physiological and biochemical characteristics. All the isolates inherently owned the ability to metabolize xylose especially the cotton stalk hydrolysate for hydrogen production with hydrogen yield (HY) higher than 100 mL·L-1. In particular, two isolates, WL1306 and WL1305 obtained higher HY, hydrogen production rate (HPR), and hydrogen production potential (HPP) using cotton stalk hydrolysate as sugar substrate than the mixed sugar of glucose & xylose, which obtained the HY of 249.5 ± 29.0, 397.0 ± 36.7 mL·L-1, HPR of 10.4 ± 1.2, 16.5 ± 1.5 mL·L-1·h-1, HPP of 19.5 ± 2.3, 31.0 ± 2.8 mL·L-1·g-1sugar, separately. The generation of soluble metabolites, such as the lactate, formate, acetate, succinate and ethanol reflected the mixed acid fermentation properties of the hydrogen production pathway.

Monitoring of microbial community structure and succession in the biohydrogen production reactor by denaturing gradient gel electrophoresis(DGGE)

To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous stirred tank reactor(CSTR)in different periods of time,and the diversity and dynamics of microbial communities were investigated by denaturing gra-dient gel electrophoresis(DGGE).The results of DGGE demonstrated that an obvious shift of microbial population happened from the beginning of star-up to the 28th day,and the ethanol type fermentation was established.After 28 days the structure of microbial community became stable,and the climax community was formed.Comparative analysis of 16S rDNA sequences from reamplifying and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria(Clostridium sp.and Ethanologenbacterium sp.),β-proteobacteria(Acidovorax sp.),γ-proteobacteria(Kluyvera sp.),Bacteroides(uncultured bacte-rium SJA-168),and Spirochaetes(uncultured eubacterium E1-K13),respectively.The hydrogen production rate increased obviously with the increase of Ethanologenbacterium sp.,Clostridium sp.and uncultured Spirochaetes after 21 days,meanwhile the succession of ethanol type fer-mentation was formed.Throughout the succession the microbial diversity increased however it decreased after 21 days.Some types of Clostridium sp.Acidovorax sp.,Kluyvera sp.,and Bac-teroides were dominant populations during all periods of time.These special populations were essential for the construction of climax community.Hydrogen production efficiency was de-pendent on both hydrogen producing bacteria and other populations.It implied that the co-metabolism of microbial community played a great role of biohydrogen production in the reactors.

Pore-scale lattice Boltzmann simulation of flow and mass transfer in bioreactor with an immobilized granule for biohydrogen production

The photo bioreaction combined with flow and mass transfer is simulated with pore-scale lattice Boltzmann （LB） method, which is the scenario of a bioreactor filled with a porous granule immobilized photosynthetic bacteria cells for hydrogen production. The quartet structure generation set （QSGS） is used to generate porous structure of the immobilized granule. The effects of porosity of the immobilized granule on flow and concentration fields as well as the hydrogen production performance are investi- gated. Higher porosity facilitates the substrate solution smoothly flowing through the porous granule with increasing velocity, and thus results in higher product concentration inside the immobilized gran- ule. Additionally, the substrate consumption efficiency increases, while hydrogen yield slightly decreases with increasing porosity, and they tend to stable for the porosity larger than 0.5. Furthermore, the LB numerical results have a good agreement with the experimental results. It is demonstrated that the pore-scale LB simulation method coupling with QSGS is available to simulate the photo hydrogen produc- tion in the hioreactor with porous immobilized granules.

The start-up of biohydrogen-producing process by bioaugmentation in the EGSB reactor

Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 - 24d） seeded with activated sludge, the butyric acid type-fermentation formed when the initial expanding rate, organic loading rate （OLR）, the initial redox potential （ORP） and hydraulic retention time （HRT） were 10%, 10.0 kg COD/（m^3·d）, -215 mV and 6.7 h, respectively. At the beginning of the second stage on day 25, the novel hydrogen-producing fermentative bacterial strain B49 （AF481148 in EMBL） were inoculated into the reactor under the condition of OLR 16. 0 kg COD/（m^3·d）, ORP and HRT about - 139 mV and 6.7 h, respectively, and then the reaction system transformed to ethanol-type fermentation gradually with the increase in OLR. When OLR, ORP and HRT were about 94.3 kg COD/（m^3·d）, -250 mV and 1.7 h, respectively, the system achieved the maximum hydrogen-producing rate of 282.6 mL H2/L reactor·h and hydrogen percentage of 51% -53% in the biogas.

The molecular biological characterization of a strain of biohydrogen-producing anaerobe in Clostridium Genus

The anaerobic process of biohydrogen production was developed recently. The isolation and identification of biohydrogen producing anaerobic bacteria with high evolution rate and yield is an important foundation of the fermented biohydrogen production process through which anaerobic bacteria digest organic wastewater. By considering physiological and biochemical traits, morphological characteristics and a 16S rDNA sequence, the isolated Rennanqilyf33 is shown to be a new species.

Hydrogen producting characteristics by a novel strain of bacteria-ethanoligenens sp. B49

The objective of this work is to investigate the fermentation capacity and metabolic characteristics of a novel strain of bacteria B49 isolated from anaerobic activated sludge. The examination was conducted in batch culture at 35 ℃. The results showed that the carbon flow gave priority to the production of ethanol, and yield of ethanol is always greater than that of acetic acid. The hydrogen and ethanol occurred simultaneously. The exponential phase of the B49's cell growth was from 12 to 22 h. Evolution of hydrogen appeared to start after the exponential phase of cell growth and reach maximum production at the early stationary phase. The rate of hydrogen production reached a maximum of 16.8 mL/h, and the percentage of hydrogen gas in the headspace of serum bottle obtained a maximum of 41 % at 22 h. The B49 was able to grow using molasses as substrate for cell growth. When the molasses was used as substrate, maximum yield of hydrogen was obtained 2460 mL/L culture at 2 % (V/V) of molasses. The hydrogen yield was increased to 3060 mL/L culture after addition of 0.5 g/L of yeast extract in the molasses medium and the yield of hydrogen was increased by 24.4%.

Length polymorphisms for intergenic spacer regions of 16S-23S rDNA in members of the new hydrogen-producing bacteria

A method based on PCR amplification of the 16S rRNA gene (rDNA)-23S rDNA intergenic spacer regions (ISR) was developed for the identification of species within the novel group hydrogen-producing anaerobes. The sizes of the PCR products varied from 1264 to 398 bp. Strain of isolate Rennanqilyf 3 was characterized as having products of 1262,398,638,437 and 436 bp. The isolate Rennanqilyf 1 had product of 1264 bp. The isolate Rennanqilyf 13 had products of 1261,579 and 485 bp. Of the 3 species of the novel group hydrogen-producing anaerobes examined, no one was indistinguishable. Two environmental isolates were identified as hydrogen-producing bacteria, which were new species in present taxon. Rennanqilyf 3 could not be associated with any Clostridium sp. studied. Rennanqilyf 1 could be classified into Clostridium genus. The combination between 16S rDNA equencing and length polymorphisms of IRS in 16S-23S rDNA is a better method for determining species of the hydrogen-producing bacteria.

The scope for manipulating the polyunsaturated fatty acid content of beef:a review

Since 1950, links between intake of saturated fatty acids and heart disease have led to recommendations to limit consumption of saturated fatty acid-rich foods, including beef. Over this time, changes in food consumption patterns in several countries including Canada and the USA have not led to improvements in health. Instead, the incidence of obesity, type II diabetes and associated diseases have reached epidemic proportions owing in part to replacement of dietary fat with refined carbohydrates. Despite the content of saturated fatty acids in beef, it is also rich in heart healthy cis-monounsaturated fatty acids, and can be an important source of long-chain omega-3（n-3） fatty acids in populations where little or no oily fish is consumed. Beef also contains polyunsaturated fatty acid biohydrogenation products,including vaccenic and rumenic acids, which have been shown to have anticarcinogenic and hypolipidemic properties in cell culture and animal models. Beef can be enriched with these beneficial fatty acids through manipulation of beef cattle diets, which is now more important than ever because of increasing public understanding of the relationships between diet and health. The present review examines recommendations for beef in human diets, the need to recognize the complex nature of beef fat, how cattle diets and management can alter the fatty acid composition of beef, and to what extent content claims are currently possible for beef fatty acids.

Optimization of hydrogen production from agricultural wastes using mixture design

Hydrogen production from food waste,cattle manure,potato pulp and pig manure was optimized through using mixture design in this study.The synergic and antagonistic effects of the four substrates on hydrogen yield,substrate conversion efficiency and pH were evaluated.The results showed that the optimal proportion of food waste,cattle manure,potato pulp and pig manure were 61.6%,38.4%,0,and 0,respectively.Under the optimal condition,hydrogen yield of 21.0 mL/g VS with VS reduction of 29.4%and pH of 5 could be obtained.The interaction between food waste and cattle manure had strongest synergistic effects.Hydrogen was mainly produced by acetic-butyric metabolic pathway,and ammonification of protein played an important role in the maintenance of pH.

Effect of illumination on the hydrogen-production capability of anaerobic activated sludge

To investigate the influence of illumination on the fermentative hydrogen production system, the hydro- gen production efficiencies of two kinds of anaerobic activated sludge （floc and granule） from an anaerobic baffled reactor were detected under visible light, dark and light-dark, respectively. The 10 mL floc sludge or granular sludge was respectively inoculated to 100 mL diluted molasses （chemical oxygen demand of 8000 mg.L^-1） in a 250 mL serum bottle, and cultured for 24 h at 37℃ under different illumination conditions. The results showed that the floc was more sensitive to illumination than the granule. A hydrogen yield of 19.8 mL was obtained in the dark with a specific hydrogen production rate of 3.52mol.kgLMLVSS.d^-1 （floc）, which was the highest among the three illumination conditions. Under dark condition, the hydrogen yield of floc sludge reached the highest with the specific hydrogen production rate of 3.52mol.kg^-1MLVSS.d^-1, and under light-dark, light, the specific hydrogen production rate was 3.11 and 2.21mol.kg^-1 MLVSS.d-1, respectively. The results demonstrated that the illumination may affect the dehydrogenase activity of sludge as well as the activity of hydrogen-producing acetogens and then impact hydrogen production capacity.