Effect of pH on glucose and starch fermentation in batch and sequenced-batch mode with a recently isolated strain of hydrogen-producing Clostridium butyricum … (original) (raw)
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World Journal of Microbiology and Biotechnology, 2005
Various medium components (carbon and nitrogen sources, iron, inoculum size) and environmental factors (initial pH and the agitation speed) were evaluated for their effects on the rate and the yield of hydrogen production by Clostridium saccharoperbutylacetonicum. Among the carbon sources assessed, cells grown on disaccharides (lactose, sucrose and maltose) produced on the average more than twice (2.81 mol-H 2 /mol sugar) as much hydrogen as monosaccharides (1.29 mol-H 2 /mol sugar), but there was no correlation between the carbon source and the production rate. The highest yield (2.83 mol/mol) was obtained in lactose and sucrose but the highest production rate (1.75 mmol/h) in sucrose. Using glucose as carbon source, yeast extract was the best nitrogen source. A parallel increase between the production rate and the yield was obtained by increasing glucose concentration up to 40 g/l (1.76 mol-H 2 /mol, 3.39 mmol/h), total nitrogen as yeast extract up to 0.1% (1.41 mol/mol, 1.91 mmol/h) and agitation up to 100 rev/min (1.66 mol-H 2 /mol, 1.86 mmol/h). On the other hand, higher production rates were favoured in preference to the yield at a neutral initial pH 7 (2.27 mmol/h), 1000 mg iron/l or more (1.99 mmol/h), and a larger inoculum size, 10%, (2.36 mmol/h) whereas an initial alkaline pH of 8.5 (1.72 mol/mol), a lower iron concentration of 25 mg/l (1.74 mol/mol) and smaller inoculum size, 1%, (1.85 mol/mol) promoted higher yield over production rate.
The present study reports hydrogen production potential by an alkaline-tolerant bacterium Clostridium butyricum strain TM-9A isolated from an estuarine river sediment sample and identified on the basis of 16S rRNA gene sequencing. Different process parameters such as initial pH, temperature and NaCl concentration affected the hydrogen production potential and growth of TM-9A strain in batch dark fermentation experiments. Glucose (10 g L -1 ) was used as substrate for an optimization study. TM-9A strain was able to tolerate up to 16 g L -1 of NaCl. Strain TM-9A produced maximum hydrogen, 57.8 mmol L -1 , at an initial pH 8 under mesophilic conditions, i.e. in the absence of NaCl. Acetic and butyric acid were the major soluble metabolites detected at 12.32 and 11.61 mmol L -1 , respectively. Hydrogen yield was 2.0-2.1 mol H 2 /mol glucose. Furthermore, the strain was also evaluated for its ability to utilize different carbohydrate-rich substrates like corn syrup (25.74 mmol L -1 ), molasses (23.44 mmol L -1 ) and starch (43.29 mmol L -1 ), sucrose (31.45 mmol L -1 ), and cellulose (4.16 mmol L -1 ), respectively for hydrogen production.
International Journal of Hydrogen Energy, 2012
A mesophilic alkaline tolerant fermentative microbe was isolated from estuarine sediment samples and designated as Clostridium butyricum TM-9A, based on 16S rRNA gene sequence. Batch experiments were conducted for investigation of TM-9A strain for its growth and hydrogen productivity from glucose, in an iron containing basal solution supplemented with yeast extract as organic nitrogen source. Hydrogen production started to evolve when cell growth entered exponential phase and reached maximum production rate at late exponential phase. Maximum hydrogen production was observed at 37 C, initial pH of 8.0 in the presence of 1% glucose. Optimization of process parameters resulted in increase in hydrogen yield from 1.64 to 2.67 mol of H 2 /mol glucose. Molar yield of H 2 increased further from 2.67 to 3.1 mol of H 2 /mol of glucose with the decrease in hydrogen partial pressure, obtained by lowering the total pressure in the head space of the batch reactor. Acetate and butyrate were the measure volatile fatty acids generated during hydrogen fermentation. TM-9A strain produced hydrogen efficiently from a range of pentose and hexose sugars including di-, tri and poly-saccharides like;
Journal of Environmental Sciences-china, 2009
The conversion of glucose to hydrogen was evaluated using continuous stirred tank reactor at pH 5.5 with various hydraulic retention times (HRT) at 30°C. Furthermore, the population dynamics of hydrogen-producing bacteria was surveyed by fluorescence in-situ hybridization using probe Clost IV targeting the genus Clostridium based on 16S rRNA. It was clear that positive correlation was observed between the cells quantified with probe Clost IV and hydrogen yield of the respective sludge. The numbers of hydrogenproducing bacteria were decreased gradually with increasing HRT, were 9.2 × 10 8 , 8.2 × 10 8 , 2.8 × 10 8 , and 6.2 × 10 7 cell/mL at HRT 6, 8, 12, and 14 h, respectively. The hydrogen yield was 1.4-1.5 mol H 2 /mol glucose at the optimum HRT range 6-8 h. It is considered that the percentage of the hydrogen-producing bacteria to total bacteria is useful parameter for evaluation of hydrogen production process.
Experimental Study of Bio-Hydrogen Production by Clostridium beijerinckii from Different Substrates
Energies
Glucose, alcohol stillage and glycerol were used as substrates for bio-hydrogen production by the newly isolated strain Clostridium beijerinckii 6A1 under batch conditions. High molar yields of hydrogen from the studied organic substrates were observed. There was a neat difference in the metabolic pathways of substrate digestion when hexose-based substrate or glycerol were used. The products of glycerol digestion showed that a pathway with no formic acid formation as intermediate was probable. In this case, considerable concentrations of acetic and propionic acid (up to 6 g dm−3) and small amounts of butanol were observed after 48 h. When glucose or hexose-based substrates were used, considerable amounts of formic acid (up to 6 g dm−3), i.e., the pathway proposed for Clostridia mixed cultures, were appropriate for the observed process of hydrogen release. For these substrates, considerable amounts of propionic acid in concentrations up to 1 g dm−3 were observed. That is why the path...
International Journal of Chemical Reactor Engineering, 2018
Comparing with other biological processes, a technological method associated with bio-energy has been developed as the result of the high possibility of fermentative hydrogen productivity; In addition, restricted fossil fuel has been also substituted. The production of fermentative hydrogen is a complicated process influenced by different factors including different kinds of micro-organisms, initial concentration of substrate, inoculum size, initial pH of the medium, concentration of nutrients metals, etc. Thus, the present study is aiming at detecting such different agents to obtain the highest yield of hydrogen and progressing its operation through improving the efficiency of these agents by reliable experimental design. Clostridium saccharoperbutylacetonicum N1-4(ATCC 13564) was applied to produce hydrogen in a batch manner. The highest yield of hydrogen has been resulted in 3.016 mol of hydrogen per mol glucose with production rate of 3.281 mole of hydrogen per hour at 37 °C, 10...