| energy conservation associated with ethanol formation from h2 and co2 in clostridium autoethanogenum involving electron bifurcation. | most acetogens can reduce co2 with h2 to acetic acid via the wood-ljungdahl pathway, in which the atp required for formate activation is regenerated in the acetate kinase reaction. however, a few acetogens, such as clostridium autoethanogenum, clostridium ljungdahlii, and clostridium ragsdalei, also form large amounts of ethanol from co2 and h2. how these anaerobes with a growth ph optimum near 5 conserve energy has remained elusive. we investigated this question by determining the specific acti ... | 2015 | 26148714 |
| optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by clostridium ragsdalei. | fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. the effects of various medium components on ethanol production by clostridium ragsdalei utilizing syngas components (co:co(2)) were investigated, and corn steep liquor (csl) was used as an inexpensive nutrient source for ethanol production by c. ragsdalei. elimination of mg(2+), nh(4) (+) and po(4) (3-) decreased ethanol produ ... | 2012 | 22805937 |
| reduction of acetone to isopropanol using producer gas fermenting microbes. | gasification-fermentation is an emerging technology for the conversion of lignocellulosic materials into biofuels and specialty chemicals. for effective utilization of producer gas by fermenting bacteria, tar compounds produced in the gasification process are often removed by wet scrubbing techniques using acetone. in a preliminary study using biomass generated producer gas scrubbed with acetone, an accumulation of acetone and subsequent isopropanol production was observed. the effect of 2 g/l a ... | 2011 | 21557204 |
| effect of nutrient limitation and two-stage continuous fermentor design on productivities during "clostridium ragsdalei" syngas fermentation. | the effect of three limiting nutrients, calcium pantothenate, vitamin b(12) and cobalt chloride (cocl(2)), on syngas fermentation using "clostridium ragsdalei" was determined using serum bottle fermentation studies. significant results from the bottle studies were translated into single- and two-stage continuous fermentor designs. studies indicated that three-way interactions between the three limiting nutrients, and two-way interactions between vitamin b(12) and cocl(2) had a significant positi ... | 2011 | 21470855 |
| effect of temperature, ph and buffer presence on ethanol production from synthesis gas by "clostridium ragsdalei". | fermentation ph, incubation temperature, and presence or absence of media buffer can alter the activity of microorganisms. for instance, carbon monoxide and hydrogen components of syngas show decreased solubility with increasing temperature, clostridium species preferentially switch from acetogenesis to solventogenesis phase at ph below 5.0, and morpholinoethanesulfonic acid (mes) added as media buffer has been shown to increase lag time for ethanol production. the objective of the present study ... | 2011 | 21377362 |
| effect of trace metals on ethanol production from synthesis gas by the ethanologenic acetogen, clostridium ragsdalei. | the effect of trace metal ions (co²+, cu²+, fe²+, mn²+, mo⁶+, ni²+, zn²+, seo₄⁻ and wo₄⁻) on growth and ethanol production by an ethanologenic acetogen, clostridium ragsdalei was investigated in co:co₂-grown cells. a standard acetogen medium (atcc medium no. 1754) was manipulated by varying the concentrations of trace metals in the media. increasing the individual concentrations of ni²+, zn²+, seo₄⁻ and wo₄⁻ from 0.84, 6.96, 1.06, and 0.68 μm in the standard trace metals solution to 8.4, 34.8, 5 ... | 2011 | 20694853 |
| development of low cost medium for ethanol production from syngas by clostridium ragsdalei. | the development of a low cost medium for ethanol production is critical for process feasibility. ten media were formulated for clostridium ragsdalei by reduction, elimination and replacement of expensive nutrients. cost analysis and effects of medium components on growth and product formation were investigated. fermentations were performed in 250 ml bottles using syngas (20% co, 15% co2, 5% h2 and 60% n2). the standard medium m1 cost is $9.83/l, of which 93% is attributed to morpholinoethane sul ... | 2013 | 24012846 |
| improved conversion efficiencies for n-fatty acid reduction to primary alcohols by the solventogenic acetogen "clostridium ragsdalei". | "clostridium ragsdalei" is an acetogen that ferments synthesis gas (syngas, predominantly h2:co2:co) to ethanol, acetate, and cell mass. previous research showed that c. ragsdalei could also convert propionic acid to 1-propanol and butyric acid to 1-butanol at conversion efficiencies of 72.3 and 21.0 percent, respectively. our research showed that c. ragsdalei can also reduce pentanoic and hexanoic acid to the corresponding primary alcohols. this reduction occurred independently of growth in an ... | 2015 | 25410829 |
| ethanol production during semi-continuous syngas fermentation in a trickle bed reactor using clostridium ragsdalei. | an efficient syngas fermentation bioreactor provides a mass transfer capability that matches the intrinsic kinetics of the microorganism to obtain high gas conversion efficiency and productivity. in this study, mass transfer and gas utilization efficiencies of a trickle bed reactor during syngas fermentation by clostridium ragsdalei were evaluated at various gas and liquid flow rates. fermentations were performed using a syngas mixture of 38% co, 28.5% co2, 28.5% h2 and 5% n2, by volume. results ... | 2016 | 26950756 |
| enhanced ethanol production by clostridium ragsdalei from syngas by incorporating biochar in the fermentation medium. | biochar contains minerals and metals that can serve as nutrients for acetogens to produce ethanol via syngas fermentation. in this study, four fermentation media containing biochar from switchgrass (sgbc), forage sorghum (fsbc), red cedar (rcbc) and poultry litter (plbc) were compared with standard yeast extract (ye) medium for syngas fermentation using clostridium ragsdalei. fermentations were performed in 250ml bottle reactors at 150rpm and 37°c with syngas containing co:h2:co2 (40:30:30) by v ... | 2018 | 28950138 |
| biocatalytic reduction of short-chain carboxylic acids into their corresponding alcohols with syngas fermentation. | short-chain carboxylic acids generated by various mixed- or pure-culture fermentation processes have been considered valuable precursors for production of bioalcohols. while conversion of carboxylic acids into alcohols is routinely performed with catalytic hydrogenation or with strong chemical reducing agents, here, a biological conversion route was explored. the potential of carboxydotrophic bacteria, such as clostridium ljungdahlii and clostridium ragsdalei, as biocatalysts for conversion of s ... | 2013 | 23172270 |