A segmented gas/liquid delivery system for continuous culture of microorganisms on insoluble substrates and its use for growth of Ruminococcus flavefaciens on cellulose

Weimer, Paul J.; Shi, Yan; Odt, Christine L.

doi:10.1007/bf00164416

Cited by 101 publications

(94 citation statements)

References 16 publications

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“…Modified Dehority Medium (MDM), described previously (Weimer et al, 1991), included either Sigmacell 20 microcrystalline cellulose (4 g l − " ; Sigma) or cellobiose (4 g l − ") as carbon and energy source. All incubations were conducted anaerobically under CO # at 39 mC.…”

Section: Methodsmentioning

confidence: 99%

“…Batch cultures were conducted in 158 ml serum bottles (containing 100 ml medium), each fitted with a butyl stopper and an aluminium crimp seal. Continuous cultures were performed in a system described previously (Weimer et al, 1991). The cellulosecontaining medium in the reservoir was homogenized by stirring and diffusive gas sparging with CO # , and was delivered as a CO # -segmented slurry to a stirring fermenter (875 ml working volume) by a peristaltic pump.…”

Section: Methodsmentioning

confidence: 99%

“…Samples were analysed for pH using a Corning model 320 pH meter, residual soluble sugars by a phenol\sulfuric acid method (Dubois et al, 1956) and fermentation acids and ethanol by HPLC (Weimer et al, 1991). Concentrations of cellulose in the reactor or reservoir were measured by a modified neutral detergent fibre method (Weimer et al, 1990).…”

Section: Methodsmentioning

confidence: 99%

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Competition among three predominant ruminal cellulolytic bacteria in the absence or presence of non-cellulolytic bacteria

Chen

Weimer

2001

Microbiology

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Competition among three species of ruminal cellulolytic bacteria -Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD-1 and Ruminococcus albus 7 -was studied in the presence or absence of the non-cellulolytic ruminal bacteria Selenomonas ruminantium or Streptococcus bovis. Co-cultures were grown under either batch or continuous conditions and populations were estimated using species-specific oligonucleotide probes to 16S rRNA. The three cellulolytic species co-existed in cellobiose batch co-culture, but inclusion of either Sel. ruminantium or Str. bovis yielded nearly a monoculture of the noncellulolytic competitor. In cellobiose chemostats, R. albus completely dominated the triculture, but R. flavefaciens became predominant over F. succinogenes and R. albus when Sel. ruminantium was co-inoculated into the chemostats. Similar effects on competition were observed in the presence of Str. bovis at a lower (0021 h N1 ), but not at a higher (0045 h N1 ) dilution rate. In cellulose batch co-cultures, R. albus was more abundant than both F. succinogenes and R. flavefaciens, regardless of the presence of the noncellulolytic species. Co-existence among the three cellulolytic species was observed in almost all cellulose chemostats, but Sel. ruminantium altered the relative proportions of the cellulolytic species. R. albus and R. flavefaciens were found to produce inhibitors that suppressed growth of R. flavefaciens and F. succinogenes, respectively. These data indicate that interactions among cellulolytic bacteria, while complex, can be modified further by non-cellulolytic species.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Competition among three predominant ruminal cellulolytic bacteria in the absence or presence of non-cellulolytic bacteria

Chen

Weimer

2001

Microbiology

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“…Batch cultures were prepared as previously described (Desvaux et al, 2000). The chemostat system used was a segmented gas-liquid continuous culture device as described by Weimer et al (1991b) with some modifications (Desvaux et al, 2001). The cultures were maintained for a period of eight to nine residence times (Desvaux et al, 2001) ; for each condition the data were the mean of at least three samples.…”

Section: Methodsmentioning

confidence: 99%

Metabolic flux in cellulose batch and cellulose-fed continuous cultures of Clostridium cellulolyticum in response to acidic environment

2001

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Clostridium cellulolyticum, a nonruminal cellulolytic mesophilic bacterium, was grown in batch and continuous cultures on cellulose using a chemically defined medium. In batch culture with unregulated pH, less cellulose degradation and higher accumulation of soluble glucides were obtained compared to a culture with the pH controlled at 72. The gain in cellulose degradation achieved with pH control was offset by catabolite production rather than soluble sugar accumulation. The pH-controlled condition improved biomass, ethanol and acetate production, whereas maximum lactate and extracellular pyruvate concentrations were lower than in the non-pH-controlled condition. In a cellulose-fed chemostat at constant dilution rate and pH values ranging from 74 to 62, maximum cell density was obtained at pH 70. Environmental acidification chiefly influenced biomass formation, since at pH 64 the dry weight of cells was more than fourfold lower compared to that at pH 70, whereas the specific rate of cellulose assimilation decreased only from 1174 to 1013 milliequivalents of carbon (g cells) N1 h N1 . The molar growth yield and the energetic growth yield did not decline as pH was lowered, and an abrupt transition to washout was observed. Decreasing the pH induced a shift from an acetate-ethanol fermentation to a lactate-ethanol fermentation. The acetate/ethanol ratio decreased as the pH declined, reaching close to 1 at pH 64. Whatever the pH conditions, lactate dehydrogenase was always greatly in excess. As pH decreased, both the biosynthesis and the catabolic efficiency of the pyruvate-ferredoxin oxidoreductase declined, as indicated by the ratio of the specific enzyme activity to the specific metabolic rate, which fell from 98 to 18. Thus a change of only 1 pH unit induced considerable metabolic change and ended by washout at around pH 62. C. cellulolyticum appeared to be similar to rumen cellulolytic bacteria in its sensitivity to acidic conditions. Apparently, the cellulolytic anaerobes studied thus far do not thrive when the pH drops below 60, suggesting that they evolved in environments where acid tolerance was not required for successful competition with other microbes.

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“…Several methods have been developed for measurement of the amount of biomass and enzymes involving analysis of total proteins [12,13] nitrogen [14], phospholipids [15], and DNA [16].…”

Section: Introductionmentioning

confidence: 99%

Effects of Dilute Acid Pretreatment on Enzyme Adsorption and Surface Morphology of Liriodendron tulipifera

Min¹,

Koo²,

Gwak³

et al. 2011

Journal of the Korean Wood Science and Technology

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A segmented gas/liquid delivery system for continuous culture of microorganisms on insoluble substrates and its use for growth of Ruminococcus flavefaciens on cellulose

Cited by 101 publications

References 16 publications

Competition among three predominant ruminal cellulolytic bacteria in the absence or presence of non-cellulolytic bacteria

Competition among three predominant ruminal cellulolytic bacteria in the absence or presence of non-cellulolytic bacteria

Metabolic flux in cellulose batch and cellulose-fed continuous cultures of Clostridium cellulolyticum in response to acidic environment

Effects of Dilute Acid Pretreatment on Enzyme Adsorption and Surface Morphology of Liriodendron tulipifera

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