Effect of pulp pH on solid phase fermentation of fodder beets for fuel ethanol production

Gibbons, William R.; Westby, Carl A.

doi:10.1007/bf01025977

Cited by 18 publications

(10 citation statements)

References 8 publications

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“…Similarly, viable counts showed corresponding cell densities of between 42 × 10 15 and 98 × 10 16 (CFU/mL) at a p -value of 0.05. The inoculum cell density of Actinobacteria and the nutrient ratio is expected to be at an optimum for the lag phase (cell replicating accessories) and log phase (cell multiplication and metabolism) of growth to maximize the organisms’ potentials, especially if products of interest are produced at the log phase [19,20]. Consequently, a starter cell density of 3 × 10 8 CFU/mL resulted in better flocculation activity, hence; it was used as the optimum inoculum cell density.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of an Exopolymeric Flocculant Produced by a Brachybacterium sp.

et al. 2013

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We evaluated the bioflocculant production potential of an Actinobacteria, which was isolated from a freshwater environment in the Eastern Cape province of South Africa. 16S rDNA nucleotide sequencing analyses revealed that the actinobacteria belongs to the Brachybacterium genus, and the sequences were deposited in the GenBank as Brachybacterium sp. UFH, with accession number HQ537131. Optimum fermentation conditions for bioflocculant production by the bacteria include an initial medium pH of 7.2, incubation temperature of 30 °C, agitation speed of 160 rpm and an inoculum size of 2% (vol/vol) of cell density 3.0 × 108 CFU/mL. The carbon, nitrogen and cation sources for optimum bioflocculant production were maltose (83% flocculating activity), urea (91.17% flocculating activity) and MgCl2 (91.16% flocculating activity). Optimum bioflocculant production coincided with the logarithmic growth phase of the bacteria, and chemical analyses of the bioflocculant showed 39.4% carbohydrate and 43.7% protein (wt/wt). The mass ratio of neutral sugar, amino sugar and uronic acids was 1.3:0.7:2.2. Fourier transform infrared spectroscopy (FTIR) indicated the presence of carboxyl, hydroxyl and amino groups, amongst others, typical for heteropolysaccharide and glycosaminoglycan polysaccharides. Bioflocculant pyrolysis showed thermal stability at over 600 °C, while scanning electron microscope (SEM) imaging revealed a maze-like structure of interlaced flakes. Its high flocculation activity suggests its suitability for industrial applicability.

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Section: Resultsmentioning

confidence: 99%

“…A set of 500 mL Erlenmeyer flasks containing 200 mL fermentation medium (MSM) were aseptically inoculated with 2% (4 mL) of the activated culture, adjusted to a cell density of about 1.5 × 10 8 CFU/mL [19,20,29]. The culture was incubated at a temperature of 28 °C in a shaker incubator for 72 h at 140 rpm.…”

Section: Methodsmentioning

confidence: 99%

Characterization of an Exopolymeric Flocculant Produced by a Brachybacterium sp.

et al. 2013

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“…Mullins and NeSmith as well as Gibbons and Westby similarly demonstrated the phenomenon of culture to nutrient ratio optimization in the production of ethanol [15,16]. …”

Section: Resultsmentioning

confidence: 99%

“…A set of 500 mL flasks containing 200 mL fermentation medium (BSM) were aseptically inoculated with activated culture, by transferring 2% (4 mL) of the culture [15,16], adjusted to cell density of about 1.5 × 10 8 cfu/mL [31] and incubating at a temperature of 28 °C for 72 h at140 rpm. After the incubation period, the fermentation broth was centrifuged (3000 rpm, 30 min, 15 °C) to separate the bacterial cells and the cell-free supernatant was assessed for flocculation activity.…”

Section: Methodsmentioning

confidence: 99%

A Freshwater Streptomyces, Isolated from Tyume River, Produces a Predominantly Extracellular Glycoprotein Bioflocculant

Nwodo

Agunbiade

Green

et al. 2012

IJMS

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We evaluated bioflocculant production by a freshwater actinobacteria whose 16S rDNA nucleotide sequence was deposited in GenBank as Streptomyces sp. Gansen (accession number HQ537129). Optimum culture conditions for bioflocculant production were an initial medium pH of 6.8, incubation temperature of 30 °C, agitation speed of 160 rpm and an inoculum size of 2% (v/v) of cell density 1.5 × 10 8 cfu/mL. The carbon, nitrogen and cation sources for optimum bioflocculant production were glucose (89% flocculating activity), ammonium sulfate (76% flocculating activity) and MgCl 2 . Bioflocculant pyrolysis showed three step decomposition indicative of three components while chemical analyses showed 78% carbohydrate and 22% protein (wt/wt). The mass ratio of neutral sugar, amino sugar and uronic acids was 4.6:2.4:3. FTIR spectrometry indicated the presence of carboxyl, hydroxyl and amino groups, typical for heteropolysaccharide. The bioflocculant showed a lattice structure as seen by SEM imaging. Its high flocculation activity suggests its suitability for industrial applicability.

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“…Eight Saccharomyces yeast strains were chosen that were isolated from distillery operations or otherwise recommended for lignocellulosic fermentations (Table 1) [6,7,15,16,18,23,24,35]. Additionally, the haploid laboratory strain, CEN.PK2-1C was included as a control.…”

Section: Chromosomal Integration and Xylose Metabolismmentioning

confidence: 99%

Engineering industrial Saccharomyces cerevisiae strains for xylose fermentation and comparison for switchgrass conversion

Hector

Dien

Cotta

et al. 2010

J Ind Microbiol Biotechnol

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Saccharomyces' physiology and fermentation-related properties vary broadly among industrial strains used to ferment glucose. How genetic background affects xylose metabolism in recombinant Saccharomyces strains has not been adequately explored. In this study, six industrial strains of varied genetic background were engineered to ferment xylose by stable integration of the xylose reductase, xylitol dehydrogenase, and xylulokinase genes. Aerobic growth rates on xylose were 0.04-0.17 h(-1). Fermentation of xylose and glucose/xylose mixtures also showed a wide range of performance between strains. During xylose fermentation, xylose consumption rates were 0.17-0.31 g/l/h, with ethanol yields 0.18-0.27 g/g. Yields of ethanol and the metabolite xylitol were positively correlated, indicating that all of the strains had downstream limitations to xylose metabolism. The better-performing engineered and parental strains were compared for conversion of alkaline pretreated switchgrass to ethanol. The engineered strains produced 13-17% more ethanol than the parental control strains because of their ability to ferment xylose.

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Effect of pulp pH on solid phase fermentation of fodder beets for fuel ethanol production

Cited by 18 publications

References 8 publications

Characterization of an Exopolymeric Flocculant Produced by a Brachybacterium sp.

Characterization of an Exopolymeric Flocculant Produced by a Brachybacterium sp.

A Freshwater Streptomyces, Isolated from Tyume River, Produces a Predominantly Extracellular Glycoprotein Bioflocculant

Engineering industrial Saccharomyces cerevisiae strains for xylose fermentation and comparison for switchgrass conversion

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