Consulta: creatorFacets:"Anastassiadis,Savas"
Registros recuperados: 4
Data/hora: 11/06/2024 12:42:11

Citric acid production from glucose by yeast Candida oleophila ATCC 20177 under batch, continuous and repeated batch cultivation
Provedor de dados: 69
Autores: Anastassiadis,Savas; Rehm,Hans-Jürgen.
The effect of air saturation on citric acid production in batch, repeated batch and chemostat cultures has been studied. It was shown that, under continuous fermentation (chemostat mode), the highest concentration of citric acid equal of 98 g/l was produced at 20% of air saturation. In contrary to continuous fermentation, displaying an optimum at 20%, 80% air saturation yielded higher values in repeated batch fermentation process. 167 g/l citric acid were produced continuously with the fill and drain technique at 4.85 days, at 80% air saturation, compared with 157.6 g/l achieved within 5.4 days at 20%. Under repeated batch fermentation, the formation rate of the generic product (Rj) as well as the specific citric acid productivity (m p) reached a maximum...
Tipo: Journal article
Palavras-chave: Air saturation influence; Chemostat; Citric acid; Citric acid fermentation; Repeated batch; Oxygen influence.
Ano: 2006
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000100005

Continuous gluconic acid production by Aureobasidium pullulans with and without biomass retention
Provedor de dados: 69
Autores: Anastassiadis,Savas; Rehm,Hans-Jürgen.
New alternative processes for the continuous production of gluconic acid by Aureobasidium pullulans, using biomass retention by cell immobilization or cross over filtration, are described in the present work. 315 g/l gluconic acid was continuously produced in chemostat cultures at 21 hrs residence time without any biomass retention. 260 g/l gluconic acid was produced in fluidized bed reactor at 21 hrs residence time. The support carrier was overgrown resulting in limitations of oxygen transfer towards the inner layers of immobilized biomass. 375 g/l gluconic acid was produced under continuous cultivation at 22 hrs of residence time with a formation rate for the generic product of 17 g/(l x h) and a specific gluconic acid productivity of only 0.74 g/(g x...
Tipo: Journal article
Palavras-chave: Biomass immobilization; Continuous fermentation; Cross over filtration; Gluconic acid fermentation; Reaction technique; Residence time.
Ano: 2006
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000500004

Oxygen and temperature effect on continuous citric acid secretion in Candida oleophila
Provedor de dados: 69
Autores: Anastassiadis,Savas; Rehm,Hans-Jürgen.
The influence of air saturation and temperature on continuous citric acid secretion was studied in chemostat cultures of Candida oleophila ATCC 20177 (var.). Simultaneous measurements of intra- and extracellular concentration of glucose, citric and isocitric acid confirmed the involvement of a specific active transport system in citrate secretion, favouring citric acid over isocitrate. An optimum air oxygen saturation of 20% and temperature of 30-31&amp;ordm;C were determined for the continuous citric acid secretion. The highest values of citric acid concentration (98 g/L), citrate to isocitrate ratio (33.3:1), volumetric citric productivity (1.8 g/(L x h)), and specific citric acid productivity (0.1 g/(g x h)), were reached at 20% air saturation at a...
Tipo: Journal article
Palavras-chave: Candida oleophila; Citric acid; Citric acid secretion.
Ano: 2006
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582006000400010

Continuous citric acid secretion by a high specific pH dependent active transport system in yeast Candida oleophila ATCC 20177
Provedor de dados: 69
Autores: Anastassiadis,Savas; Rehm,Hans-Jürgen.
The pH influence on continuous citric acid secretion was investigated in Candida oleophila ATCC 20177 (var.) under NH4+ limiting state steady conditions, using glucose. Highest citric acid concentration of 57.8 g/l, citrate/isocitrate ratio of 15.6, space-time yield of 0.96 g/(l x hr) and biomass specific productivity of 0.041 g/(g x hr) were obtained at pH 5 and 60 hrs residence time. Only 22.8 g/l (39.4%) and a ratio of 9.9 were achieved at pH 6 pH and 12.4 g/l (21.5%) and a ratio of 3.7 at pH 3. Under non producing conditions, in excess of nitrogen, biomass concentration increased at raising pH. An iron concentration of 200 ppm was determined in biomass of C. oleophila at pH 5, compared with only 26 ppm found at pH 3 (factor 7.7). Intra- and...
Tipo: Journal article
Palavras-chave: Active citrate export; Citric acid fermentation; Energy consuming citric acid secretion; Specific active transport system.
Ano: 2005
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582005000200004