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At least 181 records · Page 10Linked to original sources
PubMed2003

[Biodegradable plastic production by activated sludge with different carbon sources].

Polyhydroxyalkanoates(PHAs) are polyesters synthesized by numerous bacteria in sludge as intracellular carbon and energy storage compounds under the condition of unbalance growth. Another important aspect of PHAs is thermoplastic polyester with the remarkable characteristics of biodegradability. In this paper, using sodium acetate, sodium propionate and sodium butyrate as the unique carbon source, 5.58%, 3.90% and 4.98% PHAs of dry sludge weight were obtained by assimilated sludge as PHAs synthesis strains in the anaerobic condition, and 12.32%, 9.55% and 11.35% PHAs of dry sludge weight were obtained in the anaerobic condition. It was shown that there were large quantities strains which could accumulate PHAs as granules in the cytoplasm of cells, and the yield of PHAs in the anaerobic process were higher than that in the aerobic process. The best result was that 12.32% PHAs of dry sludge weight was obtained in the best experiment condition, and the yield of the PHAs to substrate was 30.65%. The structures of PHAs were analyzed by 1HNMR spectrum, and the relationship of the structure of PHAs and the carbon source was explained.

Biodegradation, Environmental↗
PubMedDate not supplied

Utilization of an alternative carbon source for efficient production of human alpha(1)-antitrypsin by genetically engineered rice cell culture.

Human alpha(1)-antitrypsin was produced by genetically engineered rice cells using promoter and signal peptide of a rice alpha-amylase isozyme. Batch and continuous cultures were employed to investigate the effects of alternative carbon sources on the alpha(1)-antitrypsin production. While this expression system is inducible by sugar depletion, we have found that the productivity of alpha(1)-antitrypsin increased 2.4- to 3.4-fold, compared with the control medium without carbon source, in medium containing an alternative carbon source, such as pyruvic acid and glyoxylic acid. The accumulated alpha(1)-antitrypsin in the medium containing pyruvic acid reached 18.2-24.2 mg/g-dry cell in 50-70 h by batch culture.

Carbon↗
PubMed1999

Biosynthesis of poly-beta-hydroxybutyrate and exopolysaccharides on Azotobacter chroococcum strain 6B utilizing simple and complex carbon sources.

Coproduction of poly-beta-hydroxybutyrate (PHB) and exopolysaccharides (EPS) was investigated with Azotobacter chroococcum strain 6B isolated from soil samples. The bacterium was cultured using various carbon sources solely or with 0.1 g/L of ammonium sulfate. Ammonium addition resulted in reduced PHB and EPS production with glucose, fructose, and sucrose media, but cellular mass remained constant except for sucrose. Protein was nearly twofold higher in ammonium-grown cultures. Glucose and fructose alone biosynthesized high amounts of EPS (maximum 2.1 and 1.1 g/L, respectively, at 72 h), whereas PHB was accumulated only in glucose-grown cells. Sucrose almost did not produce EPS. Conversely, PHB content was the highest obtained from all experimented conditions (1.1 g/L at 48 h, 40% cell dry wt). When a complex carbon source such as sugar cane molasses was utilized, PHB was accumulated concomitant with EPS production from the initial time to 48 h (0.75 g/L, 37% cell dry wt and 0.6 g/L, respectively), and then PHB decayed at 72 h (0.2 g/L). On the other hand, EPS continued to be biosynthesized (1.1 g/L, 72 h). PHB fractions of total intra- and extracellular biopolymers were calculated. Sucrose-modified Burk's medium without ammonium addition is suggested as a medium capable of diverting the carbon source for the production of intracellular PHB rather than EPS with A. chroococcum 6B.

Journal Article↗
PubMedDate not supplied

[Effect of carbon sources on the biosynthesis of ergot alkaloids and the activity of carbon metabolism enzymes in Penicillium sizovae].

The study was aimed at finding out how different carbon sources influenced the growth of Penicillium sizovae, the biosynthesis of epoxyagroclavine-1 and agroclavine-1 as well as the activity of key enzymes involved in the citric acid cycle, the pentose phosphate pathway and the glyoxylate cycle. The fungal growth was shown to depend on the carbohydrate substrate: it had a two-phase profile when P. sizovae was cultivated on mannitol and glucose, but not on sorbitol. The quantitative content and composition of ergoalkaloids depended on the combination of carbohydrate and organic acid substrates. The overall productivity of the mycelium (epoxyagroclavin-1+agroclavin-1) was highest when mannitol and fumarate were used. A medium with sorbitol and fumaric acid was very selective in terms of epoxyagroclavine-1 synthesis. The high level of alkaloid biosynthesis correlated with the active functioning of the pentose phosphate cycle and with the low activity of the CAC.

Carbon↗
PubMed2001

Development of hexachlorobenzene-dechlorinating mixed cultures using polysorbate surfactants as a carbon source.

The use of three nonionic polysorbate surfactants--Tween 60, 61 or 65--as the sole carbon source to sustain methanogenesis and dechlorination, as well as the effect of long-term exposure of enriched cultures to these surfactants, was investigated through the development of three sediment-derived cultures. Over a one-year period, the carbon source in these cultures was gradually switched from glucose and methanol to surfactant only, while the surfactant concentration was increased from an initial concentration of 100 mg/L to 400 mg/L. In each feeding cycle, the surfactants were partially degraded and converted to methane. Transition from glucose to Tween surfactants as the electron donor did not affect the rate, extent, and pathway of HCB transformation. These surfactants sustained the reductive dechlorination of HCB even after one year of continuous addition to the enriched cultures. This study demonstrated that reductive dechlorination of HCB sustained by the fermentation of Tween surfactants is feasible. The results support the use of anaerobically degradable Tween surfactants for the biotransformation of polychlorinated organic compounds. In principle, these surfactants could be used to simultaneously increase the bioavailability of subsurface contaminants while serving as the carbon and electron source for microbial reductive dechlorination.

Biological Availability↗
PubMed1986

Carbon source regulation of RAS1 expression in Saccharomyces cerevisiae and the phenotypes of ras2- cells.

Transcriptional analysis of the yeast RAS genes in different culture conditions suggests that the inability of ras2 mutants to grow in nonfermentable carbon sources results from the regulation of RAS1 mRNA expression. The amount of RAS1 mRNA is significantly repressed in cultures grown on the nonfermentable carbon sources ethanol and acetate. As a result, low RAS function should be expressed under these conditions in a ras2 mutant. This can explain the inability of ras2- cells to grow on nonfermentable carbon sources. This interpretation is supported by the finding that an extragenic suppressor of ras2- (sra6-15), which restores growth on ethanol or acetate, also leads to an increase in the amount of RAS1 mRNA under these conditions. The sra6-15 mutation does not alter the level of RAS1 mRNA in cells grown on glucose. The pattern of transcriptional regulation described for the RAS1 gene is not shared by RAS2, indicating differential control of the functionally homologous yeast RAS genes at the level of gene expression.

Carbon↗
PubMed2002

Effect of initial carbon sources on the electrochemical detection of glucose by Gluconobacter oxydans.

An electrochemical system consisted of Gluconobacter oxydans as a microorganism and 2-hydroxy-1,4-naphthoquinone (HNQ) as a mediator has been setup to examine the effect of initial carbon sources on the detection of glucose. Catalytic current due to the oxidation of glucose was observed only when both G. oxydans and HNQ were present. From amperometric measurements, it was found that the sensitivity strongly depended on the initial carbon sources. The sensitivity was highest for the cells cultured in a fructose-containing medium and decreased in the order, mannitol > sucrose > glucose > galactose > glycerol. The difference in sensitivity was explained by considering the current rising pattern at an initial stage of a microbial fuel cell constructed with the same components. The rising time, not the fuel cell efficiency, could directly be related to the sensitivity order. A sensor where G. oxydans was confined at the vicinity of the electrode by the semipermeable membrane was constructed. A linear response over a millimolar range of glucose concentration was observed with a cell grown in galactose-containing medium. This work demonstrates that the initial carbon source play an important role on glucose sensoring and should be considered in a real application.

Bioelectric Energy Sources↗
PubMed2005

Bat2p is essential in Saccharomyces cerevisiae for fusel alcohol production on the non-fermentable carbon source ethanol.

Branched-chain amino acids (BCAAs) are key substrates in the formation of fusel alcohols, important flavour components in fermented foods. The first step in the catabolic BCAA degradation is a transaminase step, catalyzed by a branched-chain amino acid transaminase (BCAAT). Saccharomyces cerevisiae possesses a mitochondrial and a cytosolic BCAAT, Bat1p and Bat2p, respectively. In order to study the impact of the BCAATs on fusel alcohol production derived from the BCAA metabolism, S. cerevisiae BCAAT-deletion mutants were constructed. The BCAA l-leucine was exogenously supplied during cultivations with mutants of S. cerevisiae. BAT1 deletion is not essential for fusel alcohol production, neither under glucose nor under ethanol growth conditions. The 3-methyl-1-butanol production rate of bat1Delta-cells on ethanol was decreased in comparison with that of wild-type cells, but the cells were still able to produce 3-methyl-1-butanol. However, drastic effects in fusel alcohol production were obtained in cells lacking BAT2. Although the constructed bat2Delta-single deletion strain and the bat1Deltabat2Delta-double deletion strain were still able to produce 3-methyl-1-butanol when grown on glucose, they were incapable of producing any 3-methyl-1-butanol when ethanol was the sole carbon source available. In the circumstances used, gene expression analysis revealed a strong upregulation of BAT2 gene activity in the wild type, when cells grew on ethanol as carbon source. Apparently, the carbon metabolism is able to influence the expression of BCAATs and interferes with the nitrogen metabolism. Furthermore, analysis of gene expression profiles shows that the expression of genes coding for other transaminases present in S. cerevisiae was influenced by the deletion of one or both BCAATs. Several transaminases were upregulated when a BCAAT was deleted. Strikingly, none of the known transaminases was significantly upregulated when BAT2 was deleted. Therefore we conclude that the expression of BAT2 is essential for 3-methyl-1-butanol formation on the non-fermentable carbon source, ethanol.

Alcohols↗
PubMed2001

Carbon sources affect metabolic capacities of Bacillus species for the production of industrial enzymes: theoretical analyses for serine and neutral proteases and alpha-amylase.

The metabolic fluxes through the central carbon pathways were calculated for the genus Bacillus separately for the enzymes serine alkaline protease (SAP), neutral protease (NP) and alpha-amylase (AMY) on five carbon sources that have different reduction degrees (gamma), to determine the theoretical ultimate limits of the production capacities of Bacillus species and to predict the selective substrate for the media design. Glucose (gamma=4.0), acetate (gamma=4.0), and the TCA cycle organic-acids succinate (gamma=3.5), malate (gamma=3.0), and citrate (gamma=3.0) were selected for the theoretical analyses and comparisons. A detailed mass flux balance-based general stoichiometric model based on the proposed metabolic reaction network starting with the alternative five carbon sources for the synthesis of each enzyme in Bacillus licheniformis that simulates the behaviour of the metabolic pathways with 107 metabolites and 150 reaction fluxes is developed. Highest and lowest specific cell growth rates (&mgr;) were calculated as 1.142 and 0.766h(-1), respectively, when glucose that has the highest degree of reduction and citrate that has the lowest degree of reduction were used as the carbon sources. Highest and lowest SAP, NP and AMY synthesis rates were also obtained, respectively, when glucose and citrate were used. Metabolic capacity analyses showed that the maximum SAP, NP, and AMY synthesis rates were, respectively, 0.0483, 0.0215 and 0.0191mmolg(-1)DWh(-1) when glucose uptake rate was 10mmolg(-1)DWh(-1) and specific growth rate was zero. The amino acid compositions and the molecular weights of the enzyme influence the production yield and selectivity. For SAP and NP oxaloacetate and pyruvate, for AMY oxaloacetate appear to be the critical main branch points. Consequently, for SAP and NP syntheses the fluxes towards the alanine group and aspartate group, and for AMY synthesis the flux towards the aspartate group amino acids need to be high. The results encourage the discussion of the potential strategies for improving productions of SAP, NP and AMY.

Journal Article↗
PubMed1993

Sorbitol as the Primary Carbon Source for the Growth of Embryogenic Callus of Maize.

The effects of various carbon sources on initiation and maintenance of embryogenic callus of maize (Zea mays L.) and on the regeneration of plants from embryogenic callus were studied. Growth of embryogenic callus tissue on media containing sucrose was typified by the subsequent growth of both embryogenic (regenerable) and nonembryogenic (nonregenerable) callus. Growth of embryogenic callus on sorbitol was unique among the carbon sources tested in that sorbitol supported the subsequent growth of only embryogenic callus. Further experiments demonstrated that embryogenic callus grown on sorbitol had a greater regenerative capacity (more plants produced per gram fresh weight of callus) than callus grown on sucrose. Sorbitol dehydrogenase was detected in embryogenic callus of maize at a specific activity roughly equivalent to that found in zygotic embryos of developing seeds. Nonembryogenic callus did not contain significant levels of sorbitol dehydrogenase activity.

Journal Article↗
PubMed2004

Comparison of Botryosphaeran production by the ascomyceteous fungus Botryosphaeria sp., grown on different carbohydrate carbon sources, and their partial structural features.

The influence of glucose concentration and other carbohydrates (monosaccharides: fructose, galactose, mannose; polyols: mannitol and sorbitol; disaccharides: lactose, sucrose and commercial sucrose; and industrial sugarcane molasses) were compared as sole carbon sources for the production of Botryosphaeran, an exopolysaccharide (EPS) produced by Botryosphaeria sp. The optimum glucose concentration for EPS production was 50 g l(-1). With the exception of mannitol, the fungus produced EPS on all carbon sources studied, with highest yields occurring with sucrose followed by glucose. All EPS showed exclusively glucose after acid hydrolysis and monosaccharide analysis. FTIR spectroscopy demonstrated the presence of beta-anomers indicating that all the EPS produced by Botryosphaeria sp. on the different carbon sources were essentially of the beta-D-glucan type.

Ascomycota↗
PubMed2001

Dynamic responses of Pseudomonas fluorescens DF57 to nitrogen or carbon source addition.

Cultures of Pseudomonas fluorescens DF57 were grown on different carbon and nitrogen sources. Glucose, succinate and acetate were used as carbon source and pulsed to an aerobic steady-state cultivation of P. fluorescens DF57 at D = 0.1 h(-1) with citrate as limiting carbon source. Glucose was utilised with the fastest uptake rate (19.4 C mmol l(-1) h(-1)) compared to succinate (8.8 C mmol l(-1) h(-1)) and acetate (4.3 C mmol l(-1) h(-1)). Acetate triggered an inhibition of cellular metabolism, which resulted in 2-h long growth arrest after its addition to the steady-state culture. The influence of the nitrogen source was investigated in an aerobic cultivation on a mixture of ammonium and nitrate as limiting nitrogen sources and citrate as non-limiting carbon source. When ammonia and nitrate were pulsed to the steady-state culture, they were mainly assimilated into biomass with a maximum uptake rate of 111 and 33 mg N l(-1) h(-1), respectively. Nitrate uptake was never complete as the residual concentration in the chemostat cultivation was 30 mg N l(-1) nitrate. A pulse of nitrite in the cultivation broth resulted in an inhibition of the growth but not of the primary metabolism, as nitrite was taken up at 38 mg N l(-1) h(-1), citrate was consumed and cofactors were produced continuously. In all experiments, oxygen was used as electron acceptor.

Acetic Acid↗
PubMed1988

Role of the carbon source in regulating chloramphenicol production by Streptomyces venezuelae: studies in batch and continuous cultures.

Both carbon- and nitrogen-limited media that supported a biphasic pattern of growth and chloramphenicol biosynthesis were devised for batch cultures of Streptomyces venezuelae. Where onset of the idiophase was associated with nitrogen depletion, a sharp peak of arylamine synthetase activity coincided with the onset of antibiotic production. The specific activity of the enzyme was highest when the carbon source in the medium was also near depletion at the trophophase-idiophase boundary. In media providing a substantial excess of carbon source through the idiophase, the peak specific activity was reduced by 75%, although the timing of enzyme synthesis was unaltered. Moreover, chemostat cultures in which the growth rate was limited by the glucose concentration in the input medium failed to show a decrease in specific production of chloramphenicol as the steady-state intracellular glucose concentration was increased. The results suggest that a form of "carbon catabolite repression" regulates synthesis of chloramphenicol biosynthetic enzymes during a trophophase-idiophase transition induced by nitrogen starvation. However, this regulatory mechanism does not establish the timing of antibiotic biosynthesis and does not function during nitrogen-sufficient growth in the presence of excess glucose.

Carbon↗
PubMed2004

Effect of carbon source and nitrate concentration on denitrifying phosphorus removal by DPB sludge.

Effect of added carbon source and nitrate concentration on the denitrifying phosphorus removal by DPB sludge was systematically studied using batch experiments, at the same time the variation of ORP was investigated. Results showed that the denitrifying and phosphorus uptake rate in anoxic phase increased with the high initial anaerobic carbon source addition. However once the initial COD concentration reached a certain level, which was in excess to the PHB saturation of poly-P bacteria, residual COD carried over to anoxic phase inhibited the subsequent denitrifying phosphorus uptake. Simultaneously, phosphate uptake continued until all nitrate was removed, following a slow endogenous release of phosphate. High nitrate concentration in anoxic phase increased the initial denitrifying phosphorus rate. Once the nitrate was exhausted, phosphate uptake changed to release. Moreover, the time of this turning point occurred later with the higher nitrate addition. On the other hand, through on-line monitoring the variation of the ORP with different initial COD concentration, it was found ORP could be used as a control parameter for phosphorus release, but it is impossible to utilize ORP for controlling the denitrificaion and anoxic phosphorus uptake operations.

Bacteria, Anaerobic↗
PubMed2001

Vegetative growth, aging- and light-induced conidiation of Trichoderma viride cultivated on different carbon sources.

The growth and conidiation of the aged Trichoderma viride culture grown in the dark, and after an induction by a light pulse, was examined in the presence of selected mono-, di(tri)saccharides, amino acids and alcohols as sole carbon sources. Hexoses and disaccharides, but not pentoses and amino acids, promoted proportionally both growth and conidiation induced by aging or light. All compounds but pentoses promoted the conidiation in aged cultures and photoconidiation in a close correlation. Ethanol, glycerol and ethylene glycol supported both growth and conidiation but these processes were not supported equally. Conidia formation with hexoses and amino acids as sole carbon sources seems to be a function of growth promotion, rather than of growth restriction (starvation, stress, aging). With glucose as sole carbon source the conidiation was not triggered by nutrient limitation, nor by the accumulation of waste metabolites. The aging-induced conidiation can be considered to be triggered by the genetic program of the microorganism rather than by its nutrient status.

Alcohols↗
PubMedDate not supplied

[Lipid composition of Fusarium sambucinum grown in a fermenter on media with different carbon sources].

The object of this work was to study the effect of media containing different carbon sources on the content of lipids and their fractions in the fungus Fusarium sambucinum grown in a fermenter. Molassa and ethanol were carbon sources. From 15.0 to 16.5% of lipids were found to be accumulated in the fungal mycelium. The content of neutral lipids varied from 47.3 to 68%. The fraction of neutral lipids was shown to contain fatty acid esters apart from sterols, triglycerides, free fatty acids and esterified sterols typical of the fungus. The greatest quantities of fatty acid esters were synthesized when the fungus grew on a medium with molassa. Linoleic, oleic and palmitic acids prevailed among other free and esterified fatty acids.

Carbon↗
PubMed1999

Lignin peroxidase production by Streptomyces viridosporus T7A: use of corn oil as a carbon source.

Lignin peroxidase (LiP) production cost should be reduced to justify its use in the control of environmental pollution. In this work, we studied the enzyme production by Streptomyces viridosporus T7A using glucose or corn oil as a carbon source having 0.65% yeast extract as a nitrogen source. Enzyme activity, observed using either 0.65% glucose or corn oil at 0.1, 0.5, and 1.0% concentration, was 300, 150, 300, and 200 U/L, respectively. Although higher enzyme activity was obtained in both media containing 0.65% glucose and 0.5% corn oil, the use of corn oil resulted in a better LiP stability. When combined carbon sources were used, higher values of enzyme activity (360, 350, and 225 U/L) were observed in media with 0.65% glucose and supplemented with 0.1, 0.5, and 1.0% corn oil, respectively. Although the presence of both glucose and 0.5% corn oil is favorable for LiP production, satisfactory results in terms of enzyme production and stability could be also observed using 0.5% corn oil as a sole carbon source, which may lead to reduced production costs of the LiP enzyme.

Journal Article↗