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PubMed2004

The use of micro-algal biomass as a carbon source for biological sulphate reducing systems.

An upflow anaerobic digestor was fed dried algal biomass as a carbon source to establish the feasibility of using micro-algal biomass as the sole carbon source for biological sulphate reduction. The effect of the COD:SO4 ratio on substrate consumption and sulphate removal efficiencies were assessed by varying the organic carbon content of the media. Similar COD removal efficiencies were obtained irrespective of the influent COD:SO4 ratios, which were 8.1, 11.2 and 15.0. However, the rates of COD removal did differ with influent COD:SO4 ratios. The percentage sulphate removed decreased as the ratio of COD:SO4 increased. Not all of the COD was used for sulphate reduction, with only 31% being accounted for.

Biomass↗
PubMed2003

Effect of carbon source on alkaline phosphatase production and excretion in Aspergillus caespitosus.

The effect of several carbon sources on the production of alkaline phosphatase by the thermotolerant Aspergillus caespitosus was analysed. The fungus released high levels of alkaline phosphatases into the medium after being cultured for long periods with xylan or industrial residues such as wheat raw and sugar cane bagasse in the culture media. In contrast, the alkaline phosphatase activities were found only intracellulary when the fungus was cultured in glucose-supplemented media. The pH of the medium likely affects the process of enzyme secretion according to the carbon source used. Addition of xylan or industrial residues in the culture medium stimulated the secretion of phosphatases. In contrast, media supplemented with glucose or disaccharides promoted retention of these enzymes into the cells. The subcellular location activities of alkaline phosphatases were studied using histochemical and immunochemical methods and showed that alkaline phosphatases were present in the mycelial walls and septa.

Alkaline Phosphatase↗
PubMed2005

Role of Tos3, a Snf1 protein kinase kinase, during growth of Saccharomyces cerevisiae on nonfermentable carbon sources.

In Saccharomyces cerevisiae, Snf1 protein kinase of the Snf1/AMP-activated protein kinase family is required for growth on nonfermentable carbon sources and nonpreferred sugars. Three kinases, Pak1, Elm1, and Tos3, activate Snf1 by phosphorylation of its activation-loop threonine, and the absence of all three causes the Snf(-) phenotype. No phenotype has previously been reported for the tos3Delta single mutation. We show here that, when cells are grown on glycerol-ethanol, tos3Delta reduces growth rate, Snf1 catalytic activity, and activation of the Snf1-dependent carbon source-responsive element (CSRE) in the promoters of gluconeogenic genes. In contrast, tos3Delta did not significantly affect Snf1 catalytic activity or CSRE function during abrupt glucose depletion, indicating that Tos3 has a more substantial role in activating Snf1 protein kinase during growth on a nonfermentable carbon source than during acute carbon stress. We also report that Tos3 is localized in the cytosol during growth in either glucose or glycerol-ethanol. These findings lend support to the idea that the Snf1 protein kinase kinases make different contributions to cellular regulation under different growth conditions.

Cytosol↗
PubMed1979

[Dynamics of the NADP+ and NAD+ levels in the mycelium of P. nigricans Thom strains of varying productivity depending on the carbon source].

The levels of NADP+ and NAD+ in the mycelium of the highly productive strain 117 and low productive strain B of P. nigricans were studied by the 2nd, 5th, 9th and 13th days of development on the mineral medium in the presence of glucose, succinate or acetate. It was found that at the beginning of the growth the levels of NADP+ in both strains in the presence of the same carbon source were the same, just as the levels of NAD+ in the presence of glucose or succinate. The same strain had different levels of NADP+ in the presence of different carbon sources. The levels of NAD+ depended on both the carbon source and the strain. In the presence of glucose both nucleotides were accumulated by the end of the culture development and in greater amounts by strain 117. In the presence of succinate the maximum levels were observed at the beginning of the culture growth, while in the presence of accetate the maximum levels were recorded by the end of the culture development (strain 117) and by the 19th day (strain B). It is supposed that NAD+ is transformed into adenylates in the fungi.

Acetates↗
PubMed1997

Carbon source utilization and isoenzyme analysis as taxonomic aids for toxigenic Neosartorya species and their relatives.

Collection strains representing species belonging to the genus Neosartorya and its relatives from section Fumigati of the genus Aspergillus were compared for some of their phenotypic features. The examination of both the carbon source utilization and isoenzyme patterns provided a useful tool for clustering these strains. Many species (e.g. Neosartorya hiratsukae, N. quadricincta, N. spinosa, N. aurata, N. aureola) could readily be distinguished from other species based on their specific isoenzyme and carbon source utilization spectra. Close relationship was observed between the A. fumigatus and N. fischeri strains. Aspergillus strain FRR 1266, which also revealed distinct mitochondrial DNA and nuclear DNA patterns, and amplified DNA profiles, was the closest relative of the recently described N. pseudofischeri species, and could also be distinguished from the A. fumigatus strains by its specific carbon source utilization patterns. High levels of variability were detected among N. glabra and A. viridinutans strains; most of the strains of Australian origin formed distinct clusters.

Ascomycota↗
PubMed2002

Reduction of sludge by ozone treatment and production of carbon source for denitrification.

The feasibility of ozone treatment of municipal sludge for sludge reduction and carbon source production has been investigated. Significant accumulation of solubilized organics and unsettlable micro-solids (UMS) was observed at relatively low ozone dosages while mineralization became dominant at higher dosages. Batch denitrification experiments showed that the solubilized organics and the UMS could be utilized as carbon sources for nitrogen removal. In terms of overall sludge reduction, 54% reduction of the total sludge mass could be achieved by ozone treatment at 0.2 g-O3/g-MLSS.

Carbon↗
PubMed1978

Biosynthesis and regulation of fructose-1,6-bisphosphatase and phosphofructokinase in Saccharomyces cerevisiae grown in the presence of glucose and gluconeogenic carbon sources.

The mode of synthesis and the regulation of fructose-1,6-bisphosphatase (Fbpase), a gluconeogenic enzyme, and phosphofructokinase (PFK), a glycolytic enzyme, were investigated in Saccharomyces cerevisiae after growth in the presence of different concentrations of glucose or various gluconeogenic carbon sources. The activity of FBPase appeared in the cells after the complete disappearance of glucose from the growth medium with a concomitant increase of the pH and no significant change in the levels of accumulated ethanol. The appearance of FBPase activity following glucose depletion was dependent upon the synthesis of protein. The FBPase PFK were present in glucose-, ethanol-, glycerol-, lactate-, or pyruvate-grown cells; however, the time of appearance and the levels of both these enzymes varied. The FBPase activity was always higher in 1% glucose-grown cells than in cells grown in the presence of gluconeogenic carbon sources. Phosphoglucose isomerase activity did not vary significantly. Addition of glucose to an FBPase and PFK synthesizing culture resulted in a complete loss, followed by a reappearance, of PFK activity. In the presence of cycloheximide the disappearance of glucose and the changes in the levels of FBPase and PFK were decreased significantly. It is concluded that S. cerevisiae exhibits a more efficient synthesis of FBPase after the exhaustion of glucose compared to the activity present in cells grown in the presence of exogenous gluconeogenic carbon sources. Two metabolically antagonistic enzymes, FBPase and PFK, are present during the transition phase, but not during the exponential phase, of growth, and the decay or inactivation of these enzymes in vivo may be dependent upon a glucose-induced protease activity.

Bacterial Proteins↗
PubMed1967

Analysis of sporulation mutants. I. Response of uracil incorporation to carbon sources, and other mutant properties.

Mutants deficient in sporulation were isolated and characterized with respect to antibiotic and protease activity, transformability, growth, and sporulation. All but two mutants could grow on minimal medium containing glucose. The inability of most mutants to incorporate uracil into trichloroacetic acid-precipitable material (ribonucleic acid) during the developmental period, and their response to a number of carbon sources, were used to characterize their biochemical blocks. Reproducible measurements of these responses were possible when the pH of the culture, which changed during growth and greatly influenced the rate of uracil uptake, was adjusted to 6.5. By their response to ribose and glutamate, the sporulation mutants could then be divided into four groups. All mutants of the first three groups produced antibiotic activity against Staphylococcus aureus, whereas all mutants, except one, of the fourth group produced none or very little of this activity. Mutants which did not respond to glutamate belonged to the first three groups; they also grew slowly or not at all on glutamate as sole carbon source. One of these mutants lacked succinic dehydrogenase activity. The results indicate that most of our sporulation mutants are unable to produce or utilize a natural carbon precursor, which is normally used as a slowly available carbon and energy source via the Krebs cycle when other carbon sources are used up. It enters the Krebs cycle as a precursor of alpha-ketoglutarate, probably via acetylcoenzyme A. All mutants of group four are blocked in this pathway before alpha-ketoglutarate.

Anti-Bacterial Agents↗
PubMed2005

Effects of nitrogen and carbon sources on transcription of soluble methyltransferases in Methanosarcina mazei strain Go1.

The methanogenic archaeon Methanosarcina mazei strain Gö1 uses versatile carbon sources and is able to fix molecular nitrogen with methanol as carbon and energy sources. Here, we demonstrate that when growing on trimethylamine (TMA), nitrogen fixation does not occur, indicating that ammonium released during TMA degradation is sufficient to serve as a nitrogen source and represses nif gene induction. We further report on the transcriptional regulation of soluble methyltransferases, which catalyze the initial step of methylamine consumption by methanogenesis, in response to different carbon and nitrogen sources. Unexpectedly, we obtained conclusive evidence that transcription of the mtmB2C2 operon, encoding a monomethylamine (MMA) methyltransferase and its corresponding corrinoid protein, is highly increased under nitrogen limitation when methanol serves as a carbon source. In contrast, transcription of the homologous mtmB1C1 operon is not affected by the nitrogen source but appears to be increased when TMA is the sole carbon and energy source. In general, transcription of operons encoding dimethylamine (DMA) and TMA methyltransferases and methylcobalamine:coenzyme M methyltransferases is not regulated in response to the nitrogen source. However, in all cases transcription of one of the homologous operons or genes is increased by TMA or its degradation products DMA and MMA.

Archaeal Proteins↗
PubMed1994

The glycosylation of phosphoglucomutase is modulated by carbon source and heat shock in Saccharomyces cerevisiae.

Phosphoglucomutase is the acceptor for UDP-glucose: glycoprotein glucose-1-phosphotransferase and contains Glc in a phosphodiester linkage to O-linked Man. In this study, we have characterized the glycosylation of phosphoglucomutase by Saccharomyces cerevisiae in response to heat shock and growth in media containing carbon sources other than Glc. Phosphoglucomutase synthesized under these conditions is underglucosylated relative to that synthesized during logarithmic growth in Glc. The underglucosylation results in increased UDP-glucose:glycoprotein glucose-1-phosphotransferase acceptor activity in in vitro assays and a newly appearing less negatively charged form of phosphoglucomutase resolvable by anion exchange chromatography. Utilizing a yeast strain in which phosphoglucomutase is overexpressed via a multicopy plasmid, metabolic labeling of the enzyme with [35S]Met and [3H]Man increased in response to heat shock, whereas [3H]Glc labeling decreased. The glucosylation state of phosphoglucomutase was also compared in cells grown in media containing various carbon sources and was found to be lowest in cells utilizing Gal as the sole carbon source compared with Glc or lactate. In mammalian cells, the glucosylation of phosphoglucomutase has been shown to be sensitive to changes in cytoplasmic Ca2+ and to correlate with a change in its membrane association. The change in phosphoglucomutase's oligosaccharide in Saccharomyces cerevisiae may be important to alterations in its distribution under conditions of nutrient deprivation or metabolic stress.

Gene Expression Regulation, Enzymologic↗
PubMed2005

Synthesis of polyhydroxyalkanoate (PHA) from excess activated sludge under various oxidation-reduction potentials (ORP) by using acetate and propionate as carbon sources.

Accumulation of poly hydroxyalkanoate (PHA) from excess activated sludge (EAS) was monitored and controlled via the oxidation-reduction potential (ORP) adjusting process. The ORP was adjusted and controlled by only regulating the gas-flow rate pumped into the cultural broth in which sodium acetate (C2) and propionate (C3) were used as carbon sources. Productivity of PHA and the PHA compositions at various C2 to C3 ratios were also investigated. When ORP was maintained at +30 mV, 35% (w/w) of PHA of cell dry weight obtained when C2 was used as sole carbon source. The PHA copolymer, poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), accumulated by EAS with different 3-hydroxyvalarate (3HV) molar fractions ranged from 8% to 78.0% when C2 and C3 was used as sole carbon source, By using ORP to monitor and control the fermentation process instead DO meter, the ORP system provided more precise control to the PHA accumulation process from EAS under low dissolved oxygen (DO) concentrations. Adjusting the C2 to C3 ratios in the media could control the composition such as the 3HV/3HB ratios of the PHBV. Furthermore, it might be an effective way to adjust the 3HV molar fractions in PHBV by controlling the DO concentration via the ORP monitoring system. The 3HV molar fractions in the PHBV declined with increasing ORP from -30 mV to +100 mV by adjusting the gas-flow rate (i.e. the DO concentration). It is concluded that the DO plays a very important role in the synthesis of 3HV subunits in PHBV co-polymer from the EAS. Therefore, a hypothetic metabolic model for PHA synthesis from EAS was proposed to try to explain the results in this study.

Acetates↗
PubMed2006

Polyhydroxyalkanoate (PHA) biosynthesis from structurally unrelated carbon sources by a newly characterized Bacillus spp.

A newly acquired polyhydroxyalkanoate (PHA) producing Bacillus spp. was identified to be a strain of Bacillus cereus using a range of microbiological and molecular techniques. This strain, named B. cereus SPV, was found to be capable of using a wide range of carbon sources including glucose, fructose, sucrose, various fatty acids and gluconate for the production of PHAs, an advantage for the commercial production of the polymers. The media used for the polymer production was novel in the context of the genus Bacillus. The PHA, once produced, was found to remain at a constant maximal concentration, without any degradation, a great advantage for the commercial production of the PHAs. This particular strain of Bacillus spp. was able to synthesize various PHAs with 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV) and 4-hydroxybutyrate (4HB)-like monomer units from structurally unrelated carbon sources such as fructose, sucrose and gluconate. This is the first report of the incorporation of a 4HB related monomer containing PHA by the genus Bacillus and from structurally unrelated carbon sources. The PHAs isolated had molecular weights ranging between (0.4 and 0.8) x 10(6) and low polydispersity index values (M(W)/M(N)) ranging from 2.6 to 3.4.

Bacillus cereus↗
PubMed2004

Carbohydrate carbon sources induce loss of flocculation of an ale-brewing yeast strain.

AIMS: To identify the nutrients that can trigger the loss of flocculation under growth conditions in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. METHODS AND RESULTS: Flocculation was evaluated using the method of Soares, E.V. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]. Yeast growth with metabolizable carbon sources (glucose, fructose, galactose, maltose or sucrose) at 2% (w/v), induced the loss of flocculation in yeast that had previously been allowed to flocculate. The yeast remained flocculent when transferred to a medium containing the required nutrients for yeast growth and a sole nonmetabolizable carbon source (lactose). Transfer of flocculent yeast into a growth medium with ethanol (4% v/v), as the sole carbon source did not induce the loss of flocculation. Even the addition of glucose (2% w/v) or glucose and antimycin A (0.1 mg l(-1)) to this culture did not bring about loss of flocculation. Cycloheximide addition (15 mg l(-1)) to glucose-growing cells stopped flocculation loss. CONCLUSIONS: Carbohydrates were the nutrients responsible for stimulating the loss of flocculation in flocculent yeast cells transferred to growing conditions. The glucose-induced loss of flocculation required de novo protein synthesis. Ethanol prevented glucose-induced loss of flocculation. This protective effect of ethanol was independent of the respiratory function of the yeast. SIGNIFICANCE AND IMPACT OF THE STUDY: This work contributes to the elucidation of the role of nutrients in the control of the flocculation cycle in NewFlo phenotype yeast strains.

Antifungal Agents↗
PubMed2001

GpdA-promoter-controlled production of glucose oxidase by recombinant Aspergillus niger using nonglucose carbon sources.

The gpdA-promoter-controlled exocellular production of glucose oxidase (GOD) by recombinant Aspergillus niger NRRL-3 (GOD3-18) during growth on glucose and nonglucose carbon sources was investigated. Screening of various carbon substrates in shake-flask cultures revealed that exocellular GOD activities were not only obtained on glucose but also during growth on mannose, fructose, and xylose. The performance of A. niger NRRL-3 (GOD3-18) using glucose, fructose, or xylose as carbon substrate was compared in more detail in bioreactor cultures. These studies revealed that gpdA-promoter-controlled GOD synthesis was strictly coupled to cell growth. The gpdA-promoter was most active during growth on glucose. However, the unfavorable rapid GOD-catalyzed transformation of glucose into gluconic acid, a carbon source not supporting further cell growth and GOD production, resulted in low biomass yields and, therefore, reduced the advantageous properties of glucose. The total (endo- and exocellular) specific GOD activities were lowest when growth occurred on fructose (only a third of the activity that was obtained on glucose), whereas utilization of xylose resulted in total specific GOD activities nearly as high as reached during growth on glucose. Also, the portion of GOD excreted into the culture fluid reached similar high levels (approximately equal to 90%) by using either glucose or xylose as substrate, whereas growth on fructose resulted in a more pelleted morphology with more than half the total GOD activity retained in the fungal biomass. Finally, growth on xylose resulted in the highest biomass yield and, consequently, the highest total volumetric GOD activity. These results show that xylose is the most favorable carbon substrate for gpdA-promoter-controlled production of exocellular GOD.

Aspergillus niger↗
PubMed2002

cAMP alteration of growth rate of Aspergillus fumigatus and Aspergillus niger is carbon-source dependent.

cAMP signalling has been shown to be essential for normal growth, morphology and virulence in fungal pathogens of both plants and animals. The effects of exogenous cAMP on the growth of the opportunistic pathogen Aspergillus fumigatus were compared to those of Aspergillus niger, which has previously been demonstrated to respond to extracellular cAMP. Both cAMP and phosphodiesterase inhibitors markedly reduced the radial growth rate of A. niger after 48 h on minimal medium with glucose as the carbon source, whereas the growth of A. fumigatus was not affected by cAMP. However, when glycerol, which does not initiate carbon catabolite repression, was used as a carbon source, cAMP inhibited the radial growth rate of only A. fumigatus (P<0.05). The addition of cAMP to glycerol-minimal medium resulted in a fourfold increase in protein kinase A activity in A. fumigatus cell extracts when compared with pre-treatment samples. The protein kinase A activity in A. fumigatus cell extracts from cultures grown in glucose did not change significantly with the addition of cAMP. These studies demonstrate that although the growth rates of both A. fumigatus and A. niger are sensitive to the addition of exogenous cAMP, the response of each organism is distinct and dependent on the carbon source used.

Aspergillus fumigatus↗
PubMed2002

Modeling aerobic carbon source degradation processes using titrimetric data and combined respirometric-titrimetric data: structural and practical identifiability.

The structural and practical identifiability of a model for description of respirometric-titrimetric data derived from aerobic batch substrate degradation experiments of a C(x)H(y)O(z) carbon source with activated sludge was evaluated. The model processes needed to describe titrimetric data included substrate uptake, CO(2) production, and NH(3) uptake for biomass growth. The structural identifiability was studied using the Taylor series method and a recently proposed generalization method. It showed that combining respirometric and titrimetric data allows structural identifiability of one extra parameter combination, the biomass yield, Y(H), compared to estimation on separate data sets, on condition that the nitrogen fraction in biomass (i(XB)) is known. However, data from short-term batch substrate degradation experiments were not sufficiently informative to allow practical identification of all structurally identifiable parameters. Combining respirometry and titrimetry resulted in improvements of parameter confidence intervals compared to estimation on separate respirometric or titrimetric data sets. However, the level of the improvement seems to be substrate dependent: parameter confidence intervals improved considerably more for dextrose than for acetate degradation models. Noteworthy is the finding that the half-saturation substrate concentrations can be different depending on whether they are estimated from respirometric or titrimetric data. Moreover, this difference appears to be dependent on the carbon source considered: for dextrose, titrimetry-based K(S) values are higher than respirometry-based values while for acetate the opposite was found. It was hypothesized that this can be explained by the different point in cell metabolism where the proton production or consumption takes place, leading to a corresponding difference in timing between pH effect and oxygen consumption. Finally, the biomass yield Y(H) and the nitrogen content of the biomass i(XB) could be estimated from combined respirometric-titrimetric data obtained with addition of a known amount of carbon source. Y(H) can also be estimated from r(O) data when the initial substrate concentration S(S)(0) is known. The values found correspond to values reported in literature, but, interestingly, also seem able to reflect the occurrence of storage processes when pulses of acetate and dextrose are added.

Acetates↗
PubMed1994

Fermentable and nonfermentable carbon sources sustain constitutive levels of expression of yeast triosephosphate dehydrogenase 3 gene from distinct promoter elements.

The triosephosphate dehydrogenase 3 gene (TDH3) is a glycolytic enzyme gene and is abundantly transcribed in Saccharomyces cerevisiae. The promoter region of the TDH3 gene is known to exhibit high transcriptional activity regardless of the fermentability of the carbon source and has been widely utilized to synthesize heterologous gene products in S. cerevisiae. To clarify the mechanism of constitutive transcription by the promoter, we constructed mutant promoters and analyzed the in vivo transcriptional activity of these promoters. The majority of the transcriptional potential is contained within a DNA fragment extending from nucleotides -524 to -255 (-524/-255; relative to the translation initiation codon), which consists of three cis-acting elements: a fermentable carbon source-dependent upstream activation sequence (UAS) 1 (-524/-426), a fermentable carbon source-dependent upstream repression sequence (URS) (-426/-393), and a nonfermetable carbon source-dependent UAS2 (-305/-255). This result indicates that the promoter involves two apparent promoter elements. One is fermentable carbon source-dependent, and another is nonfermentable carbon source-dependent. Southwestern analyses indicated that a novel 20-kDa protein is induced in yeast cells by shifting from a fermentable to nonfermentable carbon source. The protein interacts with two UAS1 13-base pair elements and one URS 13-base pair element, one of which had been previously designated GPE (general regulatory factor 1 (GRF1) binding site potentiator element) (Bitter, G. A., Chang, K. K. H., and Egan, K. M. (1991) Mol. Gen. Genet. 231, 22-32). We therefore termed the 20-kDa protein GPEB (GRF1-binding site potentiator element-binding protein). In addition, mutational analyses strongly suggested that UAS1, URS, and UAS2 interact with GRF1 and GPEB, GPEB, and the GCR1 (glycolysis regulation 1) gene product, respectively. We therefore concluded that constitutive transcription by the TDH3 promoter is sustained by two promoter elements and that the switch between them might be controlled by the nonfermentable carbon source-inducible GPEB.

Base Sequence↗
PubMed1977

Acetate as a carbon source for lipid synthesis in cultured cells.

Lipid synthesis from acetate and glucose has been studied in fibroblast cultures grown in lipid free medium containing various concentrations of acetate and glucose. Their role in lipid synthesis was evaluated by comparing the specific activities of total cell lipid, and sterol and fatty acid subfractions, to that of the carbon source in the medium. When glucose was present at 1000 microgram/ml (5.6 mM) and acetate at 100 microgram/ml (1.2 mM), the majority of the total cell lipid and subfractions were derived from glucose. As acetate concentrations increased, lipid synthesis from acetate increased, and glucose declined as a carbon source; in cells grown in the presence of 1000 microgram/ml (12 mM) acetate more of the lipid was derived from acetate than from glucose. When acetate was present at 1000 microgram/ml (12 mM) and glucose was varied from 1000 to 200 microgram/ml (5.6 to 1.1 mM), the relative amount of lipid synthesis from acetate was further increased. The data indicate that acetate can serve as a significant carbon source for lipid synthesis in cultured fibroblasts when it is presented to the cells at high extracellular concentrations relative to glucose.

Acetates↗