Influence Of Different Carbon Sources Research Articles

The influence of different carbon sources on the structural characteristics of the bacterial cellulose membrane (1180.15)

Recent research shows that bacterial cellulose membranes (BCm), which represent a promising biomaterial for the use in regenerative medicine, can be used as biological support and/or as a system of extended release of bioactive compounds. The objective of this work was to characterize the influence of different carbon sources (CS1 and CS2), obtained from the processing of sugar cane, on the physical and structural characteristics of the BCm. To develop this work, bacterial strains of Gluconacetobacter hansenii (ATCC 23769 ) were cultivated in media containing nitrogen source (5,6g/L) and increasing concentrations of CS1 (2.5, 5 , 7.5, 10, 12.5 and 15%) and CS2 (5, 10, 15, 20, 25 and 30%). The static culture was maintained at room temperature for 14 days. The influence of the carbon sources and the different concentrations was established by analysis of dry matter yield, tumescence capacity and ultra‐structural analysis. The best yield was obtained with the mass concentration of 10% CS1 (0.71 g/L) and 15% CS2 (0.84 g/L) and percentage of tumescence of 70,7% and 71,6 % respectively. The ultra‐structural analysis of the BCm best yield in the two sources showed a difference among the reticular structures. It was concluded that carbon sources obtained from sugar cane provided, in the concentrations mentioned above, favorable conditions for the biosynthesis of BCm by G. hansenii, with potential for the use in regenerative medicine.Grant Funding Source: Supported by: Conselho Nacional de Desenvolvimento Científico e Tecnológico ‐ CNPq

A time resolved metabolomics study: the influence of different carbon sources during growth and starvation of Bacillus subtilis.

In its natural environment, the soil, the Gram-positive model bacterium Bacillus subtilis frequently encounters nutrient limitation and other stress factors. Efficient adaptation mechanisms are necessary to cope with this wide range of environmental challenges. The ability to utilize diverse carbon sources represents a key adaptation process that allows B. subtilis to thrive in its natural habitat. To gain a comprehensive insight into the metabolism of B. subtilis, global metabolite analyses were performed during growth with glucose alone or glucose with either malate, fumarate or citrate as carbon/energy sources. Furthermore, to achieve a comprehensive coverage of a wide range of chemically different metabolites, complementary GC-MS, LC-MS and (1)H-NMR analyses were applied. This study reveals that the availability of different carbon sources results in different extracellular metabolite profiles whereas a regulated intracellular metabolite equilibrium was observed. In addition, the typical energy-starvation induced activation of the general stress sigma factor σ(B) was only observed upon entry into the stationary phase with glucose or glucose and malate as carbon sources.

Antioxidant enzyme influences germination, stress tolerance, and virulence of Isaria fumosorosea

Antioxidizing enzymes (superoxide dismutase, catalase, and glutathione peroxidae) are important enzymatic systems used to degrade hydrogen peroxide into water and oxygen, thereby lowering intracellular hydrogen peroxide levels. Entomopathogenic fungi display increased activities of antioxidizing enzymes during growth and germination, which is necessary to counteract the hyperoxidant state produced by oxidative metabolism. We studied the influence of different carbon sources on antioxidizing enzyme production by Isaria fumosorosea to determine the importance of antioxiding enzymes induction in fungal germination, stress tolerance and virulence. Conidia produced by colonies grown on hydrocarbons showed higher rates of enzyme activities compared to the control and the enzyme activities of the conidia produced on n-octacosane were higher than all the other treatments. The lipid peroxidation activities were observed as an indicative marker of oxidative damage to cells and the lowest levels of lipid peroxidation activities were observed for n-octacosane treatment. The increased enzyme activities of n-octacosane- grown conidia were accompanied by higher levels of resistance to exogenous hydrogen peroxide, reduction in germination time and higher virulence against Spodoptera exigua. Our study has helped to identify that increased activities of antioxidizing enzymes can improve the germination and tolerance to antioxidant stress response of I. fumosorosea.

The influence of different carbon sources in the carbothermal reduction and nitridation (CRN) synthesis of SiAlON from nanocomposite precursors based on Al–SBA-15

Abstract Nanocomposites of Al–SBA-15 with the organic polymers poly-4-vinyl pyridine (P4VP) and polyacrylamide (PAM) were synthesized to produce SiAlON precursors containing various carbon contents. These CRN precursors, and their products after firing under N 2 at 1450 °C for 3 h were investigated by XRD, SEM/EDS and surface area analysis (BET) to compare the influence of the organic polymer carbon source. The results were also compared with those from precursors containing carbon black as the carbon source. XRD and SEM/EDS analysis of the Al–SBA-15 confirmed the formation of mesoporous structures, while BET and pore size distribution measurements indicated that the entry of P4VP into the Al–SBA-15 nanocomposite precursor is significantly more efficient than that of PAM. Firing these precursors in nitrogen produced β-SiAlON and β-cristobalite. At all carbon concentrations the P4VP nanocomposite precursors formed significantly more SiAlON than those of the PAM and carbon black precursors, due to the proximity of a greater amount of the organic carbon source to the silica template in the P4VP composite, and possibly also to the lack of oxygen in the P4VP monomer, in contrast with PAM. At least twice the stoichiometric amount of carbon was required in all cases, with optimal SiAlON formation occurring in the P4VP precursor containing 6 times the stoichiometric amount of carbon. Increasing the carbon content further suppresses SiAlON formation, possibly due to the build-up of back pressure of CO by-products in the pores of the nanocomposite.

Production of fusarielins by Fusarium

Fusarielins constitute a relative unexplored group of secondary metabolites, which have been isolated mainly from unidentified Aspergillus and Fusarium strains. In the present study we show that the ability to produce fusarielins is restricted to a few Fusarium species. Among the 15 analyzed species fusarielins were identified only in extracts from Fusarium graminearum and Fusarium tricinctum. The influence of different carbon sources on fusarielin biosynthesis was examined and the results showed that disaccharides and dextrin in combination with arginine as sole nitrogen source increased fusarielin production. When arginine was replaced with nitrate the fusarielins were produced on a wider selection of carbon sources including all monosaccharides. Production of fusarielins in F. graminearum was also influenced by pH, cultivation time, temperature and fructose concentration with the optimal conditions being: pH6, 25°C, 26days and 60mg fructose/mL. Wheat spikes were inoculated with F. graminearum to determine whether fusarielins are produced in infected cereals and fusarielin H was detected in all samples ranging from 392 to 1865ng/g (mean: 989ng/g) indicating that fusarielins are produced during infection. The study shows that even though fusarielins are produced by a narrow list of Fusarium species, they potentially can be present in infected cereals.

Preparation and Modification of Nano-Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub> Anode Material

The spinel nano-Li4Ti5O12 was prepared by hydrothermal reaction method. The crystal structure, morphology and charge/discharge capacities were characterized by powder X-ray diffraction and Scanning electron microscopy and program-controlled tester respectively. It showed that lithium titanate synthesized by the direct hydrothermal method has a uniform particle size distribution of about 100nm in cubic shape. Investigated the influence of different carbon sources on the structure and electrochemical properties. It was found that the discharge capacities could reach 172.2, 159.8, 156.2 and 148.3mAh/g at 0.2C, 1C, 2C and 5C rates, respectively.

The Influence of Different Carbon Sources to γ-PGA’s Molecular Weight Distribution

Poly (γ-glutamic acid) (γ-PGA) is a special anionic, water-soluble and high viscous polymer [1] which is condensed by glutamate via amide linkages between their a-amino and γ-carboxylic acid groups [2]. For its excellent characters, potential applications of γ-PGA have been of interest in the past few years in a broad range of industrial fields [3]. And the decision to application of γ-PGA will be done, depending on its’ molecular weight. So this article main expresses the influence of different carbon sources to γ-PGA’s molecular weight distribution. By SDS-PAGE, we found that the molecular weight distributions of biosynthetic γ-PGA were different in the different carbon sources. All the results showed that changing the carbon source of mediums did make the biosynthetic γ-PGA’s yield and molecular weight distribution been changed.

Improved Artificial Saliva for Studying the Cariogenic Effect of Carbohydrates

Saliva is a complex fluid that possesses many important functions regarding oral health. Many in vitro studies require relatively large quantities of saliva. While natural saliva would be the material of choice, it is difficult to obtain in sufficient quantities and varies in composition. Substitutes mimicking the physicochemical properties of saliva have been developed, but these are not appropriate to study the growth of mutans streptococci. Brain Heart Infusion (BHI) has been commonly used for this, but this medium is richer in nutrients than saliva. We therefore developed artificial saliva (AS) with nutrient levels resembling those in natural saliva as a substitute for natural human saliva (HS) to study the influence of different carbon sources on mutans streptococci growth. Growth of a wild-type Streptococcus mutans strain and S. mutans ATCC 15175 in BHI, HS, and AS was monitored anaerobically. Growth of S. mutans in the modified AS was very similar to the growth in HS, both in the absence and presence of different carbon sources. We therefore conclude that the developed AS is suitable for in vitro tests on S. mutans growth.

Novel Carbon Source in Manufacture of LiFePO<sub>4</sub>/C

LiFePO4/C composite materials were synthesized by a solid-state method. The carbon source was selected from glucose, cauric acid, cinnamic acid and PVA and the influence of different carbon sources on the performances of LiFePO4/C was investigated. The crystal structure, morphology and electrochemica1 properties of LiFePO4/C were analyzed by XRD, SEM and galvano static charge-discharge method. The results show that the materials have olivine structure and that the LiFePO4 material coated with carbon gives enhanced performance in terms of practical capacity and cycleability of the cell with lithium metal piece as an anode. The specimen used PVA as the carbon source has a fine and uniform particle size and shows excellent electrochemical performances. The first discharge capacity is up to 147.5 mAh•g-1 at 0.1C rate, and after 20 times of cycling the discharge capacity is still 144.7 mAh•g-1.

Effect of carbon source on Phenobarbital metabolism by Rhizopus stolonifer

The safety and efficacy of a drug is based on its metabolism or metabolite formed. The metabolism of drugs can be studied by different in vitro models, among which microbial model became popular. In the present study, eight microbes were screened for their ability to metabolize phenobarbital in a manner comparable to humans with a model to develop alternative systems to study human drug metabolism. Among the different microbes screened, a filamentous fungi Rhizopus stolonifer metabolized phenobarbital to its metabolite which is used for further pharmacological and toxicological studies. The transformation of phenobarbital was identified by high- performance liquid chromatography (HPLC). Interestingly, Rhizopus stolonifer sample showed an extra metabolite peak at 3.11min. compared to its controls. The influence of different carbon sources in media used for growth of fungus, on metabolite production was studied, to find its effect in production of metabolite as the carbon source may influence the growth of the cell.

Microbial production of polyhydroxy alkanotes (PHA) from Alcaligens spp. and Pseudomonas oleovorans using different carbon sources

Plastics have resistance to biological breakdown that result in its accumulation in the environment. This emphasizes the need to search for biodegradable polymer, which is easily disposable and degradable. Bacteria synthesize and accumulate polyhydroxy alkanote (PHA) as carbon source under limiting conditions of nutrients. The effect of different nutrient conditions on production of PHA by Alcaligens eutrophus, Alcaligens latus and Pseudomonas oleovorans was screened and characterized in this study. The influence of different carbon sources on PHA production showed that, medium with glucose as carbon source produced the maximum PHA content of 4.14 g/l from A. eutrophus. P. oleovorans produced 2.06 g/l from n-octane as carbon source. The functional groups of the extracted PHA granules were identified as C=O group by fourier transform infrared (FTIR)spectroscopy analysis. Biodegrability studies showed that, the PHA produced is degradable by a number of soil microbes making it an ideal environmentally friendly material for regular human use. Key words: Polyhydroxy alkanotes, polymer, polyhydroxy alkanote granules, biodegradable.

Influence of carbon sources and C/N ratio on EPS production in anaerobic sequencing batch biofilm reactors for wastewater treatment

The objective of this work was to evaluate the influence of different carbon sources and the carbon/nitrogen ratio (C/N) on the production and main composition of insoluble extracellular polymers (EPS) produced in an anaerobic sequencing batch biofilm reactor (ASBBR) with immobilized biomass in polyurethane foam. The yield of EPS was 23.6 mg/g carbon, 13.3 mg/g carbon, 9.0 mg/g carbon and 1.4 mg/g carbon when the reactor was fed with glucose, soybean oil, fat acids, and meat extract, respectively. The yield of EPS decreased from 23.6 to 2.6 mg/g carbon as the C/N ratio was decreased from 13.6 to 3.4 gC/gN, using glucose as carbon source. EPS production was not observed under strict anaerobic conditions. The results suggest that the carbon source, microaerophilic conditions and high C/N ratio favor EPS production in the ASBBR used for wastewater treatment. Cellulose was the main exopolysaccharide observed in all experimental conditions.

Bioactivation of flavonoid diglycosides by chicken cecal bacteria

Flavonoids, the potent antioxidant and anti-inflammatory plant compounds, require deglycosylation for absorption across the intestine. Intestinal bacteria are indispensable for the hydrolysis of flavonoid diglycosides. We isolated, for the first time, three anaerobic Lactobacillus-like strains designated as MF-01, MF-02 and MF-03 from the cecum of chicken capable of converting flavonoid diglycosides into bioactive aglycones. All the isolated strains were found to be active in the conversion of quercetin-3-rhamnoglucoside (rutin) and hesperetin-7-rhamnoglucoside (hesperidin) into their aglyconic forms. No metabolites were detected after the fermentation tests with naringenin-7-rhamnoglucoside (naringin). The degradation rates of flavonoids and influence of different carbon sources, following incubation with isolated strains, were also monitored. Overall maltose resulted in rapid degradation of flavonoids. However, when organic acids (lactate, acetate, butyrate or propionate) were added to the basal medium as carbon source, flavonoid degradation was completely inhibited. Using consortium of three isolated strains, fructooligosaccharide (10 g L(-1)) supplementation was found to be imperative for preserving aglycone hesperitin while organic acids supplementation (10 g L(-1)) to the fermentation medium resulted in rapid degradation of hesperitin indicating that the metabolic fate of flavonoids may be related to the gut metabolic behavior. Butyrate and propionate also suppressed rutin deglycosylation by the consortium.

Influence of different carbon sources on bacterial cellulose production byGluconacetobacter xylinusstrain ATCC 53524

To determine the effect of carbon sources on cellulose produced by Gluconacetobacter xylinus strain ATCC 53524, and to characterize the purity and structural features of the cellulose produced. Modified Hestrin Schramm medium containing the carbon sources mannitol, glucose, glycerol, fructose, sucrose or galactose were inoculated with Ga. xylinus strain ATCC 53524. Plate counts indicated that all carbon sources supported growth of the strain. Sucrose and glycerol gave the highest cellulose yields of 3.83 and 3.75 g l(-1) respectively after 96 h fermentation, primarily due to a surge in cellulose production in the last 12 h. Mannitol, fructose or glucose resulted in consistent rates of cellulose production and yields of >2.5 g l(-1). Solid state (13)C CP/MAS NMR revealed that irrespective of the carbon source, the cellulose produced by ATCC 53524 was pure and highly crystalline. Scanning electron micrographs illustrated the densely packed network of cellulose fibres within the pellicles and that the different carbon sources did not markedly alter the micro-architecture of the resulting cellulose pellicles. The production rate of bacterial cellulose by Ga. xylinus (ATCC 53524) was influenced by different carbon sources, but the product formed was indistinguishable in molecular and microscopic features. Our studies for the first time examined the influence of different carbon sources on the rate of cellulose production by Ga. xylinus ATCC 53524, and the molecular and microscopic features of the cellulose produced.

Modeling the PAO–GAO competition: Effects of carbon source, pH and temperature

The influence of different carbon sources (acetate to propionate ratios), temperature and pH levels on the competition between polyphosphate- and glycogen-accumulating organisms (PAO and GAO, respectively) was evaluated using a metabolic model that incorporated the carbon source, temperature and pH dependences of these microorganisms. The model satisfactorily described the bacterial activity of PAO ( Accumulibacter) and GAO ( Competibacter and Alphaproteobacteria-GAO) laboratory-enriched cultures cultivated on propionate (HPr) and acetate (HAc) at standard conditions (20 °C and pH 7.0). Using the calibrated model, the effects of different influent HAc to HPr ratios (100–0, 75–25, 50–50 and 0–100%), temperatures (10, 20 and 30 °C) and pH levels (6.0, 7.0 and 7.5) on the competition among Accumulibacter, Competibacter and Alphaproteobacteria-GAO were evaluated. The main aim was to assess which conditions were favorable for the existence of PAO and, therefore, beneficial for the biological phosphorus removal process in sewage treatment plants. At low temperature (10 °C), PAO were the dominant microorganisms regardless of the used influent carbon source or pH. At moderate temperature (20 °C), PAO dominated the competition when HAc and HPr were simultaneously supplied (75–25 and 50–50% HAc to HPr ratios). However, the use of either HAc or HPr as sole carbon source at 20 °C was not favorable for PAO unless a high pH was used (7.5). Meanwhile, at higher temperature (30 °C), GAO tended to be the dominant microorganisms. Nevertheless, the combined presence of acetate and propionate in the influent (75–25 and 50–50% HAc to HPr ratios) as well as a high pH (7.5) appear to be potential factors to favor the metabolism of PAO over GAO at higher sewage temperature (30 °C).

Macroinvertebrate 13C variability analysis for the assessment of lake trophic functioning

The aim of this study was to better understand the relationships of within- and among-lake variability of macroinvertebrate carbon stable-isotope ratios with both lake trophic potential and lake trophic functioning. Two approaches based on the macroinvertebrate communities were undertaken on 11 French lakes: the Lake Biotic Index (LBI), a lake biological quality assessment method (Verneaux et al. 2004 a), and the carbon isotopic signatures of macroinvertebrates expressed by metrics of dispersion (standard deviation of the littoral macroinvertebrate mean δ 13 C values and differences between littoral and deep mean δ 13 C values (Δδ 13 C)). The littoral macroinvertebrate mean δ 13 C values obtained ranged from -11.7%o to -38.6‰. This great among-lake variability can be partially explained by different geological substrata on which the lakes are located and, potentially, by the lake organic matter recycling activity. Moreover, the depth-related differences in macroinvertebrate community δ 13 C (Δδ 13 C values) or macroinvertebrate taxa (taxon 13 C depletion: TΔδ 13 C) were highly correlated to the values of a LBI sub-index, which was itself correlated to hypolimnion oxygenation and deep sediment organic matter contents. This result suggests that the studied lakes showed various degrees of deep recycled carbon assimilation. The depth-related macroinvertebrate 13 C depletion may then be considered as describing the result of lake trophic functioning. However, because no correlation was observed between littoral macroinvertebrate δ 13 C variability and lake trophic potential, it seemed difficult to conclude as to the influence of different carbon sources on this potential.

Influence of different carbon sources on exopolysaccharide production by Lactobacillus delbrueckii subsp. bulgaricus (B3, G12) and Streptococcus thermophilus (W22)

Exopolysaccharides (EPSs) production was studied by Lactobacillus delbrueckii subsp. bulgaricus (B3, G12) and Streptococcus thermophilus (W22) in the medium containing various carbon sources (glucose, fructose, sucrose or lactose). For all the strains, glucose was the most efficient carbon source and B3, G12 and W22 strains produced 211, 175 and 120 EPS mg/L respectively. Also, the influence of different concentrations of glucose (5,10,15,20,25,30 g/L) on EPS production and growth was studied. The results indicated that EPS production and growth were stimulated by the high glucose concentration (30 g/L).

Regulation of in vitro bud formation of date palm ( Phoenix dactylifera L.) cv. Khanezi by different carbon sources

The influence of different carbon sources and concentrations on in vitro shoot multiplication of date palm cv. Khanezi were investigated. Sucrose, glucose, fructose and maltose sugars were used at the following concentrations; 0, 30, 60, 90 and 120 g l −1. Shoot dry weight was significantly increased with increasing sugar concentrations while little growth was obtained in the absence of sugar. Concentrations of 30 and 60 g l −1 were optimal for qualitative and quantitative shoot growth while abnormal growth was observed at 90 and 120 g l −1 possibly due to osmotic stress. Sugar type had significant effects on most parameters measured except bud formation. Fructose produced the highest values of dry weights compared with other carbon sources. In addition, glucose, fructose and maltose were almost equivalently effective as a carbon source for culture of date palm compared with sucrose. It is also noticed in this study that the root formation was enhanced as the sugar concentration increased (60 g l −1 and above). This rooting of buds generally reduced their ability to multiply during multiplication stage and occasionally inhibited bud formation especially in higher concentration of sugar.

Proteome Response ofMonascus pilosusduring Rice Starch Limitation with Suppression of Monascorubramine Production

For centuries, red mold rice has been made by fermentation of cooked rice with Monascus species. However, the influence of different carbon sources on the metabolism of Monascus cells remains unclear. We compared the proteome response of Monascus pilosus to replacement of the rice starch fraction with lactose during cultivation, using two-dimensional gel electrophoresis, matrix-assisted laser desorption-ionization time-of-flight/time-of-flight mass spectrometry, and tandem mass spectrometry to identify the proteins expressed. The results showed that cell growth and monascorubramine pigment formation of M. pilosus were sensitive to rice starch limitation during cultivation. A total of 12 proteins were identified with statistically altered expression in the cells cultivated with lactose. These deregulated proteins were involved in glycolysis, TCA cycle, energy generation, protein folding, and peptide biosynthesis. The possible metabolic flux shifts induced by rice starch limitation were discussed. The results suggested that the suppression of monascorubramine formation could be related to the necessary energy-requiring adaptations executed in response to carbon depletion during rice starch limitation.

Influence of food system conditions on N-acyl- l-homoserine lactones production by Aeromonas spp.

Eleven of 13 Aeromonas strains were shown to produce AHLs. Results of TLC showed that N-butanoyl- l-homoserine lactone (C4-HSL) was the main AHL produced in LB medium at 30 °C. The influence of different carbon sources, temperature, pH values and salt concentrations on AHL production was determined in eight A. hydrophila and one A. caviae strain. Additionally a quantitative study of C4-HSL production by A. hydrophila strain 519 under different conditions was performed. Positive results were found in the AHL induction assay for some Aeromonas strains in cultures in LB agar incubated at 12 °C after 72–96 h. The induction of the sensor strains by Aeromonas spp. occurred in LB medium supplemented with all carbon sources in a concentration of 0.5%. The production of C4-HSL by A. hydrophila 519 was found until 3.5% (w/v) of NaCl. For pHs close to the neutrality the C4-HSL production by A. hydrophila was evident after 24–48 h of incubation. A. hydrophila 519 produced C4-HSL under anaerobic conditions. Also, the AHL production by Aeromonas strains was studied in simulate agar of shrimp, fish and some vegetables. The production of AHLs was evident by almost all the test strains in shrimp simulated agar. In fish agar only for one of three fish species tested, positive results were found. Induction assay in vegetables simulated agar showed principally negative results, probably because of the presence of inhibitory compounds in these vegetables.