The influence of different nitrogen sources on the production of volatile compounds by Dipodascus aggregatus

Summary The yeast fungus Dipodascus aggregatus was grown aerobically on 9 different nitrogen sources and the production of volatile compounds determined by a gas chromatographic head-space technique. Excellent growth was supported by glutamine, aspartic acid, asparagine, (NH₄)₂-tartrate and NH₄H₂PO₄. Valine, leucine, and particularly isoleucine were utilized with a somewhat lower growth rate. Lysine was rapidly utilized after a prolonged lag phase.The highest production of volatile compounds was obtained from leucine and isoleucine. At least 20 volatile compounds were formed from each of them and many products were detected in high concentrations. Intermediate amounts of volatile compounds were produced from asparagine, the ammonium salts and valine, and low amounts from lysine, glutamine and aspartic acid.Ethyl acetate was a major product irrespective of the nitrogen source used. Regarding the pattern of volatile compounds produced, leucine, isoleucine and valine had much in common. Most of the volatile products formed from these amino acids contained a branched carbon chain and at least three high-boiling components eluted later than n-amyl acetate from the gas chromatographic column. The other six nitrogen sources could be grouped together. In general the same volatile compounds were formed from these sources, but the quantities of the individual compounds differed. Only one component eluted later than n-amyl acetate. No basic difference in production of volatile compounds was observed between the ammonium salts and -amino compounds like lysine and asparagine.     

Production of volatile organic compounds by the yeast fungus Dipodascus aggregatus

Summary The yeast fungus Dipodascus aggregatus was grown aerobically in a synthetic nutrient solution and the volatile compounds produced were concentrated. Identification of the volatiles was performed by combined gas chromatographymass spectrometry or by one of these methods. The compounds identified were 11 esters, 9 alcohols, 5 acids and 3 carbonyls.The time course production of volatile neutral compounds was followed. During the phase of no apparent growth only a few substances were formed (mostly alcohols). The rapid phase of growth was characterized by an intense synthesis of many compounds in relatively high concentrations and later a sudden decrease in the number and amounts of substances. A slow successive, decline in the number and amounts of volatile components was observed during the phase of no net growth.The volatiles emitted by the fungus were concentrated, when most of the compounds were most abundant and the relative amounts of the major volatile neutral compounds were determined. The main components were ethyl acetate, ethyl propionate and ethanol.     

The Effect of Ethanol on the Growth of Dipodascus aggregatus

Ethanol (68.2 mM) did not appreciably affect the growth of Dipodascus aggregatus with glucose (55.5 mM] as carbon source. Growth with fructose was inhibited whereas growth with galactose was stimulated by ethanol in this concentration. The fungus could grow with ethanol as the sole carbon source. D. aggregatus did not grown with maltose as the sole carbon source. Growth with maltose + ethanol started much earlier than growth with ethanol alone. The maltose concentration of the medium did not measurably decrease during growth with maltose-n ethanol. D. aggregatus did not grow with sucrose as the sole carbon source     

Effect of different carbon sources on lipase production by Candida rugosa

Different carbon sources affecting growth and lipase production in Candida rugosa were studied by using batch cultures on defined medium. Carbohydrates and acids non-related to fats did not induce lipase production. The highest yields of enzyme were obtained with lipids or fatty acids as carbon sources. Tween 80 stimulated lipase biosynthesis and secretion outside the cell. Combinations of two types of substrates, carbohydrates and fatty acids, did not improve lipase production, and in some cases, their consumption was produced in a sequential pattern. Glucose presented a repressing effect on lipase production. Moreover, glucose was found to be effective in stimulating lipase secretion by cells with a high level of cell-bound lipase activity because of their previous growth in oleic acid.     

The Effect of Various Aliphatic Aldehydes and Related Compounds on the Growth of Dipodascus aggregatus

The growth of Dipodascus aggregatus in cultures inoculated with cells from the acceleration phase of growth was stimulated by the saturated and unbranched aliphatic C(3) C(4) , and C(6) to C(11) aldehydes (80 μM]. Nonanal was most active in stimulating growth. The C(12) aldehyde inhibited growth. The C(5) , aldehyde generally inhibited growth. - Nonan did not affect growth. 2-Nonanone and 5-nonanone promoted growth insignificantly. - In cultures inoculated with cells from the exponential phase growth was unaffected or even inhibited by all the aldehydes tested. The C(4) , C(5) , C(10) , and C(11) aldehydes inhibited growth to a larger extent than nonanal.     

True cellulase production by Clostridium thermocellum grown on different carbon sources

Summary Clostridium thermocellum produced different levels of true cellulase (Avicelase) depending on the carbon source used for growth. In defined medium with fructose, the cellulase titer was seven times higher than with cells growing on cellobiose and four times higher than cells growing with glucose. During the lag phase on fructose, the differences were even more dramatic, i.e. 60 times higher than in cells growing on cellobiose and 40 times that of cells lagging or growing in glucose. In an attempt to detect factors that might contribute to these differences, we considered intracellular ATP, chemical potential (pH), electrical potential (Y), proton motive force (p), growth rate, and rates of uptake of inorganic phosphate and sugars. We noted a direct correlation between cellulase production and intracellular ATP levels and an inverse relationship of cellulase production with Y and p values. It thus appears that cellulase is best produced by cells high in ATP and low in Dp and its electrical component DY. There was no obvious relationship between the cellulase titer and the other parameters. Although the physiological significance of such correlations is unknown, the data suggest that further investigation is warranted.     

High-resolution gas chromatographic profiles of volatile organic compounds produced by microorganisms at refrigerated temperatures.

Three different strains of bacteria isolated from spoiled, uncooked chicken were grown in pure culture on Trypticase soy agar supplemented with yeast extract. The volatile organic compounds produced by each culture were concentrated on a porous polymer precolumn and analyzed by high-resolution gas chromatographic mass spectrometry. Twenty different compounds were identified. Both qualitative and quantitative differences in the chromatographic profiles from each culture were found.     

High-resolution gas chromatographic profiles of volatile organic compounds produced by microorganisms at refrigerated temperatures.

Three different strains of bacteria isolated from spoiled, uncooked chicken were grown in pure culture on Trypticase soy agar supplemented with yeast extract. The volatile organic compounds produced by each culture were concentrated on a porous polymer precolumn and analyzed by high-resolution gas chromatographic mass spectrometry. Twenty different compounds were identified. Both qualitative and quantitative differences in the chromatographic profiles from each culture were found.     

The influence of carbon sources and morphology on nystatin production by Streptomyces noursei

Carbon source nutrition and morphology were examined during cell growth and production of nystatin by Streptomyces noursei ATCC 11455. This strain was able to utilise glucose, fructose, glycerol and soluble starch for cell growth, but failed to grow on media supplemented with galactose, xylose, maltose, sucrose, lactose and raffinose. Utilisation of glucose had a negative influence on production of nystatin independent of the specific growth rate when phosphate and ammonium was in excess. Consumption of carbon sources was related to the specific growth rate. S. noursei ATCC 11455 formed mainly mycelial clumps during cultivation, while pellet growth dominated the culture of the morphologically altered high producing mutant S. noursei NG7.19. When the pellet size increased above a critical size, cell growth and nystatin production terminated. Fluorescent staining of hyphae revealed that this coincided with loss of activity inside the core of the pellets, probably due to diffusion limitation of oxygen or other nutrients.     

Wine phenolic compounds influence the production of volatile phenols by wine-related lactic acid bacteria

Aims: To evaluate the effect of wine phenolic compounds on the production of volatile phenols (4‐vinylphenol [4VP] and 4‐ethylphenol [4EP]) from the metabolism of p‐coumaric acid by lactic acid bacteria (LAB). Methods and Results: Lactobacillus plantarum, Lactobacillus collinoides and Pediococcus pentosaceus were grown in MRS medium supplemented with p‐coumaric acid, in the presence of different phenolic compounds: nonflavonoids (hydroxycinnamic and benzoic acids) and flavonoids (flavonols and flavanols). The inducibility of the enzymes involved in the p‐coumaric acid metabolism was studied in resting cells. The hydroxycinnamic acids tested stimulated the capacity of LAB to synthesize volatile phenols. Growth in the presence of hydroxycinnamic acids, especially caffeic acid, induced the production of 4VP by resting cells. The hydroxybenzoic acids did not significantly affect the behaviour of the studied strains. Some of the flavonoids showed an effect on the production of volatile phenols, although strongly dependent on the bacterial species. Relatively high concentrations (1 g l^?1) of tannins inhibited the synthesis of 4VP by Lact. plantarum. Conclusions: Hydroxycinnamic acids were the main compounds stimulating the production of volatile phenols by LAB. The results suggest that caffeic and ferulic acids induce the synthesis of the cinnamate decarboxylase involved in the metabolism of p‐coumaric acid. On the other hand, tannins exert an inhibitory effect. Significance and Impact of the Study: This study highlights the capacity of LAB to produce volatile phenols and that this activity is markedly influenced by the phenolic composition of the medium.     

Effects of different nitrogen sources on the biogas production - a lab-scale investigation

For anaerobic digestion processes nitrogen sources are poorly investigated although they are known as possible process limiting factors (in the hydrolysis phase) but also as a source for fermentations for subsequent methane production by methanogenic archaea. In the present study different complex and defined nitrogen sources were investigated in a lab-scale experiment in order to study their potential to build up methane. The outcome of the study can be summarised as follows: from complex nitrogen sources yeast extract and casamino acids showed the highest methane production with approximately 600ml methane per mole of nitrogen, whereas by the use of skim milk no methane production could be observed. From defined nitrogen sources l-arginine showed the highest methane production with almost 1400ml methane per mole of nitrogen. Moreover it could be demonstrated that the carbon content and therefore C/N-ratio has only minor influence for the methane production from the used substrates.     

The influence of carbon sources and mononucleotides on the production of extracellular alkaline phosphatase by bacillus intermedium

The biosynthesis of extracellular alkaline phosphatase in the streptomycin-resistant strainsBacillus intermedius S3-19 and S7 in the presence in the medium of 5’-nucleoside monophosphates and different sources of carbon—glucose, sodium pyruvate, sodium lactate, or glycerol—was studied. It was established that, in the presence of mononucleotides, the content of extracellular alkaline phosphatase in both strains increased; the maximal effect was caused by 5’-AMP at a concentration of 20μg/ml. In medium with a low orthophosphate content, where active biosynthesis of alkaline phosphatase occurred, 1% glucose and 0.5% pyruvate stimulated this process 2.5–4 times, and 2% sodium lactate and sodium pyruvate, on the contrary, inhibited it by 20–40%. Analysis of the dynamics of growth and accumulation of extracellular phosphatase in the presence of different sources of carbon in the medium gives evidence of an interrelationship between the biosynthesis of alkaline phosphatase and carbon metabolism inBacillus intermedius.     

Influence of different carbon sources on bacterial cellulose production by Gluconacetobacter xylinus strain ATCC 53524

Aims:  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.
Methods and Results:  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 ¹³C 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.
Conclusions:  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.
Significance and Impact of the Study:  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.     

The influence of various carbon and nitrogen sources on oil production byFusarium oxysporum

The oil-synthesizing capacityof Fusarium oxysporum, cultivated on basal nutrient medium, was evaluated using different carbon and nitrogen sources. In one of the media, molasses was also used as a principal carbon source. Media containing glucose and ammonium nitrate were found to be most efficient for oil production. Fatty acid profile of the fungal oil indicated the presence of a wide range of fatty acids ranging from C₈ to C₂₄. Fatty acid composition largely depends on the type of carbon and nitrogen sources.     

Capillary column gas chromatographic profile analysis of volatile compounds in sera of normal and virus-infected patients

Using a transevaporator sampling technique, the volatile profiles from 70 μl of serum were obtained by capillary-column gas chromatography. The complex chromatograms were interpreted by a combination of manual and computer techniques and a two-peak ratio method devised for the classification of normal and virus-infected sera. Using the K-nearest neighbor approach 85.7% of teh unknown samples were classified correctly. Some preliminary results indicate the possible use of the method for the assessment of virus susceptibility.     

Effect of different carbon sources on cellulase production by Hypocrea jecorina (Trichoderma reesei) strains

The ascomycete Hypocrea jecorina, an industrial (hemi)cellulase producer, can efficiently degrade plant polysaccharides. At present, the biology underlying cellulase hyperproduction of T. reesei, and the conditions for the enzyme induction, are not completely understood. In the current study, three different strains of T. reesei, including QM6a (wild-type), and mutants QM9414 and RUT-C30, were grown on 7 soluble and 7 insoluble carbon sources, with the later group including 4 pure polysaccharides and 3 lignocelluloses. Time course experiments showed that maximum cellulase activity of QM6a and QM9414 strains, for the majority of tested carbon sources, occurred at 120 hrs, while RUT-C30 had the greatest cellulase activity around 72 hrs. Maximum cellulase production was observed to be 0.035, 0.42 and 0.33 µmol glucose equivalents using microcrystalline celluloses for QM6a, QM9414, and RUTC-30, respectively. Increased cellulase production was positively correlated in QM9414 and negatively correlated in RUT-C30 with ability to grow on microcrystalline cellulose.     

Optimization of solid-phase microextraction conditions for gas chromatographic determination of ethanol and other volatile compounds in blood

A procedure for the determination of acetaldehyde, acetone, methanol, ethanol, 1-propanol and 2-propanol in blood was developed. Separation of analytes was carried out on DB-wax capillary column (l = 30 m, I.D. = 0.32 mm, dF = 0.5 microm) at 40 degrees C, hydrogen was used as a carrier gas (at 30 kPa) and FID as a detector. Quantification was performed with the use of 2-butanol as an internal standard. Headspace solid-phase microextraction was applied as the sample preparation technique. The usefulness of most commercially available fiber coatings was checked and 65 microm Carbowax/DVB proved most effective. Microextraction was carried out from the headspace at 60 degrees C for 10 min. The sample was stirred at 750 rpm. In order to improve the extraction efficiency of analytes, salting-out agents were also applied. Potassium carbonate turned out to be the most efficient. A 1.0-g amount of this salt and 0.1 ml of I.S. were added to 0.5 ml of sample. Validation of the worked-out method was performed. For each analyte, the limits of detection and quantification, linearity, working range, accuracy and precision were determined or tested.     

The Effect of Nonanal on Dipodascus aggregatus II. Influence of the Prehistory of the Inoculum and of the Presence of Ethanol

Nonanal, added in ethannlic solution, in concentrations lower than 40 to 80 μM did not affect the growth of Dipodascus aggregatus, provided the inoculum had been harvested from the exponential phase of growth. Growth could even be inhibited by 80 μM. If the inoculum had been grown to the exponential phase and then for another period, to the acceleration phase, in fresh liquid medium, growth was strongly promoted by 80 μM nonanal. If cells from the exponential phase were grown for another period in the supernatant fluid of centrifuged cultures from the exponential phase, 80 μM affected growth in the following way: in five different experiments growth was not stimulated, in one experiment undoubtedly promoted, and weakly stimulated in another one. The growth of cultures inoculated with cells grown only on malt agar was not affected by 80 μM nonanal. Pretreatment of cells, harvested from the acceleration phase, with nonanal (80 μM) in the presence of ethanol did not diminish the growth-promoting action of nonanal on the cultures inoculated with these cells. Nonanal, in the absence of ethanol, in a concentration of 10 μM did not affect the growth of cells, harvested from the acceleration phase, whereas 100 μM nonanal strongly inhibited growth. An attempt is made to explain the results starting from the endogenous metabolism.