Influence of carbon source on growth,biochemical composition and pigmentation of Ankistrodesmus convolutus

The unicellular chlorophyte Ankistrodesmus convolutus Corda was grown in the light using inorganic medium (Bold's Basal Medium, BBM) and BBM enriched with 0.1% w/v of glucose, sodium acetate, sodium citrate or sodium bicarbonate. Glucose supported the highest specific growth rate (μ = 0.93 d^-1) and gave the highest biomass (453 mg dry weight L^-1) at the time of harvest. Of four glucose concentrations (0.05, 0.1, 0.25, 0.5% w/v), best growth was attained at 0.1% w/v. At 0.5% w/v glucose, the cells had high carbohydrates but low lipids and proteins. The relative amounts of 16:0, 18:0, 18:1 and 18:2 increased at the expense of 18:3(n-3) in the carbon-supplemented cultures and at glucose concentrations higher than 0.1% w/v. Cultures grown on glucose had less chlorophyll and carotenoid contents than cultures grown on other carbon sources. Chlorophyll and carotenoid contents decreased with increasing glucose concentrations in the medium.     

Effects of the detergent Tween 80 on Thermomonospora curvata

Tween 80 (0.1%, v/v) added to Thermomonospora curvata growing in minimal medium caused a transient lowering of the dry cell mass, decreased the optimal growth temperature of the thermophile from 62 to 54°C, and increased extracellular esterase activity. Cells grown in the presence of Tween 80 had decreased concentrations of branched chain fatty acids and increased concentrations of oleic acid. The detergent removed surface protuberances from mycelia and increased the liberation of enzymes active against crystalline cellulose, but did not stimulate liberation of enzymes active against carboxymethylcellulose, starch or pectin.     

Effect of carbon source and sucrose concentration on growth and hexose accumulation of grape berries cultured in vitro

Using in vitro culture of isolated small berries of Vitis vinifera L. cv. Sultana, it was possible to study the effect of different carbon sources and sucrose concentration on fruit growth, hexose accumulation and soluble invertase activity during the first stage of berry development by eliminating the source tissue. Berries cultured in vitro lack stage III of berry development which is characterised by massive accumulation of water and sugars, and thereby berries reached only 30% of the weight of those grown in the plant. Sucrose and glucose were both good carbon sources for berry growth, while fructose was not as good. Berry growth, hexose accumulation and invertase activity increased as sucrose concentration increased up to 15% in the medium. Furthermore, the onset of hexose accumulation in cultured berries depended on the concentration of sucrose in the medium, starting earlier at higher concentrations. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of carbon source on growth,nitrogenase and uptake hydrogenase activities of Frankia isolates from Casuarina sp.

The effect of different carbon sources on the growth of Frankia isolates for Casuarina sp. was studied. In addition, regulation of nitrogenase and uptake hydrogenase activity by carbon sources was investigated. For each of the three isolates, JCT287, KB5 and HFPCcI3, growth was greatest on the carbon sources pyruvate and propionate. In general the carbon sources which gave the greatest growth gave the highest levels of nitrogenase activity, but repressed the activity of uptake hydrogenase. The regulation of growth, uptake hydrogenase activity and nitrogenase activity is discussed.     

Effect of growth temperature on the fatty acid composition of Mycobacterium phlei

In Mycobacterium phlei, fatty acid unsaturation increased with decreasing temperature. The 10-hexadecenoic acid content increased as the temperature was reduced from 35°C to 26–20°C. At lower temperatures tuberculostearic acid decreased while oleic and linoleic acids increased, the latter being found in M. phlei for the first time. Concomitantly palmitic acid content decreased, and the 6- and 9-hexadecenoic acids increased slightly on reducing the temperature from 35 to 10°C. Thus, down to 26–20°C palmitic acid was mainly replaced by 10-hexadecenoic acid. From this range down to 10°C, palmitic and tuberculostearic acids were replaced by oleic and linoleic acids. Consequently, fatty acid branching decreased and mean chain length increased, as the temperature was reduced. These observations support the view that regulation of membrane fatty acid composition is part of microbial temperature adaptation, and that themechanism behind the responses might be more complex than generally believed.Abbreviations ACP acyl carrier protein - FAS I (Type I) fatty acid synthetase I - FAS II (Type II) fatty acid synthetase II - MGLP methylglucose containing lipopolysaccharide - MMP methylmannose containning polysaccharide     

Extracellular enzyme production byThermomonospora curvata grown on bagasse

Summary Extracellular enzyme production by the actinomycete,Thermomonospora curvata, was characterized during growth at 55°C on bagasse as sole carbon source. Mycelia adhered to the bagasse fibers during early growth and were released in mature cultures. Extracellular protein reached a maximum on 4% (w/v) bagasse and yielded an electrophoretic profile similar to those produced on purified cellulose. Cellulase production on bagasse exceeded that observed forT. curvata on any previously employed substrate. Amylase and pectinase, which were diminished by their instability in culture fluid at growth temperature and by the lack of inducing substrate, were readily inducible by addition of starch or pectin, respectively. Extracellular activities of -glucosidase and -xylosidase remained insignificant throughout growth. Xylanase production equaled or exceeded that observed on a variety of other substrates. The combined activity of extracellular enzymes from bagasse-grownT. curvata caused a 27% solubilization of the fiber, yielding a mixture of cellooligosaccharides, cellobiose, xylobiose, glucose, xylose, fructose, arabinose and mannitol. Fractionation of concentrated extracellular proteins by size exclusion chromatography yielded single peaks for amylase and pectinase (estimated molecular weights of 58 K and 34 K respectively), while cellulase and xylanase activities were distributed throughout a series of multiple unresolved peaks spanning a molecular weight range of 26–180 K.     

Optimization of growth and fatty acid composition of a unicellular marine picoplankton,Nannochloropsis sp., with enriched carbon sources

A unicellular marine picoplankton, Nannochloropsis sp., was grown under CO₂-enriched photoautotrophic or/and acetate-added mixotrophic conditions. Photoautotrophic conditions with enriched CO₂ of 2800 l CO₂ l^–1 and aeration gave the highest biomass yield (634 mg dry wt l^–1), the highest total lipid content (9% of dry wt), total fatty acids (64 mg g^–1 dry wt), polyunsaturated fatty acids (35% total fatty acids) and eicosapentaenoic acid (EPA, 20:53) (16 mg g^–1 dry wt or 25% of total fatty acids). Mixotrophic cultures gave a greater protein content but less carbohydrates. Adding sodium acetate (2 mM) decreased the amounts of the total fatty acids and EPA. Elevation of CO₂ in photoautotrophic culture thus enhances growth and raises the production of EPA in Nannochloropsis sp.     

Influence of culture temperature on the growth,biochemical composition and fatty acid profiles of six Antarctic microalgae

The growth, biochemical composition and fatty acid profiles of six Antarctic microalgae cultured at different temperatures, ranging from 4, 6, 9, 14, 20 to 30 ^∘C, were compared. The algae were isolated from seawater, freshwater, soil and snow samples collected during our recent expeditions to Casey, Antarctica, and are currently deposited in the University of Malaya Algae Culture Collection (UMACC). The algae chosen for the study were Chlamydomonas UMACC 229, Chlorella UMACC 234, Chlorella UMACC 237, Klebsormidium UMACC 227, Navicula UMACC 231 and Stichococcus UMACC 238. All the isolates could grow at temperatures up to 20 ^∘C; three isolates, namely Navicula UMACC 231 and the two Chlorella isolates (UMACC 234 and UMACC 237) grew even at 30 ^∘C. Both Chlorella UMACC 234 and Stichococcus UMACC 238 had broad optimal temperatures for growth, ranging from 6 to 20 ^∘C (μ = 0.19 – 0.22 day^–1) and 4 to 14 ^∘C (μ = 0.13 – 0.16 day^–1), respectively. In contrast, optimal growth temperatures for NaviculaUMACC 231 and Chlamydomonas UMACC 229 were 4 ^∘C (μ = 0.34 day^–1) and 6–9 ^∘C (μ = 0.39 – 0.40 day^–1), respectively. The protein content of the Antarctic algae was markedly affected by culture temperature. All except Navicula UMACC 231 and Stichococcus UMACC 238 contained higher amount of proteins when grown at low temperatures (6–9 ^∘C). The percentage of PUFA, especially 20:5 in Navicula UMACC 231 decreased with increasing culture temperature. However, the percentages of unsaturated fatty acids did not show consistent trend with culture temperature for the other algae studied.     

Effect of growth temperature and media composition on the fatty acid composition of Bacillus stearothermophilus AN 002

The influence of growth temperature, media composition and cell age on the chemical composition of Bacillus stearothermophilus strain AN 002 has been determined. The total cellular protein decreased and the free amino acid content increased with growth temperature, in both exponential and stationary growth phase. The protein and free amino acid contents of cells were higher in the stationary phase than in the exponential phase, irrespective of growth temperature and media composition. The RNA content was only reduced in cells grown at 55° C. No significant variations were observed in the DNA and carbohydrate contents with respect to growth temperature and cell age. The total lipid and fatty acid compositions on the other hand varied as a function of growth temperature, cell age and media composition. Differences in the relative concentrations of even, odd and branched chain fatty acids were noticed. Novariation was observed in the antiiso and unsaturated fatty acids with respect to growth temperature. The unique variations in the fatty acid composition and total lipids at the growth temperature of 50° C and their variations in the stationary growth phase seem to be characteristic for B. stearothermophilus AN 002.     

Effect of carbon source and pH of the growth medium on spore germination inPhycomyces blakesleeanus

Phycomyces blakesleeanus sporangiospores responded differently to activation by physical and chemical stimuli. Spores that were physically (heat shock) activated or chemically (ammonium acetate) activated germinated and grew at pH 4.5 with the hexoses glucose, fructose, galactose, andN-acetylglucosamine, and with glycerol and amino acids. Under these conditions, physically activated spores showed a lower, although significant growth with the hexoses fructose, galactose,N-acetylglucosamine and with glycerol. On the other hand, physically activated spores incubated at alkaline pH (pH 7.3) required glucose to germinate; a requirement not observed with chemically activated spores, which showed significant growth in the other hexoses tested. Both physically and chemically activated spores incubated at pH 7.3 were unable to germinate and grow with amino acids and glycerol. These results suggest that there are different targets for activation of the spores by physical and chemical treatments. The levels of the fermentative enzymes alcohol dehydrogenase and lactate dehydrogenase and of the oxidative enzyme NAD⁺-isocitrate dehydrogenase were higher in cells grown at pH 4.5 in medium containing glucose; however, alcohol dehydrogenase and lactate dehydrogenase appear not to be affected by a change in the pH of the growth medium.     

Effect of carbon source and dissolved oxygen level on cell growth and pullulanase production byBacillus stearothermophilus G-82

Cell growth and extracellular pullulanase production ofBacillus stearothermophilus G-82 were investigated in batch culture using a defined medium with glucose, maltose, pullulan or amylopectin as carbon source. Maximum enzyme activity was with pullulan or amylopectin. Cell growth in batch culture was better under oxygen unlimited conditions, while higher total and specific enzyme activities, using pullulan or amylopectin, were obtained in oxygen-limited conditions. Enzyme accumulation took place in the late growth phase. The highest enzyme production of 300 U/I was reached when pullulan was used as carbon source in conditions of oxygen limitation.     

Complete genome sequence of Thermomonospora curvata type strain (B9)

Thermomonospora curvata Henssen 1957 is the type species of the genus Thermomonospora. This genus is of interest because members of this clade are sources of new antibiotics, enzymes, and products with pharmacological activity. In addition, members of this genus participate in the active degradation of cellulose. This is the first complete genome sequence of a member of the family Thermomonosporaceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 5,639,016 bp long genome with its 4,985 protein-coding and 76 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Effect of temperature on the viability of Bacillus stearothermophilus

One of the obligate thermophilic bacteria, Bacillus stearothermophilus, was unable to grow at temperatures below 35° C. About 80% of the population in the bacterial culture died at the temperatures, and the same extent of loss in either of the activities of oxygen consumption or synthesis of protein or nucleic acid of the organisms was observed. With the progress of death of the organisms, reduced nicotinamide-adenine dinucleotide came to be oxidized by the organisms, enzymes such as fructose-1,6-diphosphate aldolase, when the organisms were washed with phosphate buffer, were leaked out of the organisms, and an increasing amount of ribonucleoprotein was released into the culture medium. The change of the membrane state was then suggested to be one of the possible causes for the death of the organisms at the temperatures.     

Comparison of acetate- and pyruvate-dependent fatty-acid synthesis by spinach chloroplasts

In recent studies using intact chloroplasts of spinach (Spinacia oleracea L.) to investigate the accumulation of acetyl-CoA produced by the activity of either acetyl-CoA synthetase (EC 6.2.1.1) or the pyruvate-dehydrogenase complex, this product was not detectable. These results in combination with new information on the physiological levels of acetate and pyruvate in spinach chloroplasts (H.-J. Treede et al. 1986, Z. Naturforsch. 41 C, 733–740) prompted a reinvestigation of the incorporation of [1-¹⁴C] acetate and [2-¹⁴C] pyruvate into fatty acids at physiological concentrations.The K _m for the incorporation into fatty acids was about 0.1 mM for both metabolites and thus agreed with the values obtained by H.-J. Treede et al. (1986) for acetyl-CoA synthetase and the pyruvate dehydrogenase complex. However, acetate was incorporated with a threefold higher V _max. Saturation for pyruvate incorporation into the fattyacid fraction was achieved only at physiological pyruvate concentrations (<1.0 mM). The diffusion kinetics observed at higher concentrations may be the result of contamination with derivates of the labeled substrate. Competition as well as double-labeling experiments with [³H]acetate and [2-¹⁴C]pyruvate support the notion that, at least in spinach, chloroplastic acetate is the preferred substrate for fatty-acid synthesis when both substrates are supplied concurrently (P.G. Roughan et al., 1979 b, Biochem. J. 184, 565–569).Experiments with spinach leaf discs confirmed the predominance of fatty-acid incorporation from acetate. Radioactivity from [1-¹⁴C]acetate appeared to accumulate in glycerolipids while that from [2-¹⁴C]pyruvate was apparently shifted in favor of the products of prenyl metabolism.Abbreviations Chl chlorophyll - TLC thin-layer chromatography     

Influence of growth phase and carbon source on the content of rubredoxin in Acinetobacter calcoaceticus

The rubredoxin content of Acinetobacter calcoaceticus in dependence on the carbon source (acetate, n-alkanes, succinate, L-malate) and on the growth phase was studied by means of a radioimmunoassay. The method used was specific for rubredoxin from Acinetobacter calcoaceticus. The formation of rubredoxin increased with time up to the end of the logarithmic phase when n-alkanes were the sole carbon source. After growth of Acinetobacter calcoaceticus on non-hydrocarbon substrates, rubredoxin was not detected.     

Effects of carbon concentration and carbon to nitrogen ratio on the growth and sporulation of several biocontrol fungi

Effects of carbon concentration and carbon to nitrogen (C:N) ratio on six biocontrol fungal strains are reported in this paper. All fungal strains had extensive growth on the media supplemented with 6–12 g l⁻¹ carbon and C:N ratios from 10:1 to 80:1, and differed in nutrient requirements for sporulation. Except for the two strains of Paecilomyces lilacinus, all selected fungi attained the highest spore yields at a C:N ratio of 160:1 when the carbon concentration was 12 g l⁻¹ for Metarhizium anisopliae SQZ-1-21, 6 g l⁻¹ for M. anisopliae RS-4-1 and Trichoderma viride TV-1, and 8 g l⁻¹ for Lecanicillium lecanii CA-1-G. The optimal conditions for P. lilacinus sporulation were 8 g l⁻¹ carbon with a C:N ratio of 10:1 for M-14 and 12 g l⁻¹ carbon with a C:N ratio of 20:1 for IPC-P, respectively. The results indicated that the influence of carbon concentration and C:N ratio on fungal growth and sporulation is strain dependent; therefore, consideration for the complexity of nutrient requirements is essential for improving yields of fungal biocontrol agents.     

Effect of carbon and nitrogen sources on growth and solasodine production in batch suspension cultures of Solanum eleagnifolium Cav.

The effect of inoculum size, carbon sources (fructose, glucose, maltose, sucrose), nitrate and ammonia on solasodine production by Solanum eleagnifolium Cav. was studied. The specific growth rate was estimated to be 0.15–0.20 d^-1 with all sugars tested at a concentration of 90 mM. Sucrose (180 mM) produced the highest biomass value (about 2.8 mg DW ml^-1) while the lowest one was produced by maltose. Although solasodine productivity values after 11 days of culture were similar for all sugars tested, the maximum values of productivity (0.9 mg g^-1 d^-1) were achieved after 6 days of culture with sucrose (180 mM). Solasodine productivity of cultures conducted with a large inoculum (20% w/v fresh material) was double that with a small inoculum (10% w/v fresh material).     

Effect of salinity of medium on cellular fatty acid composition of marine algaPorphyridium cruentum (Rhodophyceae)

Porphyridium cruentum Näg. (clone 161) was found to grow best in medium containing between 0.45 M and 0.8 M NaCl. From studies done on growing cultures, the palmitic acid content of the cells decreased with increasing NaCl concentration of the medium. Conversely, when the culture was transferred from a 0.8 M NaCl medium to 0.2 M NaCl, the amount of palmitic acid in thePorphyridium cells increased with time of incubation and it contributed up to 64.5% of the total fatty acid content. There appears to be a negative correlation between the cellular content of palmitic acid and the growth lag. The oleic acid content varied only marginally with increasing NaCl concentration. The poly-unsaturated acid content (linolenic and arachidonic acids) decreased initially and then increased with NaCl concentration up to and beyond ca. 0.8 M NaCl respectively. At 1.5 M NaCl, the poly-unsaturated fatty acids amounted to 78.2% of the total fatty acids in the cell. For stationary phaseP. cruentum cultures, a similar relationship existed between fatty acids and NaCl concentration. However, palmitic acid was accumulated up to three-fold more when compared to the exponential culture grown in low salinity. In addition stearic acid was also found in significant quantities.