培养基和培养条件对栀子悬浮细胞合成多糖的影响

对栀子悬浮细胞合成多糖的调控因子研究表明 :B5为最适培养基 ;5～10d继代周期的细胞可以保持良好的生长状态和多糖的合成能力 ;80g L的鲜细胞的接种量有利于栀子细胞的生长和多糖的合成 ;使用单一碳源时 ,葡萄糖比蔗糖对细胞生长更有益 ,但葡萄糖成本高 ,因而混合碳源 45g L(葡萄糖 :蔗糖 =1∶1)是最佳配方 ;氮源种类对细胞生长和多糖合成没有明显的影响 ,但氮源浓度是主要因素 ,40～50mmol L是最佳浓度 ,同时运用悬浮细胞生产栀子多糖可以通过在不同时间收获的细胞来避免提取时黄色素的干扰 ,具有很好的实际意义。     

Occurrence of a capsule in Aeromonas salmonicida

Aeromonas salmonicida grown in a medium with excess glucose as carbon source produces both capsular and exocellular polysaccharides. The capsular polysaccharide is composed of glucose, mannose, rhamnose, N-acetylmannosamine and mannuronic acid in the molar ratios of approximately 5:3:0.75:2:1. The extracellular polysaccharide is similarly constituted, but in the molar ratios of approximately 4.75:10.5:1.5:2:1. The capsular and exocellular polysaccharides did not cross-react with monoclonal antibodies against the A-layer or the O-antigen lipopolysaccharide.     

Polysaccharide production in liquid cell suspension cultures of Phleum pratense L.

The production of carbohydrates by cell suspension cultures of Phleum pratense (timothy grass) is described. Extracellular polysaccharides similar in monosaccharide composition to native cell wall polymers were accumulated, together with polymers of fructose (fructans). The fructans had similar properties to the intracellular reserve polymers found in intact plants, and were found in both cells and media of young, slow-growing cultures.Production of extracellular polysaccharides differed in cultures grown on sucrose or equimolar glucose/fructose as carbon source. These differences were observed only when autoclaved media were used, and were not related to changes in either pH or osmolarity. Autoclaving medium containing radioactive glucose and fructose produced a novel, unidentified labelled compound which was absent in medium containing labelled sucrose.     

Extracellular polysaccharide production byRhizobium ciceri from Turkey

The ability of theRhizobium ciceri, to produce extracellular polysaccharides (EPS) was investigated. Tested carbon and nitrogen sources influced EPS synthesis whenR. ciceri Rc5 was grown in a chemically defined medium. Mannitol was the most efficient carbon source among the six sources tested (sucrose, glucose, arabinose, fructose, xylose and rhamnose) and sodium nitrate was the most efficient nitrogen source among the two tested (ammonium sulphate and glycine). High amounts of EPS (1182.0 and 1015 μg ml−1, respectively) were produced by the Rc5 strain in mannitol and sodium nitrate respectively, which was accompanied by a great increase in the production compared to the control.     

Temporal accumulation of mannitol and arabitol in Geotrichum candidum

The temporal depletion and accumulation of polyols were investigated in the fungus Geotrichum candidum. The major intracellular polyols were tentatively identified by paper chromatography as mannitol and arabitol. Inositol was also present in small quantities, and trehalose was also detected in appreciable concentrations.Germination and vegetative growth depended on the type and concentration of the sole exogenous carbon source. Mannitol occurred in arthrospores at 9.4% of the dry weight after several days growth in 2% (w/v) glucose solid medium, and became depleted during germination and vegetative growth in liquid medium containing 2% (w/v) glucose, 2% (w/v) sodium acetate or 25% (w/v) glucose as sole carbon source. This hexitol latter accumulated during arthrosporulation. The depletion and accumulation of ethanol-soluble carbohydrate believed to be primarily trehalose was temporally similar to that of mannitol. Arabitol accumulated intracellularly during germination and vegetative growth in sodium acetate medium and 25% glucose medium. This pentitol was not detected intracellularly at any culture age during growth in 2% glucose medium.Prolonged incubation of the culture in 25% glucose medium after stationary phase was reached resulted in the gradual disappearance of arabitol from the arthrospores simultaneously with an increase in intracellular mannitol. In comparison, ethanol-soluble carbohydrate did not change with prolonged incubation in this medium.     

The production of extracellular polysaccharides by a hydrocarbon assimilating yeast.

Investigations were made on the extracellular polysaccharides production by a hydrocarbon assimilating yeast. The yeast Candida lipolytica was grown on two different media containing n-hexadecane as the sole carbon source. Polymeric materials precipitated from the culture medium with ethanol were determined gravimetrically at various growth periods. The hydrolysis of the precipitated material and their chromatographic analysis revealed the presence of mannose, glucose and galactose in the yeast extract-containing medium. The proportions of these sugars differed at various growth periods. The hydrolysates of the polymers of the yeast extract-free medium contained more xylose than those of the yeast extract containing medium.     

Production of Extracellular Polysaccharide by a Rhizobium Species from Root Nodules of the Leguminous Tree Dalbergia lanceolaria

The ability of the Rhizobium D1 10 species, which was isolated from the root nodules of the leguminous forest tree Dalbergia lanceolaria, for the production of extracellular polysaccharides (EPS) was investigated. High amounts of EPS (765 μg/mL) were produced by the bacteria (Rhizobium D1 10) in yeast extract mannitol medium. Both growth and EPS production started simultaneously, but the EPS production was at its maximum in the stationary phase of growth at 32 h. The EPS production was maximal when the medium was supplemented with mannitol (2 %), thiamine hydrochloride (1 μg/mL) and KNO₃ (0.1 %), which was accompanied by a great increase in the production compared to the control. The EPS contained xylose, rhamnose, glucose, galactose and arabinose. The possible role of rhizobial EPS production in root nodule symbiosis is discussed.     

N-Acetyl-d-Glucosamine-Mediated Regulation of Extracellular Protease in the Entomopathogenic Fungus Beauveria bassiana

The entomopathogenic fungus Beauveria bassiana GK2016 grown in a liquid medium incorporating gelatin as the sole carbon and nitrogen source produced an extracellular serine protease (molecular weight, 35,000; pI ca. 10). Without gelatin, B. bassiana could utilize N-acetyl-d-glucosamine (GlcNAc; 2-acetamido-2-deoxy-d-glucose) as the sole source of carbon and nitrogen, and GlcNAc availability increased the storage carbohydrate content in mycelia. Synthesis of protease was repressed in gelatin medium containing GlcNAc at levels of >1.07 mumol mg of fungal dry weight. At levels below this, protease synthesis was initiated; subsequently, free amino nitrogen appeared in the medium and diauxic growth was observed. Slow feeding with GlcNAc (35.34 mug ml h) did not repress protease synthesis nor did GlcNAc accumulate in the medium above 0.5 mg ml. Increasing the rate of release of GlcNAc (83.51 mug ml h) resulted in the accumulation of GlcNAc in the medium to 2.0 mg ml, a 45% increase in growth and a decrease in protease synthesis by about 81%. Free amino acids generated from the hydrolysis of gelatin did not repress protease synthesis. These data are interpreted in terms of known interaction of B. bassiana with insect cuticular components. We suggest that the action of extracellular chitinases synthesized by B. bassiana on insect cuticle, and pursuant release of GlcNAc, may have important consequences on the regulation of other extracellular catabolic enzymes such as the protease.     

Fractionation of the beta-Linked Glucans of Bradyrhizobium japonicum and Their Response to Osmotic Potential

Bradyrhizobium japonicum USDA 110 synthesized both extracellular and periplasmic polysaccharides when grown on mannitol minimal medium. The extracellular polysaccharides were separated into a high-molecular-weight acidic capsular extracellular polysaccharide fraction (90% of total hexose) and three lower-molecular-weight glucan fractions by liquid chromatography. Periplasmic glucans, extracted from washed cells with 1% trichloroacetic acid, gave a similar pattern on liquid chromatography. Linkage analysis of the major periplasmic glucan fractions demonstrated mainly 6-linked glucose (63 to 68%), along with some 3,6- (8 to 18%), 3- (9 to 11%), and terminal (7 to 8%) linkages. The glucose residues were beta-linked as shown by H-nuclear magnetic resonance analysis. Glucan synthesis by B. japonicum cells grown on mannitol medium with 0 to 350 mM fructose as osmolyte was measured. Fructose at 150 mM or higher inhibited synthesis of periplasmic and extracellular 3- and 6-linked glucans but had no effect on the synthesis of capsular acidic extracellular polysaccharides.     

An Inhibitor-Based Method To Measure Initial Decomposition of Naturally Occurring Polysaccharides in Sediments

A method that can be used to measure the initial decomposition rates of polysaccharides in sediment samples was developed. It uses toluene to specifically inhibit microbial uptake of carbohydrates without affecting extracellular hydrolysis of polysaccharides. Accumulating carbohydrates were determined by high-performance liquid chromatography. Field-sampled litter from the common reed (Phragmites australis), which contains cellulose and arabinoxylan as its main polysaccharides, was used as a model system. Toluene concentrations of between 1 and 10% resulted in the accumulation of similar amounts of monomeric carbohydrates, which was linear over time for most neutral sugars. Toluene (3%) did not have an effect on extracellular enzyme activities, and microbial sugar uptake was completely inhibited, as demonstrated with (sup14)C-labelled xylose and glucose. Experiments with enhancement cultures and fixed reed litter suggested that enzymatic hydrolysis of polysaccharides in reed litter was the main source of glucose, xylose, arabinose, and galactose accumulation. In contrast, the accumulation of high amounts of the alditols mannitol and glucitol was probably caused by lysis of the microbial population in toluene-treated reed litter. Glucose accumulated at rates of 1.3 and 0.10 (mu)mol (middot) g of dry matter content(sup-1) (middot) h(sup-1) under aerobic and anaerobic conditions, respectively, whereas xylose accumulation rates were only 10% of the glucose accumulation rates.     

Formation and utilisation of carbon reserves by Rhizobium

The accumulation and utilisation of poly-β-hydroxybutyrate (PHB) and extracellular polysaccharide (ECPS) have been studied in Rhizobium NZP 2037 and it was found that PHB synthesis was slow during growth whereas ECPS formation was not affected. PHB synthesis only was dependent on the pH of the medium. PHB and ECPS were both used as carbon sources in the absence of other exogenous carbon. ECPS when given to starved cells as sole carbon source in the absence of nitrogen was used for PHB synthesis by the organism. In the presence of nitrogen ECPS was found to support growth. The extracellular breakdown of ECPS was demonstrated and was accompanied by the release of its constituent glucose. This was favoured by low pH.     

Isolation and characterization of agar-degrading Paenibacillus spp. associated with the rhizosphere of spinach

Agar-degrading bacteria in spinach plant roots cultivated in five soils were screened, and four strains of Paenibacillus sp. were isolated from roots cultivated in three soils. The agar-degrading bacteria accounted for 1.3% to 2.5% of the total bacteria on the roots. In contrast, no agar-degrading colony was detected in any soil (non-rhizosphere soil samples) by the plate dilution method, and thus these agar-degrading bacteria may specifically inhabit plant roots. All isolates produced extracellular agarase, and could grow using agar in the culture medium as the sole carbon source. Zymogram analyses of agarase showed that all four isolates extracellularly secreted multiple agarases (75-160 kDa). In addition, the isolates degraded not only agar but also various plant polysaccharides, i.e., cellulose, pectin, starch, and xylan.     

Role of pH and Nitrogen Limitation in the Elaboration of the Extracellular Polysaccharide Pullulan by Pullularia pullulans

During the growth of the yeastlike fungus Pullularia pullulans on glucose as sole carbon source, the cell-mass does not increase concomitantly with the elaboration of the extracellular polysaccharide pullulan, but precedes it. The conditions generated in the culture medium which activate the secretion of polysaccharide have been sought for, and, in particular, the roles of extracellular pH and nitrogen limitatation are examined.     

Identification of L-altrose in the extracellular polysaccharide from Butyrivibrio fibrisolvens strain CF3

Abstract Butyrivibrio fibrisolvens strain CF3, a stricyly anaerobic bacterial isolate from the ovine cecum, produces extracellular polysaccharides (EPS) when grown on a defined medium containing glucose as the carbon source. EPS were purified from culture supernatants and their monosaccharide composition was determined by two different procedures. Analysis of EPS hydrolysates by thin-layer chromatography (TLC) yielded spots coincident with standard glucose, altrose, and 1,6-anhydroaltrose. These results were corroborated by both gas-liquid chromatography (GLC) and GLC-mass spectroscopy (GLC-MS) of alditol acetates prepared from EPS hydrolysates. Purification of the altrose from EPS hydrolysates was accomplished by preparative paper and column chromatography. Polarimetry demonstrated the isolated altrose to have the L -configuration. The occurrence of this hexose in nature has not yet been reported.     

Isolation and Characterization of Agar-degrading Paenibacillus spp. Associated with the Rhizosphere of Spinach

Agar-degrading bacteria in spinach plant roots cultivated in five soils were screened, and four strains of Paenibacillus sp. were isolated from roots cultivated in three soils. The agar-degrading bacteria accounted for 1.3% to 2.5% of the total bacteria on the roots. In contrast, no agar-degrading colony was detected in any soil (non-rhizosphere soil samples) by the plate dilution method, and thus these agar-degrading bacteria may specifically inhabit plant roots. All isolates produced extracellular agarase, and could grow using agar in the culture medium as the sole carbon source. Zymogram analyses of agarase showed that all four isolates extracellularly secreted multiple agarases (75-160 kDa). In addition, the isolates degraded not only agar but also various plant polysaccharides, i.e., cellulose, pectin, starch, and xylan.     

Phenol degradation by immobilized cold-adapted yeast strains of Cryptococcus terreus and Rhodotorula creatinivora

Three strains were isolated from hydrocarbon-polluted alpine habitats and were representatives of Cryptococcus terreus (strain PB4) and Rhodotorula creatinivora (strains PB7, PB12). All three strains synthesized and accumulated glycogen (both acid- and alkali-soluble) and trehalose during growth in complex medium containing glucose as carbon source and in minimal salt medium (MSM) with phenol as sole carbon and energy source. C. terreus strain PB4 showed a lower total accumulation level of storage compounds and a lower extracellular polysaccharides (EPS) production than the two R. creatinivora strains, PB7 and PB12. Biofilm formation and phenol degradation by yeast strains attached to solid carriers of zeolite or filter sand were studied at 10°C. Phenol degradation by immobilized yeast strains was always higher on zeolite compared with filter sand under normal osmotic growth conditions. The transfer of cells immobilized on both solid supports to a high osmotic environment decreased phenol degradation activity by all strains. However, both R. creatinivora PB7 and PB12 strains maintained higher ability to degrade phenol compared with C. terreus strain PB4, which almost completely lost its phenol degradation activity. Moreover, R. creatinivora strain PB7 showed the highest ability to form biofilm on both carriers under high osmotic conditions of cultivation.     

Enzymatic production of l-phenylalanine from acetamidocinnamic acid: breeding of an acetamidocinnamate amidohydrolase-hyperproducing mutant

To increase the productivity of l-phenylalanine from acetamidocinnamic acid, we screened bacteria containing high acetamidocinnamate amidohydrolase activity, and strain S-5 containing high activity was isolated from soil. The bacteria were identified as Corynebacterium sp. S-5.When strain S-5 was cultured in a medium containing acetamidocinnamic acid as the sole carbon source or enzyme inducer, the formation of acetamidocinnamate amidohydrolase was observed. This was controlled by catabolite repression. When the strain was cultured in a medium containing glucose and acetamidocinnamic acid as the sole nitrogen source, it showed low acetamidocinnamate amidohydrolase activity and an increased doubling time.To obtain acetamidocinnamate amidohydrolase-hyperproducing strain, we enriched cells growing faster than strain S-5 in a medium containing glucose and acetamidocinnamic acid by continuous culture of mutagenized cells. Mutant C-23 had 12-fold the enzyme production and 3-fold the growth rate of the wild-type strain in a medium containing glucose. Acetamidocinnamate amidohydrolase formation in the mutant did not require acetamidocinnamic acid as enzyme inducer and was resistant to catabolite repression.     

Fractionation of the β-Linked Glucans of Bradyrhizobium japonicum and Their Response to Osmotic Potential

Bradyrhizobium japonicum USDA 110 synthesized both extracellular and periplasmic polysaccharides when grown on mannitol minimal medium. The extracellular polysaccharides were separated into a high-molecular-weight acidic capsular extracellular polysaccharide fraction (90% of total hexose) and three lower-molecular-weight glucan fractions by liquid chromatography. Periplasmic glucans, extracted from washed cells with 1% trichloroacetic acid, gave a similar pattern on liquid chromatography. Linkage analysis of the major periplasmic glucan fractions demonstrated mainly 6-linked glucose (63 to 68%), along with some 3,6- (8 to 18%), 3- (9 to 11%), and terminal (7 to 8%) linkages. The glucose residues were β-linked as shown by ¹H-nuclear magnetic resonance analysis. Glucan synthesis by B. japonicum cells grown on mannitol medium with 0 to 350 mM fructose as osmolyte was measured. Fructose at 150 mM or higher inhibited synthesis of periplasmic and extracellular 3- and 6-linked glucans but had no effect on the synthesis of capsular acidic extracellular polysaccharides.     

Gene sequence analysis and properties of EGC, a family E (9) endoglucanase from Fibrobacter succinogenes BL2

Abstract β-Glucosidase in Aspergillus nídulans was found to be both intracellular and extracellular. The intracellular β-glucosidase was synthesized after the exhaustion of carbon source in the medium. The extracellular enzyme appeared with autolysis of the mycelium. Biosynthesis of β-glucosidase was not induced by various carbohydrates but repressed to varying extents in the presence of glucose, glycerol, and 2-deoxyglucose. This repression was not relieved by addition of cAMP. The repression was relieved much more by mutations in the creA gene than by one in the creC gene. Thus, β-glucosidase synthesis in A. nidulans is subject to carbon catabolite repression.