Separation of membranes by flotation centrifugation for in vitro synthesis of plant cell wall polysaccharides

Summary Membranes from etiolated maize seedlings were isolated using sucrose gradients for in vitro studies of polysaccharide synthesis. Following downward centrifugation, flotation centrifugation improved the purity of membrane fractions, in particular the Golgi apparatus. Based on naphthylphthalamic acid binding to plasma membrane and inosine-5-diphosphatase activity in Golgi apparatus, flotation centrifugation removed about 70% of the plasma membrane which cosedimented with the Golgi apparatus in downward centrifugation. The addition of chelators during flotation centrifugation allowed separation of the Golgi apparatus from endoplasmic reticulum, as indicated by NADH cytochromec reductase activity. Glucan and xylan synthase activities were measured as the radioactivity incorporated from either UDP-¹⁴C-glucose or UDP-¹⁴C-xylose into 80% ethanol insoluble materials. Glucan synthase activity at a substrate concentration of 1 mM UDP-glucose without CaCl₂ was greatest in fractions enriched in Golgi apparatus, but in the presence of 3 mM CaCl₂ the activity was greatest in fractions enriched in plasma membrane. Glucan synthase activity at a substrate concentration of 10M UDP-glucose in the presence of 3 mM MnCl₂ was greatest in fractions enriched in plasma membrane, but was also high in fractions enriched in Golgi apparatus. Xylan synthase activity, at a substrate concentration of 1 M UDP-xylose in the presence of 3 mM MnCl₂, was greatest in fractions enriched in Golgi apparatus. To further characterize these synthase reactions, the glycosyl linkages of the products formed were analyzed with a gas chromatograph coupled to a radiogas proportional counter. With the substrate, UDP-¹⁴C-glucose, and fractions enriched in Golgi apparatus, both (13)- and (14)-radioactive glucosyl linkages were formed, whereas the main linkage formed by fractions enriched in plasma membrane was (13)-glucosyl. With the substrate, UDP-¹⁴C-xylose, mostly (14)-xylosyl and some terminal-xylosyl linkages were formed by fractions enriched in Golgi apparatus. Only xylan synthase activity copurified with Golgi apparatus and, because plasma membrane lacked this activity, xylan synthase may be used as a reasonable indicator of Golgi apparatus.Abbreviations ATP adenosine-5-triphosphate - CR crude fraction from downward centrifugation - FL purified fraction from flotation centrifugation - GC gas chromatography - GC-RPC gas chromatography-radiogas proportional counting - IDP inosine-5-disphosphate - NPA naphthylphthalamic acid - UDP uridine-5-diphosphate - TEM transmission electron microscopy     

Histoenzymatic characterization of sub-types of Type I fibres in fast muscles of rats

Summary The histochemical activities of succinic dehydrogenase (SDH), myofibrillar Adenosine triphosphatase (ATPase) and alpha glycerophosphate dehydrogenase were studied in serial sections of rat vastus lateralis (red) (RVL), gastrocnemius and diaphragm muscles. Three main fibre-types were distinguished. The Type I fibres of RVL and gastrocnemius muscles fell into two distinct groups: one category-Type IA showed very low ATPase activity. The second category of Type IB fibres displayed moderate ATPase reaction. The Type IA fibres were divisible into two sub-groups when tested for SDH reaction. Type IA₁ fibres possessed a homogenous distribution of diformazan·granules throughout the fibre: Type IA₂ fibres displayed characteristic moth-eaten pattern of diformazan localization. The diaphragm muscle did not show either Type IB or Type IA₂ varieties. The great majority of Type I fibres were sub-type IA₁ in the three fast muscles studied. It is also demonstrated here that an inherent heterogeneity exists between Type I fibres of diaphragm and leg muscles in regard to -GPD localization. This histochemical data emphasizes the fact that subdivision of Type I striated muscle fibres of mammalian animals into two sub-types is only approximate and that a further subcategorization is possible.     

Variant forms ofα-2-l-fucosyltransferase in human submaxillary glands from blood group ABH “secretor” and “non-secretor” individuals

The properties of the -2-l-fucosyltransferases in submaxillary gland preparations from blood group ABH secrefors and non-secretors were compared. The level of activity in the non-secretor gland homogenates amounted to about 5% only of that found in the secretor gland preparations. The enzymes from the two sources differed in solubility properties, charge and affinities for donor and acceptor substrates. The enzyme from secretor glands showed a preference for acceptors with Type 1 [d-galactosyl(1–3)-N-acetyl-d-glucosamine] structures whereas the enzyme from non-secretor glands had a preference for Type 2 [d-galactosyl(1–4)-N-acetyl-d-glucosamine] structures.These results demonstrate that expression of the secretor gene (Se) is associated with a molecular form of the -2-l-fucosyltransferase that is different from the species present in the same tissue when theSe gene is not expressed.     

Ultrastructure of cell wall and plugs of tobacco pollen tubes after chemical extraction of polysaccharides

Tobacco pollen tubes grown in vitro and from pollinated tobacco styles were treated by chemical solvents to remove one or more of the following polysaccharides from the tube walls: pectin (ethylenediamine tetraacetic acid); hemicellulose (alkali); callose (alkali; potassium hypochlorite); cellulose (cuprammonium); and all polysaccharides with exception of cellulose (H₂O₂/glacial acetic acid). Both the inner tube wall, which we had regarded as the secondary wall, and the plugs contained, in addition to callose, microfibrils of cellulose and non-cellulosic microfibrils that had pectin-like properties. When using the expressions callosic or callose layer and callose plugs in reference to pollen tubes, one should realize that they do not imply the exclusive presence of callose in the inner tube wall layer and its localized thickenings.Extended version of a contribution (poster) presented at the International Symposium Advances in Plant Cytoembryology in Lublin, Poland, in June 1980 Dedicated to Professor J. Straub (Köln-Vogelsang) on his 70th birthday in 1981     

Bulking sludge in biological nutrient removal systems

Bulking sludge problems are commonly reported in biological nutrient removal (BNR) systems. This has led to the general belief that intrinsic BNR conditions favor the growth of undesirable and excessive filamentous bacteria. The present study shows that other factors have a major role in bulking, and not the BNR conditions. These factors have been verified in well-controlled, strictly anoxic-aerobic and strictly anaerobic-aerobic sequencing batch reactor systems. The experimental results show that conditions known to be responsible for bulking sludge in aerobic systems (i.e., low concentration of electron donor and/or electron acceptor) did not lead to bulking. Even when acetate was present at very low concentrations in the aerobic stage of an anaerobic-aerobic bio-P system, the sludge settleability remained very good. This clearly demonstrates that good bio-P activity can stabilize and improve sludge settleability. The presence of microaerophilic conditions in the anoxic stage of the anoxic-aerobic system was the only factor leading to worsening sludge settling characteristics. The results are discussed in light of our previous hypothesis about the importance of diffusion-limited substrate uptake for the development of filamentous structures in biological flocs. The hypothesis is extended to anaerobic-aerobic and anoxic-aerobic conditions, typical of BNR-activated sludge systems. Taking into account the effect of feeding patterns on biochemical rates and on the development of filamentous bacterial structures, we recommend the adoption of plug-flow selector configurations, with strictly anaerobic and/or strictly anoxic conditions, wherein microaerophilic conditions are excluded, in order to maintain reliable and robust BNR performance.     

The effect of the dissolved oxygen concentration and anabolic limitations on the behaviour of Rhizobium ORS571 in chemostat cultures

Chemostat cultures of Rhizobium ORS571 limited by the supply of oxygen or an anabolic substrate contained poly--hydroxybutyrate (PHB). Low amounts of PHB (about 10%) were present in ammonia- or nitrate-limited cultures; higher amounts were found in Mg⁺⁺-limited cultures (about 20%) and in oxygen-limited nitrogen-fixing cultures (37%). A method is described to calculate Y_ATP values (g PHB-free biomass · mol^-1 ATP) from the Y_succ values (g dry wt·mol^-1 succinate) measured. Y_succ and Y_ATP values in cultures limited by the supply of an anabolic substrate and in the oxygen-limited ammonia-assimilating culture were much lower than the values found in the PHB-free succinate-limited cultures. This shows that uncoupling of growth and energy production occurred. Therefore, H₂/N₂ ratio (mol hydrogen formed per mol nitrogen fixed) in nitrogen-fixing cultures could not be calculated from the comparison of the Y_ATP value found in the nitrogen-fixing culture and the value found in the corresponding ammonia-assimilating culture.Although the optimal dissolved oxygen concentration (d.o.c.) for nitrogen-fixing cultures of Rhizobium ORS571 is 5 or 10 M, nitrogen-fixing cultures could be obtained up to a d.o.c. of 40 M. Not only nitrogenase but also hydrogenase was active at this d.o.c. However, accumulation of PHB (10%) may indicate that cultures grown at unfavourable oxygen concentrations (15–40 M O₂) were N-limited rather than energy-limited, which may be the result of partial inactivation or repression of nitrogenase at a higher d.o.c.     

Annual variation of dissolved free primary amines in estuarine water and sediment

Summary The concentration of dissolved free primary amines (DFPA), determined as fluorescamine positive material, was quantified during a one year period of a small estuary. In the water, the concentration of DFPA ranged from 1.8 M in winter, to 26.5 M in summer. In the sediment, from 16 to 56 M of DFPA occurred. The concentration varied with depth and season, and in summer months a maximum of DFPA was observed in the redox discontinuity layer. The DFPA peak in water and sediment coincided with maximum of the macrophytal biomass. About 80% of the fluorescamine positive material was identified as amino acids. Origin and distribution of primary amines in the estuarine environment are discussed.     

Heterotrophic nitrification and aerobic denitrification inAlcaligenes faecalis strain TUD

Heterotrophic nitrification and aerobic and anaerobic denitrification byAlcaligenes faecalis strain TUD were studied in continuous cultures under various environmental conditions. Both nitrification and denitrification activities increased with the dilution rate. At dissolved oxygen concentrations above 46% air saturation, hydroxylamine, nitrite and nitrate accumulated, indicating that both the nitrification and denitrification were less efficient. The overall nitrification activity was, however, essentially unaffected by the oxygen concentration. The nitrification rate increased with increasing ammonia concentration, but was lower in the presence of nitrate or nitrite. When present, hydroxylamine, was nitrified preferentially. Relatively low concentrations of acetate caused substrate inhibition (K_I=109 M acetate). Denitrifying or assimilatory nitrate reductases were not detected, and the copper nitrite reductase, rather than cytochrome cd, was present. Thiosulphate (a potential inhibitor of heterotrophic nitrification) was oxidized byA. faecalis strain TUD, with a maximum oxygen uptake rate of 140–170nmol O₂·min^-1·mg prot^-1. Comparison of the behaviour ofA. faecalis TUD with that of other bacteria capable of heterotrophic nitrification and aerobic denitrification established that the response of these organisms to environmental parameters is not uniform. Similarities were found in their responses to dissolved oxygen concentrations, growth rate and ammonia concentration. However, they differed in their responses to externally supplied nitrite and nitrate.     

Polymorphism of human liver alcohol dehydrogenase: Identification of ADH2 2-1 and ADH2 2-2 phenotypes in the Japanese by isoelectric focusing

Liver homogenate-supernatants from most Japanese exhibit an atypical pH optimum for ethanol oxidation at pH 8.8 instead of 10.5, the typical pH-activity optimum. It has been proposed that atypical livers contain alcohol dehydrogenase isozymes with ₂ subunits while typical livers contain isozymes with ₁ subunits, both produced by the ADH ₂ gene. Because it is difficult to differentiate the atypical ADH₂ 2-2 phenotype from the ADH₂ 2-1 phenotype by starch gel electrophoresis, an agarose isoelectric focusing procedure was developed that clearly separated the atypical Japanese livers into two groups, A1 and A2. The isozymes in A1 and A2 livers were purified. Type A1 livers contained a single isozyme with an atypical pH-rate profile; it was designated ₂₂. Three isozymes were isolated from A2 livers, two of which corresponded to ₁₁ and ₂₂. A third, absent from the typical and the atypical A1 livers, had an intermediate mobility; it was designated ₂₁. Type A1 livers are, therefore, the homozygous ADH₂ 2-2 phenotype, and type A2 livers, the heterozygous ADH₂ 2-1 phenotype. The ADH₂ 2-2 phenotype was found in 53% of 194 Japanese livers, and the ADH₂ 2-1 phenotype, in 31%. Accordingly, the frequency of ADH ₂ ² was 0.68.This study was supported by U.S. Public Health Service Grant AA 02342.     

Genetic control of flocculation inEscherichia coli

Summary Escherichia coli cells form flocs or aggregates by overproducing type 1 pili. When thepil operon is placed under the control of atac orlac promoter-operator sequence, the bacterial cells can be induced to form flocs by adding isopropyl--d-thiogalactopyranoside to the culture medium. This phenomenon of genetically induced flocculation can aid in the downstream processing of biological products. This paper describes the construction of two artificially controlled plasmids which cause cell flocculation. Cell aggregates 50 m in mean diameter were obtained 1 h after the cells were induced.     

O-Glycosylhydrolases of Marine Filamentous Fungi: β-1,3-Glucanases of Trichoderma aureviride

The ability to produce extracellular O-glycosylhydrolases was studied in 14 strains of marine filamentous fungi sampled from the bottom sediments of the South China Sea. The following activities were detected in the culture liquids of the fungi: N-acetyl--D-glucosaminidase, -D-glucosidase, -D-galactosidase, -1,3-glucanase, amylase, and pustulanase. -1,3-Glucanases were isolated by ultrafiltration, hydrophobic interaction chromatography, and ion exchange chromatography, and their properties were studied. Data on products of enzymatic digestion of laminaran, absence of transglycosylation activity, and the pattern of action of natural inhibitors confirmed that -1,3-glucanase belonged to the exo type. Inhibitor analysis demonstrated the role of a thiol group and tryptophan and tyrosine residues in the catalytic activity.     

Stable limited filamentous bulking through keeping the competition between floc-formers and filaments in balance

Limited filamentous bulking (LFB) was proposed to save aeration energy consumption and enhance the capacity of filaments to degrade substrates with low concentrations in activated sludge systems. Operational parameters favorable for maintaining the LFB state were investigated in an anoxic-oxic reactor treating domestic wastewater. The experiments showed that the LFB state would deteriorate with sharply decreasing temperature, reducing substrate gradients or removing anoxic zones. The balance between filaments and floc-formers could be achieved by controlling dissolved oxygen and sludge loading rates to be in optimal ranges. Eikelboom Type 0041 and CandidatusMicrothrix parvicella were the filamentous bacteria responsible for the LFB state. However, the excess growth of Eikelboom Type 021N and Sphaerotilus natans were observed when serious bulking occurred under low substrate gradients. It was demonstrated that stable maintenance of LFB for energy saving was feasible by process control and optimization.     

Large scale preparation of PA-oligosaccharides from glycoproteins using an improved extraction method

We have developed a new method for the large scale preparation of pyridylaminated (PA-) oligosaccharides from glycoproteins. Phenol/chloroform extration was adapted for the removal of protein and excess 2-aminopyridine, improving the efficiency of preparation. From a 2.5 g sample of human apo-transferrin, 25–30 mol of agalacto biantennary PA-oligosaccharide could be obtained. By increasing the concentration of PA-oligosaccharide substrate, we were able to detect a very low level ofN-acetylglucosaminlytransferase IV activity in CHO cell extracts.Abbreviations PA 2-aminopyridine - SDS sodium dodecyl sulfate - GlcNAc N-acetylglucosamine - GnT N-acetylglucosaminyltransferase - Gn,Gn-bi-PA GlcNAc1-2Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc-2-aminopyridine - Gn,Gn,Gn-tri-PA GlcNAc1-2(GlcNAc1-4)Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc-2-aminopyridine - Gn,Gn,Gn-trí-PA GlcNAc1-2Man1-3({GlcNAc1-2(GlcNAc1-6)Man1-6})Man1-4GlcNac1-4GlcNAc-2-aminopyridine - Gn,(Gn),Gn-bi-PA GlcNAc1-2Man1-3(GlcNAc1-4)(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc-2-aminopyridine     

Continuous glucose production using encapsulated mycelial-associated β-glucosidase from Trichoderma E58

Summary Cellobiose and salicin were continuously hydrolysed in a packed bed reactor containing Trichoderma sp. E-58, encapsulated in calcium alginate beads. Continuous -glucosidase activities were measured using inlet substrate concentrations of 10 mM and 35 mM for cellobiose and salicin respectively. Maximal activities achieved using the described immobilization procedure were between 70 and 90 moles substrate reacted per minute per liter of bead volume. Immobilized mycelial-associated -glucosidase activity was shown to have a half-life of greater than 1000 hours when operating continuously at 50°C.     

Short- and long-term effects of ACTH on the adrenal zona glomerulosa of the rat

Summary Short-term ACTH treatment provoked a decrease in volume of the lipid-droplet compartment in rat zona glomerulosa cells, and a rise in plasma and intracellular concentrations of corticosterone and aldosterone. It enhanced activities of 3-hydroxysteroid dehydrogenase (3HSD), 11-hydroxylase (11OH) and 18-hydroxylase (18OH). Long-term ACTH administration produced a hypertrophy of the zona glomerulosa and its parenchymal cells, a result of the increase in volume of the smooth endoplasmic reticulum and the mitochondrial compartment. The surface area per cell of mitochondrial inner membranes increased; the tubular cristae were transformed into a homogeneous population of vesicles. The plasma and intracellular concentrations of corticosterone further increased, whereas those of aldosterone fell below basal levels (the aldosterone-escape phenomenon). The activities of 3HSD and 11OH were enhanced, that of 180H decreased. Therefore, ACTH stimulates zona glomerulosa growth and transforms parenchymal elements into zona fasciculata celltypes. Cyanoketone nullified acute ACTH effects on plasma and intracellular concentrations of corticosterone and aldosterone, but did not affect the activities of 11OH and 18OH. Chronic ACTH treatment produced similar results, although 18OH activity was not suppressed. The mechanism underlying the aldosterone-escape phenomenon may thus involve a rise in the intracellular concentration of corticosterone, caused by the enhanced synthesis and activation of 3HSD and 11OH.     

Purification and characterization of two intracellular β-glucosidases from the Neurospora crassa mutant cell-1

Two intracellular -glucosidases (E.C. 3.2.1.21) were purified from the filamentous fungus Neurospora crassa, mutant cell-1 (FGSC no. 4335) and characterized. The extent of purification were 2.55- and 28.89-fold for -glucosidase A and -glucosidase B, respectively. -Glucosidase A was a dimeric protein, and B a monomeric protein, with molecular masses of 178 and 106 kDa, respectively. Both isoenzymes were glycoproteins with relatively high carbohydrate contents (-glucosidase A, 29.2%; -glucosidase B, 34.2%). The isoelectric points determined by IEF were 6.27 and 4.72, respectively. pH optima for activity were determined to be 5.0 and 5.5, and temperature optima to be 55 and 60 °C, for -glucosidases A and B, respectively. Both purified -glucosidases. especially -glucosidase B, showed relatively high stability against pH and temperature. Both enzymes were stable in the pH range of 5.0–9.0. The activities were completely retained up to 48 h at temperatures below 40 °C. At higher temperatures, enzymes were relatively unstable and lost their activities at 60 °C after 24 h. Both -glucosidases were highly activated by CuCl₂, and inhibited by SnCl₂ and KMnO₄. Hg²⁺ and Ag⁺ also inhibited severely -glucosidase B. The K _m and V _max values of the isoenzymes against cellobiose as substrate were 1.50 mM and 12.2mol min^–1 mg^–1 for -glucosidase A and 2.76 mM and 143.5 mol min^–1 mg^–1 for -glucosidase B.     

Kinetic and fluorometric behavior of a phenol fermentation

Summary The kinetic and fluorometric behavior ofPseudomonas putida (ATCC 17484) growing on phenol as the carbon limiting substrate was investigated. A model was developed to describe the behavior under dynamic conditions of flow or substrate concentration shift-up. Parameters contained in the model were estimated. It was observed that the model described the kinetic behavior reasonably well. Factors which affected the fluorescence output of the whole broth culture were also studied.     

Histochemical and immunochemical studies on mammalian striated muscle fibres

Summary In 15 rabbit and 2 human distinct types of striated muscle, it was shown that all fibres classified as type I (red) by NADH-diaphorase and myofibrillar ATPase reaction exhibit intense fluorescence when treated with a FITC-labelled antibody against human pectoral actomyosin. Type II (white) fibres showing minimal fluorescence, an intermediate fibre type can be differentiated by all three methods. In the rabbit, all three fibre types are found, whereas, in the human muscles studied, only type I and intermediate type fibres were found.Abbreviations ATPase adenosintriphosphatase (EC 3.6.1.3) - anti-PAM anti-human-pectoralis actomyosin - FITC fluoresceine-isothiocyanate     

Verhaltensontogenese der Habitatwahl beim Teichrohrs?nger (Acrocephalus scirpaceus)

Zusammenfassung In Anpassung an seinen aus vertikalen Vegetationsstrukturen zusammengesetzten Lebensraum besitzt der Teichrohrsänger die beste morphologische Ausstattung aller sechs mitteleuropäischer Rohrsängerarten für Vertikalklettern. An jungen Teichrohrsängern wurde überprüft, ob frühkindliche Erfahrungen auf verschiedenen Sitzstangen (auf senkrechten=K_s, senkrechten und waagerechten=K_m, waagerechten=V_w und waagerechten Sitzstangen mit Futter belohnt=V_w+) die spätere Wahl dieser Strukturelemente beeinflussen. Die lokomotorische Aktivität der vier Aufzuchtsgruppen wurde im Zweifachwahlversuch (horizontale gegen vertikale Sitzstangen) getestet. Mit Ausnahme der auf senkrechten Sitzstangen aufgezogenen Vögel (K_s), deren Wahlverhalten gleichverteilt war (Abb. 2), bevorzugten alle anderen Gruppen das vertikale Testsubstrat (Abb. 2 und 3). Auch die Belohnung mit Futter als positiver Verstärker der Horizontalelemente (V_w+) machte diese nur wenig attraktiver (Tab. 1). Alle Gruppen nutzten während der Testperiode das vertikale Substrat zunehmend stärker (Tab. 1). Die Zunahme rührte bei den Vögeln der beiden Kontrollgruppen (K_s und K_m) und der Versuchsgruppe waagerecht (V_w) alleine von der Erfahrung in der Versuchssituation her (Tab. 2). Die Nutzung vertikaler bzw. horizontaler Strukturelemente durch junge Teichrohrsänger wird somit bestimmt durch: 1. eine angeborene Präferenz für das artgemäße Substrat, 2. einen Novitätseffekt, bedingt durch die Aufzuchterfahrung (Wahlverhalten der K_s-Gruppe, Abb. 2), 3. Eigenerfahrung bei der Nutzung verschiedener Substrate im Versuch. Zusätzliche Wahlversuche später im Jahr (Oktober bis Dezember) mit denselben Versuchsvögeln zeigten keine Änderungen in der Substratwahl (Abb. 4).

---

Ontogeny of habitat choice in the Reed Warbler (Acrocephalus scirpaceus)

Summary The Reed Warbler shows the most specialized morphological traits for vertical climbing among the six central EuropeanAcrocephalus species. We consider this as an adaptation to the vertical structures in its habitat. In experiments with young Reed Warblers I tested whether early experience with different perches has an influence on the choice of these structures later on in life. Locomotory activity of the following groups was tested in double choice experiments (horizontal versus vertical perches):Control group vertical (K_s): raised on vertical perches, Control group mixed habitat (K_m): raised on vertical and horizontal perches, Test group horizontal (V_w): raised on horizontal perches, Test group horizontal, plus rewards (V_w+): raised on horizontal perches and additional feeders attached to the bars. With the exception of Control group vertical (K_s) which shows no choice preference (Fig. 2) all other birds prefered the vertical test substrate (Fig. 2 and 3). Even the reward (food) as a positive reinforcement of horizontal elements had little effect on their attractiveness (Tab. 1). An increase in the choice of the vertical substrate could be observed throughout the 3-day test period in all groups (Tab. 1). This increase was only due to the experience in the test situation for the birds in both control groups (K_s and K_m) and the Test group horizontal (V_w) (Tab. 2). Therefore the use of vertical or horizontal structures in Reed Warblers is determind by: 1. An innate preference for species-specific substrate, 2. Novelty due to early experience (choice behaviour of Control group vertical, Fig. 2), 3. Experience while using different substrates (experience in the test situation) which optimizes substrate choice according to proprioceptive learning. Additional choice experiments with the same test birds later on in the year (October to December) revealed the same results. Therefore it seems unlikely that there exists a preprogrammed change in substrate choice in the course of a year (Fig. 4). Although choice experiments of this kind can only include a limited part of the habitat-scheme, they are useful experimental designs for investigating specialized species whose habitats can be simulated closely in the laboratory.

     

Production of a novel syrup containing neofructo-oligosaccharides by the cells of Penicillium citrinum

A novel syrup containing neofructo-oligosaccharides was produced from sucrose (Brix 70) by whole cells of Penicillium citrinum. The efficiency of fructo-oligosaccharides production was more than 55% and those of the main carbohydrate components, 1-kestose (Fruf 21Fruf 21 Glc), nystose (Fruf 21Fruf 21 Fruf 21 Glc) and neokestose (Fruf 26 Glc12 Fruf), were 22, 14 and 11%, respectively.