Uronic acid analysis by automated anion exchange chromatography

A rapid and sensitive assay for individual uronic acids has been developed based on their separation on a 0.5 × 22-cm column of Aminex A-25 in 0.12 m Tris-acetate buffer, pH 7.4. Quantification of these sugars is accomplished by coupling the column to the analytical portion of a Technicon sugar analyzer. Each determination is complete in 3 hr, and as little as 25 nmol of uronic acid can be measured with accuracy.     

Uronic acid residues in the total hemicelluloses of oats

A new method for the estimation of uronic acid residues is described. The changes in total hemicellulose composition of the leaf and stem tissues of field-grown oat plants have been further examined. In any one such tissue, increased plant maturity is accompanied by an increase in the percentage of xylose residues and by decreases in the percentages of arabinosyl, glucosyl, and uronosyl residues. The ratio of 4-O-methyl-D-glucuronosyl to D-glucuronosyl residues increases with maturity.     

Base composition and sequence homology of deoxyribonucleic acid of thermotolerantCampylobacter from human and animal sources

A total of 31Campylobacter strains were studied. Of these, 24 were thermotolerant field isolates and 7 were reference strains. Mol% G+C was estimated by thermal denaturation and DNA-DNA-relatedness by the hydroxyapatite method. The strains identified asC. jejuni orC. coli and differentiated by the hippurate hydrolysis test formed separate, homogenous DNA homology groups. The two species were genetically more related to each other than to otherCampylobacter species. Results also show that the group of hippurate-negative thermotolerant campylobacters resistant to nalidixic acid is genetically heterogenous.     

Utilisation of iodine from different sources in pigs

Balance experiments have demonstrated that growing pigs fed a ration consisting of wheat, barley, extracted soya meal, dicalciumphosphate, and iodine‐free feeding salt utilised 48.8% of the received iodine.

The tested supplementary iodine sources included potassium iodide (KI), ethylenediamine dihydroiodide (EDDI), iodine humate (HUI) prepared from iodine acid (HIO₃), and the product P containing 0.004% iodine in an oil base (P). The amount of the supplemented iodine was in all cases 1 mg per 1 kg feed.

The utilisation of iodine from the supplements reached 93.6, 92.6, 90.7, and 67.9% for KI, EDDI, P, and HUI, respectively. The values were significantly higher compared with controls (P < 0.01). Compared with KI and EDDI, the utilisation of iodine from HUI was significantly lower (P < 0.01). The lower availability of iodine from HUI was probably due to the high binding capacity of humate.

The amount of urinary iodine excreted by control pigs receiving in the non‐supplemented ration 147.5 μg iodine per day, was 40.3 μg per day (27.3%). In the pigs receiving in the supplemented ration 1647.5 μg iodine per day, the amount of urinary iodine reached 734.9 to 805.0 μg per day (44.6 to 48.9%). The corresponding values of faecal excretion were 75.6 μg iodine per day (51.2%) for the control pigs and 106.2 to 121.1 μg iodine per day (6.45 to 7.35%) for the pigs fed the supplemented rations. A high amount of 528.6 μg iodine per day (32.1%) was excreted in the faeces by pigs of the group HUI.     

Utilization of different sulfur sources by propionic acid bacteria

The object of this work was to study the ability of propionic bacteria to utilize sulfur compounds having various degrees of oxidation. Propionibacterium shermanii was found to utilize sulfite, thiosulfate, sulfide and elemental sulfur, apart from sulfate, as a sulfur source. When the culture grew in a medium with elemental sulfur, sulfide was produced. The utilization of sulfate by P. shermanii had a peculiar character. In the process of the culture growth, the utilization of sulfate alternated with its release into the medium.     

Structural comparison of phosphorylases from different sources

All of the -glucan phosphorylases so far purified from diverse origins have similar molecular and catalytic properties, whereas they differ in regulatory properties and glucan specificities. The activity of the rabbit muscle enzyme is regulated by phosphorylation-dephosphorylation and activated by AMP. On the other hand, the potato and Escherichia coli enzymes exist only in the active form, and are unaffected by the nucleotide. To elucidate the structural bases for these differences, we have determined the complete amino acid sequence of potato phosphorylase and compared it with those of the rabbit muscle and E. coli enzymes. The monomer of the potato enzyme contains 916 amino acids with a molecular weight of 103,916. About one-fourth of the amino-terminal threonine is blocked by an acetyl group. Sequence comparison among these enzymes reveals the presence of a characteristic 78-residue insertion in the middle of the polypeptide chain of the potato enzyme. Except for the large inserted portion, 51 and 40% of the amino acids in the potato enzyme are identical with the rabbit muscle and E. coli enzymes, respectively. The regions relevant to the regulation of the activity are completely different among the three enzymes, whereas those involved in the catalytic reaction are well conserved. The potato enzyme sequence is consistent with the tertiary structure of the rabbit muscle enzyme. The 78-residue insertion is located at the junction of the amino- and carboxyl-terminal domains on the molecular surface near the glycogen-storage site. This insertion could account for the substrate discrimination of the potato enzyme. The molecular evolution of phosphorylase is discussed based on the structural comparison among the three enzymes.     

Virulence traits in Cronobacter species isolated from different sources

Cronobacter spp. ( Enterobacter sakazakii ) includes gram-negative opportunistic foodborne pathogens known as rare but important causes of life-threatening neonatal infections. However, the pathogenic mechanism is not yet clear. In this study, 43 isolates of Cronobacter, from human and nonhuman sources, were analyzed. A total of four clusters were identified and 32 DNA pulsotypes were observed by pulsed-field gel electrophoresis. In addition, 86% of the Cronobacter isolates were able to adhere to HEp-2 cells and 35% were invasive, Cronobacter sakazakii isolates being the most efficient. Twenty-six percent of Cronobacter isolates were able to form biofilms, mainly those from nonhuman sources, such as Cronobacter dublinensis and Cronobacter malonaticus . Three putative virulence genes (siderophore-interacting protein (sip), type III hemolysin (hly), and plasminogen activator (cpa)) were identified by bioinformatic analysis and then detected by PCR. The sip gene was the most frequently detected (60%; 26/43), followed by the hly gene (37%; 16/43) and the cpa gene (28%; 12/43). The three genes were identified primarily in C. sakazakii. Our data show that Cronobacter species harbor different virulence traits.     

Comparison of homoserine dehydrogenase from different plant sources

Homoserine dehydrogenase (HSD) was partially purified from castor bean, pea and wheat seedlings. The enzyme from pea had a MW of 75 000 and no sensitivity to threonine when measured in the direction of homoserine formation (forward reaction). The enzyme purified from castor bean had a MW of 290 000–350 000 and exhibited an almost complete inhibition by 1 mM threonine. Furthermore, this enzyme exhibited a polymeric nature as shown by polyacrylamide electrophoresis of the desensitized preparation and by SDS electrophoresis of the native enzyme. In wheat two isoenzymes were separated by gel filtration on Sephadex G 200. The fast-moving fraction (HSD I) was completely inhibited by threonine and exhibited a MW of 280 000, while the slow-moving fraction (HSD II) was insensitive to threonine and had a MW of 75 000. The sensitive enzyme from wheat and castor bean showed an almost absolute requirement for K⁺. The enzyme from pea and the insensitive form from wheat did not show a requirement for K⁺. For the wheat enzyme the effect of several amino acids and the main kinetic constants were studied.     

The seroresistance of enterobacteria isolated from different sources

395 representatives of the family Enterobacteriaceae, isolated from household and drinking water, from healthy and sick persons, were used as an example to demonstrate that their seroresistance was greatly connected with the type of the source from which these bacteria had been isolated. Experiments showed the phenotypic conversion of Escherichia coli towards an increase in their seroresistance on contact with human blood serum. The study revealed the pleiotropic effect produced by the action of serum on a number of other properties, responsible for survival in a macroorganism (anticomplement and antilysozyme activities, adhesive capacity and hydrophobic properties of the outer surface).     

Physico-chemical properties of seed xyloglucans from different sources

A xyloglucan (XG) was extracted from the seeds of Hymenaea courbaril (Jatobá) harvested from trees growing at different locations in Brazil. They were from Foz do Chopin Forest Reserve, State of Paraná (HC-I), Cuiaba (HC-II) and Sinope/State of Mato Grosso (HC-III), Natal/State of Rio Grande do Norte (HC-IV), Fortaleza/State of Ceará (HC-V) and Tamarindus indica (TM) from Conceição de Almeida/State of Bahia, Brazil. It was submitted to SEC-MALLS analysis and its intrinsic viscosity determined. When a solution of XG was heated to 85 °C for 2 h, there was a reduction of aggregation and the XG from the seeds of H. courbaril had a higher value of C_∞ when compared with that of from T. indica, probably due to the presence of an unique oligossacharide series present in the H. courbaril samples (XXXXG). This gives rise to a more rigid molecule when compared with the XG from T. indica.     

Homogenous reactions of cellulose from different natural sources

Two different homogenous reactions on bacterial cellulose (BC), kenaf fiber (KF) and microcrystalline cellulose (MC) were performed to monitor their chemical reactivity. The first reaction was selective oxidation of the primary hydroxyl group with sodium chlorite in the presence of catalytic amount of sodium chloride. While, the second was the formation of triester hypoiodous cellulose using potassium iodate and potassium iodide. The chemical structures of these derivatives were investigated using FT-IR and solid state ¹³C NMR spectroscopies. The BC fibrils required the shortest time among these cellulose samples for both reactions, whereas the viscosity values of BC after iodination and oxidation have the best values compared to KF and MC. FT-IR results show the absence of the hydroxy group of BC and a weak absorption band in both KF and MC. On the other hand, the crystallinity index (CI) of BC is higher than those of both KF and MC. FT-IR spectra of the oxidized different cellulose samples, confirmed the presence of a strong absorption band at around 1590 cm⁻¹ that attributed to vibration band of carbonyl group of carboxylic moiety. Moreover, in the ¹³C NMR spectrum of oxidized cellulose, the lack of signal at 62 ppm and the appearance of signal at 171 ppm indicated that the primary alcohol group is completely oxidized to carboxylic acid. These results showed that BC had a higher reactivity than other samples due to its great purity and low degree of polymerization.     

Comparative studies on the effects of anions on ATPase and acid phosphatase activities from different sources

The effect of several anions on Mg²⁺-ATPase activity [EC 3.6.1.3 [EC] ]was studied in crude extracts of the following sources: twelvespecies of bacteria, one fungus, one yeast, six species of algae,five higher plant tissues, and two animal tissues. All the materialsexamined exhibited Mg²⁺-ATPase activity at pH 7.5. Except fora few species of bacteria, blue-green alga and etiolated seedlingsof a leguminous plant, Mg²⁺-ATPases of all the materials studiedwere stimulated two- to ten-fold by the addition of Group VIanions such as sulfite, selenite, and chromate. This stimulationseems to be a common characteristic of ATPases of most bacteria,chloroplasts, and mitochondria. On the other hand, the stimulation of acid phosphatase by sulfatewas not observed in any organism other than Thiobacillus thiooxidans. (Received July 27, 1977; )