Atypical Ca<Superscript>2+</Superscript>-independent,raw-starch hydrolysing α-amylase from <Emphasis Type="Italic">Bacillus</Emphasis> sp. GRE1: characterization and gene isolation

Bacillus sp. GRE1 isolated from an Ethiopian hyperthermal spring produced raw-starch digesting, Ca²⁺-independent thermostable α-amylase. Enzyme production in shake flask experiments using optimum nutrient supplements and environmental conditions was 2,360 U l⁻¹. Gel filtration chromatography yielded a purification factor of 33.6-fold and a recovery of 46.5%. The apparent molecular weight of the enzyme was 55 kDa as determined by SDS-PAGE. Presence or absence of Ca²⁺ produced similar temperature optima of 65–70°C. The optimum pH was in the range of 5.5–6.0. The enzyme maintained 50% of its original activity after 45 min of incubation at 80°C and was stable at a pH range of 5.0–9.0. The V _max and K _m values for soluble starch were 42 mg reducing sugar min⁻¹ and 4.98 mg starch ml⁻¹, respectively. Strong inhibitors of enzyme activity included Cu²⁺, Zn²⁺ and Fe²⁺. The enzyme coding gene and the deduced protein translation revealed a characteristic but markedly atypical homology to Bacillus species α-amylase sequences. The enzyme hydrolyzed wheat, corn and tapioca starch granules efficiently below their gelatinization temperatures. Rather than the higher oligosaccharides normally produced by Bacillus α-amylases operating at high temperatures, maltose was the major hydrolysis product with the present enzyme.     

Direct fermentative production of lactic acid on cassava and other starch substrates

Lactobacillus amylovorus utilized raw corn, rice and wheat starch medium to produce lactic acid with a productivity of 10.1, 7.9 and 7.8 g lactic acid/L, but had lower productivities of 4.8 g/L and 4.2 g/L on cassava and potato starch in basal medium respectively. When peptone (1%) is added to basal medium with cassava starch as substrate, conversion rate increased from 43% conversion to 70% conversion (7.7 g lactic acid/L). The availability of some components of protein in corn starch is assumed to be the reason for high lactic acid production as compared to that of cassava starch.     

Improved extracellular transferase enzyme production by Aspergillus foetidus for synthesis of isooligosaccharides

Aspergillus foetidus was used to produce transferases that can be utilized in the synthesis of isooligosaccharides. Maltose and corn steep liquor were found to be the best carbon and nitrogen substrates at optimum concentration of 1% and 3% respectively. Surfactant Tween 80 and metal ions including Fe²⁺, Zn²⁺, Mg²⁺ and Cu²⁺ were found to have no obvious effect on the enzyme productivity. Uncontrolled pH starting with an initial value of 5.0 gave the highest transferase productivity compared with pH controlled at constant levels and control after natural fall. The optimum temperature was found to be 30v°C. Enzyme activity increased 8 fold in reactors, with better aeration and agitation condition, as compared to shake flask. The morphology of the organism was highly dependent on the nitrogen source and had great influence on enzyme productivity.     

Capitalizing on multi-element interactions through bal-anced nutrition——A pathway to improve nitrogen use efficiency in China,India and North America

A viable option for increasing nitrogen (N) use efficiency and mitigation of negative impacts of N on the environment is to capitalize on multi-element interactions through implementation of nutrient management programs that provide balanced nutrition. Numerous studies have demonstrated the immediate efficacy of this approach in the developing regions like China and India as well as developed countries in North America. Based on 241 site-years of experiments in these countries, the first-year N recovery efficiency (RE) for the conventional or check treatments averaged 21% while the balanced treatments averaged 54% RE, for an average increase of 33% in RE due to balanced nutrition. Effective policies to promote adoption are most likely those that enable site-specific approaches to nutrient management decisions rather than sweeping, nation-wide incentives supporting one nutrient over another. Local farmers, advisers and officials need to be empowered with tools and information to help them define necessary changes in practices to create more balanced nutrient management.     

Oxidovanadium(IV) complexes containing ligands derived from dithiocarbazates - Models for the interaction of VO with thiofunctional ligands

The tetragonal-pyramidal VO²⁺ complexes [VO{(RSC-S)N-NX}₂] (1-6) were synthesised by the reactions of VO(OCHMe₂)₃ with the dithiocarbazate ligands RSC(S)-NH-NX, where X = cyclo-pentyl, cyclo-hexyl or 4-Me₂N-C₆H₄-CH, and R = CH₃ or CH₂C₆H₅. The compounds were characterised by elemental analysis, IR- and mass spectrometries, and in cases of compounds 1, 3, 4 and 5, by X-ray diffraction. The chiral compound 4 (X = cyclo-hexyl, R = CH₂C₆H₅) crystallises in the C configuration. In compound 5, the VO moiety is disordered (83.3:16.7%) with respect to the plane spanned by the four equatorial ligand functions.     

Peripartum Cardiomyopathy Presenting With Ventricular Tachycardia: A Rare Presentation

A 25-year-old previously asymptomatic pregnant woman at 36 weeks'' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. This is a very rare presentation of peripartum cardiomyopathy (PPCMP) presenting with repetitive monomorphic ventricular tachycardia.     

Genetic effect on uptake of selected nutrients in some rice (O. sativa L.) varieties in phosphorus deficient soils

The influence of genes on the uptake by rice plants of certain macro- and micronutrients (calcium, magnesium, iron, manganese and zinc) was studied, by diallel (7 × 7) analysis, in P deficient upland soil. Both additive and dominant gene effects, with a preponderance of the former, were found to be responsible for the uptake of all the elements studied. Local varieties were found to be not only good yielders but also much more efficient in element uptake. Heterotic effects were observed in various crosses with respect to the uptake of all the aforementioned nutrients. Statistical analysis indicated that while the uptake of iron and zinc were negatively correlated, the uptake of manganese and calcium, manganese and zinc, calcium and magnesium and calcium and zinc were positively correlated.     

The induction of allophanate lyase during the vegetative cell cycle in light-synchronized cultures of Chlamydomonas reinhardi.

Allophanate lyase can be induced by urea or acetamide 20-40-fold within 4 h in NH4 + -deprived cultures of Chlamydomonas reinhardi. In light-synchronized cultures, allophanate lyase induction appeared to be limited to the light phase of the cell cycle, provided that culture samples were induced under ongoing illumination conditions (i.e. light induction of light phase cells and dark induction of dark phase cells). However, when culture samples were induced under constant light conditions this cell cycle pattern was abolished. Light was found to be required for allophanate lyase induction and this was shown to be due, in part, to the light requirement for inducer uptake. The relationship between allophanate lyase induction and gametogenesis is discussed.     

Studies on the assembly and stability of the metal-thiolate clusters of metallothionein in dimethyl sulfoxide.

Solvent perturbation studies in 100% dimethyl sulfoxide (Me2SO) have been carried out on rabbit liver metallothionein (MT) in an effort to learn more about the factors stabilizing the three-dimensional structure and the mechanism of cluster formation. As indicated by the electronic absorption spectra of Co7-metallothionein, the reconstituted protein preserves its structural integrity in this solvent. Minor spectral differences between water and Me2SO were fully reversible. The titration of apoMT with cobalt(II) in Me2SO, followed by UV-visible-near-infrared electronic absorption, circular dichroism, magnetic circular dichroism, and EPR spectroscopy, indicate that the protein can refold in this solvent. A comparison with the previous titration data in water reveals that the first four titration steps in both solvents are identical, indicating a thermodynamically controlled folding process. However, the reversed order of the cluster completion between Me2SO and water may suggest the involvement of a kinetically controlled folding process in the last three titration steps. A new cluster form developed with approximately nine Co(II) equivalents.