Rapid production of ethanol in high concentration by immobilized cells of Saccharomyces cerevisiae through soya flour supplementation

Summary Ethanol concentration and fermentation productivities were substantially increased when soya extract was added to the fermentation medium using immobilized cells of a locally isolated strain of S. cerevisiae. Very high concentrations, 152 and 162 g/l of ethanol, were obtained from a medium containing 300 and 350 g/l sugars respectively by supplementing the medium with soya extract. The fermentation time was also reduced by more than 50%.     

Effect of polyols on the thermostability of pullulan-hydrolysing activity from Sclerotium rolfsii

Summary The influence of various polyols on the thermostability of pullulan-hydrolysing activity fromSclerotium rolfsii was studied. The half-life of the enzyme activity at 60°C was determined to be of the order of 30 min. In the presence of xylitol and sorbitol (3 M or more) there was a significant enhancement in the thermostability of the enzyme with retention of 100% activity after incubation for 7 h at 60°C. However, ethylene glycol and glycerol were found to have no protective effect. The stabilizing efficiency was found to be dependent on the concentration of the polyhydric alcohol used and the number of OH-groups present per molecule.     

Hydrogen peroxide formation and lipid peroxidation in rat uterus—effect of hormones and vitamin E

The effect of estradiol-17β and progesterone given separately as well as in combination on the rate of hydrogen peroxide formation and lipid peroxidation in the uteri of ovariectomized rats was studied. Estradiol in 3μg dose per day per animal elicited maximum stimulatory response and progesterone (100μg), on the other hand, was without any such effect. However, progesterone given along with estradiol completely prevented the effect due to the latter. In the same way, vitamin E, a well known antioxidant was found to be extremelv effective in protecting the uterus from the highly peroxidative action of estradiol-17β.     

Metabolic engineering of Synechococcus elongatus for photoautotrophic production of mannitol

With multiple applications in food, pharmaceutical, and chemical industries as antioxidant or nonmetabolizable sweetener; the bioproduction of d -mannitol is gaining global attention, especially with photosynthetic organisms as hosts. Considering the sustainability prospects, the current work encompasses metabolic engineering of a widely used cyanobacterial strain, Synechococcus elongatus PCC 7942, and two newly isolated fast-growing cyanobacterial strains; S. elongatus PCC 11801 and S. elongatus PCC 11802, for mannitol production. We engineered these strains with a two-step pathway by cloning genes for mannitol-1-phosphate dehydrogenase (mtlD) and mannitol-1-phosphatase (mlp), where the mtlD expression was under the control of different promoters from PCC 7942, namely, P_rbc225, P_cpcB300, P_cpcBm1, P_rbcLm17, and P_rbcLm15. The strains were tested under the “switch conditions,” where the growth conditions were switched after the first 3 days, thereby resulting in differential promoter activity. Among the engineered strains of PCC 11801 and PCC 11802, the strains possessing P_rbc225-mtlD module produced relatively high mannitol titers of 401 ± 18 mg/L and 537 ± 18 mg/L, respectively. The highest mannitol titer of 701 ± 15 mg/L (productivity 60 mg/L.d, yield 895 µM/OD₇₃₀) was exhibited by the engineered strain of PCC 7942 expressing P_cpcB300-mtlD module. It is by far the highest obtained mannitol yield from the engineered cyanobacteria.     

High ethanol productivities using small Ca-alginate beads of immobilized cells of Zymomonas mobilis

Summary Zymomonas mobilis cells were immobilized into small 1 mm diameter beads of Ca-alginate in order to minimize mass transfer limitations and maximize immobilized cell activity. A combination of small bead size with a high cell concentration of 58 g dry wt. cell per lit. bead volume resulted in high ethanol productivities using a newly designed packed bed bioreactor system. Steady-state dilution rates ranging from 0.4 h^-1 to 3.9 h^-1 were run resulting in a maximum productivity of 102 g ethanol/l/h for an inlet substrate concentration of 100 g glu/l and 87% conversion. The bioreactor was run continuously at a fixed dilution rate for 384 h and short intermittent treatment of the beads with CaCl₂ temporarily increased ethanol productivity to a maximum of 116 g ethanol/l/h.     

The synthesis of 2,1′-anhydro-,2,1′:3,6-dianhydro-, and 2,1′:3,6: 3′,6′-trianhydro-sucrose

1′-O-Mesyl-6,6′-di-O-tritylsucrose and the corresponding 1′-O-tosyl derivative were prepared from 6,6′-di-O-tritylsucrose by selective sulphonylation. Both sulphonates underwent intramolecular cyclisation reactions, to give 2,1′-anhydrosucrose in high yields rather than the isomeric 1′,4′-anhydride. Sequential benzoylation, detritylation, and mesylation of the 2,1′-anhydride afforded 2,1′-anhydro-6,6′-di-O-mesylsucrose tetrabenzoate which, in the presence of base, gave 2,1′:3,6:3′,6′-trianhydrosucrose that was not identical with the product previously claimed to have this structure. Several derivatives of 2,1′-anhydrosucrose were prepared possessing different functional groups at either the 6,6′- or 4,6′-positions. Dimolar mesitylene-sulphonylation of 3,3′,4′6′-tetra-O-acetylsucrose gave the 6,1′-disulphonate, which, in the presence of alkali, gave 2,1′:3,6-dianhydrosucrose, which was transformed into the 2,1′:3,6:3′,6′-trianhydride by sequential bromination at C-6′ (carbon tetrabromide-triphenylphosphine) and base-catalysed cyclisation. Treatment of 3,3′,4′,6′-tetra-O-benzoylsucrose with sulphuryl chloride furnished the 4,6,1′-trichloro derivative, which, on alkaline hydrolysis, was converted into 2,1′:3,6-dianhydro-4-chloro-4-deoxy-galacto-sucrose.     

The novel tungsten-iron-sulfur protein of the hyperthermophilic archaebacterium, Pyrococcus furiosus, is an aldehyde ferredoxin oxidoreductase. Evidence for its participation in a unique glycolytic pathway

The anaerobic archaebacterium, Pyrococcus furiosus, grows optimally at 100 degrees C by a fermentative-type metabolism in which H2, CO2, and organic acids are end products. The growth of this organism is stimulated by tungsten, and, from it, a novel, red-colored, tungsten-iron-sulfur protein, abbreviated RTP, has been purified (Mukund, S., and Adams, M. W. W. (1990) J. Biol. Chem. 265, 11508-11516). RTP (Mr approximately 85,000) contained approximately 1W, 7Fe, and 5 acid-labile sulfide atoms/molecule and exhibited unique EPR properties. The physiological function of the protein, however, was unknown. We show here that RTP is an inactive form of an aldehyde ferredoxin oxidoreductase (AOR). The active enzyme was obtained by rapid purification under anaerobic conditions using buffers containing dithiothreitol and glycerol. AOR catalyzed the oxidation of a range of aliphatic aldehydes with an optimum temperature for activity above 90 degrees C, but it did not oxidize glucose or glyceraldehyde 3-phosphate, nor reduce NAD(P), and its activity was independent of CoA. The active (AOR) and inactive (RTP) forms of the enzyme were indistinguishable in their contents of metals and acid-labile sulfide and in their EPR properties. The latter are though to originate from two nonidentical and spin-coupled iron-sulfur clusters, whereas the tungsten in this enzyme, which was not detectable by EPR, appears to be present as a novel pterin cofactor. Inhibition and activation studies indicated that AOR contains a catalytically essential W-SH group that is not present in RTP, the inactive form. AOR is a new type of aldehyde-oxidizing enzyme and is the first aldehyde oxidoreductase to be purified from an archaebacterium or a nonactogenic anaerobic bacterium. Its physiological role in P. furiosus is proposed as the oxidation of glyceraldehyde to glycerate in a unique, partially nonphosphorylated, glycolytic pathway that generates acetyl-CoA from glucose without the participation of nicotinamide nucleotides.     

Effect of sodium butyrate on mammalian cells in culture: A review

Summary Sodium butyrate produces reversible changes in morphology, growth rate, and enzyme activities of several mammalian cell types in culture. Some of these changes are similar to those produced by agents which increase the intracellular level of adenosine 3′,5′-cyclic monophosphate (cAMP) or by analogs of cAMP. Sodium butyrate increases the intracellular level of cAMP by about two fold in neuroblastoma cells; therefore, some of the effects of sodium butyrate on these cells may in part be mediated by cAMP. Sodium butyrate appears to have properties of a good chemotherapeutic agent for neuroblastoma tumors because the treatment of neuroblastoma cells in culture causes cell death and “differentiation”; however, it is either innocuous or produces reversible morphological and biochemical alterations in other cell types.     

Synthesis,characterization and biological aspects of novel five-coordinated dimeric-Cu(II) systems

The structural and spectroscopic properties of novel five-coordinated dimeric-Cu(II) system have been investigated. The biocidal activities of all eight compounds, ligands, cupric nitrate and standard drugs against six bacteria and three fungi were determined. The DNA interaction activity of complexes was studied using spectrophotometry and electrophoresis. The superoxide dismutase (SOD)-like activity of the complexes was compared with previously reported monomeric- and dimeric copper complexes. The results support the five-coordinated dimeric square pyramidal geometry for the quinolone-Cu(II) system.