Improving ethanol tolerance of a self-flocculating yeast by optimization of medium composition

High ethanol tolerance is a desired property of industrial yeast strains for efficient ethanol fermentation. In this study, the impact of medium composition on ethanol tolerance of the self-flocculating yeast SPSC01 was investigated using a chemically defined medium. Single-factor experiments revealed that besides magnesium and calcium, zinc also exhibited significant protective effect against ethanol toxicity; addition of 0.02 g/l zinc sulfate significantly increased cell viability in the ethanol shock treatment. Metal ions of manganese, cobalt, and ferrous failed to promote ethanol tolerance, although addition of 0.02 g/l cobalt increased ethanol production without apparent influence on ethanol tolerance. Furthermore, Uniform Design method was employed to obtain the medium with high cell viability, and the key nutrient factors in the medium composition were revealed to be (NH₄)₂SO₄, K₂HPO₄, vitamin mixtures, and the metal ions of magnesium, calcium and zinc. The optimized combination of metal ions addition was (g/l): MgSO₄ 0.4, CaCl₂ 0.2, ZnSO₄ 0.01. The highest cell viability (90.2%) of SPSC01 against ethanol shock treatment was observed in the optimized medium, which demonstrated significant improvement of ethanol tolerance of the self-flocculating yeast.     

Alginate promotes production of various enzymes by Catharanthus roseus cells

When 1.0 g/l of alginate was added to a Catharanthus roseus L. cell culture, many proteins were released from the cells as detected by SDS polyacrylamide gel electrophoresis. In particular, production and/or release of 5′-phosphodiesterase (5′-PDase), catalase and chitinase by C. roseus L. cells were promoted by the addition of alginate. The promotive effects of alginate on 5′-PDase production were observed for various C. roseus cell lines and similar results were obtained when different alginates with various mannuronate/guluronate ratios and viscosities were used. In contrast, agar, agarose, and chitosan did not promote 5′-PDase production. The promotion of 5′-PDase production was not due to cell mutation, the alginate acted rather as a kind of elicitor. During 82 subcultures (577 days) in Murashige and Skoog medium containing 1.0 g/l of alginate, production and release of 5′-PDase by C. roseus L. cells were promoted without inhibition of cell growth. Received: 27 February 1997 / Revision received: 10 July 1997 / Accepted: 20 July 1997     

Plant regeneration from encapsulated somatic embryos of Carica papaya L.

Carica papaya L. (papaya) single somatic embryos (2.0 mm diameter) produced in a high-frequency liquid production system were encapsulated in two different synthetic encapsulation compounds. The frequency of regeneration from encapsulated embryos was significantly affected by (1) the concentration of sodium alginate, (2) the presence or absence of nutrient salts in the capsule, and (3) the duration of exposure to calcium chloride. A 2.5% sodium alginate concentration in a half-strength MS salts base resulted in significantly higher germination frequencies than other treatments. A relatively short (10 min) exposure to CaCl₂ provided uniform encapsulation of embryos and the highest frequencies of successful germination (77.5%). Germinated artificial seeds produced normal plantlets. Received: 12 March 1997 / Revision recieved: 24 June 1997 / Accepted: 18 July 1997     

Utilization in alginate beads for Cu(II) and Ni(II) adsorption of an exopolysaccharide produced by <Emphasis Type="Italic">Chryseomonas luteola</Emphasis> TEM05

Copper and nickel adsorption onto calcium alginate, sodium alginate with an extracellular polysaccharide (EPS) produced by the activated sludge bacterium Chryseomonas luteola TEM05 and the immobilized C. luteola TEM05 from aqueous solutions were studied. After that, the multi metal ions containing these ions together were prepared and partial competitive adsorptions of these mixtures were also investigated. The metal adsorption of gel beads were carried out at pH 6.0, 25 °C. The maximum adsorption capacities in Langmuir isotherm for calcium alginate, calcium alginate + EPS, calcium alginate + C. luteola TEM05 and calcium alginate + EPS + C. luteola TEM05 were 1.505, 1.989, 1.976, 1.937 mmol/g dry weight for Cu(II) and 0.996, 1.224, 1.078, 1.219 mol/g dry weight for Ni(II), respectively.The competitive biosorption capacities of the carrier for all metal ions were lower than single conditions.     

Utilization of Hydrocarbons by Microorganisms

The accumulation of vitamin B₂ by Pichia guilliermondii Wickerham grown on hydrocarbon was investigated. Addition of the following materials stimulated vitamin B₂ production: metal ions such as ferrous, cobalt, manganese, and calcium ions; organic nutrients such as yeast extract and casamino acid; amino acids such as proline and arginine; vitamins such as B₁, nicotinic acid, inositol, and p-aminobenzoic acid. Optimal aeration rate for vitamin B2 production was obtained in a 500-ml shaking flask containing 75 ml of the medium.     

Metal-induced expressing of mammal Metallothionein-1 gene in cyanobacteria to promote cadmium-binding preferences

The metal(zinc)-inducible smtA gene promoter (smt O-P) from cyanobacteria was applied for the expression of mouse MT-1 cDNA in the filamentous cyanobacterium Anabaena sp. PCC 7120 to enhance its metal-binding capability and to change its main binding specificity from zinc to cadmium. Shuttle expression vector pKT-MRE transformed the cyanobacterial cells by triparent conjugal transfer. Positive clones were screened and identified by streptomycin, DNA dot blot, SDS-PAGE and Western blot analysis. Photosynthetic oxygen evolution and metal atom absorption indicated that under the cadmium stress the metal-induced expression of foreign mMT-1 doubled their cadmium resistance and developed cells showing a much higher preference to absorb cadmium other than zinc in medium. The cadmium content in cell extract rose from 11% to 36%, and the cadmium cleared from media by transgenic cells rose from 18% to 62%. There was only a slight enhancement for zinc binding in the wild or transgenic type. Received: 1 March 1999 / Received last revision: 9 July 1999 / Accepted: 1 August 1999     

Kinetic analysis of metal uptake by dry and gel alginate particles

The kinetics of metal uptake by gel and dry calcium alginate beads was analysed using solutions of copper or lead ions. Gel beads sorbed metal ions faster than the dry ones and larger diffusivities of metal ions were calculated for gel beads: approximately 10⁻⁴ cm²/min vs. 10⁻⁶ cm²/min for dry beads. In accordance, scanning electron microscopy and nitrogen adsorption data revealed a low porosity of dry alginate particles. However, dry beads showed higher sorption capacities and a mechanical stability more suitable for large-scale use. Two sorption models were fitted to the kinetic results: the Lagergren pseudo-first order and the Ho and McKay pseudo-second order equations. The former was found to be the most adequate to model metal uptake by dry alginate beads and kinetic constants in the orders of 10⁻³ and 10⁻² min⁻¹ were obtained for lead solutions with concentrations up to 100 g/m³. The pseudo-first order model was also found to be valid to describe biosorbent operation with a real wastewater indicating that it can be used to design processes of metal sorption with alginate-based materials.     

Release of Metal Ions from Orthodontic Appliances: An In Vitro Study

In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily doses, two elements of concern were nickel (573 vs. 15 μg/l in the controls) and chromium (101 vs. 8 μg/l in the controls). Three ion release coefficients were defined: α, a dimensionless multiplication factor; β, the difference in concentrations (in micrograms per liter); and γ, the ion release coefficient (in percent). The elevated levels of metals in saliva are thought to occur by corrosion of the chemical elements in the alloys or welding materials. The concentrations of some groups of dissolved elements appear to be interrelated.     

Plant regeneration from alginate-encapsulated shoot tips of Phylianthus amarus schum and thonn, a medicinally important plant species

Summary A method was developed for plant regeneration from alginate-encapsulated shoot tips of Phyllanthus amarus. Shoot tips excised from in vitro proliferated shoots were encapsulated in calcium alginate beads. The best gel complexation was achieved using 3% sodium alginate and 75 mM CaCl₂·2H₂O. Maximum percentage response for conversion of encapsulated shoot tips into plantlets was 90% after 5 wk of culture on Murashige and Skoog (MS) medium without plant growth regulator. The regrowth ability of encapsulated shoot tips was affected by the concentration of sodium alginate, storage duration, and the presence or absence of MS nutrients in calcium alginate beads. Plantlets with well-developed shoot and roots were transferred to pots containing an autoclaved mixture of soilrite and peat moss (1∶1). The conversion of encapsulated shoot tips into plantlets also occurred when calcium alginate beads were directly sown in autoclaved soilrite moistened with 1/4-MS salts. Encapsulation of vegetative propagules in calcium alginate beads can be used as an alternative to synthetic seeds derived from somatic embryos.     

Sol–gel transition of alginate solution by the addition of various divalent cations: 13C-nmr spectroscopic study

¹³C-NMR spectroscopic studies have been made on alginate solutions undergoing sol–gel transition induced by four different divalent cations: Ca, Cu, Co, and Mn. From the analysis of nmr spectra and relaxation times, we have found different interaction modes existing between the Ca–alginate systems and the transition metal (Cu, Co, and Mn)–alginate systems. In the Ca–alginate systems, there exists a specific interaction characterized by a strong autocooperative binding between guluronate residues and calcium ions, and all functional groups in guluronate residues are considered to involve the interaction with calcium ions. On the other hand, in transition metal (Cu, Co, and Mn)–alginate systems, sol–gel transition is characterized by a complex formation in which the carboxyl groups in both mannuronate and guluronate residues are coordinated to metal ions. The other functional groups, like hydroxyl groups, do not participate in the binding to metal ions. It is suggested by relaxation time measurements that from a microscopic point of view the sol–gel transition phenomena can be explained as a dynamic process in which the low frequency molecular motions are dominant and increase their proportions with the formation of three-dimensional cross-links. © 1993 John Wiley & Sons, Inc.     

Trace Metal Imaging of Sulfate-Reducing Bacteria and Methanogenic Archaea at Single-Cell Resolution by Synchrotron X-Ray Fluorescence Imaging

Metal cofactors are required for many enzymes in anaerobic microbial respiration. This study examined iron, cobalt, nickel, copper, and zinc in cellular and abiotic phases at the single-cell scale for a sulfate-reducing bacterium (Desulfococcus multivorans) and a methanogenic archaeon (Methanosarcina acetivorans) using synchrotron X-ray fluorescence microscopy. Relative abundances of cellular metals were also measured by inductively coupled plasma mass spectrometry. For both species, zinc and iron were consistently the most abundant cellular metals. M. acetivorans contained higher nickel and cobalt content than D. multivorans, likely due to elevated metal requirements for methylotrophic methanogenesis. Cocultures contained spheroid zinc sulfides and cobalt/copper sulfides.     

Effect of phosphate and oxygen concentrations on alginate production and stoichiometry of metabolism of Azotobacter vinelandii under microaerobic conditions

Alginate production by Azotobacter vinelandii was studied in batch and continuous cultures under microaerobic conditions. In batch culture at a pO₂ of 2–3% (air saturation) alginate production was enhanced by decreasing the PO³⁻ ₄ level in the medium. Alginate yield from biomass (Y _P/X) reached the highest value of 0.66 g/g at the lowest phosphate level (100 mg/l), compared to 0.40 g/g and 0.25 g/g at higher phosphate levels (200 mg/l and 400 mg/l, respectively). In contrast, biomass formation behaved differently and the growth yield (Y _X/S) decreased with decreasing PO₄ ³⁻ concentrations. Moreover, the respiratory quotient (RQ) of the culture was dependent on the initial phosphate concentration, especially in the phosphate-limited phase of growth. As the initial phosphate level decreased from 400 mg/l to 100 mg/l, the average RQ value of the culture declined from 1.46 to 0.89. The low RQ value is very close to the theoretical optimum RQ, calculated to be 0.8 on the basis of the stoichiometry of the metabolic pathways for alginate formation from sucrose. This optimum RQ was also confirmed in continuous culture at different dilution rates. Independent of the dilution rate, a pO₂ value of 2–5% (air saturation) was found to be optimal for alginate production, the corresponding RQ values being 0.80–0.84. In addition, the molecular mass and composition of alginate were also found to be affected by both phosphate and oxygen concentrations. In conclusion, the RQ appears to be a useful parameter for optimum control of alginate production with this microorganism. Received: 31 March 1999 / Received revision: 2 July 1999 / Accepted: 5 July 1999     

Effects of carbon source, phosphorus concentration, and several micronutrients on biomass and geosmin production by Streptomyces halstedii

The effects of various carbon sources, phosphorus concentration, and different concentrations of the micronutrients calcium, cobalt, copper, iron, manganese, potassium, and zinc were determined on biomass dry weight production, geosmin production, and geosmin/biomass (G/B) values for Streptomyces halstedii, a geosmin-producing actinomycete isolated from the sediment of an aquaculture pond. Of the substrates tested, maltose as a sole carbon source promoted maximal growth by S. halstedii while mannitol promoted maximal geosmin production, and galactose yielded the highest G/B values. Fish-food pellets and galactose were poor substrates for growth. Increasing phosphorus concentrations enhanced geosmin production and G/B values. Of the seven micronutrients tested, zinc, iron, and copper had the most profound effects on biomass and geosmin production. Increasing zinc concentrations promoted biomass production while inhibiting geosmin production and G/B values; increasing concentrations of copper and iron inhibited biomass and geosmin production. Increased copper concentrations had the greatest effect in preventing growth and geosmin production by S. halstedii. Journal of Industrial Microbiology & Biotechnology (2001) 26, 241–247. Received 20 September 2000/ Accepted in revised form 17 January 2001     

Preparation and optical properties of alloyed ZnxCd1‐xS/alginate core/shell nanoparticles

Zn_xCd_1‐xS/alginate core/shell nanoparticles were synthesized via a colloidal route by reacting zinc and cadmium ions with sulfide ions, followed by coating with alginate. The crystal structure, morphology, size and optical properties of the core/shell nanoparticles were characterized by X‐ray diffraction, transmission electron microscopy, UV/vis and photoluminescent spectra, respectively. The Zn_xCd_1‐xS nanoparticles are spherical and have a cubic structure with a mean crystalline size of 2–4 nm. The band gap of Zn_xCd_1‐xS/alginate core/shell nanoparticles increases with increasing Zn/Cd molar ratio, and the UV/vis absorption blue‐shifts correspondingly. Two emissions related to zinc and sulfide ion vacancies were observed for the Zn_xCd_1‐xS/alginate core/shell nanoparticles due to the surface changes from the alginate coating. A cadmium‐related emission was observed for both the uncovered Zn_xCd_1‐xS and Zn_xCd_1‐xS/alginate core/shell nanoparticles, which has a significant blue‐shift with increasing Zn/Cd molar ratio. Copyright © 2014 John Wiley & Sons, Ltd.     

Plant regeneration from leaf protoplasts of evening primrose (Oenothera hookeri)

A protocol is presented for regenerating plants from leaf protoplasts of Oenothera. The method uses (1) embedding of isolated protoplasts at high cell densities in thin alginate layers, (2) initial culture in B5 medium containing 3 mg l^–1 α-naphthaleneacetic acid (NAA) and 1 mg l^-1 6-benzylaminopurine (BAP), (3) reduction of the osmotic pressure of the culture medium at early stages of culture and (4) plating of microcolonies recovered from the alginate onto solid B5 medium with 3 mg l^–1 NAA and 1 mg l^–1 BAP. The shortest time required from protoplast isolation to the appearance of shoot initials was 7 weeks. The efficiency of the procedure for protoplast to cell line formation is high (about 80%). Received: 17 February 1997 / Revision received: 6 November 1997 / Accepted: 15 November 1997     

Efficient plantlet regeneration from protoplasts isolated from suspension cultures of poplar (Populus alba L.)

We developed an efficient plant regeneration system from protoplasts for poplar (Populus alba L.). Protoplasts were isolated from 4-day-old suspension cultures derived from seed-induced calli with a yield of 6.96× 10⁶ cells/g fresh weight cells and then cultured at a concentration of 2.5×10⁵ cells/ml in NH₄NO₃-free Murashige and Skoog (MS) medium supplemented with 5 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 0.05 μM thidiazuron (TDZ) and 0.5 M glucose as a osmoticum. The plating efficiency of the cultured protoplasts was calculated at 26.5% at day 7 and 31.7% at day 14. Cell colonies were observed after culturing for 4 weeks. Regenerated colonies were propagated through subculture in liquid MS medium supplemented with 5 μM 2,4-D. Buds were induced from regenerated calli on MS medium containing 10 μM kinetin or 1 μM TDZ. Regenerated shoots were rooted on half-strength MS medium, and the plantlets were transplanted in soil. Randomly amplified polymorphic DNA analysis did not detect any DNA polymorphism among the regenerated plants. Received: 7 March 1997 / Revision received: 16 June 1997 / Accepted: 5 July 1997     

Utilization of an exopolysaccharide produced by Chryseomonas luteola TEM05 in alginate beads for adsorption of cadmium and cobalt ions

Cadmium and cobalt adsorption from aqueous solution onto calcium alginate, sodium alginate with an extracellular polysaccharide (EPS) produced by the activated sludge bacterium Chryseomonas luteola TEM05 and immobilized C. luteola TEM05 was studied. In addition, solutions containing both of these ions were prepared and partial competitive adsorption of these mixtures was investigated. Metal adsorption onto gel beads was carried out at pH 6.0 and 25 degrees C. The maximum adsorption capacities determined by fitting Langmuir isotherms to the data for calcium alginate, calcium alginate+EPS, calcium alginate + C. luteola TEM05 and calcium alginate + EPS + C. luteola TEM05 were 45.87, 55.25, 49.26, 51.81 mg g(-1) for Co(II) and 52.91, 64.10, 62.5, 61.73 mg g(-1) for Cd(II), respectively. The biosorption capacity of the carrier for both metal ions together in competition was lower than those obtained when each was present alone.     

Some properties of alginate gels derived from algal sodium alginate

Alginic acid in soluble sodium alginate turns to insoluble gel after contact with divalent metal ions, such as calcium ions. The sodium alginate character has an effect on the alginate gel properties. In order to prepare a suitable calcium alginate gel for use in seawater, the effects of sodium alginate viscosity and M/G ratio (the ratio of D-mannuronate to L-guluronate) on the gel strength were investigated. The wet tensile strengths of gel fibers derived from high viscosity sodium alginate were higher than those from low viscosity sodium alginate. The tensile strength increased with diminishing sodium alginate M/G ratio. Among the gel fibers tested, the gel fiber obtained from a sodium alginate I-5G (1% aqueous solution viscosity = 520 mPa·s, M/G ratio = 0.6) had the highest wet tensile strength. After 13 days treatment in seawater, the wet tensile strength of the gel fiber retained 36% of the original untreated gel strength. For sodium alginates with similar viscosities, the seawater tolerance of low M/G ratio alginate was greater than that of the high M/G ratio one. This study enables us to determine a suitable calcium alginate gel for use in seawater.     

Effect of basal medium, growth regulators and Phytagel concentration on initiation of embryogenic cultures from immature zygotic embryos of loblolly pine (Pinus taeda L.)

Low initiation frequency is one of the main barriers in applying somatic embryogenesis to the clonal production of Pinus species. Factors affecting initiation, including basal medium, plant growth regulators, and Phytagel concentration, have been investigated in loblolly pine (Pinus taeda L.). BM₁ basal medium proved superior to DCR₁ and LP (LP basal salts plus BM₁ organic nutrients). No extrusion from megagametophytes was exhibited on LP medium. The combination of 3 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/l 6-benzylaminopurine (BA) resulted in a higher extrusion frequency than that of 11 mg/l 2,4-D, 4.5 mg/l BA and 4.3 mg/l kinetin. Phytagel at 1 g/l resulted in the highest explant browning, but the lowest extrusion frequency, while 4 g/l Phytagel induced some dry embryogenic extrusions. Phytagel at 2 g/l was regarded as the best level for initiation of embryogenic cultures. Received: 23 December 1996 / Revision received: 22 July 1997 / Accepted: 2 September 1997     

Sulfated extracellular polysaccharide production by the halophilic cyanobacterium Aphanocapsa halophytia immobilized on light-diffusing optical fibers

 The cyanobacterium, Aphanocapsa halo-phytia MN-11, was immobilized in calcium alginate gel and coated on light-diffusing optical fibers (LDOF) for sulfated extracellular polysaccharide production. Results indicated that sulfated extracellular polysaccharide production depends on the number of immobilized cells and the light intensity. In addition, the production rate reached 116.0 mg (mg dry cells)^-1 day^-1 when the cells that were immobilized on LDOF were incubated under a light intensity of 1380 cd sr m^-2 at a cell concentration of 1.0×10⁸ cells/cm³ gel. Cells immobilized on LDOF produced about ten times more sulfated extracellular polysaccharide than those immobilized in calcium alginate beads only (11.7 mg(mg dry cells)^-1day^-1). Received: 31 March 1995/Revised last revision 12 June 1995/Accepted 26 July 1995