Effect of ammonium ion concentration on polysaccharide production by Aureobasidium pullulans in batch culture

Abstract This paper reports a laboratory study of the oxidative destruction by sodium hypochlorite (NaOCl) of ammonium ions adsorbed on relatively reduced south Texas uranium ore. Included are an assessment of reaction stoichiometry, determination of some major reaction pathways and side reactions, and identification of several pathways and side reactions, and identification of several intermediates. Adsorbed ammonium ions were completely removed by 0.5 % NaOCl, with the concentration of NH3 in the effluent falling to a very low value after 10 to 15 PV NaOCl oxidant. A small fraction (5 to 10%) of NaOCl was utilized in reacting with NH3. After the NH3 was nearly depleted, mono-, di-, and trichloramines, the expected intermediates in NaOCl oxidation of NH3, were observed. Chloramine decomposition studies showed that all three decomposed completely within 12 days. Since the ore was relatively highly reducing, the major pan of the NaOCl was, not unexpectedly, consumed in side reactions. Substantial quantities of sulfate, reflecting oxidation of sulfide minerals such as pyrite, were formed, large amounts of uranium were leached out, and substantial amounts of calcium and magnesium ions were also produced during the presaturation with NH4HCO3 preceding the oxidation stage. Introduction A leachate that has sometimes been used for in-situ leaching of uranium ores is a solution of ammonium bicarbonate (NH4HCO3) containing an oxidant-usually hydrogen peroxide (H2O2) or oxygen (O2). The ammonium ion (NH4+) introduced into the ore body upon injection of this leachate is exchanged for cations such as calcium (Ca+2 ) and sodium (Na+), which are associated with mineral species in the formation possessing available cation exchange sites. As the indigenous groundwaters reinvade the leached zone, the adsorption process is reversed with NH4+ ions being displaced from process is reversed with NH4+ ions being displaced from the cation exchange sites and returned to the ground-waters. In general, this latter process maintains the ammonia (NH3 (or NH4+ ion) concentration well above the baseline (pre-mining) value in groundwater for extended periods of time in waters produced from wells in or near the mined zone following cessation of leachate injection. Prior to abandonment of an in-situ leach-mining site by the operator, satisfactory restoration of groundwater quality must be demonstrated. Requirements for this demonstration vary with the geographical area. A summary of applicable regulations has been provided by Kasper et al. A review of the state of restoration demonstrations to Sept. 1979 has been given by Tiepel. Most of the in-situ leach operations in south Texas have been conducted in aquifers containing indigenous waters with TDS contents in the 700- to 3,000-ppm range. Ca+ 2, magnesium (Mg+2), and bicarbonate ion (HCO3 ) concentrations are high in these slightly alkaline waters. These equilibrium water compositions indicate that an appreciable fraction of the interlayer ion exchange sites of the smectite clays in the formation are occupied by Ca+2 or Mg+2 ions. SPEJ P. 387

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Morphogenesis and adhesion of Aureobasidium pullulans

Canadian Journal of Microbiology ◽

10.1139/m94-002 ◽

1994 ◽

Vol 40 (1) ◽

pp. 6-17 ◽

Cited By ~ 70

Author(s):

John H. Andrews ◽

Robin F. Harris ◽

Russell N. Spear ◽

Gee W. Lau ◽

Erik V. Nordheim

Keyword(s):

Batch Culture ◽

Aureobasidium Pullulans ◽

Cell Attachment ◽

Extracellular Polysaccharide ◽

Quantitative Detection ◽

Total Biomass ◽

Dimorphic Fungus ◽

Solid Media ◽

Carbon And Nitrogen Content ◽

Cellulose Membranes

Two strains of the dimorphic fungus Aureobasidium pullulans were grown in liquid and on solid media varying in carbon and nitrogen content, and on leaf surfaces. Hyphae were observed in all systems but comprised a very low proportion (often below quantitative detection) of the total biomass. In liquid media, hyphae were found sparsely and only in the wash-zone on walls of the culture flasks. Yeast phase growth (blastospores) occurred in pH-buffered media that were nutrient balanced, or continuously carbon-limited (fed-batch culture), or carbon-exhausted (batch culture). Blastospores exposed to conditions with limited nitrogen but sufficient organic carbon, or to acidified media, converted to swollen cells and chlamydospores. The latter morphotypes accumulated carbon internally as lipid granules, and then externally as capsular and soluble extracellular polysaccharide. They were cohesive and also adhered more strongly to cellulose membranes overlying agar media or to leaves than did blastospores. Pullulanase treatment diminished the capsules, cohesion, and adhesion. Addition of soluble extracellular polysaccharide to blastospores enhanced their adhesion to leaves. We conclude that extracellular polysaccharide can play a role in adhesion of A. pullulans.Key words: phylloplane, leaf surface, epiphytic growth, extracellular polysaccharide, cell attachment.

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Ammonia influence in anaerobic digestion of OFMSW

Water Science & Technology ◽

10.2166/wst.2009.100 ◽

2009 ◽

Vol 59 (6) ◽

pp. 1153-1158 ◽

Cited By ~ 84

Author(s):

T. Benabdallah El Hadj ◽

S. Astals ◽

A. Galí ◽

S. Mace ◽

J. Mata-Álvarez

Keyword(s):

Anaerobic Digestion ◽

Competitive Inhibition ◽

Biogas Production ◽

Gompertz Model ◽

Ammonia Concentration ◽

Ion Concentration ◽

Ammonium Ion ◽

Municipal Solid Wastes ◽

Methane Generation ◽

Thermophilic Conditions

The anaerobic digestion of the organic fraction of municipal solid wastes is taking increasing importance in the recent years. The main problem of some anaerobic digestion process is the large quantity of ammonia that is released, especially when high solid digestion is implemented. A fraction of the supernatant is treated and the remaining is recirculated to maintain the reactor in the optimum solids concentration. The question arising is if this recirculation stream should also be treated to improve biogas production. However, when doing the latter the quantity of ammonia inside the reactor increases too which could lead to inhibit the reactor operation. In this paper it appears that not only free ammonia affects the methanogenic fermentation but also ammonium ion concentration. Biogas production profiles are estimated using the Gompertz model. On the other hand, inhibition constants are fitted using a non-competitive inhibition model equation Thus, 50% inhibition of biomethane production was observed at level of 215 and 468 mg NH3_N/L under mesophilic and thermophilic conditions. However, the methane generation under mesophilic and thermophilic conditions was reduced by 50% when ammonium ion reach concentrations of 3,860 and 5,600 mg NH4+_N/L respectively. Under mesophilic conditions, pH higher than 7 impacted the methanogens bacteria negatively. This threshold pH limit, is variable under thermophilic conditions, depending on the total ammonia concentration.

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Influence of Zn2+ and Fe3+ on polysaccharide production and mycelium/yeast dimorphism of Aureobasidium pullulans in batch cultivations

Applied Microbiology and Biotechnology ◽

10.1007/bf00191190 ◽

1995 ◽

Vol 42 (6) ◽

pp. 910-915 ◽

Cited By ~ 28

Author(s):

M. Reeslev ◽

B. Jensen

Keyword(s):

Aureobasidium Pullulans ◽

Polysaccharide Production

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