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  • 1
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Production of vitamin B-12 compounds from methanol was carried out by Methanosarcina barkeri Fusaro, an anaerobic methanogen. The methanogen released about 40% to 70% of corrinoids irrespective of the culture medium used. The use of cysteine instead of Na2S as the sole sulphur source for cell growth led to an increase in the cobalt chloride concentration in the culture medium up to 16 times the normal (0.6 mg·l-1) without medium precipitation. This in turn resulted in an intracellular vitamin B-12 content of 5.6 mg·g dry cell-1, the rest being discharged into the culture supernatant; this was 87 mg·l-1, 73% of the total corrinoids after 20 repeated intermittently fed cultures and the final cell concentration was 5.8 g dry cell·l-1. Taking advantage of this, continuous production of extracellular vitamin B-12 compounds was attempted with a fixed-bed bioreactor (carrier: diatomaceous clay). At a steady state operation at space velocity of 9 to 11 day-1, the concentration of the discharged corrinoid was 6.8 to 7.9 mg·l-1, having a vitamin B-12 activity of about 4 mg·l-1. Total cell mass retained in the reactor was 39.6 g dry cell l-reactor-1. Identification of the corrinoids revealed that 19% of the total corrinoids was comprised of the vitamin B-12 Factor III (5-hydroxybenzimidazolyl cobamide) and the remainder were mainly the base-free vitamin B-12 Factor B (cobinamide and its derivatives).
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  • 2
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary An acetate-tolerant strain of Clostridium thermoaceticum (ATCC 31490), characterized as growing on a tryptone-yeast extract complex medium, was adapted to grow in a minimal medium containing glucose as sole carbon source. After five sequential batch cultures involving reducing and deleting organic materials from the original complex medium, the bacterium could grow on minimal medium with a supplement of nicotinic acid. However, growth and homoacetogenesis from glucose was remarkably retarded compared with that observed in the original complex medium. This could be strikingly improved up to the original level by replacing sodium thioglycolate (a reducing agent in the original medium) with L-cysteinλHCI supplemented to the minimal medium. Cysteine played an important role in stimulating growth and homoacetogenesis by not only supplying H2S as a sulphur source via cysteine desulphydrase (EC 4.4.1.1) but also maintaining a proper redox potential (—370 and —400 mV) in the growth phase during culture. Methionine could not serve as a sulphur source.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The use of polyurethane foam (PUF) as a microbial support carrier was evaluated with a mesophilic propionate-acclimatized sludge. The acclimatized sludge could be immobilized rapidly and stably in PUF of smaller pore size under shaking conditions. The sludge retained in PUF could maintain a high propionate metabolic activity for a long period. High conversion rates of propionate to methane of 23–65 g chemical oxygen demand (COD)·1−1 · day−1 could be achieved in reactors packed with PUF-retained sludge. A dense sludge of 0.08–0.25 g mixed-liquor volatile suspended solids (MLVSS)·cm−3 was retained in PUF. Microscopic analysis suggested that filamentous microorganisms, e.g., Methanothrix spp. could play an important role in the efficient retention of acclimatized sludge in PUF.
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  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary In the productions of biomass and vitamin B12 using methanol as the sole carbon source, it is necessary to use a medium in which methanol is the growth limiting substrate. Other inorganic salts should be in slight excess so that the yield of cells and the intracellular content of vitamin B12 do not vary. From basic principles of chemostat culture, a medium was optimized for Pseudomonas AM-1 a methanol utilizing bacterium, for the concentrations of various inorganic salts. This was done in a series of chemostat cultures at a dilution rate of 0.1 h−1. Optimum amounts of NH4 +, PO4 3- and Mg2+ were estimated from the minimum concentration of the salt at which methanol became growth limiting. The optimum concentrations of Ca2+, Fe2+, Mn2+, and Zn2+ as a group were determined in the same way. Cu2+, Mo6+, Co2+ and B3+ are required at concentrations of μg/l and they were not studied as these very low level can be introduced as contaminants from other salts. The optimum medium composition (in g/l) was as follows: (NH4)2SO4, 1.0; H3PO4, 75×10−3; MgSO4 · 7H2O, 30×10−3; CaCl2 · 2H2O, 3.3×10−3; FeSO4 · 7H2O, 1.3×10−3, MnSO4 · 4H2O, 0.13×10−3; ZnSO4 · 7H2O, 0.13×10−3; CuSO4 · 5H2O, 40×10−6; Na2MoO4, 40×10−6; CoCl2 · 6H2O, 40×10−6; H3BO3, 30×10−6 and methanol 4.
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  • 5
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A production of macerating enzymes which liquefy and hydrolyze the mandarin orange peel was studied in a solid state cultivation of Aspergillus niger on wheat bran substrate. Solid state cultivation in a 2 ℓ drum fermenter capable of interchangeable operation under dynamic or static conditions were carried out maintaining the moisture content of the substrate at 32, 39, 46, 56, 67, and 74%. Biomass grown on the solid substrate was estimated on the basis of a constant value of glucosamine content of A. niger, 50 mg glucosamine/g cell. A linear relationship between oxygen uptake rate and growth rate observed in all the experiments gave an oxygen growth yield, YX/O, of 28.5 g cell/mol O2. The rate of macerating enzyme formation was also in proportion to the growth rate irrespective of the difference of the moisture content of the substrate. The enzyme accumulation on the solid substrate, the growth rate and oxygen uptake rate were maximum when the moisture content of the substrate was maintained at ca. 56% ascending from 32 to 56 and descending from 56 to 74.
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary As the hydrolysis of mandarin orange peel with macerating enzyme (40°C, 24 h) produced 0.59 g g−1 reducing sugar per dry peel compared to 0.36 by acid-hydrolysis (15 min at 120°C with 0.8 N H2SO4), the production of single cell protein (SCP) from orange peel was studied mostly using enzymatically hydrolyzed orange peel. When the enzymatically hydrolyzed peel media were used, the utilization efficiency of reducing sugars (%) and the growth yield from reducing sugars (g g−1) were: 63 and 0.51 for Saccharomyces cerevisiae; 56 and 0.48 for Candida utilis; 74 and 0.69 for Debaryomyces hansenii and 64 and 0.70 for Rhodotorula glutinis. SCP production from orange peel by D. hansenii and R. glutinis were further studied. Batch cultures for 24 h at 30°C using 100 g dried orange peel produced 45 g of dried cultivated peel (protein content, 33%) with D. hansenii and 34 g (protein content, 50%) with R. glutinis, and 38 g (protein content, 44%) with a mixture of both yeasts.
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The resting cells of methanogen strain HU could be used as biocatalyser for converting exoge nous NADP+ into NADPH, using either formate or hydrogen as electron donor. To enhance the conversion efficiency of NADPH from NADP+, several inhibitors of methylcoenzyme M reductase were used in order to avoid further oxidation of NADPH to CH4. When methyl viologen (7.5 μmol ml-1) was added to the reaction mixture (17 mg of dry cells, 2 mg Triton X-100, 294 μmol of Na-formate and 12 μmol of NADP+ per ml reaction mixture), 9.6 μmol ml-1 NADPH (80% yield) could be produced in a 2-h reaction, compared with 7.2 μmol ml-1 NADPH (60% yield) in a 6-h reaction in the absence of methyl viologen. Molecular hydrogen istead of formate also served as electron donor to convert NADP+ into NADPH. A gas mixture of H2/N2 (75/25) yielded 9.8 μmol ml-1 NADPH (82% yield) in a 3-h reaction in the absence of formate, suggesting that H2 might be a promising, inexpensive electron donor for this reaction system.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Resting cells of a formate-utilizing methanogen (strain HU) were used as a biocatalyser for formic acid production from H2 and bicarbonate. In the presence of methyl viologen, a potent inhibitor of methanogenesis, the cells could accumulate formic acid in the reaction mixture, whereas methane was produced in the absence of the inhibitor. Under optimal conditions (pH 8.0, 32°C, 100% H2 gas phase), 674 mmol·l-1 of formic acid (31 g·l-1 yield; 33% conversion of bicarbonate) was obtained at about 0.7 atm of gas pressure. When the reaction was carried out in an ultrafiltration vessel with a hydrogen pressure of 3 atm, a final product concentration of 1.02 mol·l-1 (47 g·l-1 yield, 51% conversion) could be obtained, indicating that the hydrogen lyase system of this methanogen has a high tolerance to formic acid, bicarbonate and hydrogen. The results obtained in this work open a new perspective for the utilization of methanogens for processes other than methane production.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The selective formation of three tetrapyrroles, Co-containing corrinoids, Ni-containing factor F430 and Fe-containing cytochromes (haems) by Methanosarcina barkeri Fusaro (DSM 804) was achieved as a function of the concentrations of Co2+, Ni2+ and Fe2+ in a methanol minimmum medium. It was found that about 70% of the total tetrapyrroles synthesized was excreted into the culture supernatant. Hence, the continuous production of tetrapyrroles in a fixed-bed reactor (supporter: porous diatomaceous clay) was carried out at a dilution rate of 10 day-1 (850 ml medium/85 ml column/day). The effluent discharged from the reactor contained the excreted tetrapyrroles, the concentrations of which were dependent upon the Co2+, Ni2+ and Fe2+ concentrations in the feed medium. The maximum productivities from the reactor (1 l basis) were 52 μM corrinoids/day, 24 μM F430/day and 8 μM haems/day, respectively.
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  • 10
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Thirty-nine fungal cultures belonging to the genera of Aspergillus, Podospora, Sordaria, Cbaetomium, Iodophanus, Scleotinia, Coniella, Pellicularia and others, were examined for the production of enzymes which macerate the mandarin orange peel using a wheat bran as substrate. An isolated strain of Aspergillus niger was an excellent producer of macerating enzymes compared to other organisms tested. The peel of the mandarin orange could be macerated by the crude enzymes produced by isolated A. niger. The maceration of 1 g of peel/24 h yielded 0.57 g of reducing sugars. Expressed differently, 83% of solid peel materials were released from the peel into the water/24 h under the following conditions: a peel concentration of 8 g peel/l, a crude enzyme concentration of 1 g protein/l, a temperature of 40°C, a pH of 5, a 24 h incubation time and 120 rpm reciprocal shaking. The test of the macerating activity of commercially available hydrolases on the orange peel showed that the two samples of pectinase originating from A. niger had about the same activity as isolated A. niger whereas the two samples of cellulase originating from Trichoderma viride had remarkably lower activities than A. niger.
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