The effect of cultivation time on xanthan production by Xanthomonas spp. on glycerol containing medium

In this study, the influence of cultivation time on xanthan biosynthesis by different Xanthomonas strains, reference strain and crucifers? and pepper leaves? isolates, was examined. Biopolymer was produced by submerged cultivation of fourteen producing strains on medium with glycerol as a sole carbon source. Each experiment was performed at a laboratory level under aerobic conditions at 30?C and 150 rpm for 168 h and 240 h. Bioprocess efficacy was estimated based on the xanthan quantity and its average molecular weight that was selected as quality parameter. According to the obtained results, it can be concluded that all applied strains have a statistically significant effect on xanthan concentration in medium and on its average molecular weight, while cultivation time significantly affect the bioprocess efficacy only when biosynthesis is performed by Xanthomonas strains isolated from crucifers. Further, when only Xanthomonas strains isolated from crucifers are observed, statistically obtained data suggest that the largest amount of the best quality xanthan in applied experimental conditions can be accomplished by the cultivation of CB strain for 240 h. On the other hand, when it comes to Xanthomonas strains isolated from pepper leaves, the highest productivity is shown by PL 2, PL 4 and PL 5 strains regardless of the cultivation time, while the PL 3 strain was responsible for the synthesis of biopolymers with the highest average molecular weight. The results obtained in this study represent valuable information for development of biotechnological process for xanthan production on glycerol containing media using new producing strain.

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Synthesis of soluble dextran–hemoglobin complexes of different molecular sizes

Canadian Journal of Biochemistry ◽

10.1139/o77-055 ◽

1977 ◽

Vol 55 (4) ◽

pp. 398-403 ◽

Cited By ~ 23

Author(s):

Jian E. Chang ◽

J. Tze-Fei Wong

Keyword(s):

Molecular Weight ◽

Average Molecular Weight ◽

Optimal Conditions ◽

Experimental Conditions ◽

Molar Excess ◽

Viscosity Increase ◽

Molecular Sizes

Experimental conditions were defined that determined the synthesis of dextran–hemoglobin complexes through the alkylation of hemoglobin by N-bromoacetylaminoethylaminodextran. Using appropriate concentrations of the two reactants, over 90% yield of dextran–hemoglobin was obtained for dextrans of average molecular weight of 200 000, 110 000, 70 000, 40 000, and 20 000. Extensive viscosity increase due to crosslinking could be avoided, and a large molar excess of dextran over hemoglobin made unnecessary, under the optimal conditions.

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Bioconversion of biphenyl to a polyhydroxyalkanoate copolymer by Alcaligenes denitrificans A41

10.21203/rs.3.rs-36822/v2 ◽

2020 ◽

Author(s):

Taito Yajima ◽

Mizuki Nagatomo ◽

Aiko Wakabayashi ◽

Michio Sato ◽

Seiichi Taguchi ◽

...

Keyword(s):

Molecular Weight ◽

Carbon Source ◽

Sole Carbon Source ◽

Average Molecular Weight ◽

Gel Permeation Chromatography ◽

Nitrogen Sources ◽

Dry Weight ◽

Environmental Pollutant ◽

Genes Encoding ◽

Copolymer Poly

Abstract A polyhydroxyalkanoate (PHA) copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)], was biosynthesized from biphenyl as the sole carbon source using Alcaligenes (currently Achromobacter) denitrificans A41. This strain is capable of degrading polychlorinated biphenyls (PCBs) and biphenyl. This proof-of-concept of the conversion of aromatic chemicals such as the environmental pollutant PCBs/biphenyl to eco-friendly products such as biodegradable polyester PHA was inspired by the uncovering of two genes encoding PHA synthases in the A. denitrificans A41 genome. When the carbon/nitrogen (C/N) ratio was set at 21, the cellular P(3HB-co-3HV) content in strain A41 reached its highest value of 10.1% of the cell dry weight (CDW). A two-step cultivation protocol improved the accumulation of P(3HB-co-3HV) by up to 26.2% of the CDW, consisting of 13.0 mol% 3HV when grown on minimum salt medium without nitrogen sources. The highest cellular content of P(3HB-co-3HV) (47.6% of the CDW) was obtained through the two-step cultivation of strain A41 on biphenyl as the sole carbon source. The purified copolymer had ultra-high molecular weight (weight-average molecular weight of 3.5 × 106), as revealed through gel-permeation chromatography. Based on the genomic information related to both polymer synthesis and biphenyl degradation, we finally proposed a metabolic pathway for the production of P(3HB-co-3HV) associated with the degradation of biphenyl by strain A41.

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Bioconversion of Biphenyl to A Polyhydroxyalkanoate Copolymer by Alcaligenes Denitrificans A41

10.21203/rs.3.rs-36822/v1 ◽

2020 ◽

Author(s):

Taito Yajima ◽

Mizuki Nagatomo ◽

Aiko Wakabayashi ◽

Michio Sato ◽

Seiichi Taguchi ◽

...

Keyword(s):

Molecular Weight ◽

Carbon Source ◽

Sole Carbon Source ◽

Average Molecular Weight ◽

Gel Permeation Chromatography ◽

Nitrogen Sources ◽

Environmental Pollutant ◽

Dry Cell Weight ◽

Biphenyl Degradation ◽

Copolymer Poly

Abstract A polyhydroxyalkanoate (PHA) copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)], was biosynthesized from biphenyl as the sole carbon source using Alcaligenes (currently Achromobacter) denitrificans A41. This strain is capable of degrading polychlorinated biphenyls (PCBs) and biphenyl. This proof-of-concept of the conversion of aromatic chemicals such as the environmental pollutant PCBs/biphenyl to eco-friendly products such as biodegradable polyester PHA was inspired by the uncovering of two genes encoding PHA synthases in the A. denitrificans A41 genome. When the carbon/nitrogen (C/N) ratio was set at 21, the cellular P(3HB-co-3HV) content in strain A41 reached its highest value of 10.1%. A two-step cultivation protocol improved the accumulation of P(3HB-co-3HV) by up to 26.2% of the dry cell weight, consisting of 13.0 mol% 3HV when grown on minimum salt medium without nitrogen sources. The highest cellular content (47.6%) was obtained through the two-step cultivation of strain A41 on biphenyl as the sole carbon source. The purified copolymer had ultra-high molecular weight (weight-average molecular weight of 3.5 × 106), as revealed through gel-permeation chromatography. Based on the genomic information related to both polymer synthesis and biphenyl degradation, we finally proposed a metabolic pathway for the production of P(3HB-co-3HV) associated with the degradation of biphenyl by strain A41. This is, as it were, a metabolic link between PHA synthesis and biphenyl degradation.

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Effect of the initial glycerol concentration in the medium on the xanthan biosynthesis

Acta periodica technologica ◽

10.2298/apt1445239r ◽

2014 ◽

pp. 239-246 ◽

Cited By ~ 1

Author(s):

Zorana Roncevic ◽

Bojana Bajic ◽

Jovana Grahovac ◽

Sinisa Dodic ◽

Jelena Dodic

Keyword(s):

Xanthomonas Campestris ◽

Average Molecular Weight ◽

Process Efficiency ◽

Glycerol Concentration ◽

Agitation Rate ◽

Nitrogen And Phosphorus ◽

Experimental Conditions ◽

Batch Mode ◽

Residual Content ◽

Xanthan Production

This study is concerned with the effect of different initial glycerol concentrations in the medium on xanthan production by Xanthomonas campestris ATCC 13951. Xanthan biosynthesis was carried out in batch mode under aerobic conditions at a temperature of 30oC and agitation rate of 150 rpm for 7 days. The process efficiency was estimated based on the values of raw xanthan yield, average molecular weight of the polymer and residual content of glycerol, total nitrogen and phosphorus. Based on these results, the initial concentration of glycerol as a carbon source in the production medium was suggested. In the applied experimental conditions, high raw xanthan yield (12.15 g/l) of good quality (Mw = 2.86?105 g/mol) and the lowest amount of residual nutrients (glycerol 2.75 g/l, nitrogen 0.46 g/l and phosphorus 0.67 g/l) was achieved in the medium with the initial glycerol content of 20 g/l. The obtained results are the basis for optimization of xanthan production on glycerol containing media in order to increase the product yield and quality.

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The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064438 ◽

1971 ◽

Vol 29 ◽

pp. 76-77

Author(s):

C. E. Cluthe ◽

G. G. Cocks

Keyword(s):

Molecular Weight ◽

Ethylene Oxide ◽

Parallel Plate ◽

Average Molecular Weight ◽

Radical Reaction ◽

Free Radical Reaction ◽

Nitrogen Gas ◽

Poly Ethylene Oxide ◽

Poly Ethylene ◽

Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

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