Determinants of Urea Production and Mineral Retention in Parenterally Fed Preterm Infants

Aiken, Christopher Geoffrey Alexander

doi:10.7860/jcdr/2013/5231.3242

Cited by 2 publications

(2 citation statements)

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“…Heterologous ethylene production via mainly the P. syringae EFE has been reported for a variety of fungi [ 10 , 11 ] and bacteria [ 12 - 14 ]. A further alternative for biological ethylene production that has been investigated is the conversion of sunlight and CO 2 into ethylene via cyanobacteria [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…Several of these studies have identified factors which could be restricting the ethylene reaction and hence negatively affect the ethylene yields. The most commonly mentioned factors are; oxygen availability [ 12 , 17 ], respiration rate [ 18 ] and substrate provision [ 10 , 12 , 16 ]. Since optimal production levels are required to make biological ethylene production a feasible alternative to the traditional petroleum based production method, each of these limitations must be studied to understand the extent to which they affect ethylene yield and thereby identify approaches for improving the ethylene production ability.…”

Section: Introductionmentioning

confidence: 99%

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Identification of factors for improved ethylene production via the ethylene forming enzyme in chemostat cultures of Saccharomyces cerevisiae

et al. 2013

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BackgroundBiotechnological production of the traditional petrochemical ethylene is presently being explored using yeasts as well as bacteria. In this study we quantify the specific ethylene production levels at different conditions in continuous (chemostat) cultivation of Saccharomyces cerevisae expressing the ethylene forming enzyme (EFE) from Pseudomonas syringae.ResultsOur study shows that oxygen availability is an important factor for the ethylene formation. Maintaining a high percentage dissolved oxygen in the cultivation was found to be necessary to achieve maximal ethylene productivity. Even at oxygen levels high enough to sustain respiratory metabolism the ethylene formation was restricted. Oxygen was also important for sustaining a high respiratory rate and to re-oxidize the surplus of NADH that accompanies ethylene formation. By employing three different nitrogen sources we further found that the nitrogen source available can both improve and impair the ethylene productivity. Contrary to findings in batch cultures, using glutamate did not give a significant increase in specific ethylene production levels compared to the reference condition with ammonia, whereas a combination of glutamate and arginine resulted in a strongly diminished specific ethylene production. Furthermore, from cultivations at different dilution rates the ethylene formation was found to be coupled to growth rate.ConclusionTo optimize the ethylene productivity in S. cerevisiae expressing a bacterial ethylene forming enzyme, controlling the oxygen availability and growth rate as well as employing an ideal nitrogen source is of importance. The effects of these factors as studied here provide a basis for an optimized process for ethylene production in S. cerevisiae.

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