Fermentative production of isobutene

Isobutene (2-methylpropene) is one of those chemicals for which bio-based production might replace the petrochemical production in the future. Currently, more than 10 million metric tons of isobutene are produced on a yearly basis. Even though bio-based production might also be achieved through chemocatalytic or thermochemical methods, this review focuses on fermentative routes from sugars. Although biological isobutene formation is known since the 1970s, extensive metabolic engineering is required to achieve economically viable yields and productivities. Two recent metabolic engineering developments may enable anaerobic production close to the theoretical stoichiometry of 1isobutene + 2CO2 + 2H2O per mol of glucose. One relies on the conversion of 3-hydroxyisovalerate to isobutene as a side activity of mevalonate diphosphate decarboxylase and the other on isobutanol dehydration as a side activity of engineered oleate hydratase. The latter resembles the fermentative production of isobutanol followed by isobutanol recovery and chemocatalytic dehydration. The advantage of a completely biological route is that not isobutanol, but instead gaseous isobutene is recovered from the fermenter together with CO2. The low aqueous solubility of isobutene might also minimize product toxicity to the microorganisms. Although developments are at their infancy, the potential of a large scale fermentative isobutene production process is assessed. The production costs estimate is 0.9 € kg−1, which is reasonably competitive. About 70% of the production costs will be due to the costs of lignocellulose hydrolysate, which seems to be a preferred feedstock

The Biosynthesis of Astaxanthin-Xi: The Carotenoids In the Lobster, Panulirus Japonicus

The existence of canthaxanthin, 4-hydroxy-echinenone, 3-hydroxy-canthaxanthin and astaxanthin in the carapaces of the lobster, Panulirus japonicus was confirmed. 2. ^-Carotene, /3-zeacarotene, echinenone, isocryptoxanthin and astaxanthin were found in the internal organs. 3. It was proposed that in the lobster, dietary /3-carotene is converted to astaxanthin through the steps of isocryptoxanthin, echinenone, 4-hydroxy-echinenone, canthaxanthin and 3-hydroxy-canthaxanthin as follows: /S-carotene-\u3e isocryptoxanthin — echinenone-\u3e 4-hydroxy-echinenone - canthaxanthin-\u3e 3-hydroxy-canthaxanthin —* astaxanthin. © 1973, The Japanese Society of Fisheries Science. All rights reserved

The biosynthesis of astaxanthin.X. the carotenoids in the red carp, cyprinus carpio linne, and the interconversion of β-[15,15′-\u3csup\u3e3\u3c/sup\u3eH2]carotene into their body astaxanthin

1. 1. In red carp the existence of lutein ester, zeaxanthin ester, α-doradexanthin ester (3,3′-dihydroxy-4′-keto-α-carotene), and astaxanthin ester was confirmed. 2. 2. Dietary β- [15,15′- 3H2] carotene was not converted to astaxanthin ester, so it was shown that in red carp β-carotene was not a precursor of astaxanthin ester. 3. 3. Dietary labelled astaxanthin was transferred to the body astaxanthin ester of red carp by feeding them labelled astaxanthin. 4. 4. In red carp a metabolic pathway from lutein ester to astaxanthin ester through the α-doradexanthin ester step was proposed. © 1972

The biosynthesis of astaxanthin. XII. The conversion of labelled β-carotene-15, 15′-\u3csup\u3e3\u3c/sup\u3eH2 into body astaxanthin in the lobster, Panulirus japonicus

1. 1. Astaxanthin is the most dominant pigment in the lobster, Panulirus japonicus. 2. 2. The lobsters were cultured in a laboratory for 2 weeks by feeding the modified standard diet containing β-carotene-15,15\u27-3H2 dissolved in plant oil. 3. 3. β-Carotene was converted to their body astaxanthin via isocryptoxanthin, echinenonc, 4-hydroxyechinenone, canthaxanthin, and 3-hydroxycanthaxanthin 4. 4. The metabolic pathway from β-carotene to astaxanthin in the lobster was as follows:- β-Carotene → isocryptoxanthin → echinenone → 4-hydroxyechinenone → canthaxanthin → 3-hydroxycanthaxanthin → astaxanthin. © 1973

The Biosynthesis of Astaxanthin-XIII: The Carotenoids in the Crab, Portunus Trituberculatus

The carotenoids of crab, Portunus trituberculatus, have been separated by absorption chromatography and further characterized by their absorption spectra and their behavior on the column. In some cases, reactions for specific functional groups were performed. The existence of canthaxanthin, 4-hydroxy-echinenone, 3-hydroxy-canthaxanthin and astaxanthin was confirmed in the carapaces of crab. In the internal organs, a-carotene echinenone, isocryptoxanthin and astaxanthin were found. The following metabolic pathway from a-carotene to astaxanthin was proposed. 8-carotene — ♦ isocryptoxanthin —-\u3e echinenone —+ 4-hydroxy-echinenone —♦ canthaxanthin —+ 3-hydroxy-canthaxanthin —4 astaxanthin. © 1973, The Japanese Society of Fisheries Science. All rights reserved

The Biosynthesis of Astaxanthin—VIII: The Conversion of Labelled β-carotene-15,15\u27-\u3csup\u3e3\u3c/sup\u3eh2 into Astaxanthin in Prawn, Penaeus japonicus Bate

To clarify the metabolic pathway from β-carotene to astaxanthin which was proposed in this thesis series, the present investigation was undertaken. Astaxanthin is the dominant pigment in prawn, Penaeus japonicus Bate. Prawn were cultured in the laboratory for 21 days by feeding artificial food containing labelled β-carotene-15, 15\u27-3H2 dissolved in plant oil. In prawn, β-carotene-15,15\u27-3H2 was converted to labelled astaxanthin via echinenone, canthaxanthin and phoenicoxanthin. The metabolic pathway fromβ-carotene to astaxanthin in prawn is as follows: β-carotine--►echinenone-►canthaxanthin -►phoenicoxanthin-►astaxanthin chichesteret al.12)recently found that in a Californian strain of Artemia salina, the two step conversion of β-carotene into canthaxanthin was the apparent pathway as follows: This was achieved by feeding [14C] labelled β-carotene. /9-carotene-——^echinenone-^canthaxanthin 1 t T. t isocryptoxanthin-risozeaxanthin ^hydroxy-T-ketO\u27/S-carotene. © 1972, The Japanese Society of Fisheries Science. All rights reserved

The biosynthesis of astaxanthin-XIV. The conversion of labelled β-carotene-15,15′-\u3csup\u3e3\u3c/sup\u3eH2 into astaxanthin in the crab, Portunus trituberculatus

The crab, Portunus trituberculatus, was cultured in a laboratory for 2 weeks by feeding a special diet containing β-carotene-15,15′-3H2 dissolved in plant oil. β-Carotene-15,15′-3H2 was converted to labelled astaxanthin through the steps of isocryptoxanthin, echinenone, canthaxanthin and 3-hydroxy-canthaxanthin. A classification of aquatic animals, based on their biosynthesis of astaxanthin, is discussed. © 1973