Photosynthesis of Euglena gracilis under Cobalamin-Sufficient and -Limited Growing Conditions

Abstract

Subeeilular Fractionation and Pumification of Chloroplasts. Partial trypsin digestion ofthe pellicle followed by mild mechanical disruption of Euglena ceUs and subcellular frationation by differential centifugation were conducted according to Shigeoka et al. (19).A suspension of chloroplasts was layered on the top of continuous Percoll (Lot No. 4634) gradients and centrifuged in a swingout rotor (Hitachi Reactions of Photosynthesis. Photosynthesis resulted in net 02 evolution from cells, which were cultured in the dark in the presence of Cbl and then in the light with limiting or supplementing CbL was measured with a Kalbani-type oxygen electrode (Kyusui Kaaku Co.) in 2 ml of a reaction mixture containing an aliquot ofthe cell culture and 25 mm NaHCO3, 1 mM MgC12, and 50 mmt potassium phosphate buffer (pH 7.8). The mixture which contained 60 to 100 ug Chl ml-', was incubated at 25°C and 10,000 lux with wolfram lamp. 4C02 fixation was carried out under the same conditions as described above except that 10 mm (0.4 MCi) (final concentration) NaH'4C03 was added instead of 25 mm NaHCO3. A sample of 0.2 ml was withdrawn after a definite period through Eppendorf pipette and injected into a vial containing 0.3 ml of 0.3 N HCI. The vial was shaken for 30 mn to remove free`4C02 and the fixed radioactivity in the sample was counted with Aloka LSC 903 scintillation counter.

Bioproducts From Euglena gracilis: Synthesis and Applications

“…Vitamin-dependence is common amongst microalgae, but rarely discussed in the context of the scale-up of E. gracilis cultivation (Croft et al, 2006). Euglena gracilis shows an absolute requirement for vitamins B 1 (thiamine) and B 12 (cobalamin), so complex E. gracilis media usually contain at least 50 ng/L and 10 ng/L, respectively, of these compounds (Isegawa et al, 1987; Shigeoka et al, 1987; Croft et al, 2005; Hasan et al, 2017). Accordingly, the supplementation of both vitamins, produced either by chemical synthesis (thiamine) or extracted from bacterial sources (cobalamin), would be a factor in a scaled-up E. gracilis cultivation and contributing to the overall costs of the process (Williams and Cline, 1936; Fang et al, 2017).…”

Biochemistry and Physiology of Vitamins in Euglena

“…CN-B12 reductase, which catalyzes the conversion of CN-B12 to OH-B12, has been detected in Euglena (Watanabe et al 1988d) whereas the other enzymatic systems involved in the synthesis of AdoB12 and MeB12 have not yet been characterized in mitochondria. Although no information is currently available on the chloroplastic system for co-enzyme B12 synthesis, Isegawa et al (1987) reported that MeB12 functioned as a coenzyme of methionine synthase in chloroplasts and photosynthetic activity was decreased during B12 deficiency due to the loss of photosystem I.…”

Bioactive Compounds of Edible Purple Laver Porphyra sp. (Nori)

“…P. tenera required B 12 and took up and acquired exogenous B 12 , but it is unclear whether the growth of all Porphyra species shows B 12 dependency. Although various B 12 -requiring microalgae contained B 12 -dependent methionine synthase and methylmalonyl-CoA mutase, , the occurrence and characterization of both B 12 -dependent enzymes have not been reported in Porphyra sp.…”

“…23 P. tenera required B 12 23 and took up and acquired exogenous B 12 , 24 but it is unclear whether the growth of all Porphyra species shows B 12 dependency. Although various B 12 -requiring microalgae contained B 12 -dependent methionine synthase and methylmalonyl-CoA mutase, 25,26 the occurrence and characterization of both B 12 -dependent enzymes have not been reported in Porphyra sp. Using liquid chromatography−electrospray ionization tandem mass spectrometry analysis, two corrinoids (major, B 12 ; minor, pseudovitamin B 12 ) (Figure 2B) were also detected in Chinese dried nori (unpublished data).…”