Hideyuki Nagashima

CO2 fixation and oil production using micro-algae

The micro-alga Dunaliella tertiolecta ATCC 30929 could be grown under highly saline conditions (6% of NaCl aqueous solution) without the need for sterilization of the bio-reactor or the culture medium which would be greatly advantageous in a scale up of the culture system. Using CO2 as a carbon source, the micro-algae growth reached 1.0g/l under non-sterilized conditions after one week. The effect of contamination by other micro-organisms on the growth was negligible. The micro-alga contained 10% glycerol, and the yield of its conversion to oil by thermo-chemical liquefaction was 36%, indicating the possibility of effective oil production by CO2 fixation using such a micro-alga.

Occurrence of 2-hydroxy acids in microalgae

Abstract 2-Hydroxy acids were believed to be absent in algae until this study, in which the analysis of microalgae belonging to Chlorophyta ( Chlamydomonas reinhardtii and Chlorella pyrenoidosa ), Rhodophyta ( Cyanidium caldarium M-8 and Cyanidium caldarium RK-1) and Cyanophyta ( Anbaena variabilis , Anacystis nidulans , Oscillatoria species and Phormidium foveolarum ) is reported. 2-Hydroxy adds with carbon chain lengths of C 16 -C 26 , were found in all the algal samples studied, ranging in concentrations from 4.0 to 320μg/g dry alga. The dominant constituents are 2-hydroxyhexadecanoic, 2-hydroxynonadecanoic, 2-hydroxyhexacosanoic and a branched 2-hydroxy-C 19 acid. The distribution patterns of the acids differed significantly among the algal samples. Hence 2-hydroxy acids may be useful for the classification of algal species as well as being an important source of 2-hydroxy acids in the natural environment.

Occurrence of 3-hydroxy acids in microalgae and cyanobacteria and their geochemical significance

Abstract 3-Hydroxy acids were detected in pure cultured microalgae: Chlorophyta— Chlamydomonas reinhardtii and Chlorella pyrenoidosa and Rhodophyta— Cyanidium caldarium (two strains), and cyanobacteria (Cyanophyta)— Anacystis nidulans, Phormidium foveolarum, Anabaena variabilis and Oscillatoria sp. Normal and branched (iso and anteiso) 3-hydroxy acids in the ranges of C 8 -C 26 were found in all the samples studied at concentrations ranging from 0.036 to 2.3 and 0.000 to 0.12 mg g −1 of dry sample, respectively. The major constituents were generally even-carbon numbered normal acids with carbon chain lengths below C 20 . Microalgae and cyanobacteria may be the important sources of 3-hydroxy acids in natural environments.

Low molecular weight carbohydrates in Cyanidium caldarium and some related algae

Abstract Floridoside (2- O -glycerol-α- d -galactopyranoside) and a small amount of iso -floridoside (1- O -glycerol-α- d - galactopyranoside) were found in Cyanidium caldarium . Floridoside was also found in the red algae Porphyridium cruentum and Porphyra yezoensis , although in the latter iso -floridoside was the main component. Sucrose and glucose were found in the green algae Chlorella pyrenoidosa and Scenedesmus obliquus , and also in a blue-green alga, Anacystis nidulans . Another blue-green alga, Phormidium foveolarum , contains mostly trehalose. From these results and from morphological considerations, it is suggested that Cyanidium caldarium belongs to the primitive Rhodophyta.

Polyamines of unicellular thermoacidophilic red alga Cyanidium caldarium

Abstract Polyamines in two types of the unicellular thermoacidophilic red alga (Rhodophyta), Cyanidium caldarium , were analysed. Strain RK-1 (and strain KS-1) contained putrescine, spermidine and spermine. This polyarnine distribution pattern is similar to that found in other red algae belonging to the class Protoflorideophyceae. On the other hand, strain M-8 contained diaminopropane, norspermidine and norspermine in addition to putrescine, spermidine and spermine. Thermospermine was not detected in either type of C. caldarium . This polyainine distribution pattern is quite different from that of any eukaryotic algae. In both types of C. caldarium the concentrations of polyamines, especially tetraamines (spermine and/or norspermine) increased when the culture temperature was raised from 20 to 50°.

Floridosides in unicellular hot spring algae

Abstract Cyanidium caldarium strains RK-1, KS-1 and 001 are probably obligate autotrophs, while Chroococcidiopsis sp. strains M-8 and 002 (formerly named Cyanidium caldarium ) are facultative autotrophs. The Cyanidium strains contain floridoside (2- O -glycerol-α- d -galactopyranoside) and a small amount of iso -floridoside (1- O -glycerol-α- d -galactopyranoside), both of which are known to be distributed in Rhodophyta. The Chroococcidiopsis strains also contain floridoside, but no iso -floridoside, under various culture conditions. These results indicate that Cyanidium is clearly distinguishable from Chroococcidiopsis in iso -floridoside content and nutritional properties, and suggest that all strains tested may be closely related to Rhodophyta.

Chloroplast nucleoids in a unicellular hot spring algaCyanidium caldarium and related algae

Algal chloroplast nucleoids were compared by epifluorescent microscopy.Cyanidium caldarium strain RK-1 or 001 has a rod-shaped chloroplast nucleoid whileCyanidium caldarium (Chroococcidiopsis sp.) strain M-8 or 002 has a circular chloroplast nucleoid along the periphery of a multilobed chloroplast.

Effect of culture temperature shift on the cellular sugar accumulation of Chlorella vulgaris SO-26

Abstract We investigated the effect of culture temperature on the maximum specific growth rate and cellular sugar accumulation, and the effect of a temperature shift on the sugar accumulation of cells of an Antarctic green alga, Chlorella vulgaris SO-26, in a batch culture system. Decreases in temperature appeared to correlate with decreases in the maximum specific growth rate; on the other hand, the cellular sugar content showed a reverse tendency against temperature. We attempted to use this tendency to improve sugar productivity in Chlorella. First, we cultured Chlorella at 20°C during the logarithmic growth phase to obtain a high specific growth rate. The culture temperature was then shifted from 20°C to 14°C during the stationary growth phase to increase the cellular sugar content. As a result, we obtained a 25% increase in sugar production over that obtained by culture at 20°C throughout the culture.

Hydrocarbons and fatty acids in two strains of the hot spring alga Cyanidium caldarium

Abstract Normal alkanes (n-C14-n-C30) and a diene (C19:2) were found in Cyanidium caldarium RK-1 type with predominance of n-C17, (46.3 %), while Cyanidium M-8 type contained n-alkanes (n-C15-n-C25) and alkenes (C19:1,C21:1) with an abundance of C19:1 (43.4 %). Normal alkanoic acids of odd-carbon numbers, n-C15 (12.7%) and n-C17,(10.5%) aswell as of even-carbon numbers, n-C16 (12.7%) and n-C18 (9.8%) and C18:2 alkenoic acid (53.1%) were found in Cyanidium RK-1, while Cyanidium M-8 mainly contained n-C16 (33.5 %) alkanoic acids, C18:1(33.3 %) and C18:2 (23.7%) alkenoic acids. The acid C18:2 was present only in Cyanidium M-8. These results indicate a considerable difference between the two strains of Cyanidium caldarium, and Cyanidium RK-1 type may be unique among microalgae because it has a significant amount of odd-carbon numbered n-alkanoic acids.

Production of poly-β-hydroxybutyric acid by microorganisms accumulated from river water using a two-stage perfusion culture system

The perfusion culture system using a shaken ceramic membrane flask (SCMF) was employed to accumulate microorganisms separated from river water and to produce poly-beta-hydroxybutyric acid (PHB). Using a two-step culture method with a single SCMF, river microorganisms were cultured by separately feeding four representative carbon sources, n-propanol, lactic acid, methanol, and formic acid. After 140 h culture, the cell concentration and PHB content respectively reached 43 g/l and 35% when a propanol medium was fed. Using a two-stage perfusion culture with twin SCMFs, the seed cell mass was increased in the first SCMF and then supplied to the second flask for PHB production. As a consequence, the cellular PHB content rose to 51% in the second SCMF, while the cell concentration gradually increased to 25 g/l after 175 h perfusion culture. These results demonstrated the utility of the two-stage perfusion culture system for developing a cheap means of producing PHB coincident with wastewater treatment.