Photoheterotrophic Growth Research Articles

Effect of combined nitrogen sources on heterotrophic growth of a blue‐green alga Westiellopsis prolifica

AbstractThe autotrophic and photoheterotrophic growth of light pre‐treated and dark pre‐treated strains of Westiellopsis prolifica was decreased in the presence of NH, NO and urea in the culture medium. On dark incubation, after pre‐treatment with light as well as in the dark, the alga showed better growth response to all the combined nitrogen sources. However, only the light pre‐treated strain of the organism utilized the exogenous nitrogen sources appreciably for its dark heterotrophic growth.

Growth yield from electrons available from substrates in aerobic‐ and photoheterotrophic cultures of Rhodopseudomonas sphaeroides S

AbstractA balance of electrons available from acetic acid consumed for growth and oxygen uptake in the aerobic‐ and photoheterotrophic growth of Rhodopseudomonas sphaeroides S on acetate‐minimal medium could be realized the same as in the carbon balance. The unmeasured amounts of yeast extract consumed by the cells grown on propionate–yeast extract media were indirectly estimated from the balance equation of electrons available from carbon substrates. The specific consumption rate of the yeast extract increased with an increase in propionate consumption rate in aerobic and photoheterotrophic cultures. Growth yields from acetic acid and from propionic acid plus yeast extract were calculated on the electron level, i.e., YX/ave g cell produced/equivalent electrons available from substrate consumed. YX/ave values were 5.0 to 5.8 g cell/ave in photoheterotrophic cultures and 2.7 to 3.6 in aerobic–heterotrophic cultures regardless of different medium compositions.

Stimulation of nitrogenase activity and photosynthesis in some cyanobacteria by glyoxylate

Abstract The effect og glyoxylate on nitrogenase activity (C2H2 reduction) and photosynthesis (H14CO3 fixation and O2 evolution) was in vestigated in the three heterocystous cyanobacteria Anabaena cylindrica, A. variabiltis and N. muscorum. Glyoxylate had virtually no effect on the rate of dark respiration and was unable to sustain photoheterotrophic growth, though some slight stimulation (= 30%) of photorophic growth was noted. A considerable stimulation of both nitrogenase and photosynthetic activities was observed in presence of glyoxylate. In the light the stimulation increased with time up to about 15‐25 h after adding optimal concentrations of 4–6 mM glyoxylate. Placing glyoxylate treated samples in the dark or adding DCMU (30 μM) in the light, showed that glyoxylate initially supported significantly higher nitrogenase activity than did samples in absence of glyoxylate. However, after a prolonged incubation in the dark or in presence of DCMU glyoxylate is unable to relieve the adverse effects of such conditions. The stimulation of the nitrogenase activity was even more pronounced when the glyoxylate was added to cells preincubated in the dark (“carbon starved”) than for cells kept constantly in light. The results suggest that glyoxylate, or a metabolite, may act as an inhibitor of cyanobacterial photorespiration and this hypothesis is discussed.

Nutrient utilization and requirement under photoheterotrophic growth of Marchantia polymorpha: Improvement of the culture medium

AbstractPreviously we reported on a suspension culture of chlorophyllous cells of a liverwort, Marchantia polymorpha L., under photoheterotrophic conditions. The chemically defined medium was a modified Murashige and Skoog's medium, which contained, besides glucose, inorganic salts, a growth regulator (2,4‐D), and twenty‐four organic compounds as micro constituents. Because of this complexity, we undertook a simplification of the medium. Having examined the utilization of the major nutrients and the requirements for the micro constituents, we have succeeded in improving the medium. The new medium contains phosphate at 3.13 mM and only eight out of the twenty‐four original micro organic constituents. In this new medium, the cells grow under a well‐balanced nutritional condition, with richer chlorophyll and at a higher rate during the exponential phase than in the original medium.

Chromatium purpuratum, sp. nov., a new species of the Chromatiaceae

Enrichment cultures inoculated with fragments of the sponge Ircinia spec, under autotrophic culture conditions and with thiosulfate as sole electron donor yielded the predominant development of a small cell Chromatium strain, which is described herein as the new species Chromatium purpuratum. Autotrophically grown cells are 1.2–1.7 μm wide and 3–4 μm long. The cells are motile by means of one single polar flagellum. Intracytoplasmic membranes are present as vesicles as in the other Chromatium species. Multiplication occurs by binary fission. The photopigments are bacteriochlorophyll a and carotenoids of the okenone series. The G + C content of the type strain BN 5500 is 68.9 mole%. Chromatium purpuratum grows well photoautotrophically with sulfide or thiosulfate as electron donor. Photoheterotrophic growth is possible with various fatty acids serving as electron donor and carbon source. The new species is a marine isolate with an optimal salinity of 5% NaCl. It is compared with other known species of the genus Chromatium.

Effect of cultural conditions on the sterols and fatty acids of green algae

Six species of green algae were grown autotrophically, photohetrotrophically, and heterotrophically and their fatty acid and sterol compositions determined. Sterol composition was higher in autotrophic than in heterotrophic plants by a factor of from 2 to over 20 in five of the six species studied. Relative amounts of various sterols did not change significantly with cultural conditions. In five of the species studied, autotrophic growth produced a significant increase in the relative proportion of linolenic acid compared to that in heterotrophic or photoheterotrophic growth. This increase was usually accompanied by a corresponding decrease in oleic or linoleic acids or both.

Evidence for a cyclic PS-II-electron transport in vivo

The light-induced absorbance change of the center II P-680 reaction was investigated in autotrophically and photoheterotrophically cultivated Chlamydobotrys stellata. In addition the light-dark A 559 change was followed in order to look for a correlation between the kinetics of the cytochrome b-559 oxidation and the P-680 + reduction. In the dark period after a short laser flash, the P-680 + of the autotrophically cultivated organisms is reduced in a two-phase process with different half times, the first of approx. 30 μs and the second longer than 300 μs. Adaptation of the algae from autotrophic to photoheterotrophic growth conditions changes the 30 μs phase into one with a half time of decay of approx. 60 μs and in addition decreases the amplitude. The > 300-gms phase is changed only in its amplitude. In autotrophic organisms a significant A 559 change can be detected only in the presence of CCCP or FCCP and can be eliminated by the addition of DCMU. In photoheterotrophic C. stellata, the 559 nm signal can be measured without any treatment of the algae. High light intensity causes a reduction and low light intensity an oxidation of cytochrome b-559. These results support the previously reported hypothesis that cytochrome b-559 in photoheterotrophically cultivated C. stellata, but not in autotrophic algae, is reduced by a light driven photosystem-II reaction and oxidised by the donor site of photosystem II with a half time of approx. 60 μs. Thus photosystem II is short circuited by a cyclic electron transport via cytochrome b-559.

An investigation of heterotrophic and photoheterotrophic capabilities in marine Pyrrhophyta

Abstract The occurrence of heterotrophy and photoheterotrophy in eight dinoflagellate strains was investigated. Peridinium foliaceum (isolate 129) was tested for heterotrophic growth on fifty-four organic substrates while three other organisms: Cachonina niei, a free-living isolate of Zooxanthella microadriatica and Amphidinium carterae were tested on a more limited range of compounds. In addition, the capability for photoheterotrophic growth among the above organisms and Fragilidium heterolobum, Peridinium balticum, a second isolate of P. foliaceum and a symbiotic Z. microadriatica was investigated using the conditions of dim light and DCMU inhibited photosynthesis. No examples of heterotrophic growth were found, but the growth of six strains was stimulated by glycerol in both dim light and the presence of DCMU. In the presence of DCMU, soil extract stimulated growth in several strains. Soil extract did not support photoheterotrophic growth in any organism tested under dim light. Nitrogen limited culture...

Nitrogenase activity in Rhodopseudomonas sulfidophila

The marine purple nonsulfur bacterium, Rhodopseudomonas sulfidophila, strain W4, was capable of photosynthetic growth on dinitrogen and malate. Higher growth rates were observed when either glutamate or ammonia replaced dinitrogen as nitrogen source and when bicarbonate was omitted from the culture medium. Although ammonia was released from cells growing on malate and N2, no nitrogenase activity could be detected unless α-ketoglutarate was added to the culture medium. No nitrogenase activity was found in cultures grown in the presence of NH 4 + . In cultures grown on glutamate as nitrogen source, nitrogenase and hydrogenase activities were found to be 5.4 nmol C2H2 reduced · min-1 · mg-1 dry weight and 50 nmol methylene blue reduced · min-1 · mg-1 dry weight respectively. Such activities are significantly lower than those observed for other members of the Rhodospirillaceae e.g. Rhodopseudomonas capsulata. However, the hydrogenase activity would be sufficient to recycle all H2 produced by nitrogenase. It was indeed observed that growing cells did not evolve molecular hydrogen during photoheterotrophic growth and that H2 stimulated nitrogenase activity in resting cells of R. sulfidophila. The nitrogenase from this bacterium proved to be extremely sensitive to low concentrations of oxygen, half-inhibition occurring at between 1–1.5% O2 in the gas phase, depending on the bacterial concentration. Light was essential for nitrogenase activity. No activity was found during growth in the dark under extremely low oxygen concentrations (1–2% O2), which are still sufficient to support good growth. Resting cell suspensions prepared from such cultures were unable to reduce acetylene upon illumination. Optimum nitrogenase activities were broadly defined over the temperature range, 30–38°C, and between pH 6.9 and 8.0. The results are discussed in comparison with the non-marine purple nonsulfur bacterium, R. capsulata, which somewhat resembles R. sulfidophila.

Pyrimidine Metabolism in Lemna minor

Short term photoheterotrophic growth of Lemna minor in the presence of 100 micrograms per milliliter (440 micromolar) cytidine deoxyriboside bleaches the fronds in the absence of effect upon growth rate (Frick 1978 Plant Physiol 61: 989-992). Serial sections of mesophyll cells of green and bleached fronds were compared in the light microscope. The number of plastids in cells of comparable size was reduced during bleaching by more than 50%. The total and average plastid profile area per section in the series was reduced on the order of 70%, and the summed plastid profile area over the entire cell was reduced about 90%. Thus, cytidine deoxyri-boside-bleached mesophyll cells contained fewer identifiable plastids (50%) of smaller volume (10-30%) than the green control cells.

Changes in phosphoenolpyruvate carboxylase and ribulose-biphosphate carboxylase activities during the photoheterotrophic growth of Nicotiana tabacum (CV xanthi) cell suspensions

The capacities (in vitro ∗ ∗ in vitro experiments related in this report are enzymatic capacities measurements performed with cell-free preparations studied in optimal conditions of pH and in excess of enzyme substrate. measurements) of phosphoenolpyruvate carboxylase (PEPCase) and ribulose-biphosphate carboxylase (RuBPCase) have been studied in photoheterotrophically growing cell suspensions of Nicotiana tabacum L. (cv Xanthi). The most significant observation was the different behaviour of the two carboxylases. The PEPCase capacity expressed on a g dry wt. basis rises from an initial day O value of 200–300 μmol of CO 2 fixed to 600–800 μmol during the exponential phase and then returns to the initial value during the post-exponential and stationary phases. The RuBPCase capacity was nearly constant (90–140 μmol of CO 2 fixed) throughout the growth cycle. The peak of respiration and the high PEPCase capacity during the exponential growth phase were concomitant with an active process of soluble protein synthesis. After electrophoresis of cell-free extracts, two bands of PEPCase activity (forms I and II with R m values of 0.23 and 0.38 respectively)_and one band of RuBPCase activity ( R m of 0.27) were localized on polyacrylamide gels. The densitometric profiles of soluble proteins showed a marked enrichment of PEPCase form II band during the active phase of cell division as compared to that of cells in the stationary phase of growth. Moreover, the 2-fold increase of the specific activity (μmol CO 2 fixed/h and/mg of soluble proteins) of the PEPCase during the exponential phase suggested that the enhancement of the catalytic power of this enzyme could be due to de novo protein synthesis. The biosynthesis pattern of PEPCase was essentially that of peak enzyme in contrast with RuBPCase which showed only slight variations over the growth cycle.

Changes in Rhodopseudomonas sphaeroides isoaccepting phenylalanyl-tRNA species during transitions from chemoheterotrophic to photoheterotrophic growth

A new iso-accepting tRNAphe from extracts of chemoheterotrophic and photoheterotrophic cells of Rhodopseudomonas sphaeroides has been identified by both BDEAE cellulose and RPC-5 chromatography. Rechromatography of each of the tRNAphe species in either the acylated or deacylated state shows that they migrate as single homogeneous peaks. In steady-state chemoheterotrophic cultures of R. sphaeroides tRNA I–II phe account for 25–30% of the total phenylalanine accepting activity while in steadystate photoheterotrophic cultures tRNA I–II phe account for no more than 10% of the total phenylalanine accepting activity. During the transition from chemoheterotrophic to photoheterotrophic growth conditions the levels of tRNA I–II phe fall in an exponential manner during the first half of the intracytoplasmic membrane induction period. tRNA I phe then remains at a level 10% that of its steady-state chemoheterotrophic level as long as photoheterotrophic growth conditions remain. tRNA II phe , after dropping to 10% of its former chemoheterotrophic level then returns to a level 50% that of its chemoheterotrophic level as long as photoheterotrophic growth conditions remain.

Photosynthetic properties of a DCMU resistant strain of Euglena gracilis Z.

When present during the photoheterotrophic growth of Euglena gracilis Z; DCMU, in addition to the usual inhibition of photosynthetic electron transport, induces important losses of chlorophyll and severe disorganization of chloroplast structure. After two months of growth under these conditions, however, these parameters recover their normal properties and the cells become resistant to the dose of DCMU to which they were exposed. The sensitivity of photosynthetic electron transport to increasing concentrations of DCMU was analyzed in whole cells of the wild-type and resistant strains as well as in their respective isolated chloroplasts, using oxygen evolution and fluorescence induction to measure the DCMU effects. Another photosynthetic electron transport inhibitor, ortho-1, 10-phenanthrolene (ORPHE), believed to act at the same site as DCMU, was also used to obtain dose-response curves as for DCMU, and similar results were obtained. The results suggest that the resistance, which is a function of the dose, is due neither to the acquired ability of the cells to transform DCMU into an inactive form nor to the acquisition of a permeability barrier to DCMU. It appears that DCMU resistance is caused at the level of intracellular DCMU-sensitive reactions, particularly of photosynthetic electron transport.

H2 metabolism in the photosynthetic bacterium Rhodopseudomonas capsulata: production and utilization of H2 by resting cells.

Photoproduction of H2 and activation of H2 for CO2 reduction (photoreduction) by Rhodopseudomonas capsulata are catalyzed by different enzyme systems. Formation of H2 from organic compounds is mediated by nitrogenase and is nto inhibited by an atmosphere of 99% H2. Cells grown photoheterotrophically on C4 dicarboxylic acids (with glutamate as N source) evolve H2 from the C4 acids and also from lactate and pyruvate; cells grown on C3 carbon sources, however, are inactive with the C4 acids, presumably because they lack inducible transport systems. Ammonia is known to inhibit N2 fixation by photosynthetic bacteria, and it also effectively prevents photoproduction of H2; these effects are due to inhibition and, in part, inactivation of nitrogenase. Biosynthesis of the latter, as measured by both H2 production and acetylene reduction assays, is markedly increased when cells are grown at high light intensity; synthesis of the photoreduction system, on the other hand, is not appreciably influenced by light intensity during photoheterotrophic growth. The photoreduction activity of cells grown on lactate + glutamate (which contain active nitrogenase) is greatly activated by NH4+, but this effect is not observed in cells grown with NH4+ as N source (nitrogenase repressed) or in a Nif- mutant that is unable to produce H2. Lactate, malate, and succinate, which are readily used as growth substrates by R. capsulata and are excellent H donors for photoproduction of H2, abolish photoreduction activity. The physiological significances of this phenomenon and of the reciprocal regulatory effects of NH4+ on H2 production and photoreduction are discussed.

Enzyme Levels in Relation to Obligate Phototrophy in Chlamydobotrys

During the transition from photoheterotrophic growth on acetate to phototrophic growth on carbon dioxide, there is a decrease in isocitrate lyase and increase in ribulose-1,5-diphosphate carboxylase activity in Chlamydobotrys stellata cultures. The increase in ribulose-1,5-diphosphate carboxylase activity is the result of protein synthesis, there being a close correlation between increase in enzyme activity and protein precipitated by antibody to ribulose-1,5-diphosphate carboxylase. The purified ribulose-1,5-diphosphate carboxylase was similar to the constitutive enzyme from other green algae having a molecular weight of 530,000 and composed of two types of subunit of molecular weight 53,000 and 14,000.Enzyme assays demonstrated an incomplete tricarboxylic acid cycle in cells growing photoheterotrophically on acetate or phototrophically on carbon dioxide. Although these cells lack alpha-ketoglutarate dehydrogenase and succinate thiokinase, a cyclic flow of acetate carbon is possible in the presence of the glyoxylate cycle enzymes but the yield of adenosine triphosphate from acetate oxidation may be insufficient to support heterotrophic growth, so rendering Chlamydobotrys an obligate phototroph.

Heterotrophic growth of filamentous blue-green algae

A survey has been made of the growth response shown by 20 filamentous blue-green algal strains to the presence of organic substrates in the medium. Six strains showed no growth in the dark in the presence of any substrate. Among the other 14 strains, relative growth response to added substrates often fell in relation to the sequence: sucrose > fructose > glucose > maltose. The 20 strains can be classified according to their ability to make use of added 0·01 m sucrose. The different categories include: negligible increase in growth under any circumstances; photoheterotrophic growth only; photoheterotrophic growth + survival in dark; photo-heterotrophic + chemoheterotrophic growth. Three of the strains capable of chemoheterotrophic growth are more restricted in the dark than in the light with respect to the nitrogen sources they can use.

An anaerobic bag for photoheterotrophic growth of some rhodospirillaceae in petri dishes.

An anaerobic bag for photoheterotrophic growth of some rhodospirillaceae in petri dishes.

Glycollate oxidation and utilization by Anabaena cylindrica

In Ouchterlony double immunodiffusion tests antiserum to the glycollate oxidase of tobacco forms a single precipitin band with extracts of the prokaryotic Anabaena cylindrica, thus confirming the presence of a glycollate oxidising enzyme in this alga. The precipitin band is partially identical to that produced between the antiserum and the homologous tobacco glycollate oxidase and is fully identical with bands formed between tobacco antiserum and extracts of Chlorella vulgaris and Euglena gracilis. In vitro the enzyme, which catalyses the oxidation of glycollate to glyoxylate, couples to 2,6-dichlorophenolindophenol (DCPIP) as terminal oxidant under anaerobic conditions. Aerobic glycollate-dependent DCPIP oxidation also occurs but at a lower rate than in the absence of oxygen, suggesting that the enzyme is a facultative aerobic dehydrogenase. Of all cell-free preparations showing glycollate-dependent DCPIP reduction, over half exhibited oxygen uptake, showing that the enzyme may act as an oxidase. Glycollate-dependent DCPIP reduction, glyoxylate formation and oxygen uptake are all inhibited by antiserum to tobacco glycollate oxidase. Glycollate did not support the growth of A. cylindrica in the dark or enhance growth inthe light and there was no evidence of photoheterotrophic growth in the light in the presence of glycollate and 3-(3′4′-dichlorophenyl)-1,1-dimethylurea (DCMU) ( 10 −4 M ).

A phototrophic gliding filamentous bacterium of hot springs, Chloroflexus aurantiacus, gen. and sp. nov.

Chloroflexus aurantiacus, gen. and sp. n., is a filamentous phototrophic bacterium of hot springs. On an agar surface, holotype strain J-10-fl glides at 0.01–0.04 μm/sec. The filaments are 0.6–0.7 μm in width and indeterminate in length. Pigments include bacteriochlorophyll c and bacteriochlorophyll a (identified by spectrophotometry) in addition to β and γ-carotene and glycosides of the latter. Chlorobium vesicles are present. Photoheterotrophic growth occurs under anaerobic conditions. Aerobic chemoheterotrophic growth also occurs in darkness or light. Bacteriochlorophyll syntheses cease under aerobic conditions but some types of carotenoids continue to be made. The filament coloration is orange under all except anaerobic conditions in low light intensity where it is dull green. The pH optimum is near 8, the temperature optimum between 52° and 60°C. The DNA base composition for strain J-10-fl is 54.9 ± 1.0 moles % guanine + cytosine. Chloroflexus is unique in that there have been no previous reports of filamentous or gliding phototrophic bacteria. The combinations of bacteriochlorophylls a and c and the presence of chlorobium vesicles in a photoheterotroph and in an organism capable of aerobic growth are also unique. This metabolically versatile organism extends the taxonomic and phylogenetic limits of the “green line” of phototrophic bacteria.

Role of reduced exogenous organic compounds in the physiology of the blue-green bacteria (algae): photoheterotrophic growth of a "heterotrophic" blue-green bacterium.

Nostoc sp. (strain Mac) was shown to be capable of using glucose, fructose, or sucrose as a sole source of carbon and energy in the dark. In the light in the absence of exogenously supplied CO(2), this strain exhibited a more versatile metabolism. In addition to the three sugars above, glycerol and acetate served as sole sources of carbon. This photoheterotrophic growth in the absence of exogenously supplied CO(2) appears to involve O(2)-evolving photosynthesis. The action spectrum for photoheterotrophic growth on acetate closely resembles the action spectrum for photosynthesis. The physiology of photoheterotrophic growth was further investigated through determinations of stable carbon isotope ratios and measurements of gas exchanges. These investigations suggest that respired CO(2) from substrate oxidation is assimilated by the photosynthetic machinery.