Growth Characteristics and Substrate Specificity of Aerobic Photosynthetic Bacterium, Erythrobacter Sp. (OCh 114)

Optimal growth conditions and substrate specificity of the aerobicphotosynthetic bacterium, Erythrobacter sp. (OCh 114), wereinvestigated. Erythrobacter utilized 19 out of 26 substratestested, including several sugars and amino acids. Glycerol andlactate were the most effective as electron donors or carbonsources. Maximum growth was obtained at a salinity of about25, pH 8–9 and temperature 28°C in a glycerol-enrichedmedium. A suitable growth medium for Erythrobacter sp. (OCh114) is proposed. (Received October 18, 1985; Accepted January 10, 1986)     

Action Spectra for Inhibition by Light of Accumulation of Bacteriochlorophyll and Carotenoid during Aerobic Growth of Photosynthetic Bacteria

Action spectra for the inhibition by light of the accumulationof photosynthetic pigments during the aerobic growth of a photosyntheticbacterium, Rhodobacter sphaeroides, and an aerobic photosyntheticbacterium, Erythrobacter sp. strain OCh 114, were determinedover the range of wavelengths from 380 to 870 nm. The actionspectra for the inhibition of accumulation of bacteriochlorophyllin both R. sphaeroides and Erythrobacter sp. strain OCh 114indicated that the maximum inhibition occurred at approximately400 nm and a low level of inhibition occurred at 575 and 770nm. In R. sphaeroides, the action spectrum for the inhibitionof accumulation of carotenoid paralleled that for the inhibitionof accumulation of bacteriochlorophyll over the same range ofwavelengths. These results indicate that in both species, grownunder aerobic conditions, the same photoreceptor is involvedin the inhibition. One possible candidate for the relevant photoreceptormay be the precursor(s) to bacteriochlorophyll. It is possiblethat the photoreceptor is decomposed by light absorbed by itselfor by an unidentified photoreceptor that absorbs blue light(a photo-sensitizer). It is suggested that the accumulationof carotenoid is dependent on the stability of the bacteriochlorophyll. (Received September 16, 1988; Accepted March 2, 1989)     

Characterization of Porphobilinogen Synthase from an Aerobic Photosynthetic Bacterium, Erythrobacter sp. Strain OCh 114

Porphobilinogen synthase (formerly 5-aminolevulinic acid dehydratase,EC 4.2.1.24 [EC] ) was purified 7,405-fold from an aerobic photosyntheticbacterium, Erythrobacter sp. strain OCh 114. The molecular weightof the enzyme was determined to be 260,000 by Sephadex G-200gel filtration. The enzyme had a single pH optimum at 8.0 andshowed no requirement for metal ion and thiol compound for itsmaximum activity. The K_m value for 5-aminolevulinic acid was0.29 mM. 4,5-Dioxovaleric acid and levulinic acid were foundto be competitive inhibitors of the enzyme, with K_i values of0.65 and 0.80 mM, respectively. The enzyme was extremely labilein acidic pH and almost completely lost its activity within1 h at pH 6.0 and 30?C. This Erythrobacter enzyme seems to besimilar to the enzyme from the anaerobic photosynthetic bacteriumRhodobacter capsulatus in its molecular and catalytic properties. (Received February 17, 1988; Accepted May 9, 1988)     

Photochemical Activities of Bacteriochlorophyll in Aerobically Grown Cells of Aerobic Heterotrophs, Erythrobacter Species (OCh 114) and Erythrobacter longus (OCh 101)

Reversible photo-oxidation of cytochromes and reversible photobleachingof bacteriochlorophyll were observed in aerobically grown cellsof the aerobic heterotroph, the Erythrobacter species (OCh 114).Light inhibited O₂-uptake by cells of this bacterium and Erythrobacterlongus (OCh 101). A vesicular structure of intracytoplasmicmembrane systems was observed in sections of aerobically growncells of OCh 114. These bacteria may be called aerobic photosyntheticbacteria (i.e., photosynthetic bacteria which can utilize lightenergy under aerobic conditions but not under anaerobic conditions). (Received September 9, 1981; Accepted December 2, 1981)     

Excitation and Emission Spectroscopy of Membranes and Pigment-protein Complexes of an Aerobic Photosynthetic Bacterium, Erythrobacter sp. OCh 114

Emission and excitation spectra of steady-state fluorescencefrom membranes and isolated pigment-protein complexes of anaerobic photosynthetic bacterium, Erythrobacter sp. strain OCh114 indicated high efficiency of energy transfer from Bchl 806to Bchl 870 and from carotenoids to bacteriochlorophyll. Thus,this bacterium has a highly efficient light-harvesting systemtypical of photosynthetic bacteria. (Received August 3, 1989; Accepted January 27, 1990)     

Bacteriochlorophyll-protein complexes of aerobic bacteria,Erythrobacter longus and Erythrobacter species OCh 114

Bacteriochlorophyll(Bchl)-protein complexes were isolated from obligate aerobic bacteria, Erythrobacter longus and Erythrobacter species OCh 114. The apparent molecular weights, absorption spectra and polypeptide compositions of the light-harvesting complexes were, in general, similar to those of the light-harvesting Bchl-protein complexes of purple photosynthetic bacteria. The reaction center complexes of these bacteria also showed similar properties to those of the purple bacteria except for slightly altered polypeptides. However, the following characteristic features of the light-harvesting systems were found in these aerobic bacteria. Major carotenoids were not bound to the Bchl-protein complex in E. longus. In Erythrobacter sp. OCh 114, a new type of Bchl-protein complex which showed a single absorption band in the near infrared region at 806 nm was obtained. The reaction center of strain OCh 114 was associated with a c-type cytochrome.Abbreviations Bchl bacteriochlorophyll a - RC reaction center - SDS sodium dodecylsulfate - PAGE polyacrylamide gel electrophoresis     

Enhancement of Denitrifying Activity in Cells of Roseobacter denitrificans Grown Aerobically in the Light

The effects of light on denitrifying activity during growthwere studied in an aerobic photosynthetic bacterium, Roseobacterdenitrificans (formerly Erythrobacter sp. OCh 114). When aerobicallygrown cells were transferred to anaerobic conditions in thepresence of nitrate, this bacterium exhibited denitrifying activity,with either succinate or malate serving as an electron donorin addition to endogenous substrates. The final product of denitrificationwas identified as nitrous oxide (N₂O), a result that confirmsthe presence of nitrate and nitrite reductases, but not N₂Oreductase, in these cells. Illumination during aerobic growthcaused a marked enhancement of the denitrifying activity. Theactivity increased with increasing intensity of light up to40 mW cm^–2 and was over 20 times that in dark-grown cells.Enhancement of denitrifying activity in illuminated cells wasclosely related to increases in levels of components that areinvolved in the denitrifying pathway, namely, nitrate and nitritereductases. Development of a denitrifying system under aerobicconditions and the enhancement of denitrifying ability by lightin Roseobacter denitrificans are unique characteristics, unlikethose of other known denitrifying bacteria. (Received October 29, 1990; Accepted January 17, 1991)     

Light-Stimultated Aerobic Growth of Erythrobacter Species OCh 114

Bright light almost completely suppressed bacteriochlorophyllsynthesis in Erythrobacter species OCh 114. Consequently, theeffect of continuous illumination on growth was barely observedwhen illumination was started an inoculation and the inoculumsize was small. However, when an aerobic culture of this bacteriumgrown preliminarily in the dark was illuminated after the celldensity became high, light stimulated the growth remarkably,indicating that the utilization of light energy for growth viabacteriochlorophyll which had been formed during the growthin the dark. The maximum cell yield from a culture intenselyilluminated following preliminary growth in the dark was twofoldthat from a culture grown in the dark throughout. A continuousoxygen supply was a prerequisite for the stimulation of growthby light. Microaerobic or anaerobic incubation of a dark-grownculture in the light brought about a decrease in spheroidenonecontent and a formation of an unknown pigment. ¹ Present address: Kawaguchi Factory, Sapporo Breweries Ltd.,Namikimoto-cho, Kawaguchi, Saitama 332, Japan ² Present address: Institute of Applied Microbiology, The Universityof Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (Received October 6, 1986; Accepted January 9, 1987)     

O2-stimulated synthesis of bacteriochlorophyll and carotenoids in marine bacteria

We examined the effects of a limitation of the O₂-supply onthe syntheses of bacteriochlorophyll a_p and carotenoids in isolatesof aerobic marine bacteria, OCh 101 and OCh 114, grown heterotrophically.Whereas they formed these pigments fairly well under high aerationin the dark, a limitation of the O₂-supply resulted in the decreasedsyntheses of bacteriochlorophyll in both strains. Synthesesof carotenoids also were depressed under low aeration but toa lesser extent (especially in OCh 101) than the depressionof bacteriochlorophyll synthesis. Aerobic incubation of a cultureof OCh 101, that previously had been grown semiaerobically,induced the supplementary synthesis of bacteriochlorophyll.This induction was inhibited almost completely by chloram-phenicol.The absorption spectra of suspensions and solvent extracts ofcells grown aerobically or semiaerobically are reported. (Received May 30, 1980; )     

Photosynthetic electron transfer system is inoperative in anaerobic cells of Erythrobacter species strain OCh 114

Some of the photosynthetic reactions were measured under aerobic and anaerobic conditions in intact cells of an aerobic photosynthetic bacterium Erythrobacter species strain OCh 114 (ATCC No. 33942). In intact cells, the flash-light induced oxidation of cytochrome c-551, the continuous light-induced oxidation of reaction center bacteriochlorophyll and the continuous light-induced pH change ( ) of the suspension decreased on aerobic-anaerobic transition and almost disappeared under anaerobic conditions. These photosynthetic reactions reappeared when the suspension was aerated again. These phenomena were reconciled with the fact that Erythrobacter sp. cannot grow anaerobically even in the light. The incompetence of photoanaerobic growth of this bacterium was explained by the reduction of the primary electron acceptor (Q_I) before illumination, resulting partly from the relatively high midpoint potential of Q_I of this bacterium.Abbreviations Q_I Primary electron acceptor - E_h ambient redox potential - E_m midpoint redox potential     

O2-stimulated synthesis of bacteriochlorophyll and carotenoids in marine bacteria

We examined the effects of a limitation of the O₂-supply onthe syntheses of bacteriochlorophyll a_p and carotenoids in isolatesof aerobic marine bacteria, OCh 101 and OCh 114, grown heterotrophically.Whereas they formed these pigments fairly well under high aerationin the dark, a limitation of the O₂-supply resulted in the decreasedsyntheses of bacteriochlorophyll in both strains. Synthesesof carotenoids also were depressed under low aeration but toa lesser extent (especially in OCh 101) than the depressionof bacteriochlorophyll synthesis. Aerobic incubation of a cultureof OCh 101, that previously had been grown semiaerobically,induced the supplementary synthesis of bacteriochlorophyll.This induction was inhibited almost completely by chloram-phenicol.The absorption spectra of suspensions and solvent extracts ofcells grown aerobically or semiaerobically are reported. (Received May 30, 1980; )     

Light-induced changes of carotenoid pigments in anaerobic cells of the aerobic photosynthetic bacterium,Roseobacter denitrificans (Erythrobacter species OCh 114): reduction of spheroidenone to 3,4-dihydrospheroidenone

Roseobacter denitrificans, previously named Erythrobacter species OCh 114, synthesized spheroidenone as a major carotenoid under aerobic dark conditions. When the dark-grown cells were subjected to illumination under anacrobic conditions, many unknown yellow pigments appeared and a considerable amount of spheroidenone disappeared. Absorption maxima of these pigments were blue-shifted from those of spheroidenone. The most abundant of the pigments was isolated, and its chemical structure was determined as 3,4-dihydrospheroidenone on spectroscopic and chemical evidence. Presumably, over-reduction of the photosynthetic apparatus interfered with normal photosynthetic electron transfer and resulted in photoreduction of C=C double bond at the 3,4-position of spheroidenone.     

Characterization of a DMSP-degrading bacterial isolate from the Sargasso Sea

A bacterium which cleaves dimethylsulfoniopropionate (DMSP) to form dimethylsulfide (DMS) was isolated from surface Sargasso Sea water by a DMSP enrichment technique. The isolate, here designated LFR, is a Gram-negative, obligately aerobic, rod-shaped, carotenoid-containing bacterium with a DNA G+C content of 70%. Sequencing and comparison of its 16S ribosomal ribonucleic acid (rRNA) with that of known eubacteria revealed highest similarity (91% unrestricted sequence similarity) to Roseobacter denitrificans (formerly Erythrobacter species strain OCh114), an aerobic, bacteriochlorophyll-containing marine representative of the -Proteobacteria. However, physiological differences between the two bacteria, and the current lack of other characterized close relatives, preclude assignment of strain LFR to the Roseobacter genus. Screening of fifteen characterized marine bacteria revealed only one, Pseudomonas doudoroffii, capable of degrading DMSP to DMS. Strain LFR is deposited with the American Type Culture Collection (ATCC 51258) and 16S rRNA sequence data are available under GenBank accession number 15345.Contribution no. 8337 of the Woods Hole Oceanographic Institution     

Purification and some properties of a soluble cytochrome (cytochrome c-551) from Erythrobacter species strain OCh 114

A soluble cytochrome, cytochrome c-551 was purified from an aerobic photosynthetic bacterium Erythrobacter species strain OCh 114 (ATCC No. 33942) by ammonium sulfate fractionation, ion-exchange chromatography and gel-filtration. The cytochrome had absorption maxima at 277, 410, and 524–525 nm in the oxidized form, and at 415, 522, and 550.5 nm in the reduced form. At 77 K, the -band of the absorption spectrum of the reduced form split in two at 547 and 549 nm. The millimolar absorption coefficient at 550.5 nm was 26.8 mM^-1 cm^-1 in the reduced form. This cytochrome was an acidic protein with an isoelectric point of 4.9. Its molecular weight was determined to be 15,000 by gel-filtration on Sephadex G-100 and 14,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The midpoint potential of this cytochrome was +250 mV at pH 7.0. This cytochrome did not bind CO.     

A Denitrifying Activity in an Aerobic Photosynthetic Bacterium, Erythrobacter sp. Strain OCh 114

An aerobic photosynthetic bacterium, Erythrobacter sp. strainOCh 114, was capable of growth under anaerobic conditions inthe dark with nitrate as a terminal electron acceptor. The optimalnitrate concentration was about 6 mM for anaerobic growth, althougha wide range of concentrations from 1 to 400 mM were effective.A large amount of N₂O gas was released during this anaerobicgrowth, indicating a denitrifying activity in this bacterium.Light had no stimulating or inhibiting effect on the rates ofanaerobic growth and gas release. The enzymes responsible forthe denitrifying activity, dissimilatory nitrate and nitritereductases, were present in aerobically grown cells. (Received February 19, 1988; Accepted May 16, 1988)     

Growth, respiration and some enzymes of three strains of Ceratocystis fimbriata

Growth, respiratory activities and electrophoretic characteristicsof phosphatase and catalase in three strains of Ceratocystisfimbriata (sweet potato strain, coffee strain and prune strain)differing in pathogenicity on sweet potato roots were investigated.There were no significant differences in either growth kineticsor respiratory activity among the strains. Potassium cyanideand antimycin A inhibited oxygen uptake in sweet potato andprune strains. The oxygen uptake of endoconidia of coffee strainwas stimulated by these inhibitors. Mitochondria were preparedfrom endoconidia and mycelia of each strain, and enzyme activitiesof the electron transport system were measured. NADH₂: cytochromec oxidoreductase activity of coffee strain was higher than thatof the other strains. The electrophoretic phosphatase patternof coffee strain was identical with that of sweet potato strain,but differed from that of prune strain. On the other hand, thecatalase zymogram from prune strain was closely related to thatof sweet potato strain, but not to that of coffee strain. ¹This paper constitutes part 79 of the phytopathological chemistryof sweet potato with black rot and injury. (Received May 22, 1969; )     

Comparison of Growth Responses of Barnyard Grass (Echinochloa oryzoides) and Rice (Oryza sativa) to Submergence, Ethylene, Carbon Dioxide and Oxygen Shortage

Unlike germination of wheat (Triticum aestivum), millet (Eleucinecoracana), and sorghum (Sorghum caudatum), that of Echinochloaoryzoides (barnyard grass) and Oryza satwa (rice) was not inhibitedby poorly aerated solutions with 11 k Pa oxygen (equilibriumpartial pressure) or less In the dark, seedling shoots of riceincluded a coleoptile, and in Echinochloa, a mesocotyl alsoGrowth in fresh and dry weight of shoots was strongly depressedby poorly aerated solutions in both rice and Echinochloa butthe effects on extension differed in the two species in rice,coleoptile extension was promoted by solutions partly depletedof oxygen, and also by the absence of oxygen The stimulationin partly de-oxygenated solutions resulted from the combinedpromoting effects of small oxygen partial pressures, carbondioxide, ethylene and buoyant tension in contrast, these treatmentsneither promoted nor inhibited elongation by the Echinochloacoleoptile while severely inhibiting extension of the mesocotyl Overall, poorly aerated solutions lengthened the shoot of riceand shortened it in Echinochloa when compared with those submergedin well-aerated solutions These opposite effects were broughtabout by the same gaseous changes, i e oxygen shortage, elevatedethylene and carbon dioxide The effect on Echinochloa was almostentirely restricted to the mesocotyl, coleoptile extension beingremarkably insensitive to large increases in ethylene and carbondioxide, or to extreme oxygen shortage Seedlings of the twospecies thus have contrasting strategies for survival Stress, submergence, ethylene, oxygen shortage, carbon dioxide, adaptation, anaerobiosis, rice (Oryza sativa L), barnyard grass [Echinochloa oryzoides (Ard) Fritseh]     

Carbonic Anhydrase of Chlamydomonas reinhardtii. Cellular Distribution and Subunit Constitution in Two Strains

Cellular distribution and subunit constitution of carbonic anhydrase(CA) were compared between the CBSC strain of Chlamydomonasreinhardtii (purchased from Carolina Biological Suuply Co.)and C. reinhardtii C-9. CAs existed exclusively outside theplasma membrane inboth strains. Mol wts of the monomer and theholoenzyme from both strains were 35 kDa and 115–117 kDa,respectively. These results show that the CAs of both strainsare identical or verysimilar. ¹Present address: National Institute for Basic Biology, Myodaiji,Okazaki 444, Japan. (Received June 29, 1987; Accepted October 9, 1987)     

Free Cellular Riboflavin is Involved in Phase Shifting by Light of the Circadian Clock in Neurospora crassa

Phase shifting by light of the circadian conidiation rhythmof the Neurospora crassa strain band, of the riboflavin-deficientdouble mutant band rib2 and of the temperature-sensitive doublemutant band ribl was measured. Fluence response curves of theband strain exhibited two distinct steps, whereas those of bandribl and band rib2 revealed only one step. Maximum phase advancesobserved were 5.5 h in band and 10.4 h in the band rib strains.Sensitivity of band rib2 to light was proportional to the riboflavinconcentration in the growth medium over a 100 fold range. Extracellularflavin in the medium did not sensitize the strains. Riboflavinapplied after exposure to light showed no effect. Light sensitivitycorrelated with the level of cellular riboflavin. Four analogsof riboflavin, none of which can be phosphorylated, increasedthe sensitivity of Neurospora to light. Even at high riboflavinconcentrations in the medium, the sensitivity of the band rib2strain to light was not saturated. In addition, four riboflavinderivatives with bulky substituents at positions 3, 8 or 10of the isoalloxazine nucleus sensitized both strains. From ourdata, we conclude, that a) a cellular flavin controls the sensitivityof Neurospora crassa to light; b) that this flavin compoundis riboflavin; and c) that the active riboflavin is not proteinbound. ⁴Present address: Teikoku Women's University, Department ofHome Economics, 6-173 Touda-cho, Moriguchi-shi, Osaka, 570 Japan. (Received November 27, 1987; Accepted March 15, 1989)     

Isolation and Identification of L-Pipecolic Acid and Nicotinamide as Flower-Inducing Substances in Lemna

Flower-inducing factors in extracts of flowering Lemna gibbaG3 were investigated using Lemna paucicostata 151 as the bioassayplant. Fractions with flower-inducing activity were obtainedafter several purification steps. Two of the active substanceswere identified as L-pipecolic acid and nicotinamide by MS andNMR analyses. Both L-pipecolic acid and nicotinamide exhibited flower-inducingactivity in L. paucicostata 151 grown on one-tenth-strengthM medium containing benzyladenine, the former being ten timesas active as the latter. L-Pipecolic acid was active even at0.01 ppm (7.8 ? 10^–8 M). The effect of L-pipecolic acidon flowering strongly depended upon the presence of exogenouscytokinin. The coexistence of cytokinin seemed to be essentialfor L-pipecolic acid to exhibit flower-inducing activity. Incontrast, the effect of nicotinamide on flowering was basicallythe same as that of benzoic acid or nicotinic acid. (Received February 9, 1987; Accepted May 21, 1987)