Experimental growth of rhodobacter capsulatus atcc 11166 pure cultures in the natural light conditions of the freshwater column of rotsee, Switzerland. A proposal for a new biological method to detect light limitation levels for phototrophic bacteria (original) (raw)
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Journal of Bacteriology
Rhodopseudomonas capsulata was grown under anaerobic, photosynthetic conditions in a continuous culture device. Under light limitation, at a constant dilution rate, it was shown that cell composition, including photopigment (bacteriochlorophyll and carotenoids) and ribonucleic acid content, was not affected by incident light intensity; however, steady state culture density varied directly and linearly with light intensity. On the other hand, photopigment and ribonucleic acid levels were affected by growth rate regardless of light intensity. Additional experiments indicated a high apparent K8 for growth of R. capsulata with respect to light. These results were interpreted to mean that near the maximum growth rate (D = 0.45 h-1) some internal metabolic process became the limiting factor for growth, rather than the imposed energy limitation. A mathematical expression for the relation between steady-state culture density and dilution rate was derived and was found to adequately describe the data. A strong correlation was found between continuous cultures limited either by light or by a chemical energy source.
1986
RESUM L'absorció com a mesura del creixement d'un cultiu és, generalment, un bon parimetre. En el cas dels bacteris fototrbfics no poden utilitzar-se directament els valors d'absorció perque reflecteixen també les interferirncies del sofre i la presirncia de pigments, sobretot quan es coneix que aquests depenen de la intensitat de llum i del grau d'activitat del cultiu. En el cas de les Clorobiicies, les quals excreten sofre al medi, aquest fet és encara més patent. Un seguit de parametres lligats a I'absorció han estat analitzats estadísticament per tal de determinar el més idoni pel seguiment de les fases dels cultius de bacteris fototrofics verds. RESUMEN La absorción como medida del crecimiento de un cultivo es, en general, un buen parámetro. En el caso de las bacterias fototróficas no es posible utilizar directamente 10s valores de absorción porque incorporan también las interferencias del azufre y la presencia de pigmentos, sobre todo cuando se conoce que estos dependen de la intensidad de la luz y del grado de actividad del cultivo. En el caso de las Clorobiaceas, que excretan azufre al medio, este hecho es aún más evidente. Se han analizado estadisticamente una serie de parámetros ligados a la absorción con el fin de determinar el más idóneo para el seguimiento de las fases de 10s cultivos de bacterias fototróficas verdes. ,
Enzyme and Microbial Technology, 2006
Two mutants of Rhodobacter Capsulatus (JP91 and IR3), a photosynthetic purple non-sulfur bacterium, were grown in a batch photobioreactor under illumination with 30 mmol l −1 dl-lactate and 5 mmol l −1 l-glutamate as carbon and nitrogen source, respectively. Bacterial growth was measured by monitoring the increase in absorbance at 660 nm. The photosynthetic growth processes under different cultivated temperatures are well fitted by a specific logistic model to analyze the kinetics of photosynthetic growth of two strains, thus the apparent growth rates (k) of these photosynthetic bacteria, the variations of cell dry weight (CDW) as well as their relationship with temperature are obtained. In present work, k is (0.1465 ± 0.0146), (0.2266 ± 0.0207) and (0.3963 ± 0.0257) h −1 for JP91 and (0.1117 ± 0.0122), (0.1218 ± 0.0133) and (0.2223 ± 0.0152) h −1 for IR3 at 26, 30 and 34 • C, respectively. And the difference between CDW max and CDW 0 is (0.8997 ± 0.0097), (0.8585 ± 0.0093) and (0.9241 ± 0.0099) g l −1 for JP91 and (0.8167 ± 0.0089), (0.7878 ± 0.0086) and (0.8358 ± 0.0091) g l −1 for IR3 at 26, 30 and 34 • C, respectively. Also real-time monitoring of hydrogen production rates is acquired by recording the flow rates of photohydrogen for these two strains under different temperatures. The effects of temperature on the bacteria growth, hydrogen production capability and substrate conversion efficiency are discussed based on these results. The most preferment temperature, 30 • C, showed good substrate conversion efficiency of 52.7 and 68.2% for JP91 and IR3, respectively.
Modeling Photoheterotrophic Growth Kinetics of Rhodospirillum rubrum in Rectangular Photobioreactors
Biotechnology Progress, 2000
Based on a previously established model for radiant light transfer in photobioreactors (PBR), taking into account absorption and scattering of light, a new knowledge model for coupling radiant light energy available and local growth kinetics in PBRs for the photoheterotrophic bacteria Rhodospirillum rubrum is discussed. A revised method is presented for the calculation of the absorption and scattering coefficients. The specific characteristics of the electron-transfer chains in such microorganisms leads to definition of three different metabolic zones in the PBR, explaining the behavior of mean kinetics observed in a wide range of incident light fluxes. The model is validated in rectangular PBRs for five different carbon sources and proved robust and fully predictive. This approach can be considered for simulation and model-based predictive control of PBRs cultivating photoheterotrophic microorganisms.
Photosynthetica, 2018
Macroalgae must be able to survive in conditions of different light intensities with no damage to their physiological performance or vital processes. Irradiance can stimulate the biosynthesis of certain photoprotective compounds of biotechnological interest, such as pigments and proteins. Pterocladiella capillacea is a shade-grown alga, which play a role key in the balance of marine ecosystems. In addition, it is considered one of the best sources of bacteriological agar and agarose with a wide pharmacological potential. In order to evaluate the photosensitivity in P. capillacea under 60 (control) and moderate light intensity of 300 μmol(photon) m-2 s-1 , photosynthetic performance and chemical composition were assessed. P. capillacea showed photosensitivity without evidence of photodamage. The results indicate the possibility to increase a growth rate and probably infer productivity in long-term cultivation by stimulation at moderate light intensity. Increasing photosynthetic pigment and protein contents were also observed under medium light, an interesting result for functional ingredient approaches.
Applied and Environmental Microbiology, 1996
This article describes a novel method for the measurement of light absorption by cultures of phototrophic microorganisms. The rate of light absorption is calculated as the difference between the rate of light output from a culture containing cells and the rate of light output from a culture containing only growth medium. The specific rate of light uptake is calculated by dividing the rate of light absorption by the total biomass present in the culture. Application of the method to several case studies shows that light output from a culture varies widely depending on the absorption and scattering characteristics of the suspension.
FEMS Microbiology Letters, 1989
Cell volumes of different purple phototrophic bacteria were measured using several techniques: Coulter counter, phase contrast and epifluorescence microscopy. Volumes of Chromatium warmingii, C. minutissimum, Thiocapsa roseopersicina, and Thiocystis gelatinosa were measured as the organisms were accumulating sulfur. Cell volumes of Rhodobacter capsulatus were measured under different growth conditions including both anaerobically in the light and aerobically in the dark. Size distributions were flatter and more irregular by phase contrast microscopy than by Coulter counter. This latter technique could not be used in many cases, however, because phototrophic bacteria associate to form chains and aggregates of cells. In addition, Coulter counter measurements for organisms with capsules gave volumes intermediate between the volume of the cell and the volume of the capsule, as measured by
World Journal of Microbiology and Biotechnology
An indigenous strain of the purple non-sulphur phototrophic bacterium, Rhodopseudomonas palustris strain B1, was selected for the utilization and treatment of wastewater from a sago-starch-processing decanter. Growth of Strain B1 under anaerobic–light conditions in the carbohydrate-rich effluent was optimized by using 50% (v/v) effluent diluted in a basal minimal mineral medium with the addition to 0.1% (w/v) yeast extract. The optimum level of nitrogen source supplement, ammonium sulphate, was 1.0g/l. Highest cell mass concentration was achieved by using tungsten lamps as the light source with a light intensity of 4 klux. Under these optimal conditions, a maximum biomass of about 2.5g dry cell/l with a pigment content of about 1.1mg carotenoid/g dry weight cell was achieved after 96h of anaerobic cultivation. There was a 77% reduc n the chemical oxygen demand (COD) of the effluent. A cell yield of about 0.59g dry weight cell/g COD was obtained.
Bioresource Technology, 2012
This study investigated the effects of eight light sources on photosynthetic bacteria (Rhodopseudomonas palustris) growth and carotenoid content (CD), cultured for 144 h. Light sources were incandescent lamp (IL), halogen lamp (HL), fluorescence lamp (FL), and light-emitting diodes (LEDs) of white (LW), yellow (LY), red (LR), blue (LB), and green (LG). Dark condition served as the control. Under around 2000 lux, light sources ranked greatest to least bacterial growth effect were (LB = IL) > FL > LW = HL = LR =
1989
tetrazolium chloride (INT)toINT-formazan, andtotal numberofE.colicells as determined bytheacridine orangedirect-count method. Intheilluminated systems, decreases inCFUofE.coli andinthenumberofmetabolically active cells wereobserved. However, nodecline ofthetotal numberofE. coli cells wasobserved. Bycountmethods, different stages ofprogressive dormancy ofE.colicells were determined toexist inilluminated systems. Culturable andrecoverable cells weredefined asviable cells, and metabolically active cells andmorphologically intact cells weredefined assomnicells. Indirect activity measurements werealsodonebyusing('4C)glucose. Inilluminated systems, adecrease ofglucose uptake