Mass exchange conditions in penicillin biosynthesis in an industrial fermenter with aerodynamic foam suppressor

The mass exchange characteristics of 50 m3 industrial fermentors with aerodynamic foam suppression and the effect of the specific power input on biosynthesis of penicillin were studied. A change in the specific power input from 1.3 to 1.9 kW/m3 had no effect on the level of the antibiotic accumulation when the medium with 8 per cent of lactose was used. An increase in the aeration rate from 1 to 1.2 m3/m3 X min provided a 1.1-fold increase in the penicillin activity of the fermentation broth. The use of the device for aerodynamic foam suppression with a system of automatic control of the partial pressure of dissolved carbon dioxide allowed decreasing 1.22-fold the oil use and increasing the process productivity by 10 per cent.     

Measurement of dissolved carbon dioxide.

Several probes for measuring dissolved carbon dioxide (CO2) concentration were installed in a 68-litre fermentor and their effectiveness compared. Submerged silastic rubber tubing gave reproducible results over a wide range of operating conditions and was generally superior to all other probes evaluated. The silastic rubber probe was used to compare the partial pressure of CO2 in viscous fermentation media with that in the fermentor exhaust gas. No significant difference was found. Results show that determination of the CO2 partial pressure in the exhaust gas gives an excellent approximation of the partial pressure of dissolved CO2 in the liquid medium, eliminating the need for measurement of CO2 concentration in the broth.     

Influence of oxygenation and carbon dioxide on the growth ofRhizobium meliloti in a fermenter

A decrease in dissolved O₂ from 90% to 50% saturation in a fermenter adversely affected both blomass production ofRhizobium meliloti ATCC 9930 and viable cell number, although oxygen was never limiting. Lower amounts of dissolved oxygen, or accidental decreases in dissolved oxygen concentration, also caused appreciable acidification of the culture broth, which was the result of CO₂ accumulation in the medium. Adding CO₂ to the aeration gas mixture affected both biomass production and mean generation time in proportion to the CO₂ concentration; the effect on viable cell number was less pronounced.R. meliloti may be considered as a microorganism moderately sensitive to CO₂. GoodR. meliloti growth requires, among other things, not only sufficient aeration (oxygenation) but also good ventilation of the CO₂ evolved during the fermentation.

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Résumé La diminution de l'O₂ dissous de 90 à 50% de la saturation dans un fermenteur, a affecté de manière négative tant la production de biomasse deRhizobium meliloti ATCC 9930 que le nombre de cellules revivifiables, bien que l'oxygène ne fut jamais limitant. Des quantités diminuées d'oxygène dissous ou une diminution accidentelle de la concentration en oxygène dissous, ont également causé une acidification appréciable du milieu de culture résultant de l'accumulation de CO₂ dans le milieu. L'ajout de CO₂ au gaz d'aération a affecté tant la production de biomasse que le temps moyen de génération, proportionnellement à la concentration de CO₂; l'effet sur le nombre de cellules revivifiables était moins prononcé.R. meliloti peut être considéré comme un microorganisme modérément sensible au CO₂. Une bonne croissance deR. meliloti requiert, entre autres, non seulement une aération (oxygénation) suffisante, mais aussi une bonne ventilation du CO₂ engendré pendant la fermentation.

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Publication Number NRCC No. 32389     

Effect of carbon dioxide dissolved in water on carboanhydrase activity in various organs of carp

The carboanhydrase activity was studied in erythrocytes and tissues of carp gills and kidneys under conditions of exogenic hypercapnia induced by an increase in the level of carbon dioxide solved in the water medium. This enzymic activity in fish erythrocytes is established to be determined by the hypercapnia degree and does not depend on its duration. The carboanhydrase activity in the gills and kidneys is not changed under the effect of higher (within 0,16-1,10 mM) concentration of carbon dioxide for seven days.     

Effect of dissolved carbon dioxide on penicillin fermentations: Mycelial growth and penicillin production

The effect of dissolved carbon dioxide on the specific growth rate and the penicillin production rate of Penicillium chrysogenum was examined experimentally. The dissolved carbon dioxide was found to inhibit the specific growth rate and the penicillin production rate when the aerated submerged penicillin fermentation was exposed to influent gases of 12.6 and 20% carbon dioxide, respectively. Upon exposure to influent gases of 3 and 5% carbon dioxide, no pronounced metabolic inhibition was noted.     

Effect of elevated dissolved carbon dioxide concentrations on growth of Corynebacterium glutamicum on D-glucose and L-lactate

The effect of increased dissolved carbon dioxide concentrations on growth of Corynebacterium glutamicum was studied with continuous turbidostatic cultures. The carbon sources were either l-lactate or d-glucose. To increase the dissolved carbon dioxide concentration the carbon dioxide partial pressure of the inlet gas stream pCO2,IN was increased stepwise from 0.0003 bar (air) up to 0.79 bar, while the oxygen partial pressure of the inlet gas stream was kept constant at 0.21 bar. For each resulting carbon dioxide partial pressure pCO2 the maximum specific growth rate mu(max) was determined from the feed rate resulting from the turbidostatic control. On d-glucose and pCO2 up to 0.26 bar, mu(max) was mostly constant around 0.58 h(-1). Higher pCO2 led to a slight decrease of mu(max). On l-lactate mu(max) increased gradually with increasing carbon dioxide partial pressures from 0.37 h(-1) under aeration with air to a maximum value of 0.47 h(-1) at a pCO2 of 0.26 bar. At very high pCO2 (0.81 bar) mu(max) decreased down to 0.35 h(-1) independent of the carbon source.     

Effect of carbon dioxide on photorespiration

The isotopic CO₂ technique for measuring photorespiration was shown to be a valid technique for measuring the unidirectional inward and outward fluxes of CO₂ from a sunflower (Helianthus annuus L.) leaf in the light. The rate of photorespiration was decreased little as the CO₂ concentration was increased from 20 to 1,150 microliters per liter. This finding contradicts the widely held assumption that photorespiration is suppressed at high CO₂ concentrations. Some discussion regarding this apparent conflict is presented.     

The effect of dissolved carbon dioxide on penicillin production: Mycelial morphology

The effect of carbon dioxide on the morphology of Penicillium chrysogenum was examined. The scanning electron microscopic (SEM) study indicated that the morphology of P. chrysogenum was subject to change when exposed to various dissolved CO₂ concentrations in the medium. At low influent carbon dioxide partial pressures between 0% and 8%, the predominant morphological form of P. chrysogenum was filamentous. At higher influent carbon dioxide partial pressures of 15% and 20%, the appearance of swollen and stunted hyphae predominated, and a significant quantity of spherical or yeast-like cells were observed. It was evident that for production subject to high dissolved CO₂ concentrations the inhibition of cell growth and penicillin production related strongly to the concomitant morphological changes of P. chrysogenum.     

Effect of dissolved carbon dioxide on oxygen consumption in the Pacific white shrimp,Litopenaeus vannamei (Boone 1931)

A failure in the aeration system of Litopenaeus vannamei rearing with biofloc technology can decrease the oxygen concentrations rapidly and also increase the carbon dioxide (CO₂) concentrations at the same rate. We report here an evaluation of the effect of CO₂ on the oxygen consumption of L. vannamei. We used a continuous-flow respirometer with water recirculation equipped with a digital fiber-optic oximeter. Eight juveniles of L. vannamei (12.1 ± 1. 4 g) were used in each treatment with one per respiratory chamber (0.6 L). The shrimp were exposed to six concentrations of CO₂ (5, 30, 60, 95, 150, and 300 mgCO₂/L) with an acute exposure time of six hours. Upon treatment with 5–30 mgCO₂/L, we observed a consumption of oxygen of 0.233 ± 0.129 and 0.33 ± 0.072 mgO₂/g/h, respectively. Upon treatment with 60 mgCO₂/L, an increase was observed in the oxygen consumption (0.521 ± 0.098 mgO₂/g/h). Upon treatment with 95, 150, and 300 mgCO₂/L however, the shrimp decreased their oxygen consumption and lost their equilibrium. The CO₂ should therefore be maintained at a maximum of 5 mgCO₂/L during shrimp rearing.     

Fluxes of dissolved carbon dioxide and inorganic carbon from an upland peat catchment: implications for soil respiration

This study uses long-term water chemistry records for a circum-neutral peat stream to reconstruct a 7-year record of dissolved CO₂ and DIC flux from the catchment. Combining catchment flux with a knowledge of in-stream metabolism and gas evasion from the stream surface enables an estimate of the dissolved CO₂ content of water emerging from the peat profile to be made; furthermore, these can be used to estimate soil CO₂ respiration. In this way multi-annual records of CO₂ production can be reconstructed, and therefore inter-annual controls on production examined. The results suggest that:(i) Stream evasion of CO₂ within the catchment varied between 80 and 220 g C/m of stream/yr, while in-stream metabolism produces between 1.0 and 2.9 g C/m of stream/yr;Export of dissolved CO₂ emerging from the soil profile, above that expected at equilibrium with the atmosphere, varies between 9.6 and 25.6 tonnes,C/km²/yr; andThe export of dissolved CO₂ implies a soil respiration rate of between 64.2 and 94.9 tonnes C/km²/yr.The inter-annual variation in both dissolved CO₂ flux and soil CO₂ respiration suggests that severe drought has no long-term effect on CO₂ production and that temperature-based models of soil CO₂ respiration will be adequate in all but the severest of summer droughts. The inter-annual variation in CO₂ flux shows that CO₂ production is decoupled from dissolved organic carbon (DOC) production. The decoupling of DOC and dissolved CO₂ production shows that enzymatic-latch production of DOC is an anaerobic process and will not increase soil CO₂ respiration.     

Extraction of microalgae derived lipids with supercritical carbon dioxide in an industrial relevant pilot plant

Microalgae are capable of producing up to 70% w/w triglycerides with respect to their dry cell weight. Since microalgae utilize the greenhouse gas CO₂, they can be cultivated on marginal lands and grow up to ten times faster than terrestrial plants, the generation of algae oils is a promising option for the development of sustainable bioprocesses, that are of interest for the chemical lubricant, cosmetic and food industry. For the first time we have carried out the optimization of supercritical carbon dioxide (SCCO₂) mediated lipid extraction from biomass of the microalgae Scenedesmus obliquus and Scenedesmus obtusiusculus under industrrially relevant conditions. All experiments were carried out in an industrial pilot plant setting, according to current ATEX directives, with batch sizes up to 1.3 kg. Different combinations of pressure (7–80 MPa), temperature (20–200 °C) and CO₂ to biomass ratio (20–200) have been tested on the dried biomass. The most efficient conditions were found to be 12 MPa pressure, a temperature of 20 °C and a CO₂ to biomass ratio of 100, resulting in a high extraction efficiency of up to 92%. Since the optimized CO₂ extraction still yields a crude triglyceride product that contains various algae derived contaminants, such as chlorophyll and carotenoids, a very effective and scalable purification procedure, based on cost efficient bentonite based adsorbers, was devised. In addition to the sequential extraction and purification procedure, we present a consolidated online-bleaching procedure for algae derived oils that is realized within the supercritical CO₂ extraction plant.

     

Effect of the aeration and agitation states on tetracycline biosynthesis in semiproduction-capacity apparatus]

The results of the experiments on determination of the effect of aeration and agitation conditions on biosynthesis of tetracycline in the apparatus of semi-production capacity are discussed. It was shown that the antibiotic production level was not connected with the rate of oxygen solution expressed in the sulphite numbers, i.e. this parameter cannot be used as a scaling-up criterion. Accumulation of the antibiotic in the fermentation broth depended on the volume of the air supplied for aeration. It was determined that the level of CO2 dissolved in the fermentation broth did not reach the values having an inhibitory effect on the biosynthetic process.