Nitrogen flow through a Brachionus/Chlorella mass culture system

A model of nitrogen flow is presented through the Brachionus plicatilis/Chlorella saccharophila mass (batch) culture system, from the initial input of inorganic nitrogen to the algal culture medium to the final production of rotifers, dissolved nitrogen and particulate nitrogen.A nitrogen budget was first formulated for B. plicatilis relating ingestion, excretion, egestion, somatic growth and reproductive growth. Measurements were made on rotifers from 20° and 10° cultures.The calculated model of nitrogen flow through the rotifer/algal batch culture system estimates the percentages of the original input nitrogen which will be incorporated into algal nitrogen, rotifer nitrogen and the particulate and dissolved nitrogen pools. It is suggested that the dissolved nitrogen pool could be recycled directly for use in subsequent algal culture.     

Uptake pathway and continuous removal of nitric oxide from flue gas using microalgae

Nitric oxide (NO), a major constituent of NO_x in fossil fuel flue gas, can be removed by the microalga, Dunaliella tertiolecta, in a bubble-column-type bioreactor. The uptake pathway of NO was investigated, and it was found that little NO was oxidized in the medium before its uptake by algal cells and that NO mostly permeated directly into the cells by diffusion based on the mass balance of nitrogen and the change in nitrate and nitrite concentration in the medium in batch culture. For further application of this system, it is necessary to remove NO over a long duration, and the stability of NO removal is important. NO removal rate of about 50–60% could be maintained stably for 15 days in continuous culture under the light condition. Because the consumption of nitrate was reduced by the amount of taken NO, NO rather than nitrate is preferentially utilized as a nitrogen source for cell growth. Therefore, this algal system is useful for continuous NO removal and production of algal biomass using NO as a nitrogen source.     

Regulation of shikonin production by glutamine in Lithospermum erythrorhizon cell cultures

Amino acid analysis has shown that Lithosperum erythrorhizon cell suspension cultures which are unable to produce shikonin derivatives in LS medium containing ammonium accumulate a large quantity of glutamine, as compared with shikonin-producing cells cultured in the production medium M9 containing nitrate as the sole nitrogen source. The addition of glutamine to M9 medium proved to be strongly inhibitory to shikonin production. Furthermore, culture experiments using an inhibitor of glutaminase suggested that shikonin synthesis is not inhibited by ammonium released from glutamine but by glutamine itself. These findings indicate that the repression of shikonin synthesis occurs in close association with an accumulation of glutamine in cultured cells grown in a medium containing ammonium.     

Isolation and characterization of a symbiotic cellulolytic mixed bacterial culture

Summary By using batch-culture enrichment techniques a mixed culture of two bacterial spe cies identified as Cellulomonas flavigena and Xanthomonas sp was isolated. The capacity of both bacteria to grow as pure cultures in a min eral medium with alkaline pretreated sugar cane bagasse or cellobiose was tested. C. flavigena as pure culture was able to grow on both substrates only when yeast extract or biotin and thiamine were added to the culture medium, while Xanthomonas sp. could not grow on sugar cane ba gasse, but assimilated cellobiose if yeast extract was supplied. However, both bacteria in mixed culture grew very well on both substrates and did not require any growth factor. It was concluded that the interaction was favourable to both species. The mixed culture had the capacity to degrade a number of different agricul tural wastes and to use them as the sole carbon and energy source for the production mainly of biomass. More than 80% of pineapple bagasse, without chemical pretreatment, was used up by the microbial system.     

Nicotine production by “hairy root” cultures of Nicotiana rustica: Fermentation and product recovery

The production of nicotine by cultures ofNicotiana rustica transformed withAgrobacterium rhizogenes has been examined in a packed bed fermenter as a two-stage batch/continuous-flow system. A substantial proportion of the nicotine synthesised in the batch phase may be subsequently harvested from the medium. The possibility of improving product recovery using macroreticular adsorbents is considered.     

A method for the laboratory culture of the planktonic rotifer Keratella cochlearis (Gosse)

Procedures for the continuous laboratory culture of Keratella cochlearis in a defined medium and upon an algal food are described. Culturing success appears to be a function of food availability as well as composition. This availability requirement is satisfied by the use of test tubes and inverted titration plate concavities as culture vessels. The satisfactory culture medium contains an ammonia compound as a nitrogen source.     

Resistance to freezing in liquid nitrogen of carnation (Dianthus caryophyllus L. var Eolo) apical and axillary shoot tips excised from different aged in vitro plantlets

The ability of shoot tips from carnation (Dianthus caryophyllus L., var. Eolo) cultured in vitro to develop resistance to freezing in liquid nitrogen depends on the physiological state of the cell material and the pretreatment conditions. Regrowth rates close to 100% have been obtained with apical shoot tips isolated from 2 month-old stems, precultured on medium supplemented with sucrose (0.75M) and treated with dimethylsulfoxide (5% or more). Resistance of axillary shoot tips decreased progressively as a funtion of their distance from the apical shoot tip. During the development of the stem from axillary buds (obtained by cutting), progressive increases in the regrowth rate of frozen apices were noted, from 30% before cutting (axillary buds) to 98% after 3 weeks of culture.Abbreviations DMSO dimethylsulfoxide - LN liquid nitrogen     

In vitro organogenesis and somatic embryogenesis from leaf explants of Leucosceptrum canum sm.

Plantlets were obtained from leaf explants of a Labiatae tree — Leucosceptrum canum Sm. using plant tissue culture techniques. Two types of calli proliferated from the leaf explants when grown on different media, one of which was amenable to somatic embryogenesis. Differentiation of the embryoids started from the fourth passage of culture and continued up to the seventh passage. The number of embryoids decreased with the age of the callus. The capacity of such embryoids to form entire plantlets was studied using different nutrient mileux. Embryoids formed plantlets on Murashige and Skoog's (MS) medium fortified with benzylaminopurine plus indolebutyric acid. Organogenesis was observed in shoot-buds derived from explants of in vitro regenerated plantlets on MS basal medium supplemented with benzylaminopurine. Culture regenerated plantlets were transferred to MS medium without sucrose and growth hormones; finally transferred to pots containing sterile vermiculite where they are growing.Abbreviations MS Murashige and Skoog's medium - 2,4-D 2,4-dichlorophenoxy acetic acid - NAA naphthaleneacetic acid - IAA indoleacetic acid - IBA indolebutyric acid - Kn kinetin - BAP benzylaminopurine - CW coconut water     

Oxygen sensitivity of nitrogenase is not always a limiting factor of growth under nitrogen-fixing conditions inAzotobacter vinelandii

Summary The effect of a combined nitrogen source to oxygen sensitive mutants was examined. For some oxygen sensitive mutants, oxygen sensitivity was not restored by the addition of nitrogen compounds to their medium. One of these mutants showed oxygen resistant nitrogenase activity similar to that of a wild strain. Results imply that oxygen sensitivity of nitrogenase is not always a limiting factor of growth under aerobic nitrogen-fixing conditions inAzotobacter vinelandii.     

城市生活废水用于产油微藻培养

将废水与产油微藻培养结合起来,可以实现废水的无害化处理,还可为微藻的培养提供营养组分和大量水源。利用高产油栅藻,以城市生活废水为水源,在气泡柱式光反应器中,考察了添加不同营养组分对栅藻细胞的生长、生物质产量、总脂含量以及氮磷的去除情况的影响。结果表明：生活废水非常适合于产油微藻的培养,利用生活废水进行微藻培养中,仅需补充添加无机氮、无机磷、柠檬酸铁铵以及微量元素。但这些营养组分的加入量对藻细胞的生长、生物量和油脂积累有重要影响。在优化的废水培养基中微藻细胞浓度可达8.0 g/L左右,远高于标准BG11培养基5.0 g/L的水平。微藻细胞对于无机氮与磷有着高的吸收能力,在废水中加入185.25 mg/L以下无机氮,16.1 mg/L以下无机磷的条件下培养3~4 d后,培养液水体中未检测到有氮磷残留。由此表明利用城市生活废水培养含油微藻可以在获得微藻油脂产品的同时实现水体的无害化处理。     

Rapid derepression of in vitro nitrogenase activity in a Rhizobium strain which nodulates legumes and the nonlegume Parasponia

Using defined media and controlled gaseous conditions in vitro nitrogenase activity, as monitored by acetylene reduction, was detected after 16 hours of derepression. Specific activity of nitrogenase increased progressively over a period of 100 hours. The method used here utilises rapidly agitated cultures of Rhizobium strain ANU289, incubated at 28°C at cell densities of ca. 1×10⁹ cells ml^–1. The optimal medium for rapid derepression contained basic physiological salts with 3 mM glutamate and 50 mM sodium succinate being the only carbon and nitrogen additives. The gas phase was kept constant by a continuous flow of an air-nitrogen mixture with oxygen being maintained at 0.2%. The described culture system provides the opportunity to observe the regulation of nitrogenase activity in a near-chemostat situation.     

Growth of the yeast Hansenula anomala with nitrate as sole source of nitrogen under aerobic and anaerobic conditions

Summary The oxygen requirement ofHansenula anomala growing in batch culture on nitrate as sole source of nitrogen was examined. An aeration rate of 0.03 vvm or a constant oxygen partial pressure of 0.01 bar is sufficient for optimal growth.     

Effect of low-dose ultrasonic treatment on phystological variables inAnabaena flos-aquae andSelenastrum capricornutum

Summary Cell protein content in two species of cultured algaeAnabaena flos-aquae andSelenastrum capricornutum, was markedly enhanced by low-dose, short-duration ultrasonic treatment. Chlorophylla levels and¹⁴C-bicarbonate uptake rates were not affected by ultrasonic treatment in either species. Ultrasonically-activatedAnabaena cultures placed in media deficient in nitrogen and phosphorus produced more biomass per unit time, exhibited less cell-surface alkaline phosphatase activity per cell, and had a higher heterocyst frequency than non-sonicated, nutrient-deficient cultures. In contrast, sonicated, nutrient-deficientSelenastrum cultures grew more slowly and had higher alkaline phosphatase activity than non-sonicated variants. Collectively, the data suggest that key metabolic variables may be altered by ultrasonic treatment in algal cultures and that the magnitude and direction of change may be species-specific.     

Kinetic studies on alac-containing strain ofZymomonas mobilis

Summary Batch and continuous culture studies have been carried out on a strain ofZ.mobilis (ZM6306) which can convert lactose directly to ethanol. Previous strain development has established that thelac operon encoded on the transposon Tn951 can be expressed inZ.mobilis. Using a medium containing 80 g/l glucose and 40 g/l lactose, it was found that strain ZM6306 could convert about 13 g/l lactose to 4 g/l ethanol and 6 g/l galactose in continuous culture. Further lactose conversion is likely with increased cell concentration using a cell recycle system.     

Production of L-DOPA from cell suspension culture of Mucuna pruriens f. pruriens

Summary Production of L-DOPA was studied in cell suspension culture of Mucuna pruriens f. pruriens. Suspension culture was established in MSI medium composed of half concentration of Murashige and Skoog's salts and 2% sucrose. A two-stage cell suspension culture was developed for enhanced accumulation of L-DOPA. In the first stage, the culture system was composed of MSI medium without CaCl, which was suitable for cell growth and in the second stage MSI medium containing 42.5 mg.l^–1 KH₂PO₄ and 4% sucrose favoured L-DOPA production. A discernible higher production of L-DOPA was obtained in this two-stage cell suspension culture in comparison to single stage culture.     

A parenchymatic medium solidifier for plant in vitro culture

A new material for the solidification of liquid culture media was prepared from plant parenchyma tissues by mechanical subdivision, solute extration and dessication from ethanol. It is suitable for in vitro culture and propagation of callus as well as shoot tip cultures. The following plant materials have been grown by means of the new medium solidifier: shoot cultures of Betula pendula Roth, Gerbera jamesonii H. Bolus ex Hook and Floribunda rose "Triumph", callus tissues of Daucus carota L. and Chenopodium album L. The new solidifying material has special advantages over agar for application in the rooting phase of in vitro propagation.Abbrevations PMS parenchymatic medium solidifier - MS Murashige and Scoog's medium - IAA Indole-3-acetic acid - B biotin - K kinetin - 2,4-D 2,4-dichlorophenoxyacetic acid - ch caseine hydrolysate     

Isolated microspore culture of maize: effects of isolation technique,reduced temperature,and sucrose level

Improvements in ab initio microspore culture of maize are presented using a modified isolation technique, reduced temperature during early stages of culture, and an elevated sucrose level in the culture medium. Blending-isolation, using excised anthers, was less stressful on microspores than pressing anthers against a stainless steel sieve and resulted in a 3-fold increase in the yield of embryo-like structures (ELS). Exposure to reduced temperature (15°C) during the first 4 days of culture improved microspore viability and increased by 2-fold the number of ELS produced. Higher levels of sucrose (8.0–9.5%) also resulted in improved response. Maximum yield in the present study was 92 ELS per 100 anther equivalents, exceeding previously reported values of 15 ELS per 100 anther equivalents for ab initio microspore culture of maize. The increase in the total number ELS produced had no observable effect on their quality as evidenced by the frequency of formation of callus capable of regenerating plants.     

Foaming and enzyme activity in fungal cultures grown on sugar beet cosette

Summary Enzyme synthesis, foaming behaviour and its effects were studied using two common cellulolytic fungi;Trichoderma reesei andSporotrichum pulverulentum in a medium containing sugar beet cosette as a cellulosic substrate. Cellulase enzyme activities in the culture broth were found to be higher than the enzyme activities in natural and experimentally forced foam layers.     

Use of the disc fermenter to examine production of citric acid by Aspergillus niger

Summary The effects of mode of growth on citric acid production by A. niger were studied using surface culture, shake culture and the disc fermenter. The disc fermenter enabled the effects of medium exchange with biomass retention to be examined.     

Improved efficiency of plant regeneration from protoplasts of eggplant Solanum melongena L.

Eggplant (Solanum melongena L.) mesophyll protoplasts were obtained from in vitro growing plants of line 410 and cv. Classic. Relatively high (15%) plating efficiency was achieved using petri dishes with alternate quadrants containing reservoir medium (R medium + 1% activated charcoal) and culture medium. Shoot regeneration occurred within 6 weeks following initiation of protoplast culture.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan Israel, No. 1164-E, 1984 Series.