Biomass estimation in solid state fermentation II. On-line measurements

Summary Two methods for on-line biomass measurement were tested with success: (a) infrared (IR) estimation of cell components (glucosamine and ergosterol) and medium residues (sucrose and nitrogen) directly on solid medium; (b) the CO₂ evolution rate during cultivation. These methods were very satisfactory for following biomass changes during a defined process. The IR measurements correlated well with manual methods. The correlation between CO₂ and glucosamine measurements was very satisfactory with good precision. However, they did not permit comparison between processes.Offprint requests to: C. Desgranges     

On the nitrogen and phosphorus removal in algal photobioreactors

This study shows results of nitrogen and phosphorus removal by microalgae (tertiary treatment) in a prototype of tubular photobioreactor tested under controlled and uncontrolled conditions. The wastewater was the supernatant coming from a secondary settler of a municipal wastewater activated sludge treatment plant without nitrification and denitrification units. The algal biomass was directly selected from the supernatant and it was principally composed of genus Scenedesmus (autochthonous algae). All the experiments evaluated both nitrogen and phosphorus removal and biomass and lipid production. A satisfactory nutrients removal - about 99.9% for the nitrogen and phosphorus - and a specific biomass productivity of 0.25 g/l d have been obtained in the indoor photobioreactor; less satisfactory results have been reached in the outdoor photobioreactor because of ambient condition instability and limiting nutrients concentration.     

Pigment recovery from encapsulated-dehydrated Vaccinium pahalae (ohelo) cryopreserved cells

Pigment producing in vitro cells of Vaccinium pahalae (ohelo) were tested for their ability to survive cryopreservation and retain pigment-production capacity after encapsulation-dehydration. Preculture of cells for 6 to 8 days in a medium containing 1.0 M sucrose was essential before dehydration. Reduction of bead water content before quenching in liquid nitrogen was highly correlated (r = 0.94) with increased survival rate in cells after cryopreservation. Dehydration of beads for 4 h was satisfactory for survival of cells. After quenching in liquid nitrogen, colored cells became pale, but pigment content was recovered once cells resumed growth. After three subcultures, cells regained their maximum capacity for pigment accumulation. The percentage of colored-to-total cell volume was not influenced by cryopreservation. Encapsulation-dehydration and cryopreservation did not diminish the capacity of cells to produce anthocyanins and other flavonoids. This revised version was published online in June 2006 with corrections to the Cover Date.     

Protein nutrition in the alligator

1. Fourteen different protein-containing diets were fed to small alligators. Their rates of digestion and their nutritional values were determined by following changes in free amino acids in the plasma. 2. Fish, chicken and nutria were digested rapidly and all their component essential amino acids disappeared quickly and at the same rate. When given in the dry, fat-free form the amino acids were released and assimilated about 50% faster than when fat was included. 3. None of the isolated proteins tested (casein, gelatin, edestin, gliadin, corn gluten and soy) proved nutritionally adequate and all but gelatin digested slowly and incompletely. 4. One diet compounded of salts, vitamins and mixed commercial animal products was tested. It showed promise but it was lacking in methionine and isoleucine. 5. It was concluded that dry, powdered, preparations from whole animals could prove a satisfactory, stable diet for alligator husbandry. 6. Prolonged force-feeding of an animal diet increased the percent of nitrogen excreted as NH3 over that excreted in urates.     

Serum-free liquid medium forNeisseria gonorrhoeae

A liquid culture medium (GB) forNeisseria gonorrhoeae is described. Except hemin, the GB medium does not contain blood products. Liver digest, proteose peptone and Yeastolate were used as the main carbon/nitrogen sources. The medium permitted growth, with a satisfactory cell yield, of all but one of the 68 gonococcal strains tested. Cysteine-hydrochloride was used to achieve an adequate redox-potential of the medium. The optimal pH of the ready-to-use medium was found to be 7.4. Comparative culture studies showed that the GB medium has advantages compared to earlier recommended broth media for the growth of gonococci in the percentage of consecutive gonococcal strains isolated from clinical specimens that grew in the medium. The addition of 1.4% purified agar permitted the use of the medium as a transparent solid medium for the culture of gonococci. The possibility to make the GB medium selective for gonococci by addition of trimethoprim, polymyxin B and E, and natamycin was also evaluated. In this respect, vancomycin-colistin-nystatin and mycostatin were also tested. The GB medium is inexpensive and easy to prepare.     

Production of aflatoxins B1 and G1 in chemically defined medium

Summary Aflatoxins B₁ and G₁ were produced in a chemically defined liquid medium in stationary culture. Glucose, sucrose, and fructose were satisfactory carbon sources. Organic nitrogen compounds were essential for production of high levels of aflatoxins. Complex nitrogen sources, such as yeast extract and peptone, gave higher yields than single amino acids. Aspartate, glycine, glutamine, and glutamate were good sources of nitrogen for toxin production. Little or no aflatoxin was produced when zinc, iron, or magnesium were omitted from the medium. Manganese appeared to reduce yields of aflatoxin.     

Long-term viability of preserved eukaryotic algae

Levels of viability of Chlorella emersonii after storage of dried material for one year were 0.1% on rehydration, all other dried organisms examined in this study failed to recover after prolonged storage. In addition, no detectable recovery was observed in any of the algae tested after storage of freeze-dried cultures. Methods have also been developed to cryopreserve a range of microalgae, but no single protocol has been found to be universally satisfactory. Some strains are apparently not able to withstand cryopreservation using known methods, whilst others may be frozen successfully in the absence of cryoprotectant by plunging directly into liquid nitrogen. A two-step protocol (cooling to an intermediate subzero temperature prior to plunging into liquid nitrogen) has been used to cryopreserve the majority of strains. Where this has proven successful, post-thaw viability levels of over 95% have been attained for some algae. This paper demonstrates that, where applicable, cryopreservation allows the long-term preservation of frozen algae with no significant reduction in viability up to 22 years storage. (Previous location of Culture Collection of Algae and Protozoa) This revised version was published online in September 2006 with corrections to the Cover Date.     

Experiments on nitrogen fixation by nodulated lucerne

Summary Field experiments at five sites (two on clay loam, two on a sandy soil and one on chalky loam) compared dry-matter yields and nitrogen contents of lucerne and ryegrass. These tested Rhizobium inoculation and fertilizer treatments in an experimental design proposed by Vincent and Nutman (IBP 69(66), amended 57/68). The crop and inoculation treatments (using large inocula of effective or ineffective strains) were set out in strips across each site to minimise contamination, and the fertilizer treatments (nitrogen, limeetc.) distributed at random within strips. This proved satisfactory and allowed valid statistical analysis. The massive inoculation with the ineffective strain suppressed the few naturally occurring effectiveR. meliloti at some of the sites, and provided a basis of comparison for assessing the amounts of nitrogen fixed by the native strains and by the introduced effective strains. However, it did so only during the first year because the introduced ineffective strains were overgrown by effective strains in the second year. Hence, ryegrass without nitrogen fertilizer was a better measure of the amounts of nitrogen obtainable from the soil. Estimates of fixation ranged from 0 to more than 300 kg N ha⁻¹ at the different sites, treatment comparisons indicating the main factors limiting fixation. Parallel experiments were done using a soil core technique described by Vincent. These gave very similar results to the field trials in their first years. Studies of the changes in the populations ofR. meliloti in the field trial plots and soil cores gave information on the effects of crop and fertilizers on numbers and effectiveness of isolates and was useful in interpreting the results.     

不同小麦品种氮效率和产量性状的研究

对29个冬小麦品种进行子粒产量和氮效率的研究,结果表明,在氮胁迫条件下,供试小麦品种的子粒产量具有明显差异。缺氮条件下子粒产量的聚类分析结果表明,供试品种可划分为氮高效、中效和低效三类,氮高效品种在其中所占比例较少。在缺氮条件（N-）下,不同氮效率品种成熟期植株全氮含量差异不大,植株氮素积累量、氮效率（NUE）、吸收效率（UPE）和利用效率（UTE）均以氮高效品种最高,中效品种次之,低效品种最低。缺氮条件下较强的氮索吸收和利用能力是氮高效小麦品种氮胁迫条件下高氮效率的主要原因。     

The utilization of organic nitrogen compounds as sole nitrogen source by some freshwater phytoplankters

Seven organic compounds containing nitrogen were tested as potential sources of nitrogen for five different species of freshwater algae. The chlorococcal green algae Selenastrum and Ankistrodesmus were the most versatile with regard to nitrogen sources; the diatom Cyclotella also grew well upon some organic nitrogen compounds. The desmid Arthrodesmus grew fast only on urea, while Cryptomonas did not grow well upon any of the organic compounds tested.
More information is needed before the potential importance of organic nitrogen sources for freshwater phytoplankton can be assessed.     

Bifunctional reagents as vapour- and liquid-phase fixatives for immunohistochemistry

Synopsis Out of a total of eleven bifunctional reagents tested as fixatives for light microscopic immunohistochemistry, four were found satisfactory when applied in the vapour phase to freeze-dried blocks. These were diethylpyrocarbonate, as observed in carlier studies, dimethyladipimidate,p-benzoquinone, and diacetyl. Adequate but less satisfactory liquid-phase fixation was provided by three reagents (dimethyladipimidate, dimethylsuberimidate,p-benzoquinone).None of the eleven reagents gave optimal preservation of antigenicity and structure when tested at the ultrastructural level. Encouraging results were obtained withp-benzoquinone, however.     

Intensifying Clean Energy Production Through Cultivating Mixotrophic Microalgae from Digestates of Biogas Systems: Effects of Light Intensity,Medium Dilution,and Cultivating Time

High-strength wastewaters after being digested for biogas production in anaerobic digesters still contain substantial nutrients and organics. The anaerobic digestates from four major industries in Thailand were tested with batch cultivation of Chlorella sp. for oil production potentials. Pig farm digestate was found most suitable as the growth medium generating 0.95 g/L_medium (dry biomass), which was 1.16–3.06 times of other digestates tested. Considerable removals of nitrogen and phosphorus achieved were an added benefit to the goal of ultimate treatment of these wastewaters. Light intensity had strong influence on growth and heterotrophic metabolism up to 78 μmol/m²/s, while the dilution of digestate above 2.4× diminished growth potential and lipid production. A quadratic regression model was constructed to describe interaction of light intensity, dilution factor, and time of cultivation to lipid production with a satisfactory precision. Light intensity could influence fatty acid composition, although palmitic acid was found predominant at 47.1 %. The algae oil generated could potentially increase the total energy output from anaerobic digesters of a typical pig farm by 22 %.     

Effects of varied nitrogen stress on growth and nutrition in three Salix clones

The ability of Salix aquatica Smith, S. fragilis L. and S. viminalis L. to absorb nitrogen at varied growth rates was investigated in nutrient solutions. The effects of five nitrogen addition rates on growth rates, nitrogen contents of the plants, nitrogen concentration of the media, and dry matter distribution between roots, stems and leaves, were studied.
These clones are highly efficient in absorbing nitrogen at low concentrations in the root medium, independent of growth rate. Strong linear regressions were found between any two of the three factors: relative rate of nitrogen supply (R_N), nitrogen content (plant), and relative growth rate (R). Dry matter production per unit nitrogen taken up and unit time (N-productivity) and per unit nitrogen taken up independent of time (N-efficiency) was closely correlated to the nitrogen status of the plant. Root development was favoured in the sub-optimum treatments, and leaf development in the optimum treatments. With regard to their ability to absorb nitrogen, these Salix clones appear satisfactory for efficient short rotation energy forestry.     

A novel chemiluminescence sensor for the determination of indomethacin based on sulfur and nitrogen co‐doped carbon quantum dot–KMnO4 reaction

We report on a simple and sensitive sulfur and nitrogen co‐doped carbon quantum dot (S,N‐CQD)‐based chemiluminescence (CL) sensor for the determination of indomethacin. S,N‐CQDs were prepared by a hydrothermal method and characterized by fluorescence spectra, Fourier transform infrared spectroscopy and transmission electron microscopy. To obtain the best CL system for determination of indomethacin, the reaction of S,N‐CQDs with some common oxidants was studied. Among the tested systems, the S,N‐CQD–KMnO₄ reaction showed the highest sensitivity for the detection of indomethacin. Under optimum conditions, the calibration plot was linear over a concentration range of 0.1–1.5 mg L^?1, with a limit of detection (3σ) of 65 μg L^?1. The method was applied to the determination of indomethacin in environmental and biological samples with satisfactory results.     

新鲜土壤样品储存温度和时间对不同形态氮素的影响

土壤氮素形态及含量具有重要的生态学研究意义,而土壤样品的储存对土壤氮素含量的准确测定有很大影响.为了选择合理的土壤样品储存方法,本研究以福建省建瓯市万木林保护区罗浮栲林土壤为研究对象,测定在不同温度(25、4和-20 ℃)、不同储存时间(0、7和30 d)下土壤铵态氮、硝态氮、总氮、可溶性有机氮、氨基酸氮含量和微生物生物量氮,以及冷冻后常温培养过程中的氮素含量.结果表明: 在7 d的储存时间内,除氨基酸氮以外,常温培养样品下其余的氮素含量均有所增加;与新鲜样品相比,冷藏、冷冻样品的所有氮素含量之间均无显著性差异,且氮素含量变化较常温培养下更加稳定.因低温储存样品有刺激氮矿化的效果,在30 d储存时间内,与新鲜样品相比,除可溶性有机氮外,冷藏、冷冻样品的所有氮素含量均显著升高;两种冷储存方法之间无显著差异.因此,新鲜样品带回实验室后应及时处理;如需要冷储藏,时间不要超过半个月.如果需要较长的储存时间,则需将样品放置于更低的温度(-40或-80 ℃).在对储存土壤样品进行培养试验之前,需要进行预培养处理.在预培养过程中,除硝态氮含量呈现先下降再迅速升高的趋势外,其余氮素均随着培养时间逐渐趋近于新鲜土壤样品含量,在培养一周左右恢复到与新鲜土壤样品氮含量最为接近的状态.结合已有研究,对野外取样和风干样品需要5～14 d的预培养,冷储存样品预培养时间不应少于一周.     

Selective media for three biovars of Agrobacterium

Three selective media for the isolation of the three known biovars of Agrobacterium are described. Selectivity was based on carbon and nitrogen sources; L(—)-arabitol for biovar 1, erythritol for biovar 2 and a combination of tartrate and D-glutamate for biovar 3. The new media were compared with existing selective media. Recovery of agrobacteria from soil was very efficient and discrimination between the three biovars was satisfactory except for tartrate-utilising biovar 1 isolates which grew on the biovar 3 medium. Some strains of Pseudomonas sp. isolated from crown galls on vine could utilise octopine as a source of carbon and nitrogen.     

Evaluation of marking and tagging methods for genetic studies in carp

A variety of marking and tagging methods were tested on common carp (Cyprinus carpio L.) with the aim of identifying suitable methods for genetic studies in this and other species of carp. Elastomer and Alcian blue dye marking; Cold and Silver nitrate branding; Floy, Fingerling, Carlin disc and visible implant tags; and fin clipping were all tested on a range of sizes of common carp (from mean weights of 10–25 g up to 600–800 g). The branding and tagging methods tested did not give satisfactory retention rates. A combination of elastomer marking and fin clipping was then tested as a method for strain identification in a growth comparison trial on catla (Catla catla Hamilton) and found to be satisfactory for this purpose. Passive integrated transponders (PIT) tags were used to individually identify catla of wild or hatchery origin being grown for use as broodstock. These had almost 100% (98.8%) retention rates, but are expensive compared to most other tagging methods.     

How can miscanthus fields be reintegrated into a crop rotation?

The bioeconomy, with its aim of replacing fossil by biobased resources, is increasingly focusing on biomass production from perennial crops, such as miscanthus. To date, research on miscanthus has explored a number of cultivation aspects; however, one major issue has not yet been addressed: How can former miscanthus fields be reintegrated into a crop rotation? This encompasses the questions of which following crop most efficiently suppresses resprouting miscanthus and what happens to the soil nitrogen content after a miscanthus removal. This study aimed to answer both questions. For this purpose, four spring crops (ryegrass, rapeseed, barley, maize) and fallow as control were cultivated after a Miscanthus sinensis removal. To test the effect of the removal on soil nitrogen content, each spring crop (excluding fallow) was divided into fertilized and unfertilized plots. After the spring crop harvest, winter wheat was cultivated to clarify which spring crop had most efficiently suppressed the resprouting miscanthus. The results indicate that fertilized crops had 35% less miscanthus biomass per hectare than unfertilized crops, probably due to the higher plant density and/or better development of the fertilized crops during the growing season. The soil mineral nitrogen (N_min) content was found to increase during the vegetation period following the miscanthus removal (average +14.85 kg/ha), but was generally on a low level. We conclude that nitrogen from miscanthus residues is partly fixed in organic matter and is thus not plant‐available in the first cropping season. As some nitrogen is supplied by the decomposition of miscanthus residues, our results suggest that the crop cultivated after a miscanthus removal requires less fertilization. Of all the follow‐on spring crops tested, maize coped with the prevailing soil conditions and resprouting miscanthus most efficiently, resulting in satisfactory yields, and thus seems to be a suitable crop for cultivation after miscanthus.     

Kinetics of the inhibition by naphtholsulfonate compounds of AMP deaminase from chicken erythrocytes

The effect of a variety of naphthalene sulfonate compounds on the chicken erythrocyte AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) reaction was analyzed kinetically. Of the naphthalene sulfonate derivatives tested, the compounds with hydroxyl, sulfonate and nitrogen groups such as amino, anilino or azo groups showed an inhibitory effect. The cooperative effect of AMP, analyzed in terms of Hill coefficient, was increased from about 2 to 4 and the maximal velocity was unchanged with the addition of these compounds, suggesting the ligands as an allosteric inhibitor of the enzyme. The inhibition of AMP deaminase by naphtholsulfonate compounds can be qualitatively and quantitatively accounted for by the Monod-Wyman-Changeux model. Theoretical curves yield a satisfactory fit of all experimental saturation and inhibition curves, assuming four binding sites for AMP and the inhibitor, and various KT(I) values. The structure-activity analysis of the interaction of the naphtholsulfonate compounds with AMP deaminase has demonstrated that the affinity of the enzyme for naphtholsulfonates as the inhibitors is correlated with electronic properties of the nitrogen atoms attached to naphthalene moiety: the delocalization of lone electron pair on nitrogen through naphtholsulfonate group makes the compound less basic, resulting in more tight binding of the ligand to the enzyme. Introduction of hydrophobic group to naphtholsulfonate moiety increases the binding affinity for the enzyme, and of the inhibition. These results suggest the location of hydrophobic regions as the allosteric inhibitory sites of the enzyme for the binding of naphtholsulfonate compounds.