Growth of Salvinia molesta as affected by water temperature and nutrition II. Effects of phosphorus level

The growth of Salvinia molesta D.S. Mitchell, as affected by phosphorus supply and water temperature, was studied in a greenhouse using controlled water temperature baths at 16, 19 and 22°C. For significant responses to the phosphorus treatments to be obtained it was found necessary to use P-deficient plant propagules (containing <0.01% P on a dry matter basis). For these plants the highest relative growth rate and dry matter production occurred at 22°C when they received 10.01 mg PO₄P l^?1, but this was not significantly different from that of plants receiving 1.01 mg PO₄-P l^?1. Over a period of 21 days for plants receiving 0.02 mg PO₄ l^?1 the biomass increased 4-fold at 19°C and 6-fold at 22°C. In contrast, for plants receiving 10.01 mg PO₄-P l^?1 biomass was increased 20-fold at 19°C and 32-fold at 22°C. At the latter temperature, when receiving 60.01 mg PO₄-P l^?1, plants concentrated up to 1.3% of phosphorus on a dry matter basis, suggesting a possible use as a biological filter and purifier of contaminated waters.     

Growth of Salvinia molesta as affected by water temperature and nutrition I. Effects of nitrogen level and nitrogen compounds

The growth of Salvinia molesta D.S. Mitchell was studied in a greenhouse using controlled-temperature water-baths at 16, 19 and 22°C and 4 different nitrogen compounds (NO₃^?, NH₄⁺, NH₄NO₃ and urea) at levels up to 60 mg N l^?1. Little growth occurred at 16°C even if 20 mg N l^?1 was supplied together with other nutrients including phosphorus (2 mg H₂PO₄-P l^?1). The highest relative growth rate and total dry matter production occurred at 22°C when plants were supplied with 20 mg NH₄-N l^?1. At this temperature, the NH₄⁺ ion was superior to the NO₃^? ion or urea as a nitrogen source (almost doubling the biomass), but was not significantly better than NH₄NO₃. Over a period of 19 days for plants receiving 0.02 mg NH₄-N l^?, biomass increased 4-fold at 16°C, 9-fold at 19°C and 10-fold at 22°C. In contrast, for plants receiving 20 mg NH₄-N l^?1, biomass increased 4-fold at 16°C, 18-fold at 19°C and 38-fold at 22°C.     

Hydrogen sulphide production by Zymomonas and its elimination in a mutant strain

Strains of Zymomonas mobilis grown in media containing either glucose or sucrose were assessed for the production of hydrogen sulphide (H₂S). In a liquid medium with low glucose concentration (20 g l^?1) only a proportion of the strains tested formed H₂S, but in medium containing a higher glucose concentration (100 g l^?1) all the strains tested produced H₂S. Four Z. mobilis strains were assayed quantitatively for H₂S production and strain ZM4 was found to produce the most H₂S in glucose medium. The amount of yeast extract and glucose, and the type of sugar used in the medium affected the amount of H₂S formed by strain ZM4. A mutant, designated ZM4701, of strain ZM4 was isolated which did not produce any detectable H₂S in liquid medium containing yeast extract plus either glucose or sucrose. The nutritional requirements of ZM4701 were investigated.     

Isolation and identification of a yeast strain capable of degrading four and five ring aromatic hydrocarbons

A yeast strain AEH was isolated from oil contaminated soil and identified by analysis of 18S and 26S ribosomal DNA sequences asPichia anomala. Strain AEH was capable of degrading naphthalene, phenanthrene and chrysene, singly, and benzo(a)pyrene in combination. The yeast degraded 5.36 mg naphthalene l^?1 within 2 days, and 5.04 mg phenanthrene l^?1 and 1.54 mg chrysene 1^?1 within 10 days. When a mixture of the four polycyclic aromatic hydrocarbons (PAHs) was treated at a concentration between 2.98 mg l^?1 and 6.89 mg l^?1, degradation rates were delayed for naphthalene and phenanthrene (3.79 mg l^?1 and, 4.20 mg l^?1 within 10 days, respectively), but enhanced for chrysene and benzo(a)pyrene (3.37 mg l^?1 and, 1.91 mg l^?1 within 10 days, respectively). In a binary system, all of the other 3 PAHs could be utilized as the carbon source for the cometabolic degradation of benzo(a)pyrene with naphthale ne as the best one.     

In Vitro Clonal Propagation of Curcuma caesia Roxb and Curcuma zedoaria Rosc from Rhizome Bud Explants

Two species of Curcuma (C. caesia and C. zedoaria) have been propagated through tissue culture using rhizome bud explant. The best response for shoot multiplication was obtained on MS basal medium supplemented with 4 mg l^?1 BAP and 1.5 mg l^?1 NAA for C. caesia (3.5 ± 0.79 shoots per explant) and 1 mg l^?1 BAP + 0.5 mg l^?1 NAA for C. zedoaria (4.5 ± 0.15 shoots per explant). A maximum of 9.2 ± 0.15 and 8.9 ± 0.09 roots per explant were obtained for C. caesia and C. zedoaria, respectively when MS was supplemented with 0.5 mg l^?1 IAA. The rooted plants could be established in soil.     

Ventilation and oxygen consumption in the hagfish, Myxine glutinosa L.

Ventilation was measured directly in the hagfish, Myxine glutinosa L., by means of an electro-magnetic blood flowmeter. Ventilatory flow and frequency increased from 0.86 ± 0.27 ml·min^?, and 18.2 ± 5.1·min^?, respectively, at 7°C to 1.70 ± 0.20 ml·min^?, and 70.1 ± 9.5·min^? at 15 ·C.Standard oxygen consumption,V?O₂, was measured in non-buried hagfish. V?O₂ was 0.57 ± 0.17μl O₂·g^?1·min^?1 at 7°C, and 0.85 ± 0.12μl O₂·g^?1·min^?1 at 15°C.     

Kinetics and pathway of biodegradation of dibutyl phthalate by Pleurotus ostreatus

Dibutyl phthalate (DBP) is a plasticizer, whose presence in the environment as a pollutant has attained a great deal of attention due to its reported association with endocrine system disturbances on animals. Growth parameters, glucose uptake, percentage of removal efficiency (%E) of DBP, biodegradation constant of DBP (k) and half-life of DBP biodegradation (t_1/2) were evaluated for Pleurotus ostreatus grown on media containing glucose and different concentrations of DBP (0, 500 and 1000 mg l^?1). P. ostreatus degraded 99.6 % and 94 % of 500 and 1000 mg of DBP l^?1 after 312 h and 504 h, respectively. The k was 0.0155 h^?1 and 0.0043 h^?1 for 500 and 1000 mg of DBP l^?1, respectively. t_1/2 was 44.7 h and 161 h for 500 and 1000 mg of DBP l^?1, respectively. Intermediate compounds of biodegraded DBP were identified by GC-MS and a DBP biodegradation pathway was proposed using quantum chemical calculation. DBP might be metabolized to benzene and acetyl acetate, the first would be oxidated to muconic acid and the latter would enter into the Krebs cycle. P. ostreatus has the ability to degrade DBP and utilizes it as source of carbon and energy.     

Fish and nutrient enrichment effects on rotifers in a Mediterranean shallow lake: a mesocosm experiment

A mesocosm experiment was conducted “in situ” in a Chara dominated shallow lake near Valencia (Spain) to study top–down and bottom–up effects on rotifers by means of nutrient and fish additions. Both processes were important in determining rotifer abundance, biomass and diversity. A total of 36 mesocoms were established with triplicate treatment combinations of three fish levels (from no fish to 45 individuals of Gambusia holbrooki males) and four nutrient enrichment levels (from no additions to 10 mg l⁻¹ nitrate-N and 1 mg l⁻¹ phosphate-P). The main effect was a notable increase of planktonic and plant associated rotifers densities with fish. Rotifers benefited from mosquitofish predation on microcrustaceans and chironomids. The results showed a marked negative relationship between rotifer and cyclopoid abundances, indicating the importance of the predatory pressure of cyclopoids on rotifers. Effects on rotifer diversity were also evident, in general rotifer diversity decreased with nutrients and increased with fish. The effects of nutrients analysed at species level showed two contrasting density responses: an increase or a decrease with nutrients, which levelled off at high nutrient concentrations. High-level nutrient additions (from 5 mg l⁻¹ nitrate-N and 0.5 mg l⁻¹ phosphate-P) induced a switch to a turbid state with macrophyte disappearance. Most planktonic rotifer species, as well as plant associated ones, diminished when the turbid state was well established, especially in the mesocosms without fish. In the turbid mesocosms, relative abundance of plant-associated rotifers (as a whole) was higher than that of planktonic rotifers. The changes in rotifer species composition after the switch from a clear to a turbid water state are also described. Species of the genus Anuraeopsis, Trichocerca and Hexarthra, dominant in the clear water state, practically disappeared in the turbid water state, in which Proalides tentaculatus and Lecane nana were the main species. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez Advances in Rotifer Research     

Exogenous application of salicylic acid enhanced the rutin accumulation and influenced the expression patterns of rutin biosynthesis related genes in Fagopyrum tartaricum Gaertn leaves

Except for buckwheat, no cereal or pseudocereal contains any detectable rutin. This study was carried out to compare the rutin content in leaves treated with various concentrations of salicylic acid (SA) (50?mg?l^?1, 100?mg?l^?1, 150?mg?l^?1) for various lengths of time (2?C120?h) to those of untreated F. tartaricum. Rutin content in leaves during the early stages of SA treatment (100?mg?l^?1, 150?mg?l^?1; 24?C48?h) were higher than at other times. The highest rutin content (40.3?mg?gFW^?1) was found in leaves treated with 150?mg?l^?1 SA for 48?h. We cloned partial cDNAs of five genes known to be related to rutin biosynthesis from the leaves of F. tataricum using RACE. These genes were chalcone synthase (FtCHS), flavonol synthase (FtFLS-like), flavone 3-hydroxylase (FtF3H), 4-coumaroyl CoA ligase (Ft4CL), and 4-coumaroyl CoA ligase 2 (Ft4CL2). The protein sequences of these genes were analyzed by similarity searching and phylogenetic trees. Apart from the FtFLS-like gene, which had poor identity with F. esculentum, the other genes showed high similarity to those in F. esculentum. During the early stages of SA treatment (24?C48?h), expression levels of four genes (FtCHS, FtFLS-like, FtF3H, and Ft4CL) were higher than controls but that of Ft4CL2 was not. Most notably, the expression level of FtFLS-like 24?h after application of 150?mg?l^?1 SA was 14.79 times of the control. These results suggest that rutin content can be enhanced to great extent by SA treatment and the gene expression patterns of rutin-biosynthesis-related genes are regulated by SA.     

The distribution and conservation of threatened Sphaeriidae on British grazing marshland

Freshwater sphaeriid bivalves are poorly known ecologically, particularly uncommon species such as Pisidium pseudosphaerium (UK RDB (Red Data Book) staus = ‘rare’). In the UK, this species occupies grazing marsh where conservation opportunities might be shared with other threatened molluscs. We surveyed sphaeriids including P. pseudosphaerium and snails in 106 drainage ditches in SE England in 1999. P. pseudosphaerium occupied over half the ditches surveyed, at slightly elevated BOD (6 ± 7 mg l⁻¹ sd) but reduced calcium (64 ± 31 mg l⁻¹) and nitrate (0.5 ± 1.2 mg l⁻¹). As part of a sphaeriid assemblage comprising Sphaerium corneum, Musculium lacustre and Pisidium obtusale (=Assemblage 1), P. pseudosphaerium occurred in ditches with floating vegetation and abundant snails of conservation importance, co-occurring significantly with either Valvata macrostoma (RDB ‘vulnerable’) or Anisus vorticulus (RDB: ‘vulnerable’). A more diverse sphaeriid assemblage (=Assemblage 2) included species common in wider, deeper ditches with open water. We suggest that traditional ditch management can support both rare and representative snails and bivalves on grazing marsh. Quasi-traditional and rotational ditch clearance will favour common sphaeriids and pioneer snails during early succession; P. pseudosphaerium, V. macrostoma, A. vorticulus during mid-succession; and the snail Segmentina nitida (RDB: ‘Endangered’) in late successional ditches. In common with threatened snails, P. pseudosphaerium will also benefit from reduced eutrophication. We recommend that P. pseudosphaerium retain RDB status to ensure protection and to emphasise the need for improved ecological information.     

Effects of mineral composition and acidity of media,saccharose level,brand and quantity of agar on rooting of fruit rootstocksin vitro

The influence of the mineral composition and acidity of media, saccharose level, brand and quantity of agar onin vitro shoot rooting of P 60 and P 2 apple and quince S 1 root-stocks were compared. Among the tested salt compositions (full WMP and 1/2 WMP, full MS and 1/2 MS) the most suitable for rooting was composition of WMP. Further modifications in quantity of nitrogen, H₃BO₃ CaCl₂ and MgSO₄ of WMP medium did not have a positive effect on rooting. 30 g l^?1 saccharose gave better results than 20 g l^?1. Acidity of WMP medium tested in a pH range of 4.0 to 6.5 did not affect rooting of P 60 rootstock but media adjusted to pH 4.5 and 5.0 were better for rooting of recalcitrant P 2 rootstock. Among 4 agar brands (Difco Bacto, Oxoid No.1, Japanese commercial fibre and Japanese commercial powder) tested at 6 g l^?1, the most effective was the last one, but its quantity had no effect in the range of 3 to 10 g l^?1 for rooting of P 60 rootstock.     

In Vitro Regeneration of Achillea millefolium L from Shoot-tips and Root Segments of Seedlings

This report describes, for the first time, an efficient plant regeneration system for Achillea millefolium L (yarrow), a medicinal plant, via shoot multiplication from shoot-tips and adventitious shoot regeneration from root segments. Higher numbers of shoots were obtained when shoot-tips were cultured on MSMO medium supplemented with 3.0 mg l^?1 BA and 0.5 mg l^?1 IAA, or 5.0 mg l^?1 KIN and 1.0 mg l^?1 IBA, producing 17.3 and 17.0 shoots per explant at 100% frequency, respectively. For adventitous shoot regeneration, only root segments developed shoots when cultured on medium containing a combination of 1 mg l^?1 TDZ, 0.5 mg l^?1 IAA and 0.5 mg l^?1 GA3 (18.9 shoots per explant at 100% frequency), while other types of explants (i.e., cotyledons, leaf lamina and petiole segments) or hormonal combinations tested were found ineffective. Regenerated shoots rooted readily on MSMO medium containing different concentrations of IAA, IBA, NAA or 2,4-D, however, NAA at 0.5 mg l^?1, or IBA at 0.5 or 1.0 mg l^?1 were found to be the most productive. Nearly all of the regenerated plants (98%) survived through the hardening process when the rooted plantlets were kept at 55–65% relative humidity for 2 weeks, which were then planted in pots containing potting soil and kept at 25–35% humidity.     

Clonal Propagation and Production of Genetically Uniform Regenerants from Axillary Meristems of Adult Bamboo

The axillary bud-break and multiple bud induction were obtained from the nodal explants of field-grown culms of Bambusa tulda in liquid Murashige and Skoog’s (MS) basal medium supplemented with 2.0 mg l^?1 6-benzylaminopurine (BAP), 1.0 mg l^?1 kinetin (Kn) and 8% coconut water. Multiple shoots regenerated and proliferated in the liquid MS medium fortified with 3.0 mg l^?1 indolebutyric acid (IBA). While, in B. balcooa, MS medium supplemented with 2.5 mg l^?1 BAP and 1.0 mg l^?1 Kn induced axillary bud-break, bud multiplication and subsequently shoot elongation was obtained after three passages in the same medium. A clump with at least three shoots of both these bamboo species was used as propagule for successful root induction in half-strength MS liquid basal medium supplemented with 0.2 mg l^?1 IBA. Sympodial type of microrhizomes developed in B. tulda and the regenerants acclimatized in the soil easily. Explants collected in the month of October produced best in vitro regeneration response in these two bamboo species. Endogenous phenol content proved detrimental for efficient shoot regeneration. The clonal fidelity of the regenerants was established by RAPD analysis advocating clonal propagation through axillary meristem culture of B. balcooa and B. tulda is reliable for commercial exploitation.     

Competition between Salvinia minima and Spirodela polyrhiza mediated by nutrient levels and herbivory

We investigated the effects of initial biomass, nutrients, herbivory, and competition with Spirodela polyrhiza (L.) Schleid on Salvinia minima Baker biomass and density. S. minima populations were subjected to two levels of herbivory (control vs. two adults per plant) from the weevil Cyrtobagous salviniae Calder and Sands and eight levels of competition from S. polyrhiza, while growing in high (5 mg N l⁻¹) or low (0.5 mg N l⁻¹) nutrient conditions. Herbivory was the most important factor in S. minima biomass production while competition or fertility had no measurable impact. In contrast, S. polyrhiza biomass was mediated primarily by nutrients, not competition. There was no herbivory treatment for this plant. S. polyrhiza was superior to S. minima at converting nutrients to biomass but this did not give it a competitive advantage since S. minima biomass was unchanged when herbivory was absent. S. minima can generally overtop S. polyrhiza which, in turn, can form multiple layers within its mat. These characteristics may act to lessen competition between these species, thereby permitting their habitat sharing.     

Recovery of avocado (<Emphasis Type="Italic">Persea americana</Emphasis> Mill.) plants transformed with the antifungal plant defensin gene PDF1.2

Embryogenic avocado cultures derived from ‘Hass’ protoplasts were genetically transformed with the plant defensin gene (pdf1.2) driven by the CaMV 35S promoter in pGPTV with uidA as a reporter gene and bar, the gene for resistance to phosphinothricin, the active ingredient of the herbicide Finale® (Basta) (Bayer Environmental Science, Research Triangle Park, Durham, NC ). Transformation was mediated by Agrobacterium tumefaciens strain EHA105. Transformed cultures were selected in the presence of 3.0 mg l^?1 phosphinothricin in liquid maintenance medium for 3–4 mo. Liquid maintenance medium consisted of modified MS medium containing (per liter) 12 mg NH₄NO₃ and 30.3 mg KNO₃ and supplemented with 0.1 mg l^?1 thiamine HCl, 100 mg l^?1 myo-inositol, 30 g l^?1 sucrose, 3.0 mg l^?1 phosphinothricin, and 0.41 μM picloram. Somatic embryo development from transformed cultures was initiated on MS medium supplemented with 45 g l^?1 sucrose, 4 mg l^?1 thiamine HCl, 100 mg l^?1 myo-inositol, 10% (v/v) filter-sterilized coconut water, 3.0 mg l^?1 phosphinothricin, and 6.0 g l^?1 gellan gum. Limited plant recovery occurred from somatic embryos on semi-solid MS medium supplemented with 3.0 mg l^?1 phosphinothricin, 4.44 μM 6-benzylaminopurine (BA), and 2.89 μM GA₃; transformed shoots were micrografted on in vitro-grown seedling rootstocks. Approximately 1 yr after acclimatization in the greenhouse, transformed shoots were air-layered to recover transformed roots. Genetic transformation of embryogenic cultures, somatic embryos, and regenerated plants was confirmed by polymerase chain reaction (PCR), Southern blot hybridization, the XGLUC reaction for uidA, and application of the herbicide Finale® to regenerated plants.     

Enhanced volatile phenols in wine fermented with Saccharomyces cerevisiae and spoiled with Pichia guilliermondii and Dekkera bruxellensis

Aims: To investigate whether the presence of Pichia guilliermondii impacts on the production of volatile phenols from mixed wine fermentations with Dekkera bruxellensis and Saccharomyces cerevisiae. Methods and Results: Four inoculation strategies were performed in small‐scale fermentations involving P. guilliermondii, D. bruxellensis and S. cerevisiae using Syrah grape juice supplemented with 100 mg l^?1 of p‐coumaric acid. High pressure liquid chromatography was used for the quantification or volatile phenols. Significant high levels of 4‐ethylphenol and 4‐ethylguaicol (720 and 545 μg l^?1, respectively), as well as the highest levels of 4‐vinylphenol (>4500 μg l^?1), were observed when P. guilliermondii species was inoculated from the beginning of the fermentation. Conclusions: The metabolic interaction occurring between the high vinylphenol producer species P. guilliermondii and D. bruxellensis exhibiting a high vinylphenol reductase activity resulted in an increased production of volatile phenols in wine. Significance and Impact of the Study: Pichia guilliermondii must be considered a very important spoilage yeast in the wine industry capable of producing large amounts of volatile phenols.     

Micropropagation of Withania coagulans (Stocks) Dunal: A Critically Endangered Medicinal Herb

An efficient micropropagation protocol has been developed for Withania coagulans, a highly endangered medicinal herb and an important natural source of withanolides. Prolific multiplication of axillary buds occurred from the nodal segments taken from adult plant, and cultured on MS medium enriched with BA (0.5 mg l^?1), Kn (0.5 mg l^?1) and PG (0.5 mg l^?1). Nodal segments and shoot tips of elongated microshoots also behaved the same way in cultures and formed multiple shoots through axillary bud multiplication. Addition of PG (0.5 mg l^?1) in the regeneration medium significantly improved induction and elongation of shoot buds. Elongated shoots were placed on filter paper bridges soaked in MS medium with CC (10 mg l^?1) and PG (0.5 mg l^?1) for the initial 7 days’ pulse treatment and thereafter, they were transferred to rooting medium containing IBA (0.25 mg l^?1) + PAA (0.5 mg l^?1) + CC (2 mg l^?1). This protocol has the capacity of producing 1000 plants from one nodal segment after 4 subcultures of 2 weeks each.     

Biomass and terpenoids produced by mutant strains of <Emphasis Type="Italic">Arthrospira</Emphasis> under low temperature and light conditions

The filamentous Cyanobacterium Arthrospira is commercially produced and is a functional, high-value, health food. We identified 5 low temperature and low light intensity tolerant strains of Arthrospira sp. (GMPA1, GMPA7, GMPB1, GMPC1, and GMPC3) using ethyl methanesulfonate mutagenesis and low temperature screening. The 5 Arthrospira strains grew rapidly below 14?°C, 43.75 μmol photons m^?2 s^?1 and performed breed conservation at 2.5?°C, 8.75 μmol photons m^?2 s^?1. We used morphological identification and molecular genetic analysis to identify GMPA1, GMPA7, GMPB1 and GMPC1 as Arthrospira platensis, while GMPC3 was identified as Arthrospira maxima. Growth at different culture temperatures was determined at regular intervals using dry biomass. At 16?°C and 43.75 μmol photons m^?2 s^?1, the maximum dry biomass production and the mean dry biomass productivity of GMPA1, GMPB1, and GMPC1 were 2057?±?80 mg l^?1, 68.7?±?2.5 mg l^?1 day^?1, 1839?±?44 mg l^?1, 60.6?±?1.8 mg l^?1 day^?1, and 2113?±?64 mg l^?1, 77.7?±?2.5 mg l^?1 day^?1 respectively. GMPB1 was chosen for additional low temperature tolerance studies and growth temperature preference. In winter, GMPB1 grew well at mean temperatures <10?°C, achieving 3258 mg dry biomass from a starting 68 mg. In summer, GMPB1 grew rapidly at mean temperatures more than 28?°C, achieving 1140 mg l^?1 dry biomass from a starting 240 mg. Phytonutrient analysis of GMPB1 showed high levels of C-phycocyanin and carotenoids. Arthrospira metabolism relates to terpenoids, and the methyl-d-erythritol 4-phosphate pathway is the only terpenoid biosynthetic pathway in Cyanobacteria. The 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) gene from GMPB1 was cloned and phylogenetic analysis showed that GMPB1 is closest to the Cyanobacterium Oscillatoria nigro-viridis PCC711. Low temperature tolerant Arthrospira strains could broaden the areas suitable for cultivation, extend the seasonal cultivation time, and lower production costs.     

Acetaldehyde kinetics of enological yeast during alcoholic fermentation in grape must

Acetaldehyde strongly binds to the wine preservative SO₂ and, on average, causes 50–70 mg l^?1 of bound SO₂ in red and white wines, respectively. Therefore, a reduction of bound and total SO₂ concentrations necessitates knowledge of the factors that affect final acetaldehyde concentrations in wines. This study provides a comprehensive analysis of the acetaldehyde production and degradation kinetics of 26 yeast strains of oenological relevance during alcoholic fermentation in must under controlled anaerobic conditions. Saccharomyces cerevisiae and non-Saccharomyces strains displayed similar metabolic kinetics where acetaldehyde reached an initial peak value at the beginning of fermentations followed by partial reutilization. Quantitatively, the range of values obtained for non-Saccharomyces strains greatly exceeded the variability among the S. cerevisiae strains tested. Non-Saccharomyces strains of the species C. vini, H. anomala, H. uvarum, and M. pulcherrima led to low acetaldehyde residues (<10 mg l^?1), while C. stellata, Z. bailii, and, especially, a S. pombe strain led to large residues (24–48 mg l^?1). Acetaldehyde residues in S. cerevisiae cultures were intermediate and less dispersed (14–34 mg l^?1). Addition of SO₂ to Chardonnay must triggered significant increases in acetaldehyde formation and residual acetaldehyde. On average, 0.33 mg of residual acetaldehyde remained per mg of SO₂ added to must, corresponding to an increase of 0.47 mg of bound SO₂ per mg of SO₂ added. This research demonstrates that certain non-Saccharomyces strains display acetaldehyde kinetics that would be suitable to reduce residual acetaldehyde, and hence, bound-SO₂ levels in grape wines. The acetaldehyde formation potential may be included as strain selection argument in view of reducing preservative SO₂ concentrations.     

Coidingham Loch, S.E. Scotland

SUMMARY. 1. Coidingham Loch (Berwickshire. Scotland) (area. 8.4 ha, mean depth 2.9 m, max. depth 12.3 m) belongs to Hakansson's convex shape category. It lies in a basin of Silurian Greywackes rock within 0.25 km of coastal sea cliffs (c. 133 m a.s.l.). The theoretical hydraulic replacement time is 3.17 years. 2. The loch stratifies intermittently in summer. Fluctuations in oxygen concentration generally correspond to spells of mixing and stratification; low values of 10% saturation occur at the bottom. 3. The sum of the concentrations of major cations (Na+, K+, Ca²⁺, Mg²⁺) is in accordance with measured conductivities ranging between 380 μS cm^?1 and 420 μS cm^?1 (k.₂₅). The ratios (by equivalents) of Na⁺/Cl^? (0.04) are similar to those in sea-water, whilst values for Ca+²⁺/Cl^? (0.85–1.01) and Mg²⁺/Cl^? (0.79–0.88) reflect the bedrock. 4. Nitrate concentrations were lowest (<0.05 mg N1^?1) in summer following losses from the column of 107 mg N m^?2 1^?1, a rate corresponding well with published figures on microbial nitrate reduction. Nitrate increased at a rate of 8μg N I^?1 d^?1 to a winter maximum of 1.55 mg N I^?1. Mass balance calculations show that if this rise is attributed to run-off from surrounding land, a loss rate of 11.1 kg N ha^?1 yr^?1 would be required; this value is also commensurate with published figures. 5. Changes in phosphorus and factors controlling them contrast markedly with those of nitrate. The minimum concentration of 55 μg total P l^?1 (mainly in soluble reactive form) occurs in spring. An increase to the maximum ofc. 300 μg l^?1 in summer is sustained mainly by release from the sediments at a regular rate of 3 μg P l^?1 d^?1 (8.7 mg m^?2 d^?1). Adsorption by the sediments is considered to be the major process accounting for autumnal losses of phosphorus of 2.6 mg P M^?2d^?1. 6. Silica showed a less regular seasonal pattern, but varied some 45-fold with a maximum of 2.25 mg SiO₂, l_?1 in August.