Estimation of transport distance of fine particulate organic matter in relation to channel morphology in tailwaters of the Lake Biwa and reservoir dams

Knowledge on transport and deposition of fine particulate organic matter (FPOM) from reservoir dams is increasingly required for habitat management and restoration of dam tailwater ecosystems. Variations in the transport distance of FPOM, however, have never been studied well, particularly in relation to channel morphology, due to channel size restrictions of artificial tracers such as corn pollen when applied to larger river channels. This study aims to show the relations between FPOM retention efficiency and channel morphology in dam tailwaters using lentic plankters as tracers. We estimated the mean transport distance, S _p, by calculating downstream reduction ratios of lentic tracer plankters and calculated the deposition velocity, v _dep. Suspended FPOM samples were collected in tailwaters of two river channels below reservoir dams and two artificial canals below Lake Biwa in the Yodo River system. The longest S _p (19.2 km) and the shortest one (2.2 km) were recorded in the deep canal and shallow canal, respectively, showing a positive correlation with channel hydraulic radius. The values of v _dep were 4.7–6.4 times higher in river channels than in artificial canals. These results indicate that increasing complexity of bed morphology can minimize S _p, whereas bed degradation and armored bed materials may lead to increased S _p. Advantages of lentic plankters as tracers for estimating distance ranges of reservoir dam impact on river ecosystems are also discussed.     

Patterning of impoundment impact on chironomid assemblages and their environment with use of the self-organizing map (SOM)

The paper assesses the impact of the Jeziorsko dam reservoir on chironomid assemblages and selected environmental factors in the Warta River, Poland, by means of patterns recognized with the self-organizing map (SOM, Kohonen unsupervised artificial neural network). Over 1988–1996, in four annual cycles, a total of 233 monthly samples were collected in a seven order section of the river at two sites: WAA (backwater) located about 2 km upstream from the Jeziorsko Reservoir, and WAB (tailwater) located about 1.5 km downstream from the reservoir's dam. At each site three habitats were selected: H₁, H₂ and H₃ at WAA, and H₁₁, H₁₂ and H₁₃ at WAB. H₁ and H₁₁ were located in the depositional area close to the banks, H₂ and H₁₂ about 6–7 m towards the mid-river and H₃ and H₁₃ in the mid-river. SOM effectively vertically separated H₁ and H₁₁ (bank habitats) from H₃ and H₁₃ (the mid-river zone of both sites) and H₂ (the transition zone of the upstream site). The H₁₂ samples were scattered all over SOM but still exhibited a slight temporal gradient. At the end of the study the water discharge, especially in summers, stabilized at WAB at a level lower than natural and as a result submerged macrophytes appeared at H₁₂ making the abundance of macroinvertebrates increase very quickly. Moreover, a weaker horizontal grouping of samples by season and by site of collection (upstream or downstream from the reservoir) was observed over SOM: 1) bank upstream habitat H₁, with hydrological regime resembling natural, was separated from the downstream H₁₁, which enlarged and contracted in response to dam operation, 2) deeper habitats were less dependent on water level and this is why they underwent seasonal fluctuations. To sum up, the deepest habitats were most resistant to water level fluctuations, while the formerly most productive habitat at the tailwater WAB site, H₁₁, became the most negatively impacted. Nevertheless, the reservoir has not negatively influenced chironomid density, because the latter increased closer the mid-river, at H₁₂, where large patches of macrophytes developed.     

Patterning of impoundment impact on chironomid assemblages and their environment with use of the self-organizing map (SOM)

The paper assesses the impact of the Jeziorsko dam reservoir on chironomid assemblages and selected environmental factors in the Warta River, Poland, by means of patterns recognized with the self-organizing map (SOM, Kohonen unsupervised artificial neural network). Over 1988–1996, in four annual cycles, a total of 233 monthly samples were collected in a seven order section of the river at two sites: WAA (backwater) located about 2 km upstream from the Jeziorsko Reservoir, and WAB (tailwater) located about 1.5 km downstream from the reservoir's dam. At each site three habitats were selected: H₁, H₂ and H₃ at WAA, and H₁₁, H₁₂ and H₁₃ at WAB. H₁ and H₁₁ were located in the depositional area close to the banks, H₂ and H₁₂ about 6–7 m towards the mid-river and H₃ and H₁₃ in the mid-river. SOM effectively vertically separated H₁ and H₁₁ (bank habitats) from H₃ and H₁₃ (the mid-river zone of both sites) and H₂ (the transition zone of the upstream site). The H₁₂ samples were scattered all over SOM but still exhibited a slight temporal gradient. At the end of the study the water discharge, especially in summers, stabilized at WAB at a level lower than natural and as a result submerged macrophytes appeared at H₁₂ making the abundance of macroinvertebrates increase very quickly. Moreover, a weaker horizontal grouping of samples by season and by site of collection (upstream or downstream from the reservoir) was observed over SOM: 1) bank upstream habitat H₁, with hydrological regime resembling natural, was separated from the downstream H₁₁, which enlarged and contracted in response to dam operation, 2) deeper habitats were less dependent on water level and this is why they underwent seasonal fluctuations. To sum up, the deepest habitats were most resistant to water level fluctuations, while the formerly most productive habitat at the tailwater WAB site, H₁₁, became the most negatively impacted. Nevertheless, the reservoir has not negatively influenced chironomid density, because the latter increased closer the mid-river, at H₁₂, where large patches of macrophytes developed.     

Mesohabitat use by bullhead (Cottus gobio)

Habitat composition and connectivity within a stream vary with changing flows but the influence of changing flow on habitat use by fish is not well understood. Meso- and microhabitat surveys were used to investigate habitat use by bullhead (Cottus gobio Linnaeus) in response to discharge variation in a small tributary of the Upper Severn, England. Mesohabitat mapping surveys were carried out over a range of summer flows (0.016–0.216 m³ s⁻¹) and were coupled with direct underwater observations (snorkelling) of fish location. Five mesohabitat types—glides, runs, riffles, chutes and pools—were present in the reach at all flows surveyed and ‘backwaters’ were found at three flows. The macro-morphology of the reach comprised six riffle–pool sequences divided into 27 mesohabitats with the maximum diversity (23 mesohabitats) at intermediate flows (Q ₄₃) and only 15 mesohabitats at Q ₉₅. Despite low numbers of fish (N = 78), bullhead displayed a strong association (51% of the fish) with glides—relatively deep habitats having high rates of velocity increase with flow. However, 54% of the fish were observed in two large, persistent mesohabitats, a glide (34%) and a pool (20%), both located below a faster flowing mesohabitat. Habitat use curves based upon micro-habitat data showed bullhead favoured low velocities (<0.30 m s⁻¹), depths less than 0.30 m and a cobble substratum. This study illustrates the value of cross-scale investigations in linking fish ecology, flow and physical habitat variability and suggests mesohabitat size, persistence and arrangement may influence fish distribution.     

The effect of long-term nitrate treatment on SRB activity,corrosion rate and bacterial community composition in offshore water injection systems

Biogenic production of hydrogen sulphide (H₂S) is a problem for the oil industry as it leads to corrosion and reservoir souring. Continuous injection of a low nitrate concentration (0.25–0.33 mM) replaced glutaraldehyde as corrosion and souring control at the Veslefrikk and Gullfaks oil field (North Sea) in 1999. The response to nitrate treatment was a rapid reduction in number and activity of sulphate-reducing bacteria (SRB) in the water injection system biofilm at both fields. The present long-term study shows that SRB activity has remained low at ≤0.3 and ≤0.9 μg H₂S/cm²/day at Veslefrikk and Gullfaks respectively, during the 7–8 years with continuous nitrate injection. At Veslefrikk, 16S rRNA gene based community analysis by PCR–DGGE showed that bacteria affiliated to nitrate-reducing sulphide-oxidizing Sulfurimonas (NR–SOB) formed major populations at the injection well head throughout the treatment period. Downstream of deaerator the presence of Sulfurimonas like bacteria was less pronounced, and were no longer observed 40 months into the treatment period. The biofilm community during nitrate treatment was highly diverse and relative stable for long periods of time. At the Gullfaks field, a reduction in corrosion of up to 40% was observed after switch to nitrate treatment. The present study show that nitrate injection may provide a stable long-term inhibition of SRB in sea water injection systems, and that corrosion may be significantly reduced when compared to traditional biocide treatment.     

Spatial and temporal variation of genetic diversity and estimation of effective population sizes in Atlantic salmon (Salmo salar, L.) populations from Asturias (Northern Spain) using microsatellites

Rivers in Asturias (northern Spain) constitute the southern limit of the distribution of Atlantic salmon (Salmo salar L.) in Europe, a biological resource facing one of the more serious challenges for conservation today. In this work, eight microsatellite loci have been used to analyse samples collected in 1993 and 1999 from four Asturian rivers (Esva, Narcea, Sella, and Cares), obtaining information about the temporal and the spatial genetic variation in these populations and, in addition, estimations of their effective population sizes. The temporal analysis revealed a general decrease in all the estimated genetic variability parameters when samples from 1993 (mean A ₍₁₉₉₃₎ = 6.47, mean H _O(1993) = 0.472, mean H _E(1993) = 0.530) were compared with those obtained in 1999 (mean A ₍₁₉₉₉₎ = 6.16, mean H _O(1999) = 0.460, mean H _E(1999) = 0.490). This reduction was particularly notable for the case of the Esva river. Our results pointed to a pattern of spatial genetic differentiation inside the Asturian region (F _{ST (1993)} = 0.016 P < 0.01; F _{ST (1999)} = 0.023 P < 0.01). Using the standard Temporal Method we found estimates of N _e^{^} _(Esva) = 75.1 (33.2–267.2); N _e^{^} _(Cares) = 96.6 (40.0–507.5), N _e^{^} _(Sella) = 106.5 (39.1–9396.4) and N _e^{^} _(Narcea) = 113.9 (42.0–3693.3). The use of likelihood-based methods for the N _e^{^} estimations improved the results (smaller CIs) for the Esva and Cares rivers (N _e^{^} _(Esva) = 63.9 (32.3–165.3); N _e^{^} _(Cares) = 76.4 (38.8–202.0) using a Maximum likelihood approach) and suggested the presence of larger populations for the Sella and Narcea rivers (N _e^{^}≈200). These results showed that the Asturian Atlantic salmon populations (in particular Esva and Cares river populations) could be close to the conservation genetic borderline for avoiding inbreeding depression although we discuss some implications of the analysis of temporal genetic change in populations with overlapping generations.     

Hydro-morphologically related variance in benthic drift and its importance for numerical habitat modelling

Numerical fish-habitat modelling on various scales is considered to be state of the art in river management. However, most of the concepts applied use steady-state hydraulic parameters such as flow velocity and water depth. Herein we present analysis and discussion of the possibility of including a drift-feeding parameter (SI_F) into habitat evaluations based on multiplying suitability indices. “Sources” and “sinks” of benthic drift were identified according to both the zero-crossing and hydraulic-threshold methods in an alpine gravel-bed river. Minor differences could be determined between the two methods in a well-developed riffle–pool section. Macroinvertebrates, used for simulating benthic drift, were collected by multi-habitat sampling and appraised according to their critical threshold (τ _cr) for motion on the bed surface and sinking velocity (v _s). The findings of the calculation of drift rates using one- (1D) and two-dimensional (2D) hydrodynamic numerical models highlight a specification of best feeding position for drift-feeding fish (i.e. brown trout, grayling) considering the SI_F parameter. Riffle–pool sequences are characteristic of pristine alpine streams; our findings underline their importance as production (riffles) and consumption areas (pools) in terms of holistic river function. Moreover, the results indicate that (artificial) lateral obstruction (e.g. dams) may lead to a reduced transport rate of benthic organisms due to low bottom shear stress (<0.25 N m⁻²). Thus, deposition of drifting macroinvertebrates occurs in backwaters, with downstream impacts on benthic and fish communities.     

Nickel(II)-substituted azurin I from Alcaligenes xylosoxidans as characterized by resonance Raman spectroscopy at cryogenic temperature

Metal-substituted blue copper proteins (cupredoxins) have been successfully used to study the effect of metal-ion identity on their active-site properties, specifically the coordination geometry and metal–ligand bond strengths. In this work, low-temperature (77 K) resonance Raman (RR) spectra of the blue copper protein Alcaligenes xylosoxidans azurin I and its Ni(II) derivative are reported. A detailed analysis of all observed bands is presented and responsiveness to metal substitution is discussed in terms of structural and bonding changes. The native cupric site exhibits a RR spectrum characteristic of a primarily trigonal planar (type 1) coordination geometry, identified by the ν(Cu–S)_Cys markers at 373, 399, 409, and 430 cm⁻¹. Replacement of Cu(II) with Ni(II) results in optical and RR spectra that reveal (1) a large hypsochromic shift in the main (Cys)S → M(II) charge-transfer absorption from 622 to 440 nm, (2) greatly reduced metal–thiolate bonding interaction, indicated by substantially lower ν(Ni–S)_Cys stretching frequencies, (3) elevation of the cysteine ν(C _β –S) stretching, amide III, and ρ _s(C _β H₂) scissors vibrational modes, and (4) primarily four-coordinated, trigonally distorted tetrahedral geometry of the Ni(II) site that is marked by characteristic ν(Ni–S)_Cys stretching RR bands at 347, 364, and 391 cm⁻¹. Comparisons of the electronic and vibrational properties between A. xylosoxidans azurin I and its closely structurally related azurin from Pseudomonas aeruginosa are made and discussed. For cupric azurins, the intensity-weighted average M(II)–S(Cys) stretching frequencies are calculated to be ν(Cu–S)_iwa = 406.3 and 407.6 cm⁻¹, respectively. These values decreased to ν(Ni–S)_iwa = 359.3 and 365.5 cm⁻¹, respectively, after Ni(II) → Cu(II) exchange, suggesting that the metal–thiolate interactions are similar in the two native proteins but are much less alike in their Ni(II)-substituted forms.     

Population genetic structure of island and mainland populations of the quokka, Setonix brachyurus (Macropodidae): a comparison of AFLP and microsatellite markers

Translocation and reintroduction are important tools for the conservation or recovery of species threatened with extinction in the wild. However, an understanding of the potential genetic consequences of mixing populations requires an understanding of the genetic variation within, and similarities among, donor and recipient populations. Genetic diversity was measured using two independent marker systems (microsatellites and AFLPs) for one island and four small remnant mainland populations of Setonix brachyurus, a threatened medium sized macropod restricted to fragmented habitat remnants and two off-shore islands in southwest Australia. Microsatellite diversity in the island population (R _s = 3.2, H _e = 71%) was similar to, or greater than, all mainland populations (R _s = 2.1–3.9, H _e = 34-71%). In contrast, AFLP diversity was significantly lower in the island population (PPL = 20.5; H _j = 0.118) compared to all mainland populations (mean PPL = 79.5–89.7; mean H _j = 0.23–0.29). Microsatellites differentiated all (mainland and island) populations from each other. However, AFLP only differentiated the island population from the mainland populations—all mainland populations were not significantly differentiated from each other for this marker. Given a known time since isolation of the island population from the mainland (6,000 years ago), and an overall more conservative rate of evolution of AFLP markers, our results are consistent with mainland populations fragmenting thousands of years ago (but <6,000 years), probably as a consequence of reduced rainfall and the constriction of the preferred mesic habitat of quokkas. Our results also support a recent history of severe population bottlenecks in mainland populations, and a long history of bottlenecks of the island population, but reflect a recent explosion in numbers since European occupation of the island. Our results indicate that translocation of island populations to supplement mainland populations would introduce genetically markedly differentiated, and possibly maladapted, individuals.     

The Relative Rates of Thiol–Thioester Exchange and Hydrolysis for Alkyl and Aryl Thioalkanoates in Water

This article reports rate constants for thiol–thioester exchange (k _ex), and for acid-mediated (k _a), base-mediated (k _b), and pH-independent (k _w) hydrolysis of S-methyl thioacetate and S-phenyl 5-dimethylamino-5-oxo-thiopentanoate—model alkyl and aryl thioalkanoates, respectively—in water. Reactions such as thiol–thioester exchange or aminolysis could have generated molecular complexity on early Earth, but for thioesters to have played important roles in the origin of life, constructive reactions would have needed to compete effectively with hydrolysis under prebiotic conditions. Knowledge of the kinetics of competition between exchange and hydrolysis is also useful in the optimization of systems where exchange is used in applications such as self-assembly or reversible binding. For the alkyl thioester S-methyl thioacetate, which has been synthesized in simulated prebiotic hydrothermal vents, k _a = 1.5 × 10⁻⁵ M⁻¹ s⁻¹, k _b = 1.6 × 10⁻¹ M⁻¹ s⁻¹, and k _w = 3.6 × 10⁻⁸ s⁻¹. At pH 7 and 23°C, the half-life for hydrolysis is 155 days. The second-order rate constant for thiol–thioester exchange between S-methyl thioacetate and 2-sulfonatoethanethiolate is k _ex = 1.7 M⁻¹ s⁻¹. At pH 7 and 23°C, with [R″S(H)] = 1 mM, the half-life of the exchange reaction is 38 h. These results confirm that conditions (pH, temperature, pK _a of the thiol) exist where prebiotically relevant thioesters can survive hydrolysis in water for long periods of time and rates of thiol–thioester exchange exceed those of hydrolysis by several orders of magnitude.     

Mechanistic insight from thermal activation parameters for oxygenation reactions of different substrates with biomimetic iron porphyrin models for compounds I and II

Compound I, an oxo–iron(IV) porphyrin π-cation radical species, and its one-electron-reduced form compound II are regarded as key intermediates in reactions catalyzed by cytochrome P450. Although both reactive intermediates can be easily produced from model systems such as iron(III) meso-tetra(2,4,6-trimethylphenyl)porphyrin hydroxide by selecting appropriate reaction conditions, there are only a few thermal activation parameters reported for the reactions of compound I analogues, whereas such parameters for the reactions of compound II analogues have not been investigated so far. Our study demonstrates that ΔH ^≠ and ΔS ^≠ are closely related to the chemical nature of the substrate and the reactive intermediate (viz., compounds I and II) in epoxidation and C–H abstraction reactions. Although most studied reactions appear to be enthalpy-controlled (i.e., ΔH ^≠ > −TΔS ^≠), different results were found for C–H abstractions catalyzed by compound I. Whereas the reaction with 9,10-dihydroanthracene as a substrate is also dominated by the activation enthalpy (ΔH ^≠ = 42 kJ/mol, ΔS ^≠ = 41 J/Kmol), the same reaction with xanthene shows a large contribution from the activation entropy (ΔH ^≠ = 24 kJ/mol, ΔS ^≠ = −100 J/kmol). This is of special interest since the activation barrier for entropy-controlled reactions shows a significant dependence on temperature, which can have an important impact on the relative reaction rates. As a consequence, a close correlation between bond strength and reaction rate—as commonly assumed for C–H abstraction reactions—no longer exists. In this way, this study can contribute to a proper evaluation of experimental and computational data, and to a deeper understanding of mechanistic aspects that account for differences in the reactivity of compounds I and II.     

Impact of different pH control agents on biopesticidal activity of<Emphasis Type="Italic"> Bacillus thuringiensis</Emphasis> during the fermentation of starch industry wastewater

Different pH control agents (NaOH/H₂SO₄—SodSulp, NaOH/CH₃COOH—SodAcet, NH₄OH/CH₃COOH—AmmoAcet and NH₄OH/H₂SO₄—AmmoSulp) were used to investigate their effects on growth, enzyme production (alkaline protease and amylase), and entomotoxicity of Bacillus thuringiensis var. kurstaki HD-1 (Btk) against eastern spruce budworm larvae (Choristoneura fumiferana) using starch industry wastewater (SIW) as a raw material in a 15-l fermentor. AmmoSulp and SodSulp were found to be the best pH control agents for alkaline protease and amylase production, respectively; whereas, the fermented broth obtained by using SodAcet as pH control agents recorded the highest delta-endotoxin production of 1043.0 mg/l and entomotoxicity value 18.4 × 10⁹ SBU/l. Entomotoxicity of re-suspended centrifuged pellet in one-tenth of original volume in case of SodAcet as pH control agents was 26.7 × 10⁹ SBU/l and was the highest value compared to three other pH control agents.     

Tandem repeat markers for population genetic studies of the protected California tiger salamander (<Emphasis Type="Italic">Ambystoma californiense</Emphasis>)

Habitat loss is the single greatest threat to persistence of the critically threatened California tiger salamander (Ambystoma californiense). To aid management plans that designate critical habitat for this species, I developed and characterized 21 tetranucleotide microsatellite markers using two native populations in Santa Barbara and Alameda Counties. Allelic variation and average heterozygosities were lower in the endangered Santa Barbara population (allele range 1–4, mean 2.4; H _O = 0.308 H _E = 0.288) compared with the threatened Alameda population (allele range 2–10, mean 6.7; H _O = 0.712, H _E = 0.722). In-depth population studies using these markers will provide vital information for plans to assign critical habitat that optimize gene flow among breeding populations, as well as for identifying non-native hybrid genotypes that threaten native A. californiense stocks. Beyond the conservation goals for A. californiense, the close phylogenetic relationships within the tiger salamander complex also suggest a broad utility for population studies using these markers.     

<Emphasis Type="Italic">Escherichia coli</Emphasis> Membrane-Associated Energy-Dependent Processes and Sensitivity Toward Antibiotics Changes as Responses to Low-Intensity Electromagnetic Irradiation of 70.6 and 73 GHz Frequencies

Escherichia coli K-12(λ) was sensitive toward low-intensity (non-thermal, flux capacity 0.06 mW cm⁻²) electromagnetic irradiation (EMI) of extremely high frequency—70.6 and 73 GHz. 1 h exposure to EMI markedly depressed growth and cell viability of bacteria. Membrane-associated processes—total H⁺ efflux and H₂ evaluation by whole cells during glucose fermentation were shown to be lowered as well. At the same time, the F₀F₁-ATPase activity of membrane vesicles was little depressed with 70.6 GHz irradiation only. This finding was in conformity with non-changed N,N′-dicyclohexylcarbodiimide-sensitive H⁺ efflux. Furthermore, for understanding the different frequencies action mechanisms, the effects of antibiotics (chloramphenicol, ceftriaxone, kanamycin, and tetracycline) on irradiated cells growth and survival were determined. EMI with the frequencies of 70.6 and 73 GHz as with 51.8 and 53.0 GHz enhanced the sensitivity of bacteria toward antibiotics, but comparison revealed that each frequency had a different portion. Probably, EMI of specific frequency triggered changes in biological processes and afterward in growth and viability of bacteria, creating conditions when the action of antibiotics became facilitated.     

Evaluation of denitrification in an urban stream receiving wastewater effluent

Urban streams often contain elevated concentrations of nitrogen (N) which can be amplified in systems receiving effluent from wastewater treatment plants (WWTP). In this study, we evaluated the importance of denitrification in a stream draining urban Greensboro, NC, USA, using two approaches: (1) natural abundance of ¹⁵N–NO₃⁻ in conjunction with background NO₃⁻–N concentrations along a 7 km transect downstream of a WWTP; and (2) C₂H₂ block experiments at three sites and at three habitat types within each site. Overall lack of a longitudinal pattern of δ¹⁵N–NO₃⁻ and NO₃⁻–N, combined with high concentrations of NO₃⁻–N suggested that other factors were controlling NO₃⁻–N flux in the study transect. However, denitrification did appear to be significant along one portion of the transect. C₂H₂ block experiments showed that denitrification rates were much higher downstream of the WWTP compared to upstream, and showed that denitrification rates were highest in erosional and depositional areas downstream of the WWTP and in erosional areas upstream of the plant. Thus, the combination of the two methods for evaluating denitrification provided more insight into the spatial dynamics of denitrification activity than either approach alone. Denitrification appeared to be a significant sink for NO₃⁻–N upstream of the WWTP, but not downstream. Approximately 46% of the total NO₃⁻–N load was removed via denitrification in the upstream, urban section of the stream, while only 2.3% of NO₃⁻–N was lost downstream of the plant. This result suggests that controlling NO₃⁻–N loading from the plant could result in considerable improvement of downstream water quality.     

Kineococcus glutineturens sp. nov., isolated from soil in Yunnan, south-west China

An orange-coloured, non-spore-forming, motile and coccus-shaped actinobacterium, designated YIM 75677^T, was isolated from a soil sample collected from a dry-hot river valley in Dongchuan county, Yunnan Province, south-west China and its taxonomic position was investigated. Growth of strain YIM 75677^T occurred at 12–55 °C, pH 6.0–9.0 and NaCl tolerance up to 2 % (w/v). Cells adhered to agar media and were agglutinated tightly together. The peptidoglycan contained meso-diaminopimelic acid, alanine and glutamic acid. The whole-cell hydrolysates mainly contained glucose, galactose, mannose and ribose. The predominant menaquinone was MK-9 (H₂) and the major fatty acids were anteiso-C_15:0 and iso-C_15:0. Mycolic acids were not present. The DNA G+C content of strain YIM 75677^T was 74.8 mol%. Phylogenetic analyses based on 16S rRNA gene sequence comparisons clearly revealed that strain YIM 75677^T represents a novel member of the genus Kineococcus and is closely related to Kineococcus xinjiangensis S2-20^T (level of similarity, 98.6 %). Meanwhile, the result of DNA–DNA hybridization between strain YIM 75677^T and K. xinjiangensis S2-20^T demonstrated that this isolate represented a different genomic species in the genus Kineococcus. On the basis of phylogenetic, phenotypic and chemotaxonomic characteristics, strain YIM 75677^T represents a novel species of the genus Kineococcus, for which the name Kineococcus glutineturens sp. nov. is proposed. The type strain is YIM 75677^T (=CCTCC AA 209075^T = JCM 18126^T).     

Chemical properties of water in a flooded opencast sulphur mine

The chemical properties of water in the only flooded sulphur opencast mine in the world have been analysed. The reservoir has a depth of 22 m and is still continuously pumped, which affects the deeper tertiary aquifer. Instead of quaternary water being pumped out, tertiary water flows into the reservoir. Mineralisation of the water in this reservoir varied from 2000 to 10,000 mg dm⁻³ near the bottom. Light penetrates to 8–10 m and this photic layer is oxygenated. The hypolimnion is only partially oxygenated and contains H₂S. The monimolimnion is salty and also poisoned by H₂S. Discriminant analysis shows three layers: upper 0–10 m, transitional 10–15 m and bottom 15–22 m. Variability of the chemical properties is negligible through the year, excluding special situations such as ice melting. The transitional layer is rich in SO₄²⁻ – about 1000 mg dm⁻³ and unionized H₂S. S²⁻ oxidation is very intensive, excess CaSO₄ precipitates at a depth of 10 m resulting in opacity. Above and below, these concentrations diminish. For this zone a new name is proposed: the katalimnion. In the bottom layer, NO₃⁻ does not occur – whereas there is a high concentration of NH₄⁺. Discrimination on the basis of chemical parameters divides the vertical profile into three levels: epi- + meta- + upper half of the hypolimnion, lower half of the hypolimnion and monimolimnion. This indicates that for sampling, three levels might be sufficient. The same analysis used for time showed a low differentiation in the annual cycle. These results can help in optimizing the monitoring scheme for this pit lake and reducing its cost.     

Studies on non-symbiotic diazotrophic bacterial populations of coastal arable saline soils of India

The effect of fluctuations of salinity in three different seasons on diazotrophic populations and N₂ fixation in six mono cropped rice field soils of the coastal region of the Gangetic delta of West Bengal, India, was studied. The average pH, ECe, organic carbon and total nitrogen of the soils ranged from 4.99–7.08, 2.02–19.58 dSm⁻¹, 4.68–12.03 g kg⁻¹ and 0.44–1.70 g kg ⁻¹, respectively. The average log colony forming units of the bacterial populations and N₂-fixation in the soils varied from 4.61 to 5.86 and 2.74 to 4.52 mg N₂ fixed 50 ml ⁻¹ culture media respectively, with the lowest value recorded in summer. Recovery of microorganisms and N₂- fixation gradually decreased with extraneous addition of NaCl in the culture media. All the eight isolates were Gram positive, spore and capsule formers. They could utilize glucose, sucrose, mannitol, starch, citrate and nitrate, and were catalase and gelatinase positive, but indole, methyl red and Vogues Proskauer reaction negative. The organisms produced alkaline reaction on TSI agar slant. The acetylene reduction assay of the isolates at 0 and 1% NaCl in the culture media were 4.51–164.52 and 1.72–100.6 nmole C₂H₄ ml⁻¹ culture media in 72 h, respectively. The isolates could fix 2.42–4.45 and 2.04–4.08 mg N₂ fixed 50 ml⁻¹ culture media at 0 and 1% NaCl in the culture media respectively. 16S rDNA sequences of the isolates were similar to the species: Bacillus sp. isolate 28A, Bacillus sp. MOLA 87, Bacillus sp. By113 (B)Ydz-dh, Bacillus sp. PN13, Bacillus licheniformis strain RH101, Bacterium Antarctica 14, Bacillus sp. PN13 and Bacillus megaterium.     

Hydrogen sulfide removal from air by <Emphasis Type="Italic">Acidithiobacillus thiooxidans</Emphasis> in a trickle bed reactor

A strain of Acidithiobacillus thiooxidans immobilized in polyurethane foam was utilized for H₂S removal in a bench-scale trickle-bed reactor, testing the limits of acidity and SO₄ ²⁻ accumulation. The use of this acidophilic strain resulted in remarkable stability in the performance of the system. The reactor maintained a >98–99 % H₂S removal efficiency for c of up to 66 ppmv and empty bed residence time ≤12–15 s. Removal of >98 % H₂S was achieved under steady-state conditions, over the pH range of 0.44–7.30. Despite the accumulation of acidity and SO₄ ²⁻ (up to 97 g/L), the system operated without inhibition.     

The production of hydrogen sulphide and other aroma compounds by wine strains of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> in synthetic media with different nitrogen concentrations

The aim of this study was to evaluate the combined effect of initial nitrogen content on the production of hydrogen sulphide and other volatile compounds during alcoholic fermentation. For that propose, three commercial wine strains of Saccharomyces cerevisiae were used to ferment synthetic grape juice media under different nitrogen concentrations. H₂S was measured throughout fermentations and other aroma compounds were analyzed at the end of the experiments. The trigger levels at which an inverse relationship between the initial nitrogen present in media and total H₂S production varied among the three strains tested. For UCD522 and PYCC4072, the highest H₂S levels were produced in media with 267 mg N l⁻¹ of initial nitrogen, whereas the lowest levels were detected with nitrogen limitation/starvation conditions (66 mg N l⁻¹). Moreover, 21 other aroma compounds belonging to different chemical classes were identified and quantified by solid phase micro-extraction (SPME) coupled to gas chromatography–mass spectrometry (GC–MS). The initial nitrogen concentration more than yeast strain had a decisive effect on the final aroma composition, suggesting that modulation of nutrients emerges as a useful tool for producing desired flavour and odour compounds.