Effects of epibiotic algae on the survival, biomass and recruitment of mussels, Mytilus L. (Bivalvia : Mollusca)

Habitats composed of living 'ecosystem engineers', such as mussels, are subject to direct and indirect interactions with organisms that live among them. These interactions may affect the presence and structure of habitat, and hence, the associated taxa. We examined the direct effects of epibiotic algae on the Survival, biomass and recruitment of mussels (Mytilits L.) on the west coast of Ireland. A field experiment showed that the presence of epibiotic fucoid algae reduced the likelihood of survival of mussels during storms. We also found that the strength of attachment of mussels did not increase in the presence of epibionts. Another in situ experiment revealed that the presence of ephemeral epibiotic algal mats had no effect on the biomass of host mussels, suggesting no effect on mussel growth or production. The abundance of small mussels (

Combining bio- and chemo-catalysis: from enzymes to cells, from petroleum to biomass

In the future, biomass will continue to emerge as a viable source of chemicals. The development of new industries that utilize bio-renewables provides opportunities for innovation. For example, bio- and chemo-catalysts can be combined in 'one pot' to prepare chemicals of commercial value. This has been demonstrated using isolated enzymes and whole cells for a variety of chemical transformations. The one-pot approach has been successfully adopted to convert chemicals derived from biomass, and, in our opinion, it has an important role to play in the design of a more sustainable chemical industry. To implement new one-pot bio- and chemo-catalytic processes, issues of incompatibility must be overcome; the strategies for which are discussed in this opinion article.

Alkaline hydrolysis of trinitrotoluene, TNT

The kinetics of the alkaline hydrolysis of trinitrotoluene, TNT, in an aqueous solution is a possible approach to destroying the active agent in unwanted munitions. The kinetics are shown to have a rapid initial step, step A, in which a highly coloured species, X (lambda(max) = 450 nm) is formed via an equilibrium reaction: TNT + OH- double left right arrow X. The bimolecular rate constant for the forward part of this equilibrium process, k(1), is: 0.099 +/- 0.004, 0.32 +/- 0.02 and 1.27 +/- 0.05 dm(3) mol(-1) s(-1), at 25, 40 and 60degreesC, respectively. The activation energy for the forward process is 60 kJ mol(-1). The first-order rate constant for the reverse of this process, k(-1), is: (5.3 +/- 2.6) x 10(-4), (1.2 +/- 1.0) x 10(-3) and (7.7 +/- 2.9) x 10(-3) s(-1) at 25, 40 and 60degreesC, respectively. The activation energy for the overall equilibrium process (k(1)/k(-1)) is ca. -5 kJ mol(-1). The subsequent alkaline hydrolysis of X to form the final product P, i.e. step B, is much slower than step A and appears to comprise two processes coupled in series, i.e. steps B1 (X +2OH(-) --> Z) and B2 (Z+OH- --> P). At 25degreesC, Step B1 appears rate determining throughout the decay process. At 45 degreesC and, more so, at 60degreesC, step B appears increasingly biphasic with increasing alkaline concentrations, as step B2 begins to compete with step B1 for position as the rate determining step. The trimolecular rate constant for step B1 is: 0.017 +/- 0.001, 0.0085 +/- 0.0002 and 0.0011 +/- 0.0001 dm(6) mol(-2) s(-1) at 25, 40 and 60degreesC, respectively, and the process has an activation energy of 64 kJ mol(-1). The transition from uniform kinetics, described by step B1, to mixed kinetics, described by steps B1 and B2, as the reaction temperature and alkali concentration are increased most likely occurs because (a) step B2 has a lower activation energy than B1, although it was not possible to measure the former parameter, and (b) step B2 has a lower (1st) order dependence upon [OH-] compared with that of step B1 (2nd). The bimolecular rate constant for step B2 is 0.0035 +/- 0.03 dm(3) mol(-1) s(-1) at 60degreesC. A brief NMR study of the initial hydrolysis product in water, acetone and chloroform, coupled with UV/visible spectra, provides evidence that species X is a Meisenheimer complex.

Comparison of the efficiences of enzymatic and chemical hydrolysis of (nortestosterone and diethylstilboestrol) glucuronides in bovine urine

Residues of 19-nortestosterone (19-NT) and diethylstilboestrol (DES) are excreted in bovine urine, mainly conjugated to glucuronic acid. Prior to quantification, urine must be deconjugated, which is commonly performed by enzymatic or chemical hydrolysis. The efficiencies of two enzymatic and two chemical deconjugation methods were studied. The range of efficiencies obtained for DES were 51.8% (beta -glucuronidase, incubation at 37 degreesC overnight) and 2.7% (methanolic HCl), respectively. Similarly, efficiencies for NT ranged from 43.1% (beta -glucuronidase, incubation at 55 degreesC for 2 h) to 12.7% (methanolic HCl). The results highlight that within control laboratories significant underestimation of drug residue content in samples may occur, due to poor deconjugation. (C) 2001 Elsevier Science B.V. All rights reserved.

Reproductive biomass in Holcus lanatus clones that differ in their phosphate uptake kinetics and mycorrhizal colonization

In normal populations of the common grass Holcus lanatus there is a polymorphism for arsenate resistance, manifested as suppressed phosphate uptake (SPU), and controlled by a major gene with dominant expression. A natural population of SPU plants had greater arbuscular-mycorrhizal colonization than wild type, nonSPU plants. It was hypothesized that, in order to survive alongside plants with a normal rate of phosphate (P) uptake, SPU plants would be more dependent on mycorrhizal associations. We performed an experiment using plants with SPU phenotypes from both arsenate mine spoils and uncontaminated soils, as well as plants with a nonSPU phenotype. They were grown with and without a mycorrhizal inoculum and added N, which altered plant P requirements. We showed that grasses with SPU phenotypes accumulated more shoot P than nonSPU plants, the opposite of the expected result. SPY plants also produced considerably more flower panicles, and had greater shoot and root biomass. The persistence of SPU phenotypes in normal populations is not necessarily related to mycorrhizal colonization as there were no differences in percentage AM colonization between the phenotypes. Being mycorrhizal reduced flower biomass production, as mycorrhizal SPU plants had lower shoot P concentrations and produced fewer flower panicles than non-mycorrhizal, nonSPU plants. We now hypothesize that the SPU phenotype is brought about by a genotype that results in increased accumulation of P in shoots, and that suppression of the rate of uptake is a consequence of this high shoot P concentration, operating by means of a homeostatic feedback mechanism. We also postulate that increased flower production is linked to a high shoot P concentration. SPU plants thus allocate more resources into seed production, leading to a higher frequency of SPU genes. Increased reproductive allocation reduces vegetative allocation and may affect competitive ability and hence survival, explaining the maintenance of the polymorphism. As mycorrhizal SPU plants behave more like nonSPU plants, AM colonization itself could play a major part in the maintenance of the SPU polymorphism.

Flux and turnover of fixed carbon in soil microbial biomass of limed and unlimed plots of an upland grassland ecosystem

The influence of liming on rhizosphere microbial biomass C and incorporation of root exudates was studied in the field by in situ pulse labelling of temperate grassland vegetation with (13)CO(2) for a 3-day period. In plots that had been limed (CaCO(3) amended) annually for 3 years, incorporation into shoots and roots was, respectively, greater and lower than in unlimed plots. Analysis of chloroform-labile C demonstrated lower levels of (13)C incorporation into microbial biomass in limed soils compared to unlimed soils. The turnover of the recently assimilated (13)C compounds was faster in microbial biomass from limed than that from unlimed soils, suggesting that liming increases incorporation by microbial communities of root exudates. An exponential decay model of (13)C in total microbial biomass in limed soils indicated that the half-life of the tracer within this carbon pool was 4.7 days. Results are presented and discussed in relation to the absolute values of (13)C fixed and allocated within the plant-soil system.

Sulfated Zirconia Modified SBA-15 Catalysts for Cellobiose Hydrolysis

Zirconia modified SBA-15 becomes a very active catalyst for the selective hydrolysis of cellobiose to glucose after sulfation. Spectroscopic investigations indicate the presence of Bronsted acid sites with similar properties to those present in conventional sulfated zirconia. Indications are found that the sulfate groups attached to zirconia interact with silanol groups of SBA-15. The catalytic activity in cellobiose hydrolysis correlates well with results for temperature-programmed decomposition of i-propylamine for a range of sulfated ZrO2/SBA-15 catalysts. A glucose yield of 60% during cellobiose hydrolysis at a reaction time of 90 min at 160 degrees C is obtained.

Dilute phosphoric acid-catalysed hydrolysis of municipal bio-waste wood shavings using autoclave parr reactor system

The visibility of using municipal bio-waste, wood shavings, as a potential feedstock for ethanol production was investigated. Dilute acid hydrolysis of wood shavings with H3PO4 was undertaken in autoclave parr reactor. A combined severity factor (CSF) was used to integrate the effects of hydrolysis times, temperature and acid concentration into a single variable. Xylose concentration reached a maximum value of 17 g/100 g dry mass corresponding to a yield of 100% at the best identified conditions of 2.5 wt.% H3PO4, 175 degrees C and 10 min reaction time corresponding to a CSF of 1.9. However, for glucose, an average yield of 30% was obtained at 5 wt.% H3PO4, 200 degrees C and 10 min. Xylose production increased with increasing temperature and acid concentration, but its transformation to the degradation product furfural was also catalysed by those factors. The maximum furfural formed was 3 g/100 g dry mass, corresponding to the 24% yield. (C) 2011 Elsevier Ltd. All rights reserved.

Fermentable sugars recovery from lignocellulosic waste-newspaper by catalytic hydrolysis

The urgent need for alternative renewable energies to supplement petroleum-based fuels and the reduction of landfill sites for disposal of solid wastes makes it increasingly attractive to produce inexpensive biofuels from the organic fraction of the municipal solid waste. Therefore, municipal waste in the form of newspaper was investigated as a potential feedstock for fermentable sugars production. Hydrolysis of newspaper by dilute phosphoric acid was carried out in autoclave Parr reactor, where reactor temperature and acid concentration were examined. Xylose concentration reached a maximum value of 14 g/100 g dry mass corresponding to a yield of 94% at the best identified conditions of 2.5 wt% HPO, 135°C, 120 min reaction time, and at 2.5 wt% HPO, 150°C, and 60 min reaction time. For glucose, an average yield of 26% was obtained at 2.5 wt% HPO, 200°C, and 30 min. Furfural and 5-hydroxymethylfurfural (HMF) formation was clearly affected by reaction temperature, where the higher the temperature the higher the formation rate. The maximum furfural formed was an average of 3 g/100 g dry mass, corresponding to a yield of 28%. The kinetic study of the acid hydrolysis was also carried out using the Saeman and the two-fraction models. It was found for both models that the kinetic constants (K) depend on the acid concentration and temperature. The degradation of HMF to levulinic acid is faster than the degradation of furfural to formic acid. Also, the degradation rate is higher than the formation rate for both inhibitors when degradation is observed.