Biodegradation and biosorption of acid anthraquinone dye

The acid anthraquinone dye Tectilon Blue (TB4R) is a major coloured component from the aqueous effluent of a carpet printing plant in Northern Ireland. The aerobic biodegradation of TB4R has been investigated experimentally in batch systems, using three strains of bacteria, namely, Bacillus gordonae (NCIMB 12553), Bacillus benzeovorans (NCIMB 12555) and Pseudomonas putida (NCIMB 9776). All three strains successfully decolourised the dye, and results were correlated using Michaelis-Menten kinetic theory. A recalculation of the reaction rate constants, to account for biosorption, gave an accurate simulation of the colour removal over a 24-h period. Up to 19% of the decolorisation was found to be caused by biosorption of the dye onto the biomass, with the majority of the decolorisation caused by utilisation of the dye by the bacteria. The reaction rate was found to be intermediate between zero and first order at dye concentrations of 200-1000 mg/l. (C) 2000 Elsevier Science Ltd. All rights reserved.

Studies on the biodegradation of fosfomycin: Growth of Rhizobium huakuii PMY1 on possible intermediates synthesised chemically

The first step of the mineralisation of fosfomycin by R. huakuii PMY1 is hydrolytic ring opening with the formation of (1R, 2R)-1,2-dihydroxypropylphosphonic acid. This phosphonic acid and its three stereoisomers were synthesised by chemical means and tested as their ammonium salts for mineralisation as evidenced by release of P-i. Only the (1R, 2R)-isomer was degraded. A number of salts of phosphonic acids such as (+/-)-1,2-epoxybutyl-, (+/-)-1,2-dihydroxyethyl-, 2-oxopropyl-, (+/-)-2-hydroxypropyl-, (+/-)-1-hydroxypropyl- and (+/-)-1-hydroxy-2-oxopropylphosphonic acid were synthesised chemically, but none supported growth. In vitro C-P bond cleavage activity was however detected with the last phosphonic acid. A mechanism involving phosphite had to be discarded as it could not be used as a phosphorus source. R. huakuii PMY1 grew well on (R)- and ( S)- lactic acid and hydroxyacetone, but less well on propionic acid and not on acetone or (R)- and (+/-)-1,2-propanediol. The Pi released from (1R, 2R)-1,2-dihydroxypropylphosphonic acid labelled with one oxygen-18 in the PO3H2 group did not stay long enough in the cells to allow complete exchange of O-18 for O-16 by enzymic turnover.

Spatial genetic structuring in a vagile species, the European wood mouse

We examined the genetic structure of natural populations of the European wood mouse Apodemus sylvaticus at the microgeographic ( 30 km) scales. Ecological and behavioural studies indicate that this species exhibits considerable dispersal relative to its home-range size. Thus, there is potential for high gene flow over larger geographic areas. As levels of population genetic structure are related to gene flow, we hypothesized that population genetic structuring at the microgeographic level should be negligible, increasing only with geographic distance. To test this, four sites were sampled within a microgeographic scale with two additional samples at the macrogeographic level. Individuals (n=415) were screened and analysed for seven polymorphic microsatellite loci. Contrary to our hypothesis, significant levels of population structuring were detected at both scales. Comparing genetic differentiation with geographic distance suggests increasing genetic isolation with distance. However, this distance effect was non-significant being confounded by surprisingly high levels of differentiation among microgeographic samples. We attribute this pattern of genetic differentiation to the effect of habitat fragmentation, splitting large populations into components with small effective population sizes resulting in enhanced genetic drift. Our results indicate that it is incorrect to assume genetic homogeneity among populations even where there is no evidence of physical barriers and dispersal can occur freely. In the case of A. sylvaticus, it is not clear whether dispersal does not occur across habitat barriers or behavioural dispersal occurs without consequent gene flow.

Adsorption of Ni(SO4) on Malaysian rubber-wood ash

The possible use of wood ash as an adsorbent of nickel sulphate from dilute solutions and the effect of operating parameters were investigated in this study. The rate constants of adsorption were determined at different concentrations and temperatures. The applicability of the first-order reversible equation and an empirical kinetic model were tested to understand the kinetics of nickel sulphate removal at different concentrations. Pore diffusion was found as the rate-controlling step. The Langmuir and Freundlich isotherms were applied to find out the adsorption parameters. The activation energy of adsorption was -11.54 kJ mol-1. The value of the enthalpy change was ?H=-10.35 kcal mol-1.

Body mass and sex-biased parasitism in wood mice Apodemus sylvaticus

Male sex-biased parasitism (SBP) occurs across a range of mammalian taxa and two contrasting sets of hypotheses have been suggested for its establishment. The first invokes body size per se and suggests that larger individuals are either a larger target for parasites, trade off growth at the expense of immunity or cope better with parasitism than smaller individuals. The second suggests a sex-specific handicap whereby males have reduced immunocompetence compared to females due to the immunodepressive effects of testosterone. The current study investigated whether sex-biased parasitism is driven by host 'body size' or 'sex' using a rodent-tick (Apodemus sylvaticus-. Ixodes ricinus) system. Moreover, the presence or absence of large mammals at study sites were used to control the presence of immature ticks infesting wood mice, allowing the impacts of parasitism on host body mass and female reproduction to be assessed. As expected, male mice had greater tick loads than females and analyses suggested this sex-bias was driven by body mass as opposed to sex. It is therefore likely that larger individuals are a larger target for parasites, trade off growth at the expense of immunity or adapt behavioural responses to parasitism based on their body size. Parasite load had no effect on host body mass or female reproductive output suggesting individuals may alter behaviour or life history strategies to compensate for costs incurred through parasitism. Overall, this study lends support to the 'body size' hypothesis for the formation of sex-biased parasitism.

Studies on the biodegradation of fosfomycin: Synthesis of 13C-labeled intermediates, feeding experiments with rhizobium huakuii PMY1, and Isolation of Labeled Amino Acids from Cell Mass by HPLC

Racemic (1R*,2R*)-1,2-dihydroxy-[1- ^{13C ₁]propylphosphonic acid and 1-hydroxy-[1- 13C ₁]acetone were synthesized and fed to R. huakuii PMY1. Alanine and a mixture of valine and methionine were isolated as their N-acetyl derivatives from the cell hydrolysate by reversed-phase HPLC and analyzed by NMR spectroscopy. It was found that the carbon atoms of the respective carboxyl groups were highly 13C-labeled (up to 65 %). Hydroxyacetone is therefore considered an obligatory intermediate of the biodegradation of fosfomycin by R. huakuii PMY1.}