Bioremediation of toxic chromium from electroplating effluent by chromate-reducing Pseudomonas aeruginosa A2Chr in two bioreactors

The chromate-reducing ability of Pseudomonas aeruginosa A2Chr was compared in batch culture, with cells entrapped in a dialysis sac, and with cells immobilized in an agarose-alginate film in conjunction with a rotating biological contactor. In all three systems, the maximum Cr(VI) reduction occurred at 10 mg Cr(VI)/l. Whereas at 50 mg Cr(VI)/l concentration, only 16% of the total Cr(VI) was reduced, five spikings with 10 mg chromate/l at 2-h intervals led to 96% reduction of the total input of 50 mg Cr(VI)/l. Thus maximum Cr(VI) reduction was achieved by avoiding Cr(VI) toxicity to the cells by respiking with lower Cr(VI) concentrations. At 10 mg Cr(VI)/l, the pattern of chromate reduction in dialysis-entrapped cells was almost similar to that of batch culture and 86% of the bacterially reduced chromium was retained inside the dialysis sac. In electroplating effluent containing 100 mg Cr(VI)/l, however, the amount of Cr(VI) reduced by the cells immobilized in agarose-alginate biofilm was twice and thrice the amount reduced by batch culture and cells entrapped in a dialysis sac, respectively.     

Survival and chromate reducing ability of Pseudomonas aeruginosa in industrial effluents

The ability of a chromate-reducing Pseudomonas aeruginosa strain, isolated from tannery effluent, to survive and reduce chromate in the effluent of a tannery and an electroplating unit was evaluated. The test strain survived in the native tannery effluent but numbers fell sharply in the native electroplating effluent. Supplementation with a carbon (C), nitrogen (N) and phosphorus (P) source supported bacterial multiplication and chromate reduction in both types of effluents with almost equal efficiency. Chromate reduction, however, was not observed in the absence of C, N or P supplement, or in the chromate-reducing strain.     

Effect of eight growth media upon fermentation profiles of ten anaerobic bacteria

A study was made of the influence of eight growth media upon the fermentation end-product patterns obtained with ten species of anaerobes. Acidic and neutral end-products of fermentation were analysed by gas chromatography and the results were examined statistically by computer. Differences in end-product profile were at least as great between different media used to grow a single anaerobic species, as between different anaerobes grown in a single type of medium. When individual fermentation end-products produced by a single anaerobe species were examined, statistically significant differences were found between different media for individual end-products. It is concluded that standardisation of growth medium is essential in diagnostic laboratories concerned with identification of anaerobes with the aid of gas chromatography.     

Evaluation of the RAPID ID 32A system for the identification of Bacteroides fragilis and related organisms

S.A. JENKINS, D.B. DRUCKER, M.G.L. KEANEY AND L.A. GANGULI. 1991. This study evaluated the ability of a rapid identification system for anaerobic bacteria. ATB 32A, now renamed RAPID ID 32A (API-bioMérieux UK Ltd., Basingstoke), to identify accurately 74 strains of the 'B. fragilis group'. ATB 32A identified correctly 78.4% of strains to species level, without supplemental tests. The percentage of strains identified to species level rose to 94.6% when a supplementary test (advised by bioMérieux) for catalase production was used to differentiate between Bacteroides ovatus and Bacteroides uniformis. RAPID ID 32A is a rapid, accurate method for the identification of members of the 'B. fragilis group' isolated within a routine clinical laboratory.     

Reversible inactivation of yeast mitochondrial phenylalanyl-tRNA synthetase under oxidative stress

Background

Under oxidative stress cytoplasmic aminoacyl-tRNA synthetase (aaRSs) substrate specificity can be compromised, leading to tRNA mischarging and mistranslation of the proteome. Whether similar processes occur in mitochondria, which are major cellular sources of reactive oxygen species (ROS), is unknown. However, relaxed substrate specificity in yeast mitochondrial phenylalanyl-tRNA synthetase (ScmitPheRS) has been reported to increase tRNA mischarging and blocks mitochondrial biogenesis.

Preoperative dilatation of the cervix by single vaginal administration of 15-methyl-PGF2alpha-methyl ester.

Two different vaginal suppositories have been developed suitable for one single treatment for preoperative dilatation of the cervix prior to vacuum aspiration in late first trimester abortion. The study included 60 patients equally distributed in one control group (Group I) where vacuum aspiration was performed without pretreatment; one group (Group II) where the patients obtained 2.0 mg 15-methyl-PGF2alpha-methyl ester in a rapid releasing base six hours prior to operation and one group (Group III) where the prostaglandin dose was increased to 2.5 mg 15-methyl-PGF2alpha-methyl ester and a more slow releasing base was used and the operation performed after 12 hours. The mean cervical dilatation at operation was in Group II 9 mm and in Group III 11 mm in comparison with 4.8 mm in the control group. The bleeding at the operation was also significantly reduced.     

The alternative pathway of glutathione degradation is mediated by a novel protein complex involving three new genes in Saccharomyces cerevisiae

Glutathione (GSH), L-gamma-glutamyl-L-cysteinyl-glycine, is the major low-molecular-weight thiol compound present in almost all eukaryotic cells. GSH degradation proceeds through the gamma-glutamyl cycle that is initiated, in all organisms, by the action of gamma-glutamyl transpeptidase. A novel pathway for the degradation of GSH that requires the participation of three previously uncharacterized genes is described in the yeast Saccharomyces cerevisiae. These genes have been named DUG1 (YFR044c), DUG2 (YBR281c), and DUG3 (YNL191w) (defective in utilization of glutathione). Although dipeptides and tripeptides with a normal peptide bond such as cys-gly or glu-cys-gly required the presence of only a functional DUG1 gene that encoded a protein belonging to the M20A metallohydrolase family, the presence of an unusual peptide bond such as in the dipeptide, gamma-glu-cys, or in GSH, required the participation of the DUG2 and DUG3 gene products as well. The DUG2 gene encodes a protein with a peptidase domain and a large WD40 repeat region, while the DUG3 gene encoded a protein with a glutamine amidotransferase domain. The Dug1p, Dug2p, and Dug3p proteins were found to form a degradosomal complex through Dug1p-Dug2p and Dug2p-Dug3p interactions. A model is proposed for the functioning of the Dug1p/Dug2p/Dug3p proteins as a specific GSH degradosomal complex.