Comparison of decolorization of reactive microorganisms isolated from various sources.

Azo dyes are among the oldest man-made chemicals and they are still widely used in the textile, printing and the food industries. About 10% - 15% of the total dyes used in the industry is released into the environment during the manufacturing and usage. Some dyes and some of their N-substituted aromatic bio-transformation products are toxic and/or carcinogenic and therefore these dyes are considered to be envionmental pollutants and health hazards. These azo dyes are degraded by physico-chemical and biological methods. Of these, biological methods are considered to be the most economical and efficient. In this work, attempts were made to degrade these dyes aerobically. The organisms which were efficient in degrading the following azo dyes-Red RB, Remazol Red, Remazol Blue, Remazol Violet, Remazol Yellow, Golden Yellow, Remazol Orange, Remazol Black- were isolated from three different sources viz., wastewater treatment plant, paper mill effluent treatment plant and tannery wastewater treatment plant. The efficiency of azo dye degradation by mixed cultures from each source was analyzed. It was found that mixed cultures from tannery treatment plant worked efficiently in decolorizing Remazol Red, Remazol Orange, Remazol Blue and Remazol Violet, while mixed cultures from the paper mill effluent worked efficiently in decolorizing Red RB, Golden Yellow and Remazol Yellow. The mixed cultures from wastewater treatment plant efficiently decolorized Remazol Black.

Decolorization and degradation of H-acid and other dyes using ferrous-hydrogen peroxide system.

In this study, advanced oxidation process utilizing Fenton's reaction was investigated for the decolorization and degradation of two commercial dyes viz., Red M5B, Blue MR and H-acid, a dye intermediate used in chemical industries for the synthesis of direct, reactive and azo dyes. Effect of Fe2 +, H2O2, pH, and contact time on the degradation of the dyes was studied. Maximum color and COD removal was obtained for Red MSB, H-acid and Blue MR at 10-25 mg/l of Fe2+ dose and 400-500 mg/l of H2O2 dose at pH 3.0. The initial oxidation reaction was found to fit into first order rate kinetics and the rate of oxidation of H-acid was higher than the other dyes. Release of chloride and sulfate from the Fenton's treated Red M5B dye and sulfate from H-acid and Blue MR indicates that the dye degradation proceeds through cleavage of the substituent group.

RNA expression patterns change dramatically in human neutrophils exposed to bacteria.

A comprehensive study of changes in messenger RNA (mRNA) levels in human neutrophils following exposure to bacteria is described. Within 2 hours there are dramatic changes in the levels of several hundred mRNAs including those for a variety of cytokines, receptors, apoptosis-regulating products, and membrane trafficking regulators. In addition, there are a large number of up-regulated mRNAs that appear to represent a common core of activation response genes that have been identified as early-response products to a variety of stimuli in a number of other cell types. The activation response of neutrophils to nonpathogenic bacteria is greatly altered by exposure to Yersinia pestis, which may be a major factor contributing to the virulence and rapid progression of plague. Several gene clusters were created based on the patterns of gene induction caused by different bacteria. These clusters were consistent with those found by a principal components analysis. A number of the changes could be interpreted in terms of neutrophil physiology and the known functions of the genes. These findings indicate that active regulation of gene expression plays a major role in the neutrophil contribution to the cellular inflammatory response. Interruption of these changes by pathogens, such as Y pestis, could be responsible, at least in part, for the failure to contain infections by highly virulent organisms.

Air pollution in stone crushing industry, and associated health effects.

Stone crushers are small scale industries in the unorganised sector. They provide basic material for road and building construction. They are highly labour intensive. The various unit operations involved in stone crushing viz., size reduction, size classification and transfer operations have the potential to emit process and fugitive dust. A detailed air pollution survey was conducted at Pammal, 26 km to the southwest of Chennai. High volume and respirable particulate samplers were deployed at seventeen locations to monitor SPM and PM10 levels in ambient air. The particle size analysis indicates high percentage of finer particles and silica content posing serious health problems to the people exposed for longer duration. Personal samplers were employed to quantify the total dust and respirable particulate fraction in the work environment, which was found significantly high, when compared to the occupational safety and health standards. Fine inhalable particulate matter (PM2.5) which has more associated human health problems was found high in the work place of stone crushers. Health survey viz., Pulmonary function test, blood sample test, general clinical evaluation was conducted to assess the extent of the damage caused to the workers. This study indicates that most of the people are having respiratory problems. The measurements show that good house keeping practice is essential for effective control of dust, in addition to National Productive Council's (NPC) measures.

Global analysis of neutrophil gene expression.

A widespread, but incorrect, view of the neutrophil portrays it as a short-lived, terminally differentiated cell that has a highly condensed nucleus and hence is unable to induce gene expression. However, these cells express mRNA encoding phagocytic receptors, modulate RNA synthesis in response to lectin stimulation or glucocorticoid treatment, and upregulate genes involved in phagocytic function, such as respiratory burst activity and cytokine secretion. Most studies of neutrophil gene expression have examined cytokine stimulation and have focused on a few specific genes of known interest, rather than the global genetic repertoire of the cell. In part stimulated by the availability of gene and expressed sequence tag databases, several approaches have been developed to assess the levels of all mRNA species found in single RNA preparations. We have analyzed the regulation of gene expression in neutrophils using a gel-based method that displays 3' end fragments of cDNA generated by restriction enzymes. Our data indicate that neutrophils are capable of extensive, rapid, and complex changes in gene expression, involving at least several percent of all mRNAs present in the cell. The number and magnitude of mRNA responses are comparable to those measured on activation of normal T cells. The data also indicate that activated neutrophils are a source of newly synthesized, physiologically significant, intercellular signaling molecules.

Detection of virulent Shigella and enteroinvasive Escherichia coli by induction of the 43 kDa invasion plasmid antigen, ipaC.

The invasion plasmid antigen, ipaC (43 kDa) of Shigella spp. and enteroinvasive Escherichia coli (EIEC) could be induced in vitro by growing them in the presence of Congo red. An enzyme-linked immunosorbent assay (ELISA) using antibodies to the 43 kDa protein of Shigella has been developed for specific detection of virulent Shigella spp and EIEC. The test is independent of initial isolation of individual colonies. As few as 10(2) CFU/ml of virulent Shigella present in mixed cultures could be detected and concurrently their susceptibility to antibiotics could be analysed after an initial growth of 8-16 h in Congo red-containing medium. The test may prove useful in the diagnosis and treatment of bacillary dysentery caused either by Shigella or EIEC through their rapid identification and proper antimicrobial therapy.

Proteases and bacterial virulence: a view from the trenches.

Many species of pathogenic bacteria produce cell-surface or secreted proteases. These enzymes have high potential to enhance bacterial pathogenesis through degradation of critical host proteins and by mimicking the activity of host regulatory proteases that control important zymogen systems. Although many bacterial proteases have been implicated in virulence, there is currently no system in which both rigorous demonstration of virulence enhancement in vivo and convincing identification of the important substrate molecules has been achieved. The difficulties inherent in addressing these issues is discussed, and several interesting systems under active investigation briefly described. The potential of extracellular protease as targets for drug development is also considered.

A surface protease and the invasive character of plague.

A 9.5-kilobase plasmid of Yersinia pestis, the causative agent of plague, is required for high virulence when mice are inoculated with the bacterium by subcutaneous injection. Inactivation of the plasmid gene pla, which encodes a surface protease, increased the median lethal dose of the bacteria for mice by a millionfold. Moreover, cloned pla was sufficient to restore segregants lacking the entire pla-bearing plasmid to full virulence. Both pla+ strains injected subcutaneously and pla- mutants injected intravenously reached high titers in liver and spleen of infected mice, whereas pla- mutants injected subcutaneously failed to do so even though they establish a sustained local infection at the injection site. More inflammatory cells accumulated in lesions caused by the pla- mutants than in lesions produced by the pla+ parent. The Pla protease was shown to be a plasminogen activator with unusual kinetic properties. It can also cleave complement C3 at a specific site.

Cloning and hyperexpression of a gene encoding the heat-stable toxin of Escherichia coli.

A gene (st) coding for heat-stable toxin (STh) was identified from a plasmid of a locally isolated enterotoxigenic Escherichia coli strain. The gene was cloned and its nucleotide (nt) sequence was determined. Comparison of this nt sequence with that of another st gene reported earlier, showed a single nt substitution within the structural gene for ST. This change resulted in the replacement of proline at position 19 by alanine in the STh of the locally isolated strain. The st gene was hyperexpressed using the phage T7 or the tac promoter vector systems. A 20-fold increase in STh yield was obtained in minimal medium culture supernatants following induction of the T7 promoter. There was no significant accumulation of the precursor peptide within the periplasm of the induced cell, indicating efficient processing under conditions of enhanced transcription of the gene. The yield of STh was monitored using a competitive ELISA, which was found to be a simple and sensitive assay for determining STh concentrations. A rapid and efficient isolation procedure for STh has been developed.

Congo red-mediated regulation of levels of Shigella flexneri 2a membrane proteins.

The ability of Shigella spp. to bind Congo red from agar medium is generally correlated with their virulence properties. We used a metabolically active culture of Shigella flexneri 2a to determine the effect of Congo red on its membrane protein profiles. Virulent S. flexneri grown in the presence of Congo red at 37 degrees C showed increased levels of three proteins with Mrs of 43,000, 58,000, and 63,000 (43K, 58K, and 63K proteins) in the Sarkosyl-soluble membrane fractions. The observed phenomenon was temperature dependent. At 30 or 42 degrees C the protein levels remained unaffected by the presence of Congo red. Similar regulation of the levels of the 43K, 58K, and 63K membrane proteins was also observed with Shigella dysenteriae 1 and enteroinvasive Escherichia coli, but not with enteropathogenic E. coli. The cellular uptake of Congo red seemed to be essential, but not sufficient, for regulation. All three proteins reacted with human convalescent-phase sera in immunoblots of S. flexneri 2a Sarkosyl-soluble membrane fractions. Using the 43K-specific antiserum as the primary antibody, by indirect immunofluorescence studies, we detected an increase in the level of the 43K protein in S. flexneri which had invaded epithelial cells. These observations strongly indicate that the 43K, 58K, and 63K proteins are virulence associated. We propose that the observed regulatory effect of Congo red on membrane proteins of S. flexneri is mediated through induction. Since the same regulatory effect was also observed during the invasion of epithelial cells by S. flexneri, it is suggested that Congo red mimics some host tissue factor in vitro.

Identification and expression of the 20 kd structural protein gene of colitis bacteriophage.

The 2.3 kb BamHI fragment from the colitis bacteriophage DNA was transcribed and translated into a 20 kd structural protein P6, in a coupled transcription-translation system derived from Escherichia coli. This protein was expressed in vivo by the 2.3 kb DNA cloned in pBR322. The gene with the regulatory elements for this protein was located on the 680 bp AvaII fragment of the insert DNA. It hybridized with two RNAs of sizes 520 and 1630 nucleotides indicating that both are messengers for the 20 kd protein. Dot-blot hybridization showed that the transcripts for P6 reached a maximum level at 12 min after phage infection.