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Abstract.--Microalgae photobioreactors are among the most effective systems for capturing gaseous C[O.sub.2], the main contributor to global warming. Their capacity to generate massive amounts of biomass has been exploited serendipitously [...]

Biotechnology has emerged as an affordable, effective, and eco-friendly alternative to treat carbon disulfide ([CS.sub.2]) containing waste gases. Carbon disulfide is a chemical of widespread use both in the past and in the present. Its industry demand has dramatically changed over the last two decades and is expected to grow in future in step with those industries involving fibre, mining, rubber products, and the agro-chemical sector. This compound, classified as a hazardous air pollutant about 20 years ago, has been re-appraised, as increasingly restrictive pollution standards are expected to be introduced. An array of physical-chemical technologies for treating [CS.sub.2] containing air are already in use, but they have a series of drawbacks, such as high energy consumption (incineration, thermal oxidation), the immobilization of the contaminant solely from one phase to another (adsorption), and the generation of secondary by-products that require additional treatment (hydrolysis). Thus, technological research on affordable processing alternatives is of considerable interest for related industries using or producing [CS.sub.2]. The biological technologies whose efficiency is based on the activity of microorganisms to biodegrade air pollutants overcome many of the disadvantages of conventional techniques and are especially useful for the removal of relatively low concentrations of pollutants. In this paper, the main properties, sources, and uses of [CS.sub.2] are summarized, and alternative biotreatments for [CS.sub.2] are reviewed. Several applications of the technical and economical feasibility of biofilters and biotrickling filters are shown, although their widespread industrial application still requires further research. Key words: carbon disulfide, bioreactors, air pollution control, biotechnology, industrial emissions. La biotechnologie devient une alternative abordable, efficace et eecologiquement acceptable pour traiter les deechets gazeux contenant du disulfure de carbone ([CS.sub.2]). Le [CS.sub.2] est une substance chimique d'utilisation tresrepandue dans le passe; aussi bien que presentement. Sa demande industrielle a fortement change; au cours des deux dernieeres decades et l'on s'attend a ce qu'elle prenne de l'expansion dans le future, de concert avec l'engagement de ces industries dans les secteurs de la fibre, des mines, des produits du caoutchouc et du secteur agrochimique. Ce compose, classified comme dangereux polluant de l'air il y a environ 20 ans a ete reeevalue, car on s'attend a l'introduction de nouveaux standards de plus en plus restrictifs de pollution. On utilise deja un ensemble de technologies physico-chimiques pour traiter l'air contenant du [CS.sub.2], mais ils preesentent des probleemes comme une forte consommation d'energie (incineration, oxydation thermique) l'immobilisation du contaminant uniquement d'une phase a une autre (adsorption) et la generation de produits secondaires qui neecessitent un traitement additionnel (hydrolyses). Ainsi, la recherche technologique de procedes alternatifs abordables presente un inteeret considerable pour les industries utilisant ou produisant du disulfure de carbone. Les techniques biologiques, dont l'efficacite est basee sur l'activite de microorganismes degradant les polluants de l'air, evitent plusieurs des desavantages des techniques conventionnelles et deviennent particulieerement utiles pour eeliminer les contaminants a faibles concentrations. Les auteurs passent en revue et reesument les principales proprietees ainsi que les sources et les usages du [CS.sub.2], et examinent les traitements biologiques alternatifs. On presente plusieurs applications de la faisabilite technique et economique des biofiltres et des filtres par biotrickling, bien que leurs applications industrielles generaliseees demandent encore des recherches. Mots-cles: disulfide de carbone, bioreeacteurs, controle de la pollution de l'air, biotechnologie, emissions industrielles. [Traduit par la Redaction], 1. Introduction Carbon disulfide ([CS.sub.2], CAS Reg. No. 75-15-0) is also known as carbon bisulphide or dithiocarbonic anhydride (ATSDR 1996). Carbon disulfide is a colourless to faintly yellow liquid. The [...]

Wide range of dyes and dyestuffs used in textile manufacturing are xenobiotic compounds and attract stricter to strict environmental regulations. The ability of microbial consortia to decolorize and metabolize dyes has long been known, and the use of bioremediation based technologies for treating textile wastewater has attracted interest. These dyes are decolorized by microbial consortia but technologies for their complete mineralization are still not developed. The most logical concept for the removal of azo dyes in biological wastewater treatment systems is based on anaerobic treatment, for the reductive decolorization, in combination with aerobic treatment, for the degradation of the by-products (aromatic amines) generated in the anaerobic bioreactor. Several research and review articles were published on anaerobic decolorization; however, research on complete mineralization of dyes through sequential anaerobic-aerobic bioreactors has received greater attention recently. Bioremediation through sequential anaerobic-aerobic bioreactor system has been reviewed in this article with critical appraisal using data generated through our experiments. While reviewing this work, we realized the importance of microbial diversity in a treatment unit to better understand the functional status to enhance the mineralization activity of the bioreactor. Key words: azo dyes, biodiversity, bioremediation, two-stage, sequential bioreactor. Un ensemble de teintures et substances tinctoriales utilisees dans la fabrication des textiles constituent des composesxeenobiotiques et appellent des reglementations environnementales severes a tresseveres. On connait depuis longtemps la capacite; des populations microbiennes a decolorer et meetaboliser les teintures, et l'utilisation de technologies basees sur la bioremediation pour traiter les eaux usees des industries textiles souleve beaucoup d'interet. Les populations microbiennes arrivent a decolorer ces teintures, mais les technologies pour les mineeraliser completement ne sont pas encore developpees. Le concept le plus logique pour debarrasser les colorants de type azo des systemes de traitement des eaux usees implique un traitement anaeirobie, pour assurer la decoloration reductive, en combinaison avec un traitement aerobie pour degrader les sous-produits (amines aromatiques) genres pendant la phase anaeirobie. Il existe plusieurs articles et revues sur la decoloration anaeerobie; cependant, ce n'est que recemment que la recherche sur la mineralisation complete des teintures avec des reacteurs sequentiels anaerobie-aeerobie a recju une attention soutenue. Les auteurs passent ici en revue la bioremediation en systemes de bioreacteurs anaeerobie-aeerobie, avec une evaluation critique des domtoes generees dans ces experiences. Tout en realisant cette revue, les auteurs ont constate l'importance de la biodiversite microbienne dans une unite; de traitement, pour mieux comprendre le statut fonctionnel permettant d'acceileerer l'activite; de mineralisation du bioreeacteur. Mots-cles: teintures de type azo, biodiversite, bioremediation, deux etapes, bioreacteur sequentiel. [Traduit par la Redaction], Introduction Bioremediation is a pollution-control technology that uses natural biological species to catalyze the degradation or transformation of various toxic chemicals to less harmful forms. Xenobiotic compounds are not naturally [...]

Bioreactors are enclosed, rigid structures or vessel used to contain the material undergoing biological processing and is used for the accelerated bio-oxidation, which needs more attention and control than the second phase. Several types of reactors are described that include vertical bioreactors, horizontal bioreactors, longitudinal reactors, lateral movement reactors and horizontal cylindrical bioreactors/rotating drums.

An Escherichia coli cell-free expression system is encapsulated in a phospholipid vesicle to build a cell-like bioreactor. Large unilamellar vesicles containing extracts are produced in an oil-extract emulsion. To form a bilayer the vesicles are transferred into a feeding solution that contains ribonucleotides and amino acids. Transcription-translation of plasmid genes is isolated in the vesicles. Whereas in bulk solution expression of enhanced GFP stops after 2 h, inside the vesicle permeability of the membrane to the feeding solution prolongs the expression for up to 5 h. To solve the energy and material limitations and increase the capacity of the reactor, the [alpha]-hemolysin pore protein from Staphylococcus aureus is expressed inside the vesicle to create a selective permeability for nutrients. The reactor can then sustain expression for up to 4 days with a protein production of 30 [micro]M after 4 days. Oxygen diffusion and osmotic pressure are critical parameters to maintain expression and avoid vesicle burst. [alpha]-hemolysin | cell-free protein expression | membrane-anchoring polypeptide

New ways are being found to reduce the greenhouse gases emitted by landfills. Among the new methods are methane recovery and anaerobic bioreactors.

Research is conducted on the oligonucleotide probe detection of fatty acid-beta-oxidizing bacteria to characterize the biogas reactor microbial community. Hybridization results are included.

Hydrogen and formate are ideal electron donors for the biotransformation of technetium, a Uranium 235-derived radioactive isotope believed to cause nuclear contamination. Results gathered from a study conducted on the resting cells of Desulfovibrio desulfuricans revealed that technetium reduction was minimal when lactate and ethanol were used as substrates. However, when hydrogen and formate substrates were utilized, increased reduction was observed along the periphery of the cells. The results point to the possible use of sulfate-reducing bacteria for wastewater cleanup properties.

Three new 16S and 23S rRNA-targeted probes for phylogenetic groups within the beta subclass of the class Proteobacteria were developed for the derivation of a higher taxonomic resolution of the molecular techniques. These were designed in the course of the first-ever application of fluorescent in situ hybridization to examine microbial community structure and dynamics in the fermentor and the bioreactor during start-up, using a laboratory-scale fixed-bed bioreactor degrading a mixture of aromatic compounds.

The double coupling of glucose metabolism and citronellol esterification by acetyl coenzyme A (acetyl-CoA) in Hansenula saturnus cells present in an interface bioreactor produces citronellyl acetate. A high glucose content and citronellol addition increase accumulation of citronellyl acetate in the cells. The triple coupling of acetyl-CoA production, reduction of citronellal to citronellol and esterification of the citronellol by acetyl-CoA also produces citronellyl acetate. The coupling methods permit the formation of citronellyl acetate in the absence of acetyl donors.

Characterization of attachedmicrobial communities was done in this study using the combined techniques of selective polymerase chain reaction (PCR) amplification, comparative sequencing and oligonucleotide probe hybridization. PCR amplification was selective but not specific. Visualization of specific sulfate-reducing bacterial population was provided by in situ hybridization with fluorescent oligonucleotide probes.

Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes and quantitative analysis of the hydA genes at both the DNA and mRNA levels were used to understand the succession of the bacterial community and dynamics of hydrogen producers in a hydrogen-producing bioreactor. The hydrogen production rate and oxidation reduction potential (ORP) values were found to be consistent with the succession of dominant bacterial species during the different phases of the hydrogen-producing process.

The growth and product formation by the engineered strain is studied in bioreactors in order to analyze the effects of pH, calcium and carbon dioxide and oxygen availability. The studies have shown that malic acid production with the engineered Saccharomyces cerevisiae strain is transferred from shake flasks to 1- liter batch bioreactors by simultaneous optimization of four process parameters, pH and concentrations of C[O.sub.2], calcium and [O.sub.2].

Stirred three-electrode anaerobic bioreactors controlled by potentiostats and nondestructive voltammetry techniques are used for describing the growth and characterization of thin viable biofilms of Geobacter sulfurreducens. The technique has provided a basis to catalog quantifiable, defined electron transfer phenotypes as a function of potential, electrode material, growth phase, and culture conditions and also a framework to compare with other species.

A study conducted to analyze the pollutant removal efficiency of aged-refuse-based bioreactor for sewage treatment is discussed.

A report on molecular evidence that ammonia-oxidizing archaea (AOA) occur in activated sludge bioreactors, used to remove ammonia from wastewater is presented. This demonstrates the presence of molecular markers for AOA, including an archaeal ammonia monooxygenase subunit A (amoA) cluster, which is widespread in activated sludge bioreactors.

BioDeNOx is an integrated physiochemical process for the removal of nitrogen oxides (NOx) from flue gases. The flue gas is purged through a scrubber containing a solution of Fe(II)EDTA(super 2-) that binds the NOx to form a Fe(II)EDTA.NO(super 2-) complex and subsequently this complex is reduced in the bioreactor to dinitrogen by microbial denitrification.

This article describes isolation of protease producing bacteria from Antarctic soil using a packed column in a bioreactor mimicking natural ecosystems. Results show isolation of 75 aerobic heterotrophs from such a system fed with a casein-containing medium at 10 C. Phenotypic analyses show they are mainly psychrotrophs belonging to diverse groups of bacteria.