Search

ANALYSIS OF THE PHYLOGENETIC DIVERSITY OF NEW SURFACE ACTIVE COMPOUND-PRODUCING BACTERIA

Recently we isolated two Gordonia sp. strains able to produce two different types of SACs (Surface-active compounds): extracellular bioemulsan(s), able to produce stable emulsions but not to reduce surface tension, and biosurfactant(s), able to reduce Surface tension. The aim of this work was to evaluate the potentialities of the strains and their synthesised products in bioremediation and soil washing technologies. Microcosm bioremediation experiments were carried Out with aliphatic hydrocarbon contaminated soil, while batch soil washing experiments were carried out with crude oil contaminated soil. Bioremediation results showed that the bioemulsan is able to reduce final concentration of recalcitrant branched hydrocarbons. On the other hand, results from soil-washing experiments demonstrated that the bioemulsan effectively removes crude oil from soil. Overall results are encouraging for a field scale application of SACs by Gordonia in soil remediation.

Gordonia sp. BS29 is a hydrocarbon-degrading bacterium isolated from a site chronically contaminated by diesel. The strain produces extracellular bioemulsifiers, able to produce stable emulsions, and cell-bound glycolipid biosurfactants, able to reduce surface tension. The aims of this work were to investigate the cultural factors affecting the production of the cell-bound biosurfactants by Gordonia sp. BS29 and to find the optimal composition of growth medium for the production. The cultural factors which have a significant influence on surfactant biosynthesis, identified by a two level 2(8-2) Fractional Factorial Design, were the type and concentration of the carbon source, the concentrations of phosphates and sodium chloride, and the interactions among these factors. On these factors, a flask-scale optimisation of cultural conditions was carried out. Then, a steepest ascent procedure and a Central Composite Design were applied to obtain a second order polynomial function fitting the experimental data near the optimum. In the optimised cultural condition we obtained a 5-fold increase in the biosurfactant concentration compared to the un-optimised medium (26.00), reaching a Critical Micelle Dilution value (129.43) among the highest in literature. The optimisation procedure did not change the number and type of the glycolipid biosurfactants produced by Gordonia sp. BS29. © 2009 Elsevier Ltd. All rights reserved.

Bacteria able to produce surface active compounds (SACs) were isolated from hydrocarbon-contaminated environments. The phylogenetic diversity of the isolates was evaluated by 16S rRNA gene analysis. The production of bioemulsifiers and biosurfactants was determined on strains representative of 18 different bacterial genera. Cupriavidus sp. BSNC28C produced extracellular biosurfactants which reduce the surface tension into the culture medium up to 37.1 mN m-1. Sixteen strains, belonging to 11 different genera, released extracellular emulsifiers able to stabilise oil-water emulsions. Among them, the strains Bradyrhizobium sp. BSNC30A and Bosea sp. BSNC5B showed emulsification activities comparable to those of synthetic surfactants. Overall, the novel SAC-producing strains characterised in this work display promising features for the future development of economically efficient industrial-scale biotechnological processes. © 2009 Elsevier Ltd. All rights reserved.

A wide range of structurally different surface active compounds (SACs) is synthesised by many prokaryotic and eukaryotic microorganisms. Due to their properties, microbial SACs have been exploited in environmental remediation techniques. From a diesel-contaminated soil, we isolated the Gordonia sp. strain BS29 which extensively grows on aliphatic hydrocarbons and produces two different types of SACs: extracellular bioemulsans and cell-bound biosurfactants. The aim of this work was to evaluate the potential applications of the strain BS29 and its SACs in the following environmental technologies: bioremediation of soils contaminated by aliphatic and aromatic hydrocarbons, and washing of soils contaminated by crude oil, polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Microcosm bioremediation experiments were carried out with soils contaminated by aliphatic hydrocarbons or PAHs, while batch soil washing experiments were carried out with soils contaminated by crude oil, PAHs or heavy metals. Bioremediation results showed that the BS29 bioemulsans are able to slightly enhance the biodegradation of recalcitrant branched hydrocarbons. On the other hand, we obtained the best results in soil washing of hydrocarbons. The BS29 bioemulsans effectively remove crude oil and PAHs from soil. Particularly, crude oil removal by BS29 bioemulsans is comparable to the rhamnolipid one in the same experimental conditions showing that the BS29 bioemulsans are promising washing agents for remediation of hydrocarbon-contaminated soils. © 2009 Elsevier Ltd. All rights reserved.

Life-threatening RNA viruses emerge regularly, and often in an unpredictable manner. Yet, the very few drugs available against known RNA viruses have sometimes required decades of research for development. Can we generate preparedness for outbreaks of the, as yet, unknown viruses? The VIZIER (VIral enZymes InvolvEd in Replication) (http://www.vizier-europe.org/) project has been set-up to develop the scientific foundations for countering this challenge to society. VIZIER studies the most conserved viral enzymes (that of the replication machinery, or replicases) that constitute attractive targets for drug-design. The aim of VIZIER is to determine as many replicase crystal structures as possible from a carefully selected list of viruses in order to comprehensively cover the diversity of the RNA virus universe, and generate critical knowledge that could be efficiently utilized to jump-start research on any emerging RNA virus. VIZIER is a multidisciplinary project involving (i) bioinformatics to define functional domains, (ii) viral genomics to increase the number of characterized viral genomes and prepare defined targets, (iii) proteomics to express, purify, and characterize targets, (iv) structural biology to solve their crystal structures, and (v) pre-lead discovery to propose active scaffolds of antiviral molecules.

Life-threatening RNA viruses emerge regularly, and often in an unpredictable manner. Yet, the very few drugs available against known RNA viruses have sometimes required decades of research for development. Can we generate preparedness for outbreaks of the, as yet, unknown viruses? The VIZIER (VIral enZymes InvolvEd in Replication) (http://www.vizier-europe.org/) project has been set-up to develop the scientific foundations for countering this challenge to society. VIZIER studies the most conserved viral enzymes (that of the replication machinery, or replicases) that constitute attractive targets for drug-design. The aim of VIZIER is to determine as many replicase crystal structures as possible from a carefully selected list of viruses in order to comprehensively cover the diversity of the RNA virus universe, and generate critical knowledge that could be efficiently utilized to jump-start research on any emerging RNA virus. VIZIER is a multidisciplinary project involving (i) bioinformatics to define functional domains, (ii) viral genomics to increase the number of characterized viral genomes and prepare defined targets, (iii) proteomics to express, purify, and characterize targets, (iv) structural biology to solve their crystal structures, and (v) pre-lead discovery to propose active scaffolds of antiviral molecules., authorCount :35

Life-threatening RNA viruses emerge regularly, and often in an unpredictable manner. Yet, the very few drugs available against known RNA viruses have sometimes required decades of research for development. Can we generate preparedness for outbreaks of the, as yet, unknown viruses? The VIZIER (VIral enZymes InvolvEd in Replication) (http://www.vizier-europe.org/) project has been set-up to develop the scientific foundations for countering this challenge to society. VIZIER studies the most conserved viral enzymes (that of the replication machinery, or replicases) that constitute attractive targets for drug-design. The aim of VIZIER is to determine as many replicase crystal structures as possible from a carefully selected list of viruses in order to comprehensively cover the diversity of the RNA virus universe, and generate critical knowledge that could be efficiently utilized to jump-start research on any emerging RNA virus. VIZIER is a multidisciplinary project involving (i) bioinformatics to define functional domains, (ii) viral genomics to increase the number of characterized viral genomes and prepare defined targets, (iii) proteomics to express, purify, and characterize targets, (iv) structural biology to solve their crystal structures, and (v) pre-lead discovery to propose active scaffolds of antiviral molecules.

Life-threatening RNA viruses emerge regularly, and often in an unpredictable manner. Yet, the very few drugs available against known RNA viruses have sometimes required decades of research for development. Can we generate preparedness for outbreaks of the, as yet, unknown viruses? The VIZIER (VIral enZymes InvolvEd in Replication) (http://www.vizier-europe.org/) project has been set-up to develop the scientific foundations for countering this challenge to society. VIZIER studies the most conserved viral enzymes (that of the replication machinery, or replicases) that constitute attractive targets for drug-design. The aim of VIZIER is to determine as many replicase crystal structures as possible from a carefully selected list of viruses in order to comprehensively cover the diversity of the RNA virus universe, and generate critical knowledge that could be efficiently utilized to jump-start research on any emerging RNA virus. VIZIER is a multidisciplinary project involving (i) bioinformatics to define functional domains, (ii) viral genomics to increase the number of characterized viral genomes and prepare defined targets, (iii) proteomics to express, purify, and characterize targets, (iv) structural biology to solve their crystal structures, and (v) pre-lead discovery to propose active scaffolds of antiviral molecules.

Three new bacterial strains (M22, BS25 and BS29) belonging to the Gordonia genus were isolated from a site chronically contaminated by diesel. Those Gordonia strains were able to grow using a wide range of straight and branched aliphatic hydrocarbons as carbon and energy sources and to produce at least two classes of surface-active compounds. Emulsifying agents were released in the culture medium when bacteria grew both on hydrocarbons and water-soluble substrates. Cell-bound biosurfactants, which reduce the surface tension, were produced on hydrocarbons; however, their production was significantly lower on water soluble substrates. The relationship of growth phase, surface-active compound production and cell-surface properties was analyzed in kinetic experiments on hydrocarbons. Gordonia sp. BS29 synthesized, and released extracellularly, bioemulsans during the exponential phase with n-hexadecane as carbon and energy source. The production of biosurfactants started in the exponential phase and their concentration increased during the following linear growth. Furthermore, the adhesion of bacterial cells to hydrocarbons decreased during growth. Our results led us to hypothesize a change in the mode by which Gordonia cells access the substrate during growth on hydrocarbons. © 2007 Federation of European Microbiological Societies.

The investigated contaminated site is situated in the proximity of a former crude oil refinery. Contamination took place in the 1970s, following the spilling of huge amount of diesel. GC/MS analyses demonstrate that the major components of nonaqueous liquid phase contaminant mixture are branched alkanes and alkyl-substituted naphthalenes. In the site, bioslurping technology was under experimental investigation. The aim of this work was: (1) to evaluate whether the weathered diesel hydrocarbons present as residual contamination can be further degraded by stimulation of indigenous microorganisms; (2) to monitor the effect of the bioslurping on the hydrocarbondegrading bacterial community; and (3) to characterize the weathered diesel-degrading bacterial community. Enumeration of hydrocarbon-degrading bacteria and respirometric tests were carried out during bioslurping treatment. An increase in number and metabolic activity of degrading bacteria was demonstrated. Hydrocarbon-degrading bacteria enriched from capillary fringe and from the NAPL samples were isolated and characterized by 16S ribosomal RNA gene analysis. The majority of the isolates were assigned to the Actinomycetales or to the Rhizobiales orders. A new Gordonia strain (M22) was selected and its degradation capabilities were evaluated. Gordonia sp. M22 strain was capable of degrading the major components of the contaminant mixture.