Engineered Bacteria Mop Up Mercury Spills


ScienceDaily (Aug. 11, 2011) — Thousands of tons of toxic mercury are released into the environment every year. Much of this collects in sediment where it is converted into toxic methyl mercury, and enters the food chain ending up in the fish we eat. New research, published in BioMed Central’s open access journal BMC Biotechnology, showcases genetically engineered bacteria which are not only able to withstand high levels of mercury but are also able to mop up mercury from their surroundings.

These mercury-resistant bacteria, developed by researchers from Inter American University of Puerto Rico, Bayamon Campus, contained either the mouse gene for metallothionein or the bacterial gene for polyphosphate kinase. Both strains of bacteria were able to grow in very high concentrations (120µM) of mercury, and when the bacteria containing metallothionein were grown in a solution containing 24 times the dose of mercury which would kill non-resistant bacteria, they were able to remove more than 80% of it from the solution in five days.

Dr Ruiz who led the research said, “The inclusion of heavy metal scavenging molecules in bacteria provides a viable technology for mercury bioremediation. This method not only would allow us to clean up mercury spills from the environment but the high accumulation of mercury within the transgenic bacteria also provides the possibility of recycling it for further industrial applications.”


Global phenotypic characterization of bacteria

Barry R. Bochner Biolog Inc., Hayward, CA, USA, FEMS Microbiol Rev 33 (2009) 191–205

The measure of the quality of a systems biology model is how well it can reproduce and predict the behaviors of a biological system such as a microbial cell. In recent years, these models have been built up in layers, and each layer has been growing in sophistication and accuracy in parallel with a global data set to challenge and validate the models in predicting the content or activities of genes (genomics), proteins (proteomics), metabolites (metabolomics), and ultimately cell phenotypes (phenomics). This review focuses on the latter, the phenotypes of microbial cells. The development of Phenotype MicroArrays, which attempt to give a global view of cellular phenotypes, is described. In addition to their use in fleshing out and validating systems biology models, there are many other uses of this global
phenotyping technology in basic and applied microbiology research, which are also described.

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Bacteria eating viruses help fight food pathogens: EFSA study

By MIke Stones, 18-May-2009

“Bacteria eating” viruses, known as bacteriophages, could be an effective way of eliminating specific food pathogens, according to a recent report from the European Food Safety Authority’s BIOHAZ Panel.

Some bacteriophages, under specific conditions, could be used to eliminate specific pathogens in milk and meat products, concluded the study.

The panel, which deals with biological hazards in the field of food safety and food-borne diseases, noted that bacteriophages tend to persist longer than their hosts and behave as inert particles in the environment.

But, their long-term antibacterial activity is reduced on dry surfaces and their persistence in food varies with each bacteriophage, and with the conditions of application. Factors include: Dose, and physical and chemical factors associated with the food such as pH and moisture levels. For example, refrigeration temperatures improve the persistence of bacteriophages on the surfaces of meat and dairy products.

Environmental factors

However, after reviewing peer-reviewed scientific literature, the panel was unable to conclude whether or not bacteriophages can protect against bacteria in cases where the food becomes re-contaminated. The effectiveness of bacteriophages against re-contamination of food may vary according to the characteristics of the food, the type of bacteriophage and how it is used, and environmental factors.

The panel recommended further research to gauge the persistence of bacteriophages in foods and their ability to prevent recontamination with bacterial pathogens. Research should focus on specific combinations of bacteriophages, pathogens and foods, it said.

The panel’s study stemmed from a request from European Commission for the European Food Safety Authority (EFSA) to advise on the use of bacteriophages on food of animal origin. It was asked to particularly focus on the mode of action of bacteriophages on carcasses, meat and dairy products.

Bacterial cells

Bacteriophages occur in a broad range of habitats in nature and can be isolated from meat, milk and derived products. They replicate best on growing bacterial cells, but can also reproduce on cells which are not in a growing phase.

The US Food and Drug Administration first approved the use of bacteria eating viruses as food additives in ready-to-eat meat and poultry to protect against Listeria three years ago.