Bees are important contributors to the economies of many countries, but as Travis Glare and Maureen O’Callaghan discuss in this article in Microbiology Today, they are many threats to the survival on the humble bee, including the risk of disease from micro-organisms:
There are many threats to bee survival, including the risk of disease caused by micro-organisms. The vast majority of our knowledge of bee diseases focuses on the honey bee, Apis mellifera, although there are actually over 20,000 species, both stingless and stinging, from those with solitary lifestyles to complex societies such as honey bee hives. Viruses, fungi, protozoa and bacteria are all known to cause infections in bees, sometimes leading to collapse of colonies, and causing serious threats to the bee-keeping industry. Bees have two distinct life forms, brood (egg, larva and pupal stages which develop within the hive) and adult. Most diseases are specific to just one of these life stages. While the list of diseases is quite long, only a few are of serious concern to apiculturists.
Bioremediation can be defined as a process that uses microorganisms, fungi, green plants or their enzymes to return the natural environment altered by contaminants to its original condition. A major advantage of bioremediation is its reduced cost compared to conventional cleanup techniques – the cost of remediation for all contaminated sites in the USA alone is estimated to be $1.7 trillion (Molecular approaches in bioremediation. Curr Opin Biotechnol. Nov 12 2008). In addition, bioremediation is often a permanent solution providing complete transformation of the pollutant to its molecular constituents like carbon dioxide and water rather than a partial method that transfers wastes from one phase to another. Unfortunately, there are many man-made compounds that lack good biological catalysts, and many instances where good biocatalysts fail to transform pollutants in the environment.
Bacteria have enormous potential for cleaning up wastes; however, the interactions between bacteria and pollutants are complex and suitable outcomes do not always take place. Hence, molecular approaches are being applied to enhance bioremediation. One advance in bioremediation to improve the stability of the biocatalyst is to create a system where degradation occurs in the area near the roots of plants known as the rhizosphere. In rhizoremediation, the bacteria degrade the pollutants while the plant roots provide a niche for the microorganism and key nutrients. The advantages of rhizoremediation include the ability of plant roots to provide a large surface area for bacterial propagation and biofilm formation, the roots transport the bacteria through the contaminated soil, the roots provide a niche for the bacteria by providing nutrients, and the roots facilitate oxygen exchange. Successful rhizoremediation systems have been established for pollutants such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), fuels, metals, and pesticides such as parathion.
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Directed evolution or DNA shuffling is a powerful mutagenesis technique that mimics the natural molecular evolution of genes in order to efficiently re-design them. Its power lies in the fact that it can introduce multiple mutations into a gene in order to create new enzymatic activity, which can be discovered by a suitable method of selection (bioassays). Family shuffling applies DNA shuffling to groups of related genes to combine them in a manner that accelerates directed evolution. Genome shuffling recombines the chromosomes of several bacteria to enhance the activity of the whole organism.
Metabolic engineering involves redirecting a cell’s metabolism to achieve a particular goal using recombinant engineering. This technique has been used to create bacterial strains that degrade chlorinated ethenes through the addition of several cloned enzymes to the cell. Metabolic engineering has also been used successfully to handle difficult mixtures of pollutants.
Whole-transcriptome profiling using DNA microarrays has the advantage that the relative amount of transcripts from the whole genome may be easily determined compared to such techniques like proteomics. To understand the metabolism of bacteria in the rhizosphere, researchers have begun to utilize whole-genome profiling.
Although a tremendous amount of work remains to be performed, significant advances have been made through protein engineering and through metabolic engineering for the purposes of bioremediation. However, even though whole-transcriptome profiling and proteomics are utilized routinely in some disciplines, they remain to be utilized extensively in bioremediation. Furthermore, it is important to ensure engineered strains for field use are competitive; rhizoremediation can provide a niche for these engineered bacteria. Chromosomal integration of introduced genes can limit horizontal gene transfer to other species, but this should also be empirically verified to ensure that no adverse environmental effects occur.
The evolution of oxygenic photosynthesis had a profound impact on the Earth’s surface chemistry, leading to a sharp rise in atmospheric oxygen between 2.45 and 2.32 billion years (Gyr) ago and the onset of extreme ice ages. The oldest widely accepted evidence for oxygenic photosynthesis has come from hydrocarbons extracted from approximately 2.7-Gyr-old shales in the Pilbara Craton, Australia, which contain traces of biomarkers (molecular fossils) indicative of eukaryotes and suggestive of oxygen-producing cyanobacteria. The soluble hydrocarbons were interpreted to be indigenous and syngenetic despite metamorphic alteration and extreme enrichment of 13C relative to bulk sedimentary organic matter. Here we present micrometre-scale, in situ 13C/12C measurements of pyrobitumen (thermally altered petroleum) and kerogen from these metamorphosed shales, including samples that originally yielded biomarkers. Our results show that both kerogen and pyrobitumen are strongly depleted in 13C, indicating that indigenous petroleum is lighter than the extracted hydrocarbons. These results are inconsistent with an indigenous origin for the biomarkers. Whatever their origin, the biomarkers must have entered the rock after peak metamorphism approximately 2.2 Gyr ago and thus do not provide evidence for the existence of eukaryotes and cyanobacteria in the Archaean eon. The oldest fossil evidence for eukaryotes and cyanobacteria therefore reverts to 1.78–1.68 Gyr ago and approximately 2.15 Gyr ago, respectively. Our results eliminate the evidence for oxygenic photosynthesis approx 2.7 Gyr ago and exclude previous biomarker evidence for a long delay (approximately 300 million years) between the appearance of oxygen-producing cyanobacteria and the rise in atmospheric oxygen 2.45–2.32 Gyr ago.
Huge numbers and variety of bacteriophages exist on our planet. In this article in Microbiology Today, Graham Hatfull describes this massive reservoir of unidentified genetic information:
You may well be under the impression that the largest number of undiscovered species – and the greatest pool of unknown genes – lie within the considerable biodiversity of the tropical rain forests. Not so. A compelling argument can be made that the biggest reservoir of unidentified genetic information is all around us, in the global population of bacteriophages.
BBC News reports that Britain is running out of mycologists. There were 32 in the 1990s, but just eight now. Scientists say we should be worried as, without a British research base, other countries could stand to make lucrative fungi-based discoveries in everything from medicine to engineering.
Unbelievable as it sounds, leaf-cutter ants developed the secret of agriculture over 50 million years ago. In this article in Microbiology Today, Garret Suen and Cameron Currie describe how freshly-cut leaves are incorporated into gardens for the growth of a specialized fungus that the ants use for food:
Until about a decade and a half ago, research on fungus-growing ants focused primarily on the ants and their foraging behaviour. It wasn’t until the early 1990s that this focus shifted to the fungus gardens and their associated microbial communities. Since the ant gardens are maintained in soil chambers, they are routinely exposed to a number of potential pathogens that could infect and overtake a garden. In fact, many of the ant colonies do become overgrown by fungal pathogens, often resulting in the death of the colony. Intensive sampling of the fungal communities within the gardens revealed that a specialized microfungal pathogen selectively attacks the gardens of the fungus-growing ants.
Currently applied indicator organism systems, such as coliforms, are not fully protective of public health from enteric viruses in water sources. Waterborne disease outbreaks have occurred in systems that tested negative for coliforms, and positive coliform results do not necessarily correlate with viral risk. It is widely recognized that bacterial indicators do not co-occur exclusively with infectious viruses, nor do they respond in the same manner to environmental or engineered stressors. Thus, a more appropriate indicator of health risks from infectious enteric viruses is needed.
Torque teno virus is a small, non-enveloped DNA virus that likely exhibits similar transport characteristics to pathogenic enteric viruses. Torque teno virus is unique among enteric viral pathogens in that it appears to be ubiquitous in humans, elicits seemingly innocuous infections, and does not exhibit seasonal fluctuations or epidemic spikes. Torque teno virus is transmitted primarily via the fecal-oral route and can be assayed using rapid molecular techniques. We hypothesize that Torque teno virus is a more appropriate indicator of viral pathogens in drinking waters than currently used indicator systems based solely on bacteria.
To test the hypothesis, a multi-phased research approach is needed. First, a reliable Torque teno virus assay must be developed. A rapid, sensitive, and specific PCR method using established nested primer sets would be most appropriate for routine monitoring of waters. Because PCR detects both infectious and inactivated virus, an in vitro method to assess infectivity also is needed. The density and occurrence of Torque teno virus in feces, wastewater, and source waters must be established to define spatial and temporal stability of this potential indicator. Finally, Torque teno virus behavior through drinking water treatment plants must be determined with co-assessment of traditional indicators and enteric viral pathogens to assess whether correlations exist.
If substantiated, Torque teno virus could provide a completely new, reliable, and efficient indicator system for viral pathogen risk. This indicator would have broad application to drinking water utilities, watershed managers, and protection agencies and would provide a better means to assess viral risk and protect public health.
Leptospirosis is a relatively rare bacterial disease in humans but also affects a wide range of animals, including mammals, birds, amphibians and reptiles. It is caused by infection with Gram-negative spirochaete bacteria of the genus Leptospira.
The infection is usually transmitted to humans when fresh water that has been contaminated by animal urine comes into contact with unhealed breaks in the skin, eyes or the mucous membranes. In the UK, leptospirosis is most frequently associated with rat urine, but a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep and even marine mammals are also able to carry and transmit the disease. The causative bacteria are likely to be found on muddy riverbanks, ditches, gullies, and muddy livestock rearing areas which wild or farmed animals use regularly. There is a direct link between the amount of rainfall and the incidence of leptospirosis, making it a seasonal disease in temperate climates and year-round in tropical climates. The incubation period can be anywhere from 4 to 14 days and in humans the symptoms include high fever, severe headache, chills, muscle aches, and vomiting, and may include jaundice, red eyes, abdominal pain, diarrhea and a rash. Weil’s disease, a term which has often been used for leptospirosis in general, is reserved for severe multisystem disease with severe jaundice and impaired kidney function.
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It has recently been reported that a 56-year-old British woman has died from leptospirosis after being scratched by a wild rat that had been trapped in a wire bird feeder in her garden. The woman was injured while trying to free the animal. In fact, leptospirosis is an uncommon disease in the UK with a total of 15-30 cases reported yearly. 18 fatal cases were reported in England and Wales between 1988 and 2006. The disease occurs sporadically throughout the world, but a recent public health warning about leptospirosis was issued in Thailand after an outbreak involving 2030 cases and 46 deaths in the northeastern region of the country. This outbreak occurred as a result of heavy flooding across Thailand during September and October 2008.
Bioremediation is a process which uses microorganisms or their enzymes to return the natural environment altered by contaminants to its original condition.
Bees are important contributors to the economies of many countries, but as Travis Glare and Maureen O’Callaghan discuss in this article in Microbiology Today, they are many threats to the survival on the humble bee, including the risk of disease from micro-organisms:
