MicrobiologyBytes

I’ve written quite a lot on MicrobiologyBytes about the growing threat from Bluetongue virus. New figures from the European Commission now show that BTV 8, the epidemic strain of the virus, has been virtually eradicated from mainland Europe after an extensive vaccine campaign.

Tens of thousands of cases of bluetongue, predominantly the BTV8 strain, were identified across Europe in 2007 and 2008. The numbers dropped significantly in 2009 and are on course for a further significant decline this year.

The latest figures from the European Commission show incidence of BTV 8 has declined to just two recorded cases, while rare European cases of other strains are also on the way down.

Bluetongue virtually eradicated in Europe. Farmer’s Guardian, 2 November 2010

Related:

• Bluetongue virus
• Midges and the emergence of bluetongue virus in northern Europe
• How does bluetongue virus survive the winter?

Marine natural products are a continued focus for drug discovery and have provided many important therapeutic agents. Lead compounds with biomedical potential have been isolated from marine invertebrates, bacteria, and fungi. Each year numerous compounds with an array of biological activities are reported, but to-date only 13 molecules have entered into the clinical pipeline. Four molecules have been approved for clinical use, one of which is approved only in the EU. The approved molecules include two nucleosides based on sponge-derived nucleosides, a cone snail peptide, and a metabolite isolated from a tunicate. Marine microbes have received growing attention as the sources for bioactive metabolites and have great potential to increase the number of marine natural products in clinical trials. The sustainable and economic supply of the active pharmaceutical ingredient is often easier to achieve for compounds produced through microbial fermentation approaches versus the cultivation of slower growing macroorganisms.

Marine natural products provide an excellent opportunity to study diverse and unique compounds not readily accessible from any other source leading to expansion of the pharmaceutical pipeline. Marine microbes can produce unique compounds covering new chemical space, and the utility of marine natural products is expanding beyond its original role in identification of new prototype drug leads into fields of study involving sustainable supplies of unique molecules using biosynthesis in conjunction with synthesis. Perhaps the greatest impact marine natural products has played is in revealing that unexplored and previously inaccessible chemical space can contribute to growth in the pharmaceutical pipeline. Improved methodologies in fermentation technologies, biosynthesis, and synthesis provide opportunities to both create and supply drug leads that would not be available by any single method independently. As a result pharmaceutical biotechnology in the future is certain to provide increasingly sophisticated molecular architecture assembled using biosynthesis and synthesis in concert.

The expanding role of marine microbes in pharmaceutical development. Curr Opin Biotechnol. Oct 16 2010
Marine microbes have received growing attention as sources of bioactive metabolites and offer a unique opportunity to both increase the number of marine natural products in clinical trials as well as expedite their development. This review focuses specifically on those molecules currently in the clinical pipeline that are established or highly likely to be produced by bacteria based on expanding circumstantial evidence. We also include an example of how compounds from harmful algal blooms may yield both tools for measuring environmental change as well as leads for pharmaceutical development. An example of the karlotoxin class of compounds isolated from the dinoflagellate Karlodinium veneficum reveals a significant environmental impact in the form of massive fish kills, but also provides opportunities to construct new molecules for the control of cancer and serum cholesterol assisted by tools associated with rational drug design.

Related:

• Biofilms Use Chemical Weapons
• New Approach for the Discovery of Antibiotics
• Predator and Prey

From the first molecules of oxygen produced by marine cyanobacteria ~3.5 billion years ago to the methanogens luxuriating in the warm, carbon-rich swamps of the Carboniferous period, microbial processes have long been key drivers of, and responders to, climate change. It is widely accepted that microorganisms have played a key part in determining the atmospheric concentrations of greenhouse gases, including carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) (which have the greatest impact on radiative forcing), throughout much of Earth’s history. What is more open to debate is the part that they will play in the coming decades and centuries, the climate feedbacks that will be important, and how humankind might harness microbial processes to manage climate change. The feedback responses of microorganisms to climate change in terms of greenhouse gas flux may either amplify (positive feedback) or reduce (negative feedback) the rate of climate change. With the twenty-first century projected to experience some of the most rapid climatic changes in our planet’s history, and with biogenic fluxes of the main anthropogenic greenhouse gases being tied integrally to microorganisms, improving our understanding of microbial processes has never been so important.

Microorganisms and climate change: terrestrial feedbacks and mitigation options. (2010) Nature Reviews Microbiology 8, 779 doi:10.1038/nrmicro2439
Microbial processes have a central role in the global fluxes of the key biogenic greenhouse gases (carbon dioxide, methane and nitrous oxide) and are likely to respond rapidly to climate change. Whether changes in microbial processes lead to a net positive or negative feedback for greenhouse gas emissions is unclear. To improve the prediction of climate models, it is important to understand the mechanisms by which microorganisms regulate terrestrial greenhouse gas flux. This involves consideration of the complex interactions that occur between microorganisms and other biotic and abiotic factors. The potential to mitigate climate change by reducing greenhouse gas emissions through managing terrestrial microbial processes is a tantalizing prospect for the future.

Related:

• Calcifying cyanobacteria and carbon capture
• Climate change influences infectious disease in the Arctic and the tropics
• Extreme Weather Events And Epidemics

On the 11th October at the Society for Applied Microbiology hosted a lecture by Proffessor Willy Verstraete on Microbial Resource Management. Here’s the blurb:

In the 21st century, we are faced with a set of challenges: from climate change to the need for renewable energy sources, the threat of new pandemics and the general demise in environmental quality. The role of micro-organisms in each of these challenges is crucially important and to fully understand how microbes play a part, we must better explore our microbial resources as they currently exist – in culture collections or at evolved environmental sites. We need to develop key strategies to deal with microbial communities, instead of thinking in terms of haphazard assemblages of species. A pragmatic approach to this problem is proposed in this lecture, making use of current developments in molecular methods. Also, a list of potential environmental biotech solutions which are appropriate to the current market economy are presented. By upgrading the services of microbial communities through implementing Microbial Resource Management (MRM) and combining these communities with novel technology, we can indeed address these challenges.

And here’s the lecture:

Eben Bayer talks about MycoBond, a technology that uses a filamentous fungi to transform agricultural waste products into strong composite materials. MycoBond products include packaging and styrofoam substitute and in-development rigid insulation board for builders. These products require less energy to create than synthetics like foam, because they’re quite literally grown. Equally compelling, at the end of their useful life, they can be composted or used as garden mulch.

Nematode worms burrowing through the soil encounter thousands of species of bacteria, but how do they find safe food choices from this vast buffet? A major part of the nematode’s ability to distinguish between food sources relies on a sophisticated chemosensory system that enables it to sense and respond to a wide range of volatile and water-soluble chemicals. During the past decade, the roundworm Caenorhabditis elegans has become a popular model for the study of host/pathogen relationships, leading to a wealth of information about microbial virulence factors and host defense pathways. Although the complicated interactions between C. elegans and the many pathogens that it encounters in the soil have become clearer in recent years, there is still much to learn. What are the cues that worms use to detect food sources? How do worms choose which bacterial species to eat and which to leave alone? Once a pathogen is encountered, what are the microbial killing mechanisms and the nematode’s survival mechanisms? This paper provides a rare view of one C. elegans/pathogen relationship. It describes the signals Bacillus nematocida uses to attract C. elegans, the virulence factors it uses to kill worms from within, and the specific host proteins targeted.

A Trojan horse mechanism of bacterial pathogenesis against nematodes. (2010) PNAS USA 107 (38) 16631–16636
Understanding the mechanisms of host–pathogen interaction can provide crucial information for successfully manipulating their rela- tionships. Because of its genetic background and practical advantages over vertebrate model systems, the nematode Caenorhabditis elegans model has become an attractive host for studying microbial pathogenesis. Here we report a “Trojan horse” mechanism of bacterial pathogenesis against nematodes. We show that the bacterium Bacillus nematocida B16 lures nematodes by emitting potent volatile organic compounds that are much more attractive to worms than those from ordinary dietary bacteria. Seventeen B. nematocida-attractant volatile organic compounds are identified, and seven are individually confirmed to lure nematodes. Once the bacteria enter the intestine of nematodes, they secrete two proteases with broad substrate ranges but preferentially target essential intestinal proteins, leading to nematode death. This Trojan horse pattern of bacterium–nematode interaction enriches our understanding of microbial pathogenesis.

Related:

• Nematode provides new animal model for emerging pathogen

Fungi reproduce both sexually and asexually, producing a vast array of structures which have evolved over time to suit habitat and in some cases host. These structures are of great economic importance to society. Approximately 48% of the world’s food crop yield is lost due to plant diseases, of which the majority are caused by fungi. For most fungal diseases, the primary sources of inoculum are sexual and/or asexual spores. As well as economic losses, fungi can have positive economic benefits for agriculture, such as biocontrol of plant diseases. Numerous fungi have been successfully developed as biocontrol agents (BCAs) of plant diseases and the majority of these are sold as spore preparations.

The global fungal BCA market is dominated by species of the ubiquitous ascomycete Trichoderma. In general, commercial preparations of Trichoderma spp. for biological control consist of bulk-produced conidia (asexual spores), but good biocontrol activity in the environment relies upon the fungus remaining vegetative, and thus antagonistically active. The ideal Trichoderma BCA produces ample conidia in a cost-effective manner during production and maintains long periods of vigorous vegetative growth during usage. Understanding the factors that control this morphogenic switch from mycelia to conidia is integral to biocontrol research. Over 50 years of studies on conidiation in the genus have established Trichoderma as a model for asexual reproduction in fungi. This review presents what is known about the physiological responses of Trichoderma to the environmental cues that induce conidiation, and provides insights into the molecular basis of these responses, including an examination of the signal transduction pathways which link environmental signals to physiological outputs. Understanding species-specific differences in metabolic adaptations to the environment should assist biocontrol design and implementation. Knowledge of the appropriate conditions for maximal yields of viable spores would likely reduce production costs. Knowledge of survivability and vigour within a complex environment could enable targeting of biocontrol strains to the soil or foliar condition appropriate for their species. It may also be possible to create designer BCAs which incorporate desired traits through protoplast fusion or genetic modification.

Reproduction without sex: conidiation in the filamentous fungus Trichoderma. Microbiology 2010 156: 2887-2900
Trichoderma spp. have served as models for asexual reproduction in filamentous fungi for over 50 years. Physical stimuli, such as light exposure and mechanical injury to the mycelium, trigger conidiation; however, conidiogenesis itself is a holistic response determined by the cell’s metabolic state, as influenced by the environment and endogenous biological rhythms. Key environmental parameters are the carbon and nitrogen status and the C:N ratio, the ambient pH and the level of calcium ions. Recent advances in our understanding of the molecular biology of this fungus have revealed a conserved mechanism of environmental perception through the White Collar orthologues BLR-1 and BLR-2. Also implicated in the molecular regulation are the PacC pathways and the conidial regulator VELVET. Signal transduction cascades which link environmental signals to physiological outputs have also been revealed.

Related:

• Bacterial endophytes
• High Tech Fungi

In a damning indictment of the UK government, Nature says:

The killing fields. Nature 467, 368 (23 September 2010) doi:10.1038/467368a

Related:

• Culling badgers a low priority for curbing cattle tuberculosis (PNAS article)
• Public health and bovine tuberculosis
• Irish badger cull ‘futile’ in controlling bovine tuberculosis
• David Willetts warned over science cuts by universities
• Science is Vital Campaign

Researchers examined the responses of various microorganisms (viruses, bacterial cells, bacterial and fungal spores, and lichens) to selected factors of space (microgravity, galactic cosmic radiation, solar UV radiation, and space vacuum) in space and laboratory simulation experiments. In general, microorganisms tend to thrive in the space flight environment in terms of enhanced growth parameters and a demonstrated ability to proliferate in the presence of normally inhibitory levels of antibiotics. The mechanisms responsible for the observed biological responses, however, are not yet fully understood. A hypothesized interaction of microgravity with radiation-induced DNA repair processes was experimentally refuted.

The survival of microorganisms in outer space was investigated to tackle questions on the upper boundary of the biosphere and on the likelihood of interplanetary transport of microorganisms. It was found that extraterrestrial solar UV radiation was the most deleterious factor of space. Among all organisms tested, only lichens (Rhizocarpon geographicum and Xanthoria elegans) maintained full viability after 2 weeks in outer space, whereas all other test systems were inactivated by orders of magnitude. Using optical filters and spores of Bacillus subtilis as a biological UV dosimeter, it was found that the current ozone layer reduces the biological effectiveness of solar UV by 3 orders of magnitude. If shielded against solar UV, spores of B. subtilis were capable of surviving in space for up to 6 years, especially if embedded in clay or meteorite powder (artificial meteorites). The data support the likelihood of interplanetary transfer of microorganisms within meteorites, the so-called lithopanspermia hypothesis.

Space microbiology. (2010) Microbiol Mol Biol Rev. 74(1): 121-56

Related:

• They Came From Space – or did they?
• Bugs in space
• Is microbial life on Mars possible?