486 - Biohybrid Bacteria Build Biomass

Azotobacter vinelandii

This episode: Incorporating light-absorbing molecules into bacterial membranes can allow bacteria to use solar energy to transform nitrogen gas into fertilizer!
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Show notes:
Microbe of the episode: Wheat dwarf virus

 

Takeaways

Turning nitrogen gas into biologically useful compounds, such as protein or ammonia for fertilizer, is an essential part of the global nitrogen cycle and therefore, for agriculture. Today much fertilizer is produced from nitrogen gas by a chemical process that requires large amounts of energy, contributing to global warming. But certain bacteria can perform the same process using special enzymes much more efficiently.

In this study, a light-absorbing molecule was inserted into the cell membrane of some of these bacteria, allowing them to use light energy directly to power the nitrogen converting enzymes. These "biohybrids" were able to produce convert significantly more nitrogen gas and produce additional bacterial biomass from it, showing promise for using such an approach for more sustainable microbial fertilizer production.

Journal Paper:
Chen Z, Quek G, Zhu J, Chan SJW, Cox‐Vázquez SJ, Lopez‐Garcia F, Bazan GC. 2023. A Broad Light‐Harvesting Conjugated Oligoelectrolyte Enables Photocatalytic Nitrogen Fixation in a Bacterial Biohybrid. Angew Chem Int Ed 62:e202307101.

Other interesting stories:

• Update on using mosquito bacteria to block mosquito-borne viruses

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483 - Recycling Resources Raises Robustness

E. coli

This episode: Adding tags to proteins to increase their degradation can help engineered bacteria grow and survive better under various conditions!
Download Episode (7.3 MB, 10.4 minutes)

Show notes:
Microbe of the episode: Lactococcus virus sk1

News item

Takeaways

Engineering bacteria with new genetic pathways allows us to use them in many new and promising applications. Some of these are industrial fermentations, growing large quantities of bacteria to use as catalysts for production of chemicals of interest, such as biofuels. But in other cases, engineered microbes can be most useful in less controlled environments, such as the soil. In these situations, the engineering can throw off their natural metabolic balance, making them less tolerant of the stresses of such environments.

In this study, a solution to this issue was tested using protein tags that signal the bacterial enzymes to degrade the engineered proteins. A variety of tags allowed for a variety of rates of degradation, allowing engineers to tune in the ideal rate. Bacteria with these engineered tags grew better in nutrient limited conditions than those without.

Journal Paper:
Szydlo K, Ignatova Z, Gorochowski TE. 2022. Improving the Robustness of Engineered Bacteria to Nutrient Stress Using Programmed Proteolysis. ACS Synth Biol 11:1049–1059.

Other interesting stories:

• Microbes found in tap water could influence composition of the gut microbiome (paper)

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475 - Modifying Mixed Microbiota

Escherichia coli

This episode: New techniques allow specific modifications in certain members of a complex community of microbes, without isolating them in pure culture first!
Download Episode (11.5 MB, 16.7 minutes)

Show notes:
Microbe of the episode: Tomato golden mosaic virus

News item

Takeaways

The technology for understanding and manipulating microbial genetics has come a long way in a short time. It used to take years even to sequence a small genome, and now thousands can be sequenced in just a few days. The technology to change and even create genetic sequences is also much further advanced now than just a few decades ago. But still, many analyses and modifications require a pure culture of a microbe to carry out.

This study tested a method for modification of single or multiple species in a community of many. The method allows for identification of which species were successfully modified in targeted ways, and can allow the modified species to be extracted and studied individually.

Journal Paper:
Rubin BE, Diamond S, Cress BF, Crits-Christoph A, Lou YC, Borges AL, Shivram H, He C, Xu M, Zhou Z, Smith SJ, Rovinsky R, Smock DCJ, Tang K, Owens TK, Krishnappa N, Sachdeva R, Barrangou R, Deutschbauer AM, Banfield JF, Doudna JA. 2022. Species- and site-specific genome editing in complex bacterial communities. 1. Nat Microbiol 7:34–47.

Other interesting stories:

• Microbes that degrade plastic may be increasing in response to plastic pollution
• Algae in ocean communicate with each other using fluorescence

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466 - Microbes Mining Mars Minerals

Basalt close up
By Helgi, CC BY-SA 4.0

This episode: Bacteria are able to extract metals from rocks for industrial use, even in microgravity!

Download Episode (6.2 MB, 9.0 minutes)

Show notes:
Microbe of the episode: Decapod ambidensovirus 1

News item

Takeaways

As humanity makes progress toward becoming an interplanetary species, consideration is needed on how travelers can survive and thrive in distant places. These methods may look very different from what works well on Earth, with differences in gravity, atmosphere, and access to resources. For example, mining for materials for construction may not be feasible using methods common on Earth. An alternative may be biomining, using microbes that can selectively extract and purify specific metals from minerals.

In this study, the European Space Agency tested the ability of several microbes to extract vanadium from rocks in different gravity conditions, on the International Space Station. Two out of three microbes were able to extract twice as much vanadium as was extracted in the absence of microbes, both on a planet and up in space.

Journal Paper:
Cockell CS, Santomartino R, Finster K, Waajen AC, Nicholson N, Loudon C-M, Eades LJ, Moeller R, Rettberg P, Fuchs FM, Van Houdt R, Leys N, Coninx I, Hatton J, Parmitano L, Krause J, Koehler A, Caplin N, Zuijderduijn L, Mariani A, Pellari S, Carubia F, Luciani G, Balsamo M, Zolesi V, Ochoa J, Sen P, Watt JAJ, Doswald-Winkler J, Herová M, Rattenbacher B, Wadsworth J, Everroad RC, Demets R. 2021. Microbially-Enhanced Vanadium Mining and Bioremediation Under Micro- and Mars Gravity on the International Space Station. Front Microbiol 12:663.

Other interesting stories:

• A prokaryote with internal metabolic compartments (paper)

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461 - Ingrained Invader Inhibits Infectors

Lambda phage
By Hans-Wolfgang Ackermann
Swiss Institute of Bioinformatics
CC BY 4.0

This episode: Training a phage strain on bacteria can increase its ability to control those bacteria for much longer than an untrained phage!

Download Episode (5.7 MB, 8.3 minutes)

Show notes:
Microbe of the episode: Pepper yellow leaf curl Indonesia virus

News item

Takeaways

With resistance to antibiotics spreading more and more among deadly bacteria, finding alternatives to treat infections is becoming more important. One option is phage therapy, using viruses that infect bacteria to weaken or wipe out pathogens, but this can be tricky. Sometimes it takes too long to prepare an effective population of phage for treatment, and sometimes the target pathogen evolves resistance to the phage too quickly

In this study, a phage that was trained, or pre-evolved, to infect specific bacteria more effectively, was able to dominate the population consistently and prevent it from becoming fully resistant. For comparison, against an untrained strain of the same phage, the bacteria developed almost complete resistance after several days.

Journal Paper:
Borin JM, Avrani S, Barrick JE, Petrie KL, Meyer JR. 2021. Coevolutionary phage training leads to greater bacterial suppression and delays the evolution of phage resistance. Proc Natl Acad Sci 118.

Other interesting stories:

• Engineered gut bacteria could sense and indicate bowel inflammation

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445 - Living Lurking Landmine Locators

Bioluminescence over landmine
By Shemer et al. 2020,
Microb Biotechnol
CC BY-NC

This episode: Engineered bacteria encapsulated in little beads sense chemicals from landmines and give off light!

Download Episode (6.4 MB, 9.3 minutes)

Show notes:
Microbe of the episode: Bifidobacterium pullorum

Takeaways

Landmines are a good way to take an enemy by surprise and do some damage. They're so good that some places in the world still aren't safe to go decades after a conflict, due to intact landmines hidden in the area. In order to detect them from a distance to aid in disarming efforts, we need something very good at detecting the faint odor they give off—something like bacteria!

In this study, bacteria are engineered to detect breakdown products of TNT in landmines and produce light—bioluminescence. These bacteria are encapsulated in polymer beads and are stable for months in the freezer, and could accurately pinpoint a landmine buried in sand for a year and a half.

Journal Paper:
Shemer B, Shpigel E, Hazan C, Kabessa Y, Agranat AJ, Belkin S. Detection of buried explosives with immobilized bacterial bioreporters. Microb Biotechnol https://doi.org/10.1111/1751-7915.13683.

Other interesting stories:

• Wastewater treatment plant could power itself from electricity produced by microbes
• Microbial exposures correlate with presence or lack of allergies in both people and their dogs

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436 - Copper Concentrates Culture Current

Geobacter sulferreducens
By Mantapia11147,
CC BY-SA 4.0

This episode: Copper electrodes, rather than killing bacteria in microbial fuel cells, allow them to generate higher densities of electric current!

Download Episode (5.0 MB, 7.2 minutes)

Show notes:
Microbe of the episode: Xipapillomavirus 2

News item

Takeaways

Copper is widely used as a way to make surfaces and materials antimicrobial, to cut down on the spread of pathogens in hospitals and other environments. Among other mechanisms, it reacts with oxygen to form reactive oxygen species that are very harsh on microbial proteins. But copper is also a good electrical conductor, which would be useful to use in microbial fuel cells, which exploit bacterial metabolism to generate electricity. Microbes form biofilms on an electrode and transfer electrons to it as a way for them to generate energy. Most such fuel cells have used graphite electrodes to avoid toxicity.

In this study, fuel cell bacteria grew well on a copper electrode in an oxygen-free environment. The copper actually allowed them to increase the amount of current they produced per unit of area, as ionic copper diffused through the biofilm and allowed electrons to flow through the biofilm to the electrode from layers farther from the electrode that otherwise would not have access. Even graphite electrodes could be improved by adding these copper ions to the biofilm directly.

Journal Paper:
Beuth L, Pfeiffer CP, Schröder U. 2020. Copper-bottomed: electrochemically active bacteria exploit conductive sulphide networks for enhanced electrogeneity. Energy Environ Sci 13:3102–3109.

Other interesting stories:

• Lizard gut microbes are affected by temperature, and may affect lizard heat tolerance (paper)
• Phages in ice show evidence of trading genes easily to adapt to new environments

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435 - Invader Introducing Infrared Invokes Immunity

Mouse with darkened tumor
By Yi et al. 2020,
Sci Adv 6:eaba3546
CC BY-NC 4.0

This episode: Combining Salmonella with something called photoimmunotherapy to attack tumors in multiple ways!

Download Episode (8.2 MB, 11.9 minutes)

Show notes:
Microbe of the episode: Shimwellia blattae

Takeaways

Distinguishing healthy from unhealthy tissue is one of the big challenges when dealing with cancer. Since cancer is derived from healthy tissue, there are many similarities between them that make it hard to target it specifically. This is especially important when cancer is spread in multiple places throughout the body, as opposed to a single tumor that can be removed locally.

In this study, bacteria modified to make them safer were injected into mice with tumors. The bacteria alone were capable of doing some damage to the tumors, and this damage happened to make the tumors darker. Using this color change, the scientists targeted the tumors with lasers to heat them up and kill them in an isolated manner. This had the added benefit of inducing an immune response against the cancer that could target it throughout the body.

Journal Paper:
Yi X, Zhou H, Chao Y, Xiong S, Zhong J, Chai Z, Yang K, Liu Z. 2020. Bacteria-triggered tumor-specific thrombosis to enable potent photothermal immunotherapy of cancer. Science Advances 6:eaba3546.

Other interesting stories:

• Bacteria could help make nylon more sustainably
• Glowing bacteria living in nematodes that kill insects may also interact with and protect plant roots (paper)

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434 - Killer Carries Compact Cas

T4 bacteriophage
By Victoramuse
CC BY-SA 4.0

This episode: Large phage discovered that contains a compact version of the CRISPR/Cas defense/gene editing system!

Download Episode (5.9 MB, 8.6 minutes)

Show notes:
Microbe of the episode: Stenotrophomonas virus IME13

News item

Takeaways

CRISPR/Cas systems have made a lot of things in gene editing much easier in certain organisms. It's almost as easy as just getting the cells to produce the Cas protein and putting in an RNA sequence to tell it where to go! But in some cases, these requirements are too much to work well.

In this study, a more compact version of CRISPR/Cas was discovered in large bacteriophages. These systems help the viruses compete with other viruses and defend against host defenses sometimes. The Cas protein is half the size of the standard Cas most used in gene editing, and it has fewer other requirements to function in new cells, so it could be better in versatility and potential in applications with strict space constraints.

Journal Paper:
Pausch P, Al-Shayeb B, Bisom-Rapp E, Tsuchida CA, Li Z, Cress BF, Knott GJ, Jacobsen SE, Banfield JF, Doudna JA. 2020. CRISPR-CasΦ from huge phages is a hypercompact genome editor. Science 369:333–337.

Other interesting stories:

• Example of how cooperation becomes more beneficial than independence
• Programming bacteria to detect and kill specific other microbes in a mixed community (paper)

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427 - Simple Cells Stay Strong

Fluorescent SimCells
By Fan et al. 2020,
PNAS 117(12):6752
CC BY 4.0

This episode: Bacterial cells with their genomes removed can still be active and useful!


Download Episode (10.2 MB, 14.9 minutes)

Show notes:
Microbe of the episode: Rosavirus A

Takeaways

Microbes have amazing biochemical transformation abilities, creating and breaking down many compounds and proteins. This makes them great candidates for many purposes, in medicine, industry, and environmental remediation. In some of these purposes, though, there are risks associated with adding foreign microbes, especially engineered ones, that can replicate themselves and possibly persist, into new places.

To avoid this risk, this study turns intact bacteria into SimCells, simplified entities with most of their genetic material removed, leaving only the proteins and other components and just enough DNA to accomplish desired tasks. These SimCells were able to continue performing tasks for around 10 days before running out of the cellular resources needed to keep going. One of these tasks was producing a compound that damaged cancer cells in a dish but left non-cancerous cells unharmed.

Journal Paper:
Fan C, Davison PA, Habgood R, Zeng H, Decker CM, Salazar MG, Lueangwattanapong K, Townley HE, Yang A, Thompson IP, Ye H, Cui Z, Schmidt F, Hunter CN, Huang WE. 2020. Chromosome-free bacterial cells are safe and programmable platforms for synthetic biology. Proc Natl Acad Sci 117:6752–6761.

Other interesting stories:

• Biofuel-producing bacteria can generate electricity at the same time (paper)
• Using dried microbial biomass as fertilizer works pretty well (paper)

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421 - Nucleocapsids Navigate Nano Nuggets

Gold nanorods bound to phage
Used with permission

This episode: Using phages to target gold nanoparticles to infecting bacteria, then using light to heat the nanoparticles just enough to kill the bacteria!

Thanks to Huan Peng and Raymond Borg for contributing!


Download Episode (10.6 MB, 15.4 minutes)

Show notes:
Microbe of the episode: Pantoea agglomerans

News item

Takeaways
Viruses that infect bacteria, bacteriophages, are often very good at overcoming bacterial defenses and killing them. This raises the possibility, and many times actuality, of using phages to treat bacterial infections that are no longer treatable with antibiotics. But bacteria can evolve resistances to viruses as well as drugs, and using multiplying, evolving entities as treatments in people raises questions about the safety and consistency of the treatment.

This study circumvents these questions by using phages for delivery and targeting of bacteria rather than the therapeutic agent itself. The actual treatment is done with tiny rods of gold, gold nanorods, bound to the phage surface. When a certain wavelength of light hits these nanorods, they vibrate enough to generate enough heat in their immediate surroundings to render nearby bacteria nonviable. Thus the infection is treated in a very localized, targeted way that doesn't leave any active bacteria or phages behind. The authors have plans to study this approach as a topical treatment of wounds.

Journal Paper:
Peng H, Borg RE, Dow LP, Pruitt BL, Chen IA. 2020. Controlled phage therapy by photothermal ablation of specific bacterial species using gold nanorods targeted by chimeric phages. Proc Natl Acad Sci 117:1951–1961.

Other interesting stories:

• Two bacteria growing together on agar make pretty patterns
• Marine bacteria kill and digest other bacteria (paper)

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BacterioFiles 414 - Producing Proton Power Perpetually

Microalgae Chlamydomonas reinhardtii

This episode: Microalgae can produce hydrogen, but other metabolic pathways take priority, except when special engineered hydrogenase enzymes can overcome this limitation!

Download Episode (8.4 MB, 12.2 minutes)

Show notes:
Microbe of the episode: Alphapapillomavirus 11

Takeaways
There are many options being explored as ways to replace fossil fuels. Electricity and batteries are good, but they have their limitations, especially for long-distance high-energy travel such as airplanes. Hydrogen is one good option: high energy density, clean-burning, simple to produce. Microbes can produce hydrogen through various metabolic pathways, including fermentation, nitrogen fixation byproduct, and photosynthesis. However, competing metabolic pathways make microbial hydrogen production less efficient.

In this study, scientists engineer a hydrogenase enzyme for hydrogen production in microalgae that can compete better with carbon fixation as a destination for the electrons and protons that hydrogen production requires. This engineered enzyme allowed the algae to produce hydrogen continuously, even during photosynthesis.

Journal Paper:
Ben-Zvi O, Dafni E, Feldman Y, Yacoby I. 2019. Re-routing photosynthetic energy for continuous hydrogen production in vivo. Biotechnol Biofuels 12:266.

Other interesting stories:

• Plants use arsenic-dumping genes from bacteria to get essential nutrients
• Another study engineering better viruses for phage therapy

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BacterioFiles 405 - Coated Colonizers Counteract Corrosion

Coated bacteria on a coated surface
Rijavec et al. 2019, Adv Sci 1901408

This episode: Coating metal surfaces with artificial biofilms could help keep the surfaces corrosion-free even in the ocean!

Download Episode (6.3 MB, 9.1 minutes)

Show notes:
Microbe of the episode: Hymenopteran ambidensovirus 1

Takeaways
The ocean can be a harsh place for metal surfaces. Between the water, the salt, and oxygen (near the surface), corrosion is a common reality. Microbes in the ocean can contribute to this too, degrading metal structures to obtain energy for their metabolism. They colonize surfaces in biofilms that can be difficult to remove, a process called biofouling.

In this study, instead of trying to remove or prevent biofilms on surfaces, artificial biofilms were created by coating the surfaces and specially selected bacterial cells with polymers. This approach did not prevent colonization by other organisms in the sea, but preliminary results suggested that the community that did take up residence was not as corrosive as the communities found on uncoated steel.

Journal Paper:
Rijavec T, Zrimec J, Spanning R van, Lapanje A. 2019. Natural Microbial Communities Can Be Manipulated by Artificially Constructed Biofilms. Adv Sci 6:1901408.

Other interesting stories:

• Some microbe biofilms can protect outdoor metal sheets from corrosion
• How bacteria can be helpful for growing edible mushrooms (review)

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BacterioFiles 399 - Conductor Creating Carbon Canvases

Scanning probe microscope
image of graphene
By U.S. Army Material Command
CC BY 2.0

This episode: Bacteria can aide the production of the useful material graphene, using their ability to add electrons to external surfaces!

Download Episode (7.7 MB, 11.3 minutes)

Show notes:
Microbe of the episode: Brevibacterium frigoritolerans

News item

Takeaways
Advanced materials often take advanced techniques to create, but they offer numerous benefits: increased strength and flexibility, smaller size, more options. One such material is graphene, which is basically a sheet of carbon atoms linked together like chainmail. It is only a single atom thick but is amazingly strong, mostly transparent, and good at conducting heat and electricity.

The trick is, it's hard to make in large quantities cheaply and easily. Sheets of carbons can be obtained from blocks of graphite, but these sheets are graphene oxide, which lack the desirable properties of graphene. Chemical methods can be used to remove the oxidation, but they are harsh and difficult. Luckily, bacteria are great at microscopic remodeling. In this study, electron-transferring bacteria are able to reduce the graphene oxide to graphene with properties almost as good as are achieved by chemical reduction.

Journal Paper:
Lehner BAE, Janssen VAEC, Spiesz EM, Benz D, Brouns SJJ, Meyer AS, van der Zant HSJ. 2019. Creation of Conductive Graphene Materials by Bacterial Reduction Using Shewanella oneidensis. ChemistryOpen 8:888–895.

Other interesting stories:

• Frog skin gut bacteria correlate with resistance to deadly virus
• Skin microbiota could be transplanted to treat skin conditions (paper)

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BacterioFiles 396 - Bacteria Boost Blood Bank Budgets

Red blood cells

This episode: Bacterial enzymes could convert donated blood to be compatible with more people in need!

Download Episode (8.0 MB, 11.7 minutes)

Show notes:
Microbe of the episode: Cucumber leaf spot virus

News item

Takeaways
Blood transfusions using donated blood save many lives. Unfortunately, most donations can't be given to just anyone that needs blood; there must be a match in blood type between donor and recipient, or else a life-threatening reaction could occur in the recipient's body. So type A can't donate to type B, or vice versa, but type O is compatible with the other types.

In this study, bacterial enzymes found in human gut microbes have the ability to cleave off the unique type A and B sugars on the surface of red blood cells. This could allow the conversion of all donated blood to type O, greatly increasing the blood bank supply, but more testing is needed to develop the process.

Journal Paper:
Rahfeld P, Sim L, Moon H, Constantinescu I, Morgan-Lang C, Hallam SJ, Kizhakkedathu JN, Withers SG. 2019. An enzymatic pathway in the human gut microbiome that converts A to universal O type blood. Nat Microbiol 4:1475–1485.

Other interesting stories:

• Interesting new protist has novel swimming stroke
• Quantum dot-microbe hybrids power conversion of carbon dioxide to useful stuff

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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BacterioFiles 389 - Prokaryotes Pacify Protein Problem

E. coli bacteria

This episode: Engineered bacteria could help people digest an essential nutrient when they can't digest it themselves!

Download Episode (8.5 MB, 9.3 minutes)

Show notes:
Microbe of the episode: Kadipiro virus

News item (paywall)

Science-Based Medicine blog article about phenylketonuria, Synlogic, and engineering bacteria to treat this disorder, with lots of good detail

Takeaways
Treating genetic disorders can be very difficult. Sometimes they can be managed, with lifestyle, diet, or medication, but cure has almost always been out of the picture. With a disorder such as phenylketonuria (PKU), for example, in which the body is unable to fully metabolize the amino acid phenylalanine, diet and medication may work to some extent.

In an effort to provide better options for PKU, scientists at Synlogic, Inc have created a strain of Escherichia coli that produces phenylalanine-degrading enzymes in the gut. The hope is that ingesting this bacterium could allow PKU patients to be less restrictive with their diet.

Journal Paper:
Isabella VM, Ha BN, Castillo MJ, Lubkowicz DJ, Rowe SE, Millet YA, Anderson CL, Li N, Fisher AB, West KA, Reeder PJ, Momin MM, Bergeron CG, Guilmain SE, Miller PF, Kurtz CB, Falb D. 2018. Development of a synthetic live bacterial therapeutic for the human metabolic disease phenylketonuria. Nat Biotechnol 36:857–864.

Other interesting stories:

• Probiotic molecule induces protection in mice against viral brain infection
• E. coli growing with artificially synthesized genome (Extra information)

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BacterioFiles 386 - Cupola Contaminant Cleaners

Pisa cupola painting
By JoJan, CC BY-SA 3.0

This episode: Bacteria help gently clean residue off artworks painted on stone!

Download Episode (5.6 MB, 6.1 minutes)

Show notes:
Microbe of the episode: Cellulophaga virus Cba171

Takeaways
More and more cleaning products these days contain an ingredient called "enzymes." These are proteins that break down contaminants biologically instead of just removing them chemically, in a targeted manner.

In a similar approach, this study explores applying bacteria directly to classic artwork painted directly on stone, to clean up residues on the surface. These bacteria can produce enzymes on site and degrade the contaminants while leaving the underlying paint intact.

Journal Paper:
Ranalli G, Zanardini E, Rampazzi L, Corti C, Andreotti A, Colombini MP, Bosch‐Roig P, Lustrato G, Giantomassi C, Zari D, Virilli P. 2019. Onsite advanced biocleaning system on historical wall paintings using new agar-gauze bacteria gel. J Appl Microbiol 126:1785–1796.

Other interesting stories:

• Mouth bacteria prevent gum disease by interfering with activity of other bacteria (paper)
• Despite identical genetics, individual bacteria can behave differently through random variation

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BacterioFiles 381 - Chlorophyll Can Convey Cancer Characteristics

Tumor imaging by MSOT
By Peters et al. 2019,
Nat Commun 10:1191, CC BY 4.0

This episode: Pigmented bacteria can be used in a cancer imaging technique that combines light and sound!

Download Episode (8.9 MB, 9.75 minutes)

Show notes:
Microbe of the episode: Streptomyces bellus

Takeaways
Because "cancer" is a general term that describes many different forms of disease affecting different cells in different parts of the body, effective cancer treatment relies on understanding the location and physiology of the cancer in a given patient. New imaging technologies for diagnosis and analysis of cancer and for cancer research can be very valuable, especially if they don't require big investments of money and space.

One promising imaging technology is called multispectral optoacoustic imaging, or MSOT. This uses pulses of light to create vibrations as pigments in tissues absorb the light and undergo thermal expansion; these vibrations are then detected by ultrasound technology. This approach allows good resolution and depth of imaging without large equipment like MRI machines, but the best results require adding pigments into the body.

In this study, scientists showed that the photosynthetic pigments of purple non-sulfur bacteria can be useful in this optoacoustic imaging, providing a somewhat long-term, nontoxic approach. It proved especially interesting when they discovered that the wavelength spectrum changing over time was an indication of macrophage activity in the tumors.

Journal Paper:
Peters L, Weidenfeld I, Klemm U, Loeschcke A, Weihmann R, Jaeger K-E, Drepper T, Ntziachristos V, Stiel AC. 2019. Phototrophic purple bacteria as optoacoustic in vivo reporters of macrophage activity. Nat Commun 10:1191.

Other interesting stories:

• Figuring out the structure of bacterial nanowires

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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BacterioFiles 376 - Pressurized Pollutant Pulls Products

Bacillus megaterium
By Osmoregulator, CCBY-SA 3.0

This episode: Supercritical carbon dioxide and bacteria that can grow in it make a great combination for biofuel production!

Download Episode (9.4 MB, 10.2 minutes)

Show notes:
Microbe of the episode: Flexibacter aggregans

Takeaways
Biofuels are an important part of humanity's move away from non-renewable resources. They have a higher energy density than batteries are yet able to achieve, giving them significant advantages for transportation purposes in which tapping into an electric grid isn't possible. Depending on the biofuel, they also have the advantage of existing infrastructure: we don't need to build a whole new system of charging or refueling stations, but can use the systems already in place.

However, biofuels as a collection of technologies still need some refinements. Yields for the more potentially sustainable approaches are low, and the lower the concentration of a soluble fuel, the more difficult it is to separate it from the non-fuel components of a fermentation. Microbial products also face the risk of contamination of a fermentation by unwanted organisms that use up the substrate without producing desirable products.

In this study, supercritical carbon dioxide is considered as a fix for both of these problems. The gas is pressurized to a point at which it is indistinguishable from liquid. A strain of Bacillus megaterium is specially selected as capable of growing and fermenting in this environment, while contaminants are inhibited. The solvent potential of supercritical carbon dioxide also serves as a way to extract the biofuel product—in this case, isobutanol—from the aqueous part of the culture medium. While it needs some development, this approach yields promising results.

Journal Paper:
Boock JT, Freedman AJE, Tompsett GA, Muse SK, Allen AJ, Jackson LA, Castro-Dominguez B, Timko MT, Prather KLJ, Thompson JR. 2019. Engineered microbial biofuel production and recovery under supercritical carbon dioxide. Nat Commun 10:587.

Other interesting stories:

• Yeast adopted useful iron-capturing bacterial protein

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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BacterioFiles 375 - Prepared Pathogen Preserves Perception

This episode: A cancer-killing virus could help increase success of treatment of a form of eye cancer in children!

Download Episode (8.0 MB, 8.7 minutes)

Show notes:
Microbe of the episode: Acanthamoeba polyphaga mimivirus

News item

Takeaways
Cancer obviously is a serious concern, and can be tricky to treat because there are endless varieties in all different places in the body, each of which can have its own expected progression, aggressiveness, and methods of treatment to take into account.

Even more serious is when the cancer is in very young children, as is often the case with a cancer of the eye called retinoblastoma. There are about 8000 cases of this disease per year, and when treatment is unsuccessful, it can lead to the loss of one or both eyes.

In this study, investigators looked into using a cancer-targeting, oncolytic virus to complement the normal treatment of chemotherapy. The virus for the most part remained localized to the eye where it should be, and targeted the cancer instead of healthy cells, and so seems promising. In the small trial with two patients included in this study, the virus didn't cause a complete recovery, but showed some modest promising results.

Journal Paper:
Pascual-Pasto G, Bazan-Peregrino M, Olaciregui NG, Restrepo-Perdomo CA, Mato-Berciano A, Ottaviani D, Weber K, Correa G, Paco S, Vila-Ubach M, Cuadrado-Vilanova M, Castillo-Ecija H, Botteri G, Garcia-Gerique L, Moreno-Gilabert H, Gimenez-Alejandre M, Alonso-Lopez P, Farrera-Sal M, Torres-Manjon S, Ramos-Lozano D, Moreno R, Aerts I, Doz F, Cassoux N, Chapeaublanc E, Torrebadell M, Roldan M, König A, Suñol M, Claverol J, Lavarino C, De TC, Fu L, Radvanyi F, Munier FL, Catalá-Mora J, Mora J, Alemany R, Cascalló M, Chantada GL, Carcaboso AM. 2019. Therapeutic targeting of the RB1 pathway in retinoblastoma with the oncolytic adenovirus VCN-01. Sci Transl Med 11:eaat9321.

Other interesting stories:

• Exploring how microbes can influence the flavor of coffee

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

Subscribe: Apple Podcasts, RSS, Google Play. Support the show at Patreon, or check out the show at Twitter or Facebook.