The latest Business updates from the science industry


by Heather Hobbs Bacterium demonstrates robust Light Harvesting Architecture


An interesting investigation made by a collaboration of European and British scientists, suggests that a novel bacterium discovered eight years ago conducts an ancient form of photosynthesis. The new organism, a rare bacterial genus Gemmatimonas discovered in Lake Tian E Hu (Swan lake) in the Gobi desert, was found to contain bacteriochlorophyll, a pigment related to chlorophylls found in plants.


Following analysis of its genome, Dr Pu Qian Lead author of the study commented: “This structural and functional study has exciting implications because it shows that G. phototrophica has independently evolved its own compact, robust and highly effective architecture for harvesting and trapping solar energy.”


In their paper ‘2.4 Å structure of the double-ring Gemmatimonas phototrophica photosystem’[1] the scientists describe how they used electron cryomicroscopy collected


in four different


Since the pigments in the outer ring have higher energy than the pigments in the center of the ring the whole arrangement serves as a funnel. The energy absorbed by the pigments at the periphery of the complex is transfered within several picoseconds down the energy gradient to the centre of the complex where it is transformed into metabolic energy.


Dr Alistair Siebert, Principal Beamline Scientist: HeXI, the electron Bio-Imaging Centre (eBIC, Diamond Light Source) commented: “This work is part of a long-established collaboration with these expert laboratories who have worked extensively to characterise the fundamental mechanisms of light-harvesting and biological organisms.”


photochemistry in labs;


initially, at Basel University, with which they got a projection map of the complex. Data was then collected at eBIC (Electron Bio-Imaging Centre), at Diamond Light Source in the UK, from which a 3.4 Å resolution structure was obtained. Further data collection was done at the CEITECH in the Czech Republic. Combining the two datasets produced a 3.2 Å model and a fi nal data collection performed at Thermo Fisher Scientifi c resulted in the 2.4 Å resolution structure.


Their work revealed the detailed structure of the photosynthesis complex, which comprises 178 pigments bound to more than 80 protein subunits. The light harvesting subunits are arranged in two concentric rings around the reaction centre which converts the absorbed light energy into an electrical charge. “The architecture of the complex is very elegant. A real masterpiece of Nature,” said Dr Michal Koblizek from the Institute of Microbiology, Czech Academy of Sciences. “It has not only good structural stability, but also great light harvesting effi ciency.”


Photosynthetic complex from bacterium Gemmatimonas phototrophica – (courtesy: Dr Tristan I. Croll,


University of Cambridge, UK)


“This novel complex illustrates an alternative means to achieve the spectral gradient required for ultra-rapid and effi cient light-harvesting by utilising a novel double-ring pigment assembly – a unique alternative solution.


“The team used four different cryoEM facilities worldwide and the early access to high-end instrumentation, state of the art direct detectors, high throughput data collection methods and on the fl y data processing available at eBIC at


Diamond Light Source was a crucial component in the projects’ success.”


More information online: ilmt.co/PL/O1dv


1. ‘2.4 Å structure of the double-ring Gemmatimonas phototrophica photosystem’ published on 16 February in Science Advances, the team show how this enigmatic organism harvests light energy (Qian et al. Science Advances,https://www.science.org/doi/ 10.1126/sciadv. abk3139.


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Swan lake in northern China where the bacterium Gemmatimonas phototrophica was collected (courtesy: Professor Fuying Feng)


TEM image of Bacterium Gemmatimonas phototrophica – (courtesy: Jason Dean BSc. from the Institute of Microbiology, Czech Academy of Sciences, Trebon)


Graphene Oxide offers Promising Potential as Bone Repair Scaffold


Working towards development of an alternative to the use of bone grafts for repairing diseased or damaged bone, researchers at McGill University have used the Canadian Light Source (CLS) at the University of Saskatchewan to advance a novel method for growing synthetic bone tissue.


Bone tissue engineering is focused on growing bone cells in scaffolds in the lab and transferring these structures into the damaged area inside the body. The material used for the scaffold needs to have an interconnected network of small and large pores to enable nutrients and cells to spread into the damaged area and help generate new bone tissue. The McGill team took the


approach of modifying the internal structure of Graphene oxide an ultrathin, extra strong compound that is being used increasingly in electronics, optics, chemistry, energy storage and biology. One of its unique properties is that when stem cells are placed on it, they tend to transform into bone-generating cells called osteoblasts.


The multidisciplinary group – comprising researchers from McGill’s Departments of Mining and Materials Engineering, Electrical Engineering, and Dentistry – found that adding an emulsion of oil and water to the graphene oxide, then freezing it at two different temperatures, yielded two different sizes of pores throughout the material.


Professor Marta Cerruti said that when they ‘seeded’ the now- porous scaffolding with stem cells from mouse bone marrow, the cells multiplied and spread inside the network of pores, a promising sign the new approach could eventually be used to regenerate bone tissue in humans.


“We showed that the scaffolds are completely biocompatible, that the cells are happy when you put them in there, and that they’re able to penetrate all through the scaffold and colonise the whole scaffold,” she stated.


Yiwen Chen, the team’s scaffold and Marta Cerruti (Credit: Canadian Light Source)


The researchers used the BMIT-BM beamline at the CLS to visualise the different sized pores inside the scaffolding as well as the growth and spread of the cells. Lead researcher Yiwen Chen, a PhD student working under Cerruti, said their work would not have been possible without the synchrotron because the low density of graphene oxide means it absorbs only a very small amount of light.


Experimental Floor at the CLS Synchrotron (Credit: Canadian Light Source)


“To our knowledge, this is the fi rst time that people have used synchrotron light to see the structure of graphene oxide scaffolds,” said Chen.


Although widespread clinical application of this approach may still be many years away, Cerruti thinks their work could enable other researchers to learn more about how stem cells morph into bone cells.


“Maybe this will lead to a better understanding of the biology of bones that we wouldn’t understand otherwise,” she said. “Perhaps in the shorter term we can use the methods in the lab to better understand bone and perhaps develop new drugs.”


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