Biology subjects

Davey, M. P.

Publications and source records attributed to Davey, M. P..

2 recordsLinked to original sources

bioRxiv2019

Physiological and molecular responses of a newly evolved auxotroph of Chlamydomonas to B12 deprivation

The corrinoid B12 is synthesised only by prokaryotes yet is widely required by eukaryotes as an enzyme cofactor. Microalgae have evolved B12 dependence on multiple occasions and we previously demonstrated that experimental evolution of the non-requiring alga Chlamydomonas reinhardtii in media supplemented with B12 generated a B12-dependent mutant (hereafter metE7). This clone provides a unique opportunity to study the physiology of a nascent B12 auxotroph. Our analyses demonstrate that B12 deprivation of metE7 disrupted C1 metabolism, caused an accumulation of starch and triacylglycerides and a decrease in photosynthetic pigments, proteins and free amino acids. B12 deprivation also caused a substantial increase in reactive oxygen species (ROS), which preceded rapid cell death. Surprisingly, survival could be improved without compromising growth by simultaneously depriving the cells of nitrogen, suggesting a type of cross protection. Significantly, we found further improvements in survival under B12 limitation and an increase in B12 use-efficiency after metE7 underwent a further period of experimental evolution, this time in coculture with a B12-producing bacterium. Therefore, although an early B12-dependent alga would likely be poorly adapted to B12 deprivation, association with B12-producers can ensure long-term survival whilst also providing the environment to evolve mechanisms to better tolerate B12 limitation.

biochemistry↗

bioRxiv2019

Bionic 3D printed corals

Symbiotic corals have evolved as a highly optimised photon augmentation system leading to space-efficient microalgal growth and photosynthetic quantum efficiencies that approach theoretical limits1-3. Corals are characterized by an elastic animal tissue hosting microalgae and a light scattering calcium carbonate skeleton that maximizes light delivery towards otherwise shaded algal-containing tissues4,5. Rapid light attenuation due to algal self-shading is a key limiting factor for the upscaling of microalgal cultivation6,7. Coral-inspired light management systems could overcome this limitation and facilitate scalable bioenergy and bioproduct generation8,9. Here, we developed 3D printed bionic corals capable of growing various types of microalgae with cell densities approaching 109 cells mL-1, up to 100 times greater than in liquid culture. The hybrid photosynthetic biomaterials are produced with a new 3D bioprinting platform which mimics morphological features of living coral tissue and the underlying skeleton with micron resolution, including their optical and mechanical properties. The programmable synthetic microenvironment thus allows for replicating both structural and functional traits of the coral-algal symbiosis. Our work defines a new class of bionic materials capable of interacting with living organisms, that can be exploited for the design of next generation photobioreactors7 and disruptive approaches for coral reef conservation10.

bioengineering↗