Some microorganisms, such as lactic acid bacteria or yeasts, have been helping humans since time immemorial. Since the last century, they have helped humans as a kind of cellular factories to produce important medicines, some industrial chemicals, biofuels, food ingredients or promising new materials. For this production they need sugar, most often glucose from plants. Scientists have now explored how bacteria can "learn" to process new groups of sugars, for example from waste plant biomass.
A team of scientists from the Department of Experimental Biology at Masaryk University's Faculty of Science has discovered how bacteria adapt to new sources of carbon and energy, and has developed an efficient process that allows the adaptation to be accelerated and used in modern biotechnology. The research, on which the team collaborated with foreign scientists from Australia, Germany and Spain, has been published in the prestigious journal Nature Communications. "The published research allows us to better understand how bacteria 'learn' to process new groups of sugars, the transformation of which can make biotechnological production of useful substances cheaper and more widespread," says Pavel Dvořák, team leader from Masaryk University and coordinator of the published work.
Thanks to their simple body structure, rapid reproduction, ease of manipulation and diverse 'pipelines' of cell metabolism, microorganisms help humans in the industrial production of, for example, important pharmaceuticals, but also promising new materials such as biodegradable plastics. Bacteria produce these important substances mostly from sugars in starch, most commonly glucose from corn or wheat grains, or from potatoes. However, their use can in some cases be seen as wasteful, as these crops are also used to feed the human population. "That's why it's better to look for other sugars, such as xylose, which is the second most abundant sugar on planet Earth after glucose, and which is stored in the indigestible-to-humans component of residual plant biomass - which, in simple terms, is almost all that remains of a plant in the field when you harvest corn or wheat grains," explains Dvořák. But this is not easy, because industrial bacteria are often unable to process these sugars. "It's like a vegetarian learning to eat meat that his body hasn't been used to," Dvořák says, exaggerating the process of gradually accustoming the microorganisms.
Figure 2. The method of Synthetically Primed Adaptation presented in the study by the authors from Masaryk University allows a kind of 'molecular agreement' between the desired genetic modifications and the existing metabolic pipeline in the bacterial cells. The bacterium gets used to the new 'component' (shown here as a new piece of the puzzle) inserted into its metabolic pipeline more easily thanks to the action of laboratory evolution. In the current study, this allowed Pseudomonas putida to adapt more easily to the sugar xylose, which is abundant in the indigestible component of residual plant biomass (the example of cereal straw used here). Bacteria will thus be able to use the sugars from this type of material for the biotechnological production of chemicals that have so far been prepared from fossil sources.
"Using the example of the biotechnologically exploited bacterium Pseudomonas putida, we have shown how these microscopic helpers can be effectively taught to process sugars from waste biomass," says study co-author Barbora Popelářová from the Section of Microbiology at the Faculty of Science of the Masaryk University. "For this purpose, we examined the metabolism of the studied bacterium in detail, inserted new 'components' into it at the DNA level using metabolic engineering methods, and at the same time, through the action of laboratory evolution in the test tube, allowed the bacterium to get used to the new 'components' and the new sugar. This was successful and we were subsequently able to decipher how the bacterium adapted to the new sugar. You could say that we had a glimpse of evolution, but its direction was largely determined by our targeted interventions in the bacterium's metabolism," says Popelářová.
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