[Music] [Music] microbes are and it's it's the way CDU was defining microbes in 1878 it was a doctor okay a military doctor he was defining them as invisible life and for me it's in the only a size issue microbes are small organisms that you cannot see if you don't have a microscope and it encompass a huge fellow genetic diversity of things that started to diversify well before the multitude our organism so not only it's highly diverse but also it's small so it can be everywhere without you to see it and nowadays there is this view that everything is embedded in tons of microbes which we called micro biota I [Music] like to go back to the definition by the guy who created the world hacker in the 19th century was establishing this as the way organisms are using their living environments to update it a bit it's the relationship between living organisms that are together in a living together and the relationship also to the biotic physical chemical environment nowadays having the idea that micro biota are everywhere first of all how skin on our God having this idea that micrometer are everywhere it turns out ecology to be mainly the relationship between microbes and between material organisms and microbes it turns out to be now a major issue in ecology [Music] yes the gut microbiota have been disseminating a bit the rest of the microbiota and the fact is that if you look at a plant for example there are microbes everywhere especially cos cells in plants have a cell wall with small holes between the cell walls of the different people cells where microbes can't think for example that in a leaf in one gram of leaf you have hundred millions of bacteria so it's really everywhere in the plant first of all the root of the roots of the plants they really need colonization by fungi to be able to exploit the soil so from head to tune the plant is having a micro biota and if you shift to animals then the colonization is a bit different it's not between each cells it's in on the surface and in the wall in the cracks of the animal it's not going within the tissues but still it's there for the police to take human I have a slide here which is nice for that you can see that we have microbiota on the skin of course and it's it's like a thousand billions of bacteria you have them also on on the head and you're given some photosynthetic bacteria they're funny you having of course in the mouth the edge of a juice - interesting we know that we also have it in the vagina for for the ladies or it's very important for further functions and equilibrium of this organ so it's in every old every surface of animals but be you a plant or an animal you are filled with microbes and a number of these microbes is the same magnitude order then the one of our cell number it's 10,000 million of human cells for 10,000 millions of bacteria [Music] so we have some experimental data on this even on humans when you take antibiotics you are killing a lot of your gut microbiota and it results in huge change in gene expression in the intestinal cells you are more prone to Jerry are you have some less resilient community in the gut so we know that there is some dysfunctioning when there is punctual disturbance but there is more due to I Gina we now in Europe and in America in westernized countries have much less diverse microbiota and it turns out that this is an expression to those illness which are arising in the modernity like asthmatic problems like autoimmune problems like even autism those problems which are now raising fast because over ten years we have three times more of teasin for example those problems which are which will be for example problem in ten years we see that one European out of two will have such a modern problem which did not exist so much in the nineteenth century and we know now that within the complex determinism of those complex illness I don't think so simple one of the issue is the fact that we don't have a sufficiently diverse micro biota especially when we are young and grow an established or immune system nervous system and so on because micro buta human microbiota is helping to establish a normal development in the youth so we see what happens when there is a disturbance of those micro biota there is a disturbance of us because in a way our functioning on health is the result of microbial ecosystem in part we are in a way an ecosystem service of a microbial ecosystem and when this ecosystem is disturbed we are disturbed as a result of that because the service is not brought anymore I think it's a delicate question because in ecology we have this idea of equilibrium first of all we discussed the concept of resilience which is going back to the previous step and behind there is the idea that the previous step was an equilibrium but be careful that in ecology there is no equivalent is changing because there is evolution in ecological systems as well everything can be modified everything can be changed and we just discussed that the fact that for example our gut ecosystem was recently by way of the westernization of our way of living modified I think that the most important is to conceive the equilibrium in ecology not as something which is fixed and stable because by the way it can be destabilized but exactly as your equilibrium when you are biking when you are biking you are not in equilibrium in this world in this sense that you will not fall but really you can fall when you're bike but you rectify and you have a kind of dynamic equilibrium and the equilibrium of a micro biota will be exactly the same as in equilibrium in ecology it really fluctuations around a state which you wish to have because it gives the best ecological services it gives the best health in the case of the micro biota so what we have to learn is not to think of a perfect state which would not change but how to organize fluctuation with fluctuations within a ranch which is fitting our expectations in terms of goal for example for human or animal health