yeasts are everywhere and if I look very carefully at these plums I can see that on the surface they're looking slightly kind of Milky in places the milkiness is due to the growth of microorganisms I now need to roll that Plum very carefully onto some special jelly a jelly that contains nutrients that will grow the microorganisms I'm hoping that the microorganisms that were on the surface of the plum will now be transferred to the surface of this jelly this jelly contains food that will make the yeast cells grow but this takes time and so what we need to do is to encourage the cell CS to grow we're going to put it in the warm and we're going to leave it there for 1 to 2 days this is called an incubator and it's just a heater it will keep the microorganisms nice and warm my plate has been in the incubator now this oven for just over a day and I can see that there are things growing on it I can see clearly that there are lots and lots of cells that have grown into colonies all over that food and what you will notice is that where I rolled it I've got organisms growing but where the fruit didn't roll nothing is growing these yeast cells that are growing all over the surface of this jelly have come from the plums that we used yesterday but to really check I need to make a slide and to look at those cells underneath the microscope I'm going to light the buns and burner because we're going to do some microbiology work I've got my microscope slide here and I've got my yeast cells there and I'm going to take a small colony with what is called an inoculating loop I need to sterilize this Loop so I turn my bunson so it gives a nice raw which you can probably hear I hold the loop like this and I get the wire red hot that sterilizes the wire but it's now too hot to use so I just wait a few seconds 1 2 3 4 5 I touch the jelly where nothing is growing no it's not too hot and now I'm just going to stroke the surface a very gentle stroke and as I stroke the surface that little colony of cells gets caught on the loop I'm now going to place them onto the microscope slide I sterilize the loop by Gent drawing it through the flame so it gets red hot it is now quite hot so I'll just lie it down like that now I need to spread those cells out I place a drop of water onto my cells and now I need to spread that out with my Loop I'm going to spread out those cells to form a very thin layer the cells have dried onto the surface of my glass slide and what I need to do now is to glue those cells to the glass and the easiest and simplest way is to pass them very quickly into that bunson the stain is a little messy so I'm going to put the slide in the plastic dish and I'm going to add one or two drops of this bright red stain the dye hasn't gone all the way over the cells so what I would normally do is take a loop and just gently move the dye over the cells so that they are all stained once they have stained I need to wash off the stain I've got some water here I'm going to pick up this side of the slide and gently wash the surface like this and I think you can see that we've got nice pink cells and I'm very gently going to blot the surface to get rid of the excess water water this is special oil that is used in microscope work I need a drop there right in the very middle I have to place this slide on the microscope and then set it up now that sometimes takes a little bit of time to get everything just right I take my slide over to the microscope stage and I place it here I turn on the power because in the bottom is a bulb and the light goes through the slide up through these which are called objectives into the eyepiece which is here now I have to adjust the slide I can move it backwards and forwards from side to side so that the area I want to look at is directly underneath I'm going to use this lens here which is called an oil immersion lens and I lift the stage up you can see it coming up and I put the lens just into the oil now I need to look down the microscope I adjust just the width for my eyes and the focus I gently Focus down down and yes there they are the most beautiful yeast cells I've seen for a long [Music] time