Here's a recipe if interested
How to make LAB:
The first step is to collect bacteria from the air using water that has been used to rinse rice. You can use any kind of rice for this. Simply put it in a pot with warm water, mix the rice around and then drain the water [now milky]. The water is now a rich source of carbohydrates. This liquid will attract microbes from the air, among them lactobacillus. Get a container, fill halfway with with the water that you have drained from the rice. Cover the container with a clean rag and let stand outside the house for a couple of days to a week
When is it ready?
When you see a light layer on the top (mold) and smells a little sour (like yogurt and yeast). This indicates the liquid is infected with microbes. This occurs more rapidly in warm temperatures because microbes are more active, therefore the time it takes to to create an effective culture is relative because we do not do it under controlled laboratory conditions.
When it is done the liquid will be separated into three different layers:
Top layer: floating carbohydrates left over from fermentation and possibly mold.
Middle layer: lactic acid and other bacteria. We will use this layer.
Bottom layer: Starch, byproduct of fermentation
Remove the middle layer by filtering the liquid or using a siphon. This layer contains the highest concentration of lactic acid bacteria and the lowest concentration of unnecessary by-products
Get a new container, bigger than the first. Take the rice water and mix at a ratio of 1 part rice water to 10 parts of milk. By saturating with milk (lactose), we do not allow other microbes to proliferate, leaving only lactobacillus.
TIP: The best milk to use is unpasteurised natural milk. However, any milk can be used even powdered milk. In my experience, the best is natural unpasteurized milk (the curds also make a better cheese), but just use whatever is available.
You want to keep this next stage as anaerobic as possible. Use a sealed container with a one way air valve.
Note: Beware of bubbling during this phase. The container should not be completely filled or it may go through the valve. After approximately one week (depending on the temperature), you will see that the milk is curdled (Carbohydrates, proteins and fats) and separated in two two layers. The water below will be yellow – this is the serum (whey), enriched with Lactic acid bacteria from milk fermentation. The water below is what we use. You want to extract this.
NOTE: Remember that the curds (the top layer of the fermented milk), are an excellent food and can be used to make a delicious cheese. They are enriched with healthy nutrients and microbes. If you are not interested in cheese feed them to your pets or animals or even your compost pile. There is no waste in natural agriculture!
The whey can be kept in the fridge for up to two weeks but for our purposes we want it to last longer and be more effective (and not take up space in the fridge). To preserve add an equal portion of brown sugar or molasses to the whey. So, if you have 1l of whey, add 1kg of brown sugar or 1L of molasses. This way it can be stored at room temperature (out of direct sunlight) for up to a year.