To grow a culture of bacteria, you need to control food, temperature, oxygen levels, pH and the disposal of waste products.
If you do not control the conditions, the food will run out and because of the metabolism of the microbes the temperature will rise rapidly. The oxygen levels will fall due to the microbes respiring. The waste product carbon dioxide can lower the pH and take up the oxygen space. Other waste products can build up and poison the microbes. So, eventually all the microbes will die.
At an industrial scale, fermenters are used to produce ideal conditions (double every 20mins) for microbes to grow. These will be used for drugs, food, etc.
Fermenters are designed to react to changes and solve the problems created by growing such a large amount of microbes. They have an oxygen supply that can be released regularly so the microbes can respire. They have a 'stirrer' to move the microbes so there is an even temperature and the oxygen and food is evenly spread out. They have a water cooler to remove the excess heat produced by the microbes respiring. They have sensors that monitor all conditions so changes can be made.
Mycroproteins a high protein, low fat meat substitute and it can be given a range of flavours to suit people's needs.
It is grown using the fungus Fusarium. This grows on a sugar syrup in large specialised fermenters. It needs aerobic conditions and it can double it's mass every 5 hours. It is then harvested, purified, dried and processed to make mycroprotein.