When studying the growth of bacteria, a number of factors are important to keep in mind. The first thing to keep in mind is that most bacteria reproduce asexually by duplicating their DNA and splitting in a process known as binary fission. Many factors are important for bacteria to reproduce, and each specific type of bacteria has exact conditions that it prefers for it to be able to survive and reproduce. Many of these factors include temperature, pH, and osmotic pressure. In terms of your question, osmotic pressure is the most important factor to consider. Due to the large amount of water located in a bacteria cell, these cells need specific environments where osmolarity is neither too high nor low to reproduce. In the case of low extracellular osmotic pressure (more water present) water will be forced into the cell and cause it to burst. If osmotic pressure is high (less water present) in the extracellular environment, water will flow out of the cell to even out the osmotic differences. This leads to compression of the cell and can lead to cell death. Some bacteria are less sensitive to osmotic pressure than others, and have ways to regulate the amount of water that can pass through their membrane. In general, bacteria tend to grow best in wet, moist environments. Hope this helps!