![]() ![]() ![]() For this process to take place, a rigid mesh-like layer called the cell wall, which lies outside the cell membrane, needs to be remodelled. Then the membrane that surrounds the mother cell moves to surround the forespore and engulf it. To make a spore, the bacterial cell divides to make a larger mother cell and a smaller forespore cell. Some bacteria, such as Bacillus subtilis, form spores when starved of food, which enables them to lie dormant for years and wait for conditions to improve. Hence, we establish a biophysical mechanism for the creation of a force for engulfment based on the coordination between cell wall synthesis and degradation. We propose a simple model for engulfment in which the junction between the septum and the lateral cell wall moves around the forespore by a mechanism resembling the ‘template model’. Here, we show that membrane migration is driven by cell wall remodeling at the leading edge of the engulfing membrane, with peptidoglycan synthesis and degradation mediated by penicillin binding proteins in the forespore and a cell wall degradation protein complex in the mother cell. However, the force generation mechanism for forward membrane movement remains unknown. Subsequently, the mother cell membrane engulfs the forespore in a phagocytosis-like process. Sporulation initiates with an asymmetric cell division, creating a large mother cell and a small forespore. Hope you enjoyed this topic and see you next week for more exciting pictures of microorganisms.When starved, the Gram-positive bacterium Bacillus subtilis forms durable spores for survival. From this information, it can be said that the bacterial cells that contain endospores inside of the cell have received some kind of environmental stress, while the free endospores are dormant and the bacterial cells without the endospores have not received environmental stress. The endospores will stay remain inactive until a bacterial cell needs it again as a result of environmental stress. Once the bacteria relieves itself of environmental stress, the endospores get released from the bacterial cell and the cell itself will be destroyed. When these bacteria receive stress from the environment that limits their growth, they begin to form endospores from vegetative cells. So what's the importance of these so called endospores? Well for Bacillus megaterium, it is use as a survival mechanism. Then there are a few endospores that remained inside the bacterial cells. These free endospores above appear to be a cluster of two rather large endospores. When looking at the picture above you can see that some spores are outside the cells which are commonly known as free endospores. This lets us know exactly where each cell is and whether or not the endospores are inside the cells or outside. This process allows us to see the endospores in green while the cells appear pink. There was no discoloration process, commonly performed in differential staining, for spore staining. In spore staining, Malachite green dye was used to stain the endospores as well as Safranin, commonly used in Gram staining, was used to stain the cells. This week in microbiology lab we spore stained Bacillus megaterium shown above at 1000x (1000 times) more than what we can see with the naked eye. ![]()
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