a hodgepodge of thoughts @v-lajean - Tumblr Blog

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Aside from temperature, the dryness of your setup should also be controlled. Desiccation is when an organism or object is dried to the point where not a single drop of moisture remains. Some species of bacteria can’t stand very arid conditions, while others love it! There are also species of microorganisms that merely tolerate dryness, remaining viable, but no longer growing. These species remain in a suspended state for years until proper growing conditions are provided for it to resume growth. Lyophilization is the application of this concept in laboratories. There’s a huge chance that you’ll encounter this the next time you do labwork with microbes.

With this in mind, it is crucial to determine which species remain pathogenic when in dry conditions. There is always an off-chance that the cloth you’re holding, or the seemingly safe sample you’re testing contains a dried, but pathogenic strain of bacteria, which in turn would cost either your, your coworkers’, or your patients’ health and safety.

Another factor of note when preparing your very own culture is osmotic pressure. Osmotic pressure refers to the force between two different solute concentrations separated by a membrane only permeable by the solvent. In simpler terms, this is basically the force that stops the flow of solvent. Osmotic pressure is key to preparing proper bacterial cultures since the wrong kind of environment may cause your culture to die.

When a microorganism is subjected to a hypotonic (low solute) solution, water will flow into the cell and cause lysis or bursting, since the cell interior has a higher concentration than the environment. In order to counter this, some species have evolved rigid cell walls that maintain structure and shape. On the other hand, when a specimen is placed in hypertonic (high solute) solution, the organism will plasmolyze, which is essentially the dehydration and subsequent shriveling of the cell. The water leaves the cell because there is a higher solute concentration in the environment. Some species of bacteria have evolved mechanisms to counter this. Halophiles are salt-tolerating bacteria that “salt-out” or expend energy to remove the salt aggregations that can kill non-halophilic species. Most species of bacteria love isotonic solutions. This is when the solute concentrations of both the bacteria and environment reach an equilibrium, thus no longer causing a change in volume.

Much Ado About Bacterium

It’s no secret that there are living beings even smaller than what we can see. Bacteria is everywhere! Think about your favorite foods. The spicy-sour kick from kimchi, the tangy-sweet aftertaste from yogurt, and other unique tastes from fermented food are all thanks to bacteria! As quickly as it is to prepare fermented food at home, culturing bacteria for a laboratory setting takes more time and care. For instance, you have to take note of the conditions for your bacteria to grow. Different kinds of bacteria require different specific conditions to ensure optimal growth.

Bacteria require a particular temperature range in order to actually grow. There are three distinct cardinal temperatures to be taken into account here: minimum growth temperature, maximum growth temperature, and optimal growth temperature. Minimum growth temperature is the lowest possible temperature for the bacteria to be able to grow. Maximum growth temperature, on the other hand, is the highest possible temperature that can induce growth. Minimum and maximum temperatures represent the lowest and highest border in the temperature range. The optimal growth temperature is a value (or a range of values) within the growth range that represents the natural living conditions of the organism.

For instance, Polaromonas vacuolata can only grow between -1.5 to 12°C, with 4°C being its optimum temperature. -1.5°C is its minimum growth temperature, and 12°C is its maximum. With these values, we can infer that P. vacuolata LOVES the cold. In fact, it was first discovered off the coast of Antarctica. Brrr!

P. vacuolata is a psychrophile! Which means it can grow at 0°C and have optimal temperatures on or below 15°C. Mesophiles grow between 20 - 45°C. Most bacteria are part of this category. Cool, right? Finally, we have the thermophiles, which grow at 45°C and higher. It’s terrifying to think what kind of habitats these bacteria live in.

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I often forget Ryoma from Fire Emblem Fates is a human with armor rather than some half-human half-crustacean abomination; so when I see photos of him without the armor I get very frightened