Can virus and bacteria survive in salt water?

Updated May 11

The keyword is “halophile”. Like other types of extremophiles, most of these are in the domain Archaea, which are kind of like bacteria, but kind of different.

The issue with salt water is that, a high concentration of sodium chloride in the surrounding water environment, might suck out the water that is inside the cell. That is called “osmosis”.

A way to avoid this is to have a compensating solute inside the cell, which does not have to be sodium, and can be a range of other things. Those substances keep the water inside the cell from being sucked out. It takes energy and certain genetic information to do this.

It isn’t exactly a matter of just “surviving”. They are adapted to their environment, and actually need it.

If you took them out of their normal high-salt water environment, and put them into distilled water (theoretically zero salt) they would die. A similar issue exists for hyperthermophiles, which would freeze to death at room temperature. These are some reasons why culturing and studying extremophiles is a major hassle.

As for viruses, they don’t “survive” anything, because they aren’t technically alive in the first place.

A virus may have a protein coat (capsid), which might be disrupted by a high-salt environment. However, as with bacteria, some species may be quite happy with it.

Some other viruses are “enveloped”, and are coated with part of the membrane of the host cell that they had infected and escaped from. Those are a lot more fragile, and may be deactivated just by sitting around exposed to the air for awhile (e.g. that cold/flu virus that sat on the elevator button for a couple of days). So I would expect those to be vulnerable to every threat, including high salt.

Fun Fact #1: “Salt” doesn’t just mean sodium chloride table salt. It really relates to ionic compounds, like a metal and a non-metal.

Fun Fact #2: The most abundant biological unit on Earth is bacteriophages. They are viruses that infect bacteria, and the oceans (salt-water) are full of them. I only really know a lot about one (1, n=1, a single, solitary one) virus, and it is one of these, and apparently quite durable in many environments.

Why don’t we use the antibodies of recovered patients to treat antibiotic-resistant bacteria? We spend time developing new, chemically synthetic, small molecules as new antibiotics to treat the previously untreatable resistant bacteria.

Updated Mar 20

Thanks for the A2A.

As I recall, when your body produces antibodies in response to an infection, it tries out a very large number of randomly-generated antibodies. When one of those random ones “fits” onto the surface of the microbe, then your body starts producing more of that particular antibody. You can make a range of antibodies which fit onto different surface features of the microbe.

Those antibodies that work to help clear the infection are very specific to the microbe that you have.

If you took your antibodies from your blood and purified them, the process would be resource-intensive, and expensive. Also, the new patient may be infected with a microbe that is different to yours, so your antibodies won’t fit onto it. Even the same species can have mutations that will prevent the binding.

Some viruses are particularly rapid with these mutations, and can do it during the infection of one person. HIV does this, which is one of a few reasons why a vaccine is so difficult to make. It becomes a “moving target”.

I’m not sure of the level of risk that, antibodies transferred from one individual to another would be viewed as foreign enough to trigger a negative reaction. In scientific research, there are “secondary” antibodies available, that bind to other antibodies, but these are produced by a process involving two different species of animals (e.g. a rabbit and a goat).

Some gamma globulins are occasionally administered, in limited contexts. Also, a new mother’s first dose of breast milk contains some immune components, although only a small amount will get through to the infant’s bloodstream, and for a short time period after birth.

Speaking of which, antibodies are proteins, so (unless you are only a couple of days old), your digestive system will chop them up into very short peptides before absorption into your bloodstream. That makes it impossible to take them in a pill, and they would need to be injected, instead.

There is another peptide-based possibility being studied, called bacteriocins. They are made by bacteria to attack each other, and the mechanisms are not yet understood. They are apparently fairly narrow-spectrum, and you still wouldn’t be able to take them orally.

Conventional antibiotics work on a range of different microbes (including narrow-spectrum and broad-spectrum drugs). There are a few general mechanisms. Some disrupt bacterial cell walls, some disrupt bacterial protein synthesis, etc. You don’t necessarily even need to know the exact species causing the infection.

Antibiotics are often used in a prophylactic (preventative) effort. You might have an injury, or a surgical procedure, where you don’t have any infection (yet), but there is a risk, and you need generalised protection. In my experience, penicillin derivatives seem to be the standard choice in that situation.

In order for phagocytes to consume pathogens, they release pseudopods to engulf the pathogen. How do phagocytes do this, do they have some kind of muscle or is it something within the cytoplasm?

Answered Jan 26

Pseudopodia are sort of like fingers that form and sort of blob out of the surface of the cell that is making them.

Inside the cell, there is always a sort of girder-like supporting structure/network called the cytoskelton. This gives the cell physical support and shape, a bit like a person’s skeleton.

However, the cytoskeleton can grow or shrink very quickly, and can be made to grow in a certain place and certain direction, as needed.

The cytoskeleton is partly made of a building block called actin. It is a protein that can be stacked into long strings. Stacking it in a certain way causes the pseudopod “fingers” to poke outwards. Kind of like growing a new arm, just because you needed one at that moment.

Later, the actin filament gets taken apart, and the pseudopod shrinks back.

In your muscle tissues (where the components are more fixed in place), actin is partnered with another protein called myosin, to do contraction (pulling). There, the strings sit there parallel to each other, and contraction is a sliding motion (the chemical and mechanical actions are somewhat complicated).

In the phagocytes, there is a further process called (strangely enough) phagocytocis, in which your cell pulls in the pathogen, and puts it into a vesicle (like a bag) where the pathogen is dissolved by enzymes. This involves proteins on the cell surface pulling a small area inwards, to form the vesicle.

Some other cells, like amoeba stages of some single-cell protozoa organisms can also use pseudopodia to reach out and pull themselves along (similar to crawling).

What is the best YouTube channel to study microbiology?

Answered Dec 20, 2017

Thanks for the A2A.

On YouTube (or the internet in general), there isn’t just one single resource that I can recommend.

However, I have a page of links for science students (of all levels) at:

Links For Science Students

Please excuse the formatting, as I still need to work on that. However, these are the best links that I have found so far, and are somewhat categorised by field of study, with a few comments.

This page will improve in the near future, but generally, these are the links that I have appreciated, for biology, biochemistry, chemistry, mathematics, and , of course, microbiology.

Where did the first bacteria on earth come from?

Answered Dec 16, 2017

Thanks for the A2A.

The answer is (drum-roll, please…)

Nobody knows.

It was a really, really long time ago.

Perhaps, somehow, a little bubble in the water on a beach got some amino acids and nucleic acids (specifically RNA) into it. Those molecules may have formed from water (containing various stuff dissolved in it) dripping onto a rock that heated and cooled off each day.

Perhaps it arrived, frozen in the ice of a comet or meteorite, from some other planet.

Nobody knows, and there is probably zero way for anyone to ever know.

That sounds kind of “zen”, doesn’t it?

Are there any study to design bacteria so they can produce all essential nutrients by photosynthesis?

Answered Dec 15, 2017

Thanks for the A2A.

The answer is “no”, because photosynthesis is about using the energy from sunlight, to help use carbon dioxide as a building-block to put together sugar molecules, which are made of carbon, hydrogen, and oxygen. Those sugars function as energy storage (which is how plants survive every night), and also as building material, which is how plants grow new stems, leaves, etc.

Some bacteria can do photosynthesis for sugar-assembly, but there are many other essential nutrients.

If the organism has the necessary enzymes, they can use certain “carbon skeletons” (including acetyl-CoA and Krebs cycle intermediates) as building blocks for lipids and part of amino acids.

However, it still needs to get certain other, vital things from the environment (which cannot be generated by photosynthesis, either by bacteria or by plants).

It needs things like:






Those need to be obtained from the environment, which can be anything from the jelly-like medium in a petri dish, based on various recipes, by microbiologists (ahem), to just the regular, random soil in your backyard (different places support different microbes).

Another commentator seemed to interpret your question as being about food for humans. And the answer on that is “no”, because your food needs to get the above-listed nutrients from someplace that isn’t just photosynthesis.

What would the earth be like if there are no bacteria to decompose animal and plant remains?

Updated Feb 6, 2018

Those are called saprophytes, although there is a wide range, and some fungi also perform this function.

If no decomposition was happening at all, then the nutrients wouldn’t be available for recycling into plants, so my guess is that all other life on earth would eventually starve. It might take awhile.

Also, partly decayed plant and animal matter is among the things consumed by worms, insects, etc, so it would disrupt the food-chain / food-web from that angle, as well.

Edited To Add: Another group of bacteria whose absence would be disastrous are the participants in the nitrogen cycle, because all plants need nitrogen in a form that is generated by those bacteria.

Edited To Add Again: I recall reading an article stating that, plant matter (fallen leaves, etc) near the Chernobyl nuclear disaster site wasn’t breaking down as normal. If true, that suggests that, the radiation has harmed a range of saprophyte bacteria and fungi. This could have a sort of secondary impact on the ecosystems there, for future plants and animals.

Could chemicals be used to mutate strains of bacteria and/or fungus and/or viruses?

Answered Dec 13, 2017

Sure, you can use certain chemicals to cause genetic mutations.

The catch is that, the mutations will be totally random, and you cannot direct it to any particular part of the genome.

You could randomly disable important genes, by causing a SNP or a frameshift error, and kill the microbe.

The keyword is, “random”.

Why do hand soaps say they clean 99.9% of bacteria and not 100% or 95.6% for instance?

Answered Dec 12, 2017

All of that is advertising hype. Don’t worry about any of it. Just use the cheapest regular soap that you can get at your local supermarket.

The whole “antibacterial” claim is rubbish.

From a microbiologist perspective, these “antibacterial” products are a bad thing. (long, scientific story).

Just buy whatever soap is the cheapest, and which your skin feels OK about.

What is the best textbook on medical microbiology?

Answered Dec 12, 2017

I have used Medical Microbiology by Murray, et. al.

With these textbook recommendation concerns, I suggest going to your university library, and looking at what they have on the shelf (or in the library catalogue). Especially see if they have multiple copies of a certain book. That will often be the one that your lecturers/professors are working with.