New study challenges some dogmas about marine microbial life (phys.org)
Typically, bacterial growth rates are calculated by simply counting cells over time, but if you have a type that is dying/getting eaten fast and also dividing fast then the population can look static even though it's actually a fast grower. Some researchers decided to use a different technique where they microscopically look at individual cells and see what portion of them are in the process of cell division to estimate the growth rates that way. For most bacteria, this gave the same results as expected from the typical total cell count method, but not for all bacteria.
The single most abundant group of bacteria in the open ocean and on reefs was found to have a mismatch.
"For example, we found that the most common group of bacteria in the ocean, called SAR11, divides almost ten times faster than assumed." Moreover, in many cases the measured growth rates do not match the abundance of the respective bacteria in the water.
"If bacteria divide often but are not abundant, it suggests that they are a popular victim of predators or viruses," Brüwer explains. "The timing of bacterial proliferation was also surprising: SAR11 bacteria frequently divided before the onset of the algal bloom in the North Sea. From where they took the required energy to do so is still a mystery."
This group of bacteria shows up in our aqubiomics reports as "pelagibacteraceae". And it's interesting in a few ways...
It's a low nutrient bacteria - it grows better on seawater controls than on nutrients from algae or corals. It dominates the cell counts in low nutrient reefs/open ocean. For these reasons and because the numbers tend to be pretty stable, it was assumed to be a slow grower with slow die-off and low levels of predation. In the hobby it is a very significant member of our microbiome - unless you run UV. No other bacterial family is affected nearly as much by UV. For the pelagibacteraceae, UV is like an on/off switch.
Until now, it has been assumed that SAR11, which have very small cells, get by with little nutrients, do not divide very often and are eaten only rarely because of their small size. In contrast, other larger bacteria, for example the Bacteroidetes, are seen as popular food, multiplying quickly and disappearing just as quickly when predators and viruses get on their trail. The new study by Brüwer and his colleagues paints a very different picture.
"Our results influence our understanding of element cycles, especially the carbon cycle, in the ocean," Brüwer says. "The most abundant bacteria in the ocean, SAR11, are more active and divide faster than previously believed. This could mean that they need fewer nutrients and are a more popular food source for other organisms than suspected. Also, the general turnover of bacteria during algal blooms seems to be faster than we thought."
Here's @AquaBiomics talking about this group of bacteria in reefs and our tanks.
talk at PNWMAS meeting (59:50 in video)
Typically, bacterial growth rates are calculated by simply counting cells over time, but if you have a type that is dying/getting eaten fast and also dividing fast then the population can look static even though it's actually a fast grower. Some researchers decided to use a different technique where they microscopically look at individual cells and see what portion of them are in the process of cell division to estimate the growth rates that way. For most bacteria, this gave the same results as expected from the typical total cell count method, but not for all bacteria.
The single most abundant group of bacteria in the open ocean and on reefs was found to have a mismatch.
"For example, we found that the most common group of bacteria in the ocean, called SAR11, divides almost ten times faster than assumed." Moreover, in many cases the measured growth rates do not match the abundance of the respective bacteria in the water.
"If bacteria divide often but are not abundant, it suggests that they are a popular victim of predators or viruses," Brüwer explains. "The timing of bacterial proliferation was also surprising: SAR11 bacteria frequently divided before the onset of the algal bloom in the North Sea. From where they took the required energy to do so is still a mystery."
This group of bacteria shows up in our aqubiomics reports as "pelagibacteraceae". And it's interesting in a few ways...
It's a low nutrient bacteria - it grows better on seawater controls than on nutrients from algae or corals. It dominates the cell counts in low nutrient reefs/open ocean. For these reasons and because the numbers tend to be pretty stable, it was assumed to be a slow grower with slow die-off and low levels of predation. In the hobby it is a very significant member of our microbiome - unless you run UV. No other bacterial family is affected nearly as much by UV. For the pelagibacteraceae, UV is like an on/off switch.
Until now, it has been assumed that SAR11, which have very small cells, get by with little nutrients, do not divide very often and are eaten only rarely because of their small size. In contrast, other larger bacteria, for example the Bacteroidetes, are seen as popular food, multiplying quickly and disappearing just as quickly when predators and viruses get on their trail. The new study by Brüwer and his colleagues paints a very different picture.
"Our results influence our understanding of element cycles, especially the carbon cycle, in the ocean," Brüwer says. "The most abundant bacteria in the ocean, SAR11, are more active and divide faster than previously believed. This could mean that they need fewer nutrients and are a more popular food source for other organisms than suspected. Also, the general turnover of bacteria during algal blooms seems to be faster than we thought."
Here's @AquaBiomics talking about this group of bacteria in reefs and our tanks.
talk at PNWMAS meeting (59:50 in video)
