How prey bacteria shape the community structure of their predators:
Predator and prey interactions have been noticed and studied since as far back as anyone can remember, unfortunately for microbiologists there havent been many studies as far down as microbes. This is due to numerous reasons; the most obvious being that it just isnt as easy due to the sheer range in sizes of them and that most microbes are minute, so compared to studying fish the difficulties are easy to spot.
Thankfully Huan Chen et al, decided to look at Bacteriovorax and how its prey; Vibrio vulnificus & Vibrio parahaemolyticus affect its population structure and number. The method that was used was to have flasks full of seawater and a specific concentration of the Bacteriovorax and either the V.vulnificus or the V.parahaemolyticus within the same flask as the predator and to monitor the abundance of the prey at specific time periods after the two were added together.
The results shown by this study showed that in the presence of a ready supply of prey a significant multiplication of abundance was demonstrated and this increase was extremely quick, the exact speed was a thousand fold increase within 24hours, from the 24 hour time mark to the 48 hour mark. This increase led to a 2-4 fold log of prey reduction. Along with this it was shown that the Bacteriovorax had a faster predation on the V.p compared to the V.v. There were two clusters studied to see if there was a preferential prey for the predator and what was found was that V.v was preferential in one and V.p in the other, so although the rate of predation may have been quicker, given a choice of one or the other there isnt a favourite. Aswell as this as expected the paper showed that with an increase in prey this led to the standard predator-prey fluctuation where then predator levels increased and prey abundance decreased.
The reason why this paper is important and interesting is due to the fact that it is the start of a hopefully increasing area of study and it provides a backbone for the future studies. So it's important to the ever growing field of marine microbiology.
I hope more studies are done like this as it's always interesting to study predator and prey interactions and as there hasnt been much in this field it will be interesting to see just how far down the trophic scale predation plays a major part.
Here is the webpage if you want to read this paper:
http://www.nature.com/ismej/journal/v5/n8/pdf/ismej20114a.pdf
Huan Chen, Rana Athar, Guili Zheng and Henry N Williams
ISME J 5: 1314-1322; advance online publication, February 17, 2011; doi:10.1038/ismej.2011.4
Hi Oliver,
ReplyDeleteI saw you and Anna have reviewed the same paper and decided it must be worth a read!
I have to say I agree with what Anna is saying about the applicability of this kind of research. Whilst I appreciate it is a field in its very infancy, I still think to make any real generalisations on how biotic factors may act as a selection pressure to change community structure, more variables and species should be considered, and certainly over a longer time period. From what I can make out this study spanned 120hours; at the 72hours point Bx reached its maximum population number whilst its prey Vv was at its lowest point, in the 24hours after this the Bx population showed signs of decay whilst the Vv began to recover; yes this does begin to look like a typical predator prey oscillation, but do the Vv make a full recovery? Does the oscillation pattern continue over generations? or does the predator begin to totally dominate over time?
I think what I am trying to say isn’t a criticism of the rational, method, results or even conclusions the authors have come to, I think it’s a great paper and a really good start to what is potentially a huge field of research. I’m rather questioning any speculative inferences that we can make at this point from such a basic set of data.
Hi Vicky, I agree it would have been interesting to see this experiment continued over a longer time period to potentially get a cyclical trend of prey/predator. I don't think Bacteriovorax will be able to fully dominate, because it needs its prey not only as food source, but also as growth and multiplication chamber. So no prey means no multiplication, actually a very neat negative feedback system regulating both predator and prey abundance.
ReplyDeletehey, sorry about the late reply, havent been on in a while, in answer to your questions vicky as far as i can tell from the information published neither of the prey make a full recovery and as the experiment was quite short there was only time for one obvious oscillation. As you stated the data set was only small and seems to just be providing a backbone for future research but in my opinion the oscillations would continue if you carried on the experiment for longer with possibly just a decreasing maximum number of each of the prey sp. if you get what im saying? Hopefully another experiment will be performed over a longer period and this field will continue to grow. Hope this helps.
ReplyDeleteAnd as for reviewing the same paper, thats probably my bad, i mustve missed her review.
Hello again guys,
ReplyDeleteAnna, can you go over what you mean by multiplication chamber please.
And Oliver I agree; I think this microbe-microbe, biological interactions field, if done properly, could potentially improve our understanding of not just the ecology of what is living where and why, but a thorough experimental approach may enable us to get a better understanding of what biological interactions are acting as selection pressures and driving the evolution of communities. This paper is certainly a good step in the right direction.
Similar to viruses, Bdellovibrio is an obligate parasite, so it requires a host to multiply (although I am not sure whether that applies to all Bdellovibrios, some might be faculative parasites). Rendulic et al. (2004) published an interesting paper where they report the entire genome of a bdellovibrio and how certain genes are involved in the different stages of attack, formation of bdelloplast (joint structure of prey and Bdellovibrio) and cell division. Their findings also suggest that B. bacteriovorus is capable of protein biosynthesis only while it has access to amino acids from its prey.
ReplyDeleteSince Bdellovibrio prey on several pathogens, it is of particular interest to study the enzymes that are involved in the attack and permeation of the cell wall. These degradative enzymes could help developing antimicrobial agents or even living antibiotics.
I hope this answers your question, Vicky. Here is the link to the paper: http://www.sciencemag.org/content/303/5658/689.full
Thanks Anna that certainly does answer my question!
ReplyDelete