Bdellovibrio-and-like organisms (BALOs) are ubiquitous predatory bacteria which prey on other gram-negative bacteria. They have been shown to prey on many pathogens however cannot be cultured using eukaryotic cells which gives them potential to become very useful anti-microbial agents. The idea of this study is to see if they could potentially be used to rid seafood of pathogenic vibrios before human consumption.
They isolated BALOs from the marine environment using Vibrio parahaemolyticus as the host bacteria by adding 5g of sediment with 50ml of host culture and incubating at 30 degrees. They then plated out the culture using a double layer agar technique. Bacteria were isolated from plaques which formed after 2-3 days and continued to grow which helped to distinguish between BALOs and viruses. The isolates were then identified using electron microscopy followed by PCR. The isolates were then tested for lysis on 40 potentially human pathogenic strains of vibrio which covered 7 different species.
4 strains of BALOs were identified, isolated and coded BDW01 to BDW04. Individually BDW01, BDW02, BDW03 and BDW04 could lyse 36.6, 39.0, 65.8 and 63.4% of the vibrios respectively. In combination the four BALOs could lyse 87.8% of the vibrios tested which is pretty impressive bearing in mind this is the first study on their effectiveness on vibrios. BDW03 and BDW04 were both smaller with longer flagella than the other two bacteria.
The current methods of heat treatment, high pressure processing and depuration have major drawbacks including changes to food texture, cost, and lack of effectiveness. For this reason this study shows very promising results for a possible new technique for post harvest processing. Another positive attribute of these bacteria is that prey resistance is very rare and if present at all is usually some form of plastic phenotypic response. BALOs are really cool bacteria that could be incredibly useful however there hasn’t really been much research on them. Most research seems to be in the medical field using terrestrial species and it has only really been in the last 7 years or so that their immense diversity in the marine environment has been recognised.
A review of: Cai, J., Zhao, J., Wang, Z., Zou, D., Sun, L. (2007) Lysis of vibrios by Bdellovibrio-and-like organisms (BALOs) isolated from marine environment. Journal of Food Safety, 28: 220-235.
7 comments:
Hi Matt,
Cool paper!
I was wondering if once arrived in the human intestine, through BALOs-treated fish consumption, these bacteria could eventually start killing also our gut microflora microbes, counteracting in this way all the potential beneficial effect that you described.
Hi Matt,
interesting study, it seems to have great applications...
Do the authors suggest how BALOs could be used in aquaculture?
Could BALOs,after isolation, be administrated with food or rearing water to fish or other cultured organisms, as often occur with probiotics,for instance?Can they be used directly on animals affected by patogens?
I agree, the range of possible application seems impressive. I have come across a couple of other descriptions of how BALOs can effect the ecology of various different microbial assemblages, but its application in the marine environment is an exciting determination yet to be made. Would be intreguing to see if it could be robustly applied in aquaculture. I think it will be interesting to track this thread of research as it develops further.
Hi,
They probably would feed on our microflora but they could probably be removed before consumption through depuration or starvation, I think they cant survive very long (maybe 20hrs) without prey. Even if they were consumed they have never been shown to decrease health in any animals or plants and i think are naturally present in many anyway. BALOs can also show a high degree of specificity so it could be possible to find some isolates which are specific towards vibrios. I think it could be used for seafood processing and has had a lot of success in lowering salmonella levels in other food processes. As far as using them in aquaculture i really dont know, i would imagine it would take a lot of research and be incredibly difficult. I think they have had some success with studies on terrestrial species like chickens but would probably be a lot harder in aquaculture. I think using them in processing is a more realistic target but i dnt really think there has been enough research to do anything with them yet or soon. They still dont really know what makes them target certain prey and trying to mass produce these things i would imagine to be incredibly difficult.
Hey Valentina ( and Matt!) I was doing some reading and came across his paper talking about aquaculture in china and its development and it was talking about how they have used this bdellovibrio in aquaculture and that it has contributed to improve the performance of fish, shrimp crab and sea cucumbers.
Ive attached a link to the paper
http://www.sciencedirect.com/science/article/pii/S0044848609001124
Thats quite cool ill have to read that. The chinese seem to love these things, they ve done loads of papers on them.
Hey Arainna,
I read that review u mentioned and they only briefly mention their uses in aquaculture and the original papers are all in chinese, but thanks anyway
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