Please note: This article has been reviewed by Bekki already, but as I have already written it, I thought it would be a waste not to post it.
Vibrio and Pseudomonas
are both well-known aquaculture pathogens and have been previously associated
with major diseases of aquatic organisms. Vibrio
and Vibrio harveyi are primary
pathogens of marine fish and crustaceans, and bacteria belonging to the genus Pseudomonas are affiliated with black
spot bacterial necrosis in prawns. As a greater number of pathogens continuously
develop antibiotic resistance, one of the major challenges in aquacultures
these days is to prevent bacterial diseases.
Biofilms are generally important for the
survival, virulence and stress resistance of bacteria and can act as reservoirs
for pathogens allowing recurrent infections. Hamza et al. (2015) tested the anti-biofilm potential of a cell free
supernatants (CFS) of a tropical marine epibiotic bacterium Bacillus licheniformis D1 isolate to
prevent or disrupt, aquaculture associated biofilms. This may be potential for
a natural way to deal with the problems described above. The marine epibiotic
bacterium B. licheniformis was
isolated from the surface of green mussel, Perna
viridis, collected from near shore regions of Kovalam, Tamil Nadu, India. The
ability of CFS to inhibit biofilm formation of test cultures (V. harveyi and P. aeruginosa) and to disrupt biofilms of V. harveyi and P. aeruginosa
that have been allowed to form in advance, were both tested in this study. The
biofilm growth of V. harveyi and P. aeruginosa was inhibited up to 80.46
and 77.51% respectively, when co-incubated with CFS of B. licheniformis. CFS also disrupted pre-formed biofilms of both
the test cultures with comparable efficiency. Latter was determined by
performing ONPG assays, where the results revealed that the CFS effectively
disrupted cytoplasmic membranes, leading to the leakage of cytoplasm and
finally to death of the bacterial cells.
Hamza et
al. (2015) and several previous studies revealed the potential of marine
bacteria dealing with bacterial biofilms. The protein BLDZ1, derived from the
same bacterium, for instance was found to be effective in disrupting biofilms
of other microorganisms. It seems that B.licheniformis may have a great
potential in helping to deal with diseases found in aquacultures. However, it
should be noted, that V. harveyi
biofilm formation was especially found in low salinity (NaCl = 1%), and P. aeruginosa in media that lacked NaCl.
The effectiveness of B. licheniformis
tested in the present study therefore mainly accounts for aquacultures in
fresh-water or estuarine habitats. Further investigations are needed for the
marine sector.
Hopefully we can find some more of these
“heroes” of aquaculture. Wouldn`t it be great if we were able to cram fish and
other farmed animals into even smaller space, not having to worry about
diseases? I am sure this would just solve all the problems associated with intense
aquaculture…
Hamza F,
Kumar AR, Zinjarde S (2015) Antibiofilm potential of a tropical marine Bacillus
licheniformis isolate: role in disruption of aquaculture associated
biofilms. Aquaculture Research 1-9, doi:10.1111/are.12716
Hi Tabea, thanks for this. No worries about posting it twice, your interpretation made it your own! You mentioned Vibrio and Vibrio harveyi at the start- which was the first vibrio sp .please? Random that B. licheniformis was collected from a mussel, was this the only place where it can be found? How did the authors first know about the anti-biofilm potential of this bacteria- has there been previous research or was it a wild stab? What would be useful was to test the temperature tolerances of this B. licheniformis as well- i completely agree with you that the tolerances of this organism may not make it as robust. Is this inhibitory effect specific to just the two bacteria tested or other bacteria too? The other worry is viral infection of crustaceans and mollusks, which may not be as easy to tackle! Sorry so many questions- loving biofilm research!
ReplyDeleteHi Elyssa, Sorry for that super late reply (I think we all know that the dissertation was taking up our lives for the last view weeks).
DeleteFirst I mentioned Vibrio and Vibrio harveyi, however I think I missunderstood the paper a little bit (or maybe they have not made it really clear). What I actually wanted to say (as well as the paper) that vibriosis is caused by bacteria included in the genus Vibrio; and Vibrio harveyi is a primary pathogen of marine fish and crustaceans. So basically Vibriosis can be caused by different Vibrio sp. but in marine fish and crustaceans its mainly associated with Vibrio harveyi. They don`t say why they have collected B. licheniformis t from a mussel (they don`t explain it very well), but I assume that it is the place it has been found before.
There is been quite a lot of previous work done on B. licheniformis and biofilms, f.e. Dusane et al. 2013. In the present study it was really more about the biology happening behind it, to explain how CFS actually exhibited antimicrobial activity and mediated cell death.
They not actually using B. licheniformis itself but their extracted CFS which is an extracellular protein isolated from the bacterium, however I think it would be interesting to know if it the disruption and prevention of biofilms works the same in all latitudes (considering that B. licheniformis is a tropical bacterium). However they are using a marine Bacterium to treat freshwater species so I am not sure if environmental factors actually play a big part.
The same protein was found to be effective in disrupting biofilms of other micro-organisms such as Candida albicans BH, Pseudomonas aeruginosa PAO1 and Bacillus pumilus TiO1 (Dusane et al. 2013 for mor information!).
What are your thoughts of this? I know that your dissertation was considering salinity treatments as anti-biofouling methods. Do you think this method present here would be more advantegous?
Let me know if you have any more questions :)
Thankyou for the response. Do you think as they only looked at CFS this is not actually representing what will go on in the natural environment- as the CFS could be resilient to certain factors however the actual bacteria organism may not be if this makes sense? I am not sure what you mean... do you mean using bacteria to control biofouling would be better than different salinity treatments?, If so they have already done loads of work on this, and it does work but it's a very difficult and small scale method. Completely different to salinity treatments :) Thanks
DeleteWell I don`t actually think that B. licheniformis would ever interfer with biofouling communities tested here (esp. as B. licheniformis is marine). Using CFS of B. licheniformis would be basically like applying antifouling paint, just that it is a 'natural' component and will therefore probably not as harmful as artifical antifouling methods (I am not 100% sure if I got your question right and if I did that I have answered it so please ask again!!!).
DeleteWhat do you mean? Salinity treatments or Bacteria treatments are only used on a small scale?
Yah I get what you mean- however that would probably anti-foul biofilms? and very specific! But yeah good idea :) How easy would CFS be able to extracted? Thanks :)
ReplyDeleteTo prepare the CFS, B.licheniformis is isolated from the surface of green mussel and identfied based on rDNA sequence analysis. The bacterium is then grown in the labs for 36 h and then centrifuged for 10 minutes and then filtered. So it is apretty straight forward and quick process
Delete