The search for novel antimicrobials has taken to our oceans; this could be the source of a range of revolutionary antibiotics and other useful drugs. Defence strategies, of both microorganisms and hosts, need to be are highly refined in marine ecosystems due to the fiercely competitive environment. This environment contains numerous bioactive compounds and through identification and isolation we can exploit them possibly providing us new life changing drugs.
This study focused on the bacterial strain D323. It is an Alphaproteobacterium which belongs to the family Rhodobacteraceae. It has been reported to have closely associated with healthy marine sponges however not in diseased individuals suggesting it plays a significant role in host defence. D323 is known to have significant antibacterial activity the authors aim to develop understanding of what are the causative compounds involved and the spectrum of activity.
Previous studies proved unsuccessful at isolating and identifying the active compounds produced by D323. Gas-Chromatography Mass-Spectrometry initially revealed the presence of phenol a known antimicrobial however further tests showed this provided no antimicrobial activity. The precise role on phenol is not known however they speculate it could be the precursor for the synthesis of other phenolic-based defence compounds. Through purification and chemical analysis, using Gas-Chromatography Mass Spectrometry, D323 was shown to produce Tropodithietic acid (TDA). This compound is known to have significant antimicrobial properties.
To test the spectrum of inhibition of TDA they use a variety of marine strains. The tests showed the compound was a very effective against a wide range of bacteria including common marine epibionts. It was shown to be highly active against the strain Nautella sp.R11 which is commonly associated with bleaching disease. Interestingly the only strains that were resistant to the inhibitory effects of TDA also were capable of producing TDA. This could suggest that they possess a mechanism that prevents auto-inhibition. The wide activity spectrum of TDA indicates that it could be used as a defence compound not only to defend themselves but possibly also hosts from heavy microbial colonisation. Further investigations will need to be carried out to determine if TDA is produced in sufficient quantities in a natural environment to prevent potentially pathogenic microorganisms from colonising producers and hosts.
This area is extremely exciting as we have explored such a small percentage of our marine environments. There could be countless opportunities for us to discover new drugs that could have a major impact on our lives. Also understanding the processes that protect our corals and sponges will be vital in developing strategies to protect them.
I found that this paper was laid out in a very unconventional way. Throughout the results and discussion they used many acronyms that were not explained until the end of the paper. This made it hard read through the paper and fully absorb the information.
The Biology episode of Channel 4’s Brave new world discusses the use of secondary metabolites from marine algae found around Panama as a possible cure for cancer. They have already had success in lab trials with breast cancer cells. I would really recommend watching this series and this episode in particular as it is a fascinating area of research.
Review of: Penesyan, A. et al., 2011. Identification of the antibacterial compound produced by the marine epiphytic bacterium Pseudovibrio sp. D323 and related sponge-associated bacteria. Marine drugs, 9(8), pp.1391-402.
2 comments:
Hi Dave
Interesting blog mate.
I was just wandering if the researchers knew or suggested how TDA worked in inhibiting cell growth? Sounds like it could be an area of research that may get alot of funding in coming years.
I think this compound has been described before several years ago in members of the roseobacter Claude. Do the authors make any reference to that discovery? These bacteria are very abundant, so it is likely that sponges will contain large numbers of them by filtration from the water.
Post a Comment