Algal biotechnology: An answer for the biofouling?

Quorum Sensing Inhibition by Asparagopsis taxiformis, a Marine Macro Alga: Separation of the Compound that Interrupts Bacterial Communication

 

Biofilms are communities of microbes sheathed in extracellular polymeric substances (see Munn’s book for more). Biofilm formation is controlled by quorum sensing (QS), as we know QS is density-dependent gene regulation through signals produced by bacteria. Many pathogenic bacteria in biofilms use QS as a regulatory mechanism for their production of virulence factors. Therefore, QS can be used as a drug target instead of antibiotics which has lead to emergence of drug resistance. It is known that quorum sensing inhibitors increase the susceptibility of bacterial biofilms to antibiotics; as a consequence this has led to the scientific community concentrating on QS inhibitors. We all know of some of the implications of biofilms, for instance harmful contamination of bacteria on important farmed animals and fouling of important coastal structures. Traditionally we solved this problem with organotins, but they are highly toxic, non-biodegradable and have long-term effects. There is an urgent need for nontoxic antifouling compounds. The occurrence of fully grown biofilm on marine algae is a rare event. Marine algae have effective defence mechanisms to prevent biofilm formation, such as QS inhibition, some of which have already been described. However, the authors believe we need to screen more seaweed for identification of new QS inhibitors.

 

In this investigation, Jha et al screened 30 marine algae extracts for their QS inhibitory potential by using a reporter strain Chromobacterium violaceum CV026. The C. violaceum CV026 is a mutant strain incapable of producing AHL signals making it a versatile and easy-to-use reporter that responds to extracellular AHLs. Samples that showed growth inhibition, as well as QS inhibition, were fractionated using five different solid phase extraction (SPE) cartridges, in order to separate two distinct activities, antibacterial and quorum sensing inhibition.

 

Amongst the 30 different algae seaweeds tested for quorum sensing inhibition using CV026 Jha et al found that Asparagopsis taxiformis showed the greatest QS inhibition. This was done by analysing the zones of inhibition found in the samples. The anti quorum sensing activity of A. taxiformis was further confirmed using the sensor strain, Serratia liquefaciens MG44.  This is the first report of the quorum sensing inhibition property of A. taxiformis and to successfully report capability of different SPE cartridges to separate quorum sensing inhibitor and antibacterial compounds which is important because it supports the notion that the QSI is based on the interference of bacterial signalling, rather than antibacterial activity. These results could be huge but I feel the authors have left their work unfinished here, therefore making the huge potential investigation negligible.  To my understanding of this study the Authors have not distinguished what compound is causing the QS inhibition that is reported. Jha et al successfully identified a compound which caused this inhibition but this was not identified, they suspect it is  “2-dodecanoyloxyethanesulfonate”. But what is it and was it in the other 29 algae? Is it completely new to science or is it a compound we already know of? If the latter then I feel we are back to square 1. What do you think?