Friendly, non - polar, biofilm inhibitors, derived form the symbionts of seagrasses.

Bintang Marhaeni, Ocky Karna Radjasa3, Miftahuddin Majid Khoeri, Agus Sabdono, Dietriech G. Bengen, Herawati Sudoyo (2011) Antifouling Activity of Bacterial Symbionts of Seagrasses against Marine Biofilm-Forming Bacteria Journal of Environmental Protection, 2, 1245-1249

Biofouling, as mentioned in many of the reviews is a major problem in the marine environment and is costly to marine industries. The formation of biofilms on the bottom of boats and other machinery has led to the production of chemicals such as TBT to help remove such fouling but these can create a more dangerous environmental problem. This review focusses on a journal that investigates a potential environmentally friendly solution using bacterial symbionts of seagrasses as antifoul. The report here focusses on seagrasses Thalassia hemprichii and En- halus acoroides after reports on the potential of other seagrasses to remove biofilm. Research into the bacteria associated with the seagrasses could, therefore, offer an alternative commercial anti – foulant.

Both the bacteria associated with the seagrass and the biofilm – forming bacteria were isolated, purified and identified in the lab using morphological features. Antifouling activity of the bacterial symbionts was determined using an overlay method. Each biofilm bacteria was mixed with soft agar medium which was then poured onto agar surfaces previously inoculated with bacterial symbionts. Also twenty microliters of each extract onto paper discs that had previously been placed on agar surfaces contained the biofilm – forming bacterium. Any antibacterial activity was described by inhibition around the bacterial colonies.

Biofilm – forming bacteria are a primary target for anti - fouling products as they provide important targets or cues for larval settlement and therefore the development of the large biofilms unwanted in the marine industry. Four bacterial symbionts (3 from E. acoroides and 1 Thalassia hemprichii) were able to inhibit the growth of the biofilm bacteria however crude extracts from said bacteria, here, were found to be much better at inhibiting the growth of biofilm - forming bacteria. Finding an environmentally friendly biofilm inhibitor is a large very popular area in marine microbiology at the moment, but there are some benefits to the endophtye and epiphytes of the seagrasses investigated in this paper. Firstly, as extracts were shown to inhibit growth more effectively it suggests that there is a diverse number of chemicals produced by the secondary metabolites of the seagrass’ symbionts. This could increase the viability of these symbionts as future anti - fouling products. Secondly, many of these extracts were found to be non – polar, therefore it is less likely they will be washed away with ease in a marine environment, another attractive feature. Furthermore, sustainable seagrass ecosystems provide the perfect habitat for growing such symbiont making the bacteria available for large scale commercial use.

The secondary metabolites mentioned have not yet been characterised or purified however this would be an obvious next step in the research here, enabling, possibly the production of a successful environmentally friendly biofilm inhibitor.