Not just for the Bathroom...

Marine sponges are well known for harbouring a wide variety of microbes which have been found to have a mixture of roles, including protection, pathogens and competitors.  Sponges are also the most prolific marine producers of novel compounds, many of which are of pharmaceutical and biotechnological importance. The structural similarity between the compounds found in sponges and compounds found in sponge microbiota suggest that they could in fact be of microbial origin. Sponge-associated microorganisms have recently received renewed attention, with much research focusing on the production of bioactive compounds. This research has found that bacteria belonging to the actinobacteria genera are the largest producers of these secondary metabolites.

The aim of this investigation is to analyse the compounds produced by bacteria from two species of sponge (Suberites carnosus – non-calcarious, and Leucosolenia sp. - calcarious) in an effort to produce novel antibacterials to combat drug resistant pathogens, which are becoming a big problem in the medical industry.

Samples of the sponge species were collected at a 15m depth from Lough Hayne, Co. Cork in November 2008. Bacteria from these samples were cultivated on agar over a period of two months, during which time they were incubated at 18^oC and checked regularly for distinguishable colonies.  After the incubation period, the cultivated bacteria underwent deferred antagonism and well diffusion assays, PCR and phylogenetic analysis of the 16S rRNA gene.

For both sponge species, analysis of 16S rRNA sequences revealed that the dominant phylum of bacteria found was Protebacteria, and the most abundant in both cases was γ – Proteobacteria. The genetic identity of over 98% of the isolates found in both sponge species are already known to science. However, some isolates, especially from Leucosolenia sp. are not. A result like this is not unexpected, as calcarious sponges have been subject to little research before now. A wide range of the bacteria found in both sponge species displayed antimicrobial activity during analysis, though more of the isolates from the sponge species S. carnosus showed this than those from Leucosolenia sp. This can be explained by different genera and species isolated in both, as the dominant genera of bacteria found was different in each species of sponge (Pseudoalteromonas and Vibrio in Leucosolenia sp., and Pseudovibrio and Spongiobacter in S. carnosus).

The authors summarised that in both sponge species, a high level of anti-microbial activity was found. Leucosolenia sp was found to produce more effective antifungal compounds, whereas S. carnosus appeared to contain more microbes with antibacterial properties. The researchers did struggle to isolate the compounds responsible for this activity in many cases however, meaning that the paper lends itself easily to further research. Overall, the findings from this paper may prove to be useful in future, particularly to the medical industry.

A review of Flemer B., Kenedy J., Margassery L.M., Morrissey J.P., O’Gara F. and Dobson A.D.W. (2011) Diversity and Antimicrobial Activities of Microbes from Two Irish Marine Sponges, Suberites carnosus and Leucosolenia sp., Journal of Applied Microbiology, 112, 289-301