Samples of the sponge Haliclona simulans were collected from Irish waters and subjected to a culture-independent analysis to determine the microbial, polyketide synthase (PKS) and non-ribosomal peptide synthase (NRPS) diversity. 16S rRNA gene libraries were prepared from total sponge, bacterial enriched sponge and seawater samples. Eight phyla from the Bacteria were detected in the sponge by phylogenetic analyses of the 16S rRNA gene libraries. The most abundant phylum in the total sponge library was the Proteobacteria (86%), with the majority of these clones being from the gamma-Proteobacteria (77%); two groups of clones were dominant and together made up 69% of the total. Both of these groups were related to other sponge-derived microbes and comprised novel genera. Within the other bacterial phyla groups of clones representing novel candidate genera within the phyla Verrucomicrobia and Lentisphaerae were also found. Selective enrichment of the bacterial component of the sponge prior to 16S rRNA gene analysis resulted in a 16S rRNA gene library dominated by a novel genus of delta-Proteobacteria, most closely related to the Bdellovibrio. The potential for the sponge microbiota to produce secondary metabolites was also analysed by polymerase chain reaction amplification of PKS and NRPS genes. While no NRPS sequences were isolated seven ketosynthase (KS) sequences were obtained from the sponge metagenome. Analyses of these clones revealed a diverse collection of PKS sequences which were most closely affiliated with PKS from members of the Cyanobacteria, Myxobacteria and Dinoflagellata.

The two biocides have different spectra of antimicrobial activity. PQ-1 has mainly antibacterial activity, whereas MAPD was active against all of the test organisms, particularly the fungi.

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The results indicate that OPTI-FREE EXPRESS would remain highly efficient in the case of noncompliance with disinfection procedures.

This study shows that random transposon mutagenesis is an effective tool for the elucidation of mechanisms of action and resistance to biocides. The results support our previous findings that PQ-1 is active against the cytoplasmic membrane of S. marcescens.