Profiling Antimicrobial Peptides Present in Microbial Communities From The Port Water of Subic Using Metagenomic Analysis of Paired-End Shotgun Sequence Reads

Abstract

Subic Bay is a coastal marine ecosystem with a variety of habitats and marine organisms. Despite its ecological importance, the microbial communities in this bay have not been thoroughly studied, and human activities may have impacted these microbial communities, disrupting the delicate ecosystem balance. A diverse port water community has the potential to produce biologically active compounds such as antimicrobial peptides (AMPs). The study analyzed the 3rd sampling run of year 2 paired-end metagenomic sequences provided by the PORTEC project; with bioinformatic pipelines such as assembly, genome annotations and peptide mapping. Taxonomic profiling identified Proteobacteria and Firmicutes as the most abundant phyla. Actinomycetes' low abundance could be explained by factors such as intense competition from other microorganisms, a scarcity of suitable substrates, fluctuating water levels and oxygen availability, and high salinity and alkaline pH in the port water. AMP prediction resulted in 86 putative peptides, suggesting adaptability and resistance to microbial infections within the community. When these sequences were compared to existing databases, only four of them showed similarities to known entries. Among the matches, an amino acid sequence ("VVVVVVVVVVVVVVVVVVVVVVVVVVVC") was found in multiple uncharacterized proteins. Peptides high in valine are uncommon which suggest that they have no specific advantages; however, studies show that they improve protein stability or functionality, implying the presence of metabolic pathways that confer a survival advantage.