Abstract:
Ballast water in shipping vessels is a mobile vector for the global transfer of microorganisms and
antimicrobial resistance genes. The discharge of ballast water during its voyage and passive flow
of water through sea currents can introduce harmful microorganisms in the vicinity of the
receiving ports. Despite the Philippines’ numerous ports, studies regarding the ecological
significance of ballast water discharge is limited. This study focused on profiling the taxonomic
composition and resistome of the water samples from the first sample retrieval in the Port of
Matnog. Paired-end metagenomic sequences from the water samples were used for the generation
of the taxonomic and resistome profile. Taxonomic profiling using MetaPhlAn showed that
phylum Bacteroidetes dominated the waters, suggesting the influence of anthropogenic effluents
from the urban communities in the microbial composition. Identification of
potentially-pathogenic genera also poses the risk of disease transmission. Resistome datasets were
generated using the DugesiaAMR pipeline and revealed that all four primary resistance types -
drugs, biocide, metals, and multi-drug resistance- were present in the water samples. Genes
conferring resistance to drugs dominated the resistome profile with tetracycline gene groups
exhibiting the highest relative abundance. The dominance of these resistance genes also suggested
the increased pollutants, particularly antibiotics, from residential and commercial areas. Due to
the diversity of taxonomic groups and resistance genes profiled, the Port of Matnog can be
considered a potential hotspot for resistance transmission and proliferation. Findings of this study
can be further used for comparison in determining the taxonomic and resistome changes in
subsequent sample retrievals in the Port of Matnog and in different ports of the Philippines.
