Phylogenetic Analysis of Vibrio parahaemolyticus Isolated from Baseco Beach, Manila Bay Based on 16S rRNA

Abstract

Baseco Beach is a major port in southwestern Luzon in Manila Bay and is associated with many anthropogenic activities (Sotto et al., 2015). In 2019, putative Vibrio species were isolated from Baseco Beach, Manila Bay (Tesoro et al., 2019) and this study through 16S rRNA sequencing, confirmed one of the five isolates (W4), isolated from seawater, to be Vibrio parahaemolyticus following Basic Local Alignment Search Tool (BLAST). Phylogenetic analysis using the 16S rRNA sequence of V. parahaemolyticus W4, was done using the software MEGAX with existing V. parahaemolyticus, V. fluvialis, and V. cholerae strains from the National Center for Biotechnology Information (NCBI) as reference strains. V. parahaemolyticus W4 formed a clade with V. parahaemolyticus MF372385.1 (Vp9), FM204867.1 (Vp3), and FM204866.1 (Vp4), with V. parahaemolyticus MF372385.1 being the closest. Based on existing literature, V. parahaemolyticus Vp9 is an AHPND-positive strain, possessing the pirA virulence gene. Meanwhile, V. parahaemolyticus Vp3 contains toxR, tlh, and alt genes, and V. parahaemolyticus Vp4 contains toxR, tlh, and tdh genes. Interestingly, published studies found that W4, Vp9 and Vp3 were all resistant to ampicillin. Although the three closest V. parahaemolyticus strains to isolate W4 possessed virulence and antibiotic resistance genes (ARG), further genomic analysis on W4 is still needed since these genes can be passed through horizontal gene transfer (HGT). To our knowledge, this is the first study to have phylogenetically analyzed a putative V. parahaemolyticus isolate from Baseco Beach, Manila Bay with that of existing data elucidating on the possible public health concern possessed by this isolate. It is recommended to further assess the growth physiology and determine the presence of other ARG and virulence genes through molecular biology techniques such as Polymerase Chain Reaction (PCR).