Multi-platform characterization of oysters (Magallana bilineata) in Bacoor bay area as a seafood product and bioindicator

• Main Author: Canonizado, April Star L.
• Format: text
• Language: English
• Published: Animo Repository 2022
• Subjects: Oysters > Philippines > Cavite; Microplastics; Metabolites; Volatile organic compounds; Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etdm_chem/7; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1006&context=etdm_chem
• Institution: De La Salle University

Marine pollution is one of the environmental concerns that affects the country. It is caused by unregulated sewage discharges and anthropogenic sources that pollute not only the water but also the seafood products such as oysters. Due to the filter-feeding nature of oysters, pollutants can be ingested and may accumulate affecting the nutritional quality of the oysters. There is a need to investigate using multi-platform approach the quality of oysters produced in Bacoor Bay, which lies in the highly industrialized and populated area of Metro Manila and Cavite, Philippines. Oyster samples from the three farms in Bacoor Bay (sample groups) and each farm from Naic in Cavite and Aklan (control groups) were collected for three months (June, July and August) to detect microplastic ingestion, evaluate the volatile organic compounds (VOCs), and assess the metabolomic and nutritional profile. Using FTIR-ATR and SEM-EDS there were no microplastics detected in all the oyster samples using the 10% KOH digestion protocol, which suggests that the oysters may be not an effective bioindicator for microplastic detection. The VOC profile using GC-MS showed that 6 out of 14 VOCs detected were associated with the green and grassy odors of fresh oysters: 1-penten-3-ol, pentanal, hexanal, heptanal, 3,5-Octadien-2-one and (E,E)-3,5- Octadien-2-one. The nasty odor compounds such as indole and trimethylamine were vii not detected confirming that the oyster samples were fresh. The NMR metabolomic profile of the oysters showed that the nutrient profile of oysters in each farm are composed of significant concentrations of glucose and six essential amino acids (valine, leucine, isoleucine, threonine, methionine, and phenylalanine). The June and July samples experienced anaerobic metabolism in response to an environmental stressor. On the other hand, the July and August samples need a high demand of methionine for antioxidant defense. August samples of the five farms have a similar decrease in branched amino acids, which indicates the disruptions in their amino acid metabolism due to an environmental stressor. There were high accumulation of betaine and alanine and a slightly lower accumulation of hypotaurine and trimethylamine in the June and July samples for osmotic regulation of oysters at high salinity. In general, the variation of the peak intensities in the NMR spectra of all farms in each of the three months were caused by disruptions in the oyster’s metabolism due to effect of exposure to an environmental stressor such as high salinity.