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Journal Articles - UP - MSI

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    Potential of sediment bacterial communities from Manila Bay (Philippines) to degrade low-density polyethylene (LDPE)
    Gomez, Norchel Corcia F.; Onda, Deo Florence L. (Springer, 2022-12-24)
    The persistence of plastics and its effects in different environments where they accumulate, particularly in coastal areas, is of serious concern. These plastics exhibit signs of degradation, possibly mediated by microorganisms. In this study, we investigated the potential of sediment microbial communities from Manila Bay, Philippines, which has a severe plastics problem, to degrade low-density polyethylene (LDPE). Plastics in selected sites were quantified and sediment samples from sites with the lowest and highest plastic accumulation were collected. These sediments were then introduced and incubated with LDPE in vitro for a period of 91 days. Fourier transform infrared spectroscopy detected the appearance of carbonyl and vinyl products on the plastic surface, indicating structural surface modifications attributed to polymer degradation. Communities attached to the plastics were profiled using high-throughput sequencing of the V4-V5 region of the 16S rRNA gene. Members of the phylum Proteobacteria dominated the plastic surface throughout the experiment. Several bacterial taxa associated with hydrocarbon degradation were also enriched, with some taxa positively correlating with the biodegradation indices, suggesting potential active roles in the partial biodegradation of plastics. Other taxa were also present, which might be consuming by-products or providing nourishment for other groups, indicating synergy in utilizing the plastic as the main carbon source and creation of a microenvironment within the plastics biofilm. This study showed that sediment microbes from Manila Bay may have naturally occurring microbial groups potentially capable of partially degrading plastics, supporting previous studies that the biodegradation potential for plastics is ubiquitously present in marine microbial assemblages.
    We would like to acknowledge the Protected Area Management and Biodiversity Section of the Conservation and Development Division of the Department of Environment and Natural Resources—National Capital region for allowing us to conduct field work in LPPCHEA. As well as local government units of Brgy. Bucana in Ternate, Brgy. Bucana Malaki in Naic, Brgy. San Rafael III in Noveleta, and Brgy. Baseco in Manila for allowing us to conduct field work and sample collection. We would also like to acknowledge the Marine Research Center under the Marine Environmental Protection Command of the Philippine Coast Guard for providing assistance during one of our fieldworks. Members of the Microbial Oceanography Laboratory for helping during field works. And to Daniel John E. Purganan and Justine Marey S. Bitalac for helping us obtain CLS micrographs.
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    Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay
    Hosono, Takahiro; Su, Chih-Chieh; Siringan, Fernando; Amano, Atsuko; Onodera, Shin-ichi (Elsevier, 2010)
    We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with 210Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.