# Integrated Metabolomic, Molecular, and Morphological Insights into the Degradation of Polychlorinated Biphenyls (PCB) by Priestia megaterium MAPB-27

## TL;DR

This study explores how the bacterium Priestia megaterium MAPB-27 degrades PCBs and adapts metabolically to biphenyl, offering insights for bioremediation and industrial use.

## Contribution

The study provides integrated metabolomic, molecular, and morphological insights into PCB degradation by a specific bacterial strain.

## Key findings

- MAPB-27 degrades various chlorinated biphenyls with high efficiency for trichlorobiphenyl.
- Key metabolites like benzoic acid and 2,3-dihydroxybenzoic acid were identified in PCB degradation.
- Active metabolic pathways include glyoxylate and fatty acid biosynthesis.

## Abstract

Polychlorinated biphenyls
(PCBs) are persistent organic pollutants
that cause profound deleterious effects on the environment and human
health. Exposure to PCBs and biphenyl can induce changes in cellular
metabolite levels. However, metabolic responses to utilize and adapt
to PCBs are not well understood. Therefore, this study meticulously
examined the PCB degradation potential, gene expression, and metabolic
responses of Priestia megaterium MAPB-27
exposed to biphenyl. MAPB-27 showed growth and chemotaxis toward PCB
degradation intermediates such as biphenyl, dihydroxy biphenyl, benzoate,
and catechol. We employed GC-MS/MS to elucidate disparities in the
main metabolic pathways in the biphenyl-exposed MAPB-27 through variations
in metabolite composition and PCB biodegradation, while Field-emission
scanning electron microscopy (FESEM) was used to study cell morphology.
GC-MS/MS analysis highlighted the degradation of trichlorobiphenyl,
tetrachlorobiphenyl, pentachlorobiphenyl, and hexachlorobiphenyl by P. megaterium MAPB-27, exhibiting 92.5, 62.9, 3.7,
and 2.4%, respectively. GC-MS/MS analysis identified 4-dihydroxy-2-oxo-valerate,
benzoic acid, and 2,3-dihydroxybenzoic acid as the major degradative
metabolites in MAPB-27. MAPB-27 extract also contains metabolites
with a wide range of direct industrial applications, such as poly­(3-hydroxybutyrate)
(3-hydroxybutyrate), a biobased organic acid (3-hydroxypropionoic
acid), and antibacterial and antifungal compounds (phenyllactic acid,
4-hydroxyphenyllactic acid, and β-sitosterol). Glyoxylate and
dicarboxylate metabolism and fatty acid biosynthesis were observed
to be the active metabolisms in MAPB-27 grown in biphenyl-supplemented
Minimal Medium. Overall, the results of this study provided important
insights into microbial adaptation to biphenyl and the biodegradation
of PCB. Thus, the P. megaterium MAPB-27
strain can be used for the development of efficient PCB biodegradation
strategies and for the exploration of industrial applications.