Distribution and potential roles of microbial protoporphyrin IX in marine sediments

ABSTRACT

Protoporphyrin IX (PPIX) serves as a pivotal precursor in the biosynthesis of porphyrins, playing a crucial role in both biological metabolism and biogeochemical cycling. This study investigates the spatial dynamics and co-occurrence patterns of PPIX within the microbial community of marine sediment. The concentrations of PPIX ranged from 7.38 - 91.33 ng/g. Clear patterns in spatiotemporal dynamics in the PPIX were observed, with a more pronounced spatial rather than seasonal variation. Notably, the PPIX and its derivatives in brackish sediment samples exhibited distinct characteristics from those found in saltwater samples. The Spearman test found that PPIX has a positive relationship with chlorophyll-a and pheophytin-a but not with chlorophyll-b or pheophytin-b. Significant positive correlations were identified between PPIX and nitrogen nutrients. Network and variation partitioning analyses highlighted the potential interactions between PPIX and microbial lineages. These findings indicate that PPIX is necessary for microorganisms and widely distributed in sedimentary environments. Additionally, this study underscores the influence of organic matter on microbial community composition and its responsiveness to environmental variations. These insights contribute to a comprehensive understanding of the potential ecological roles of PPIX within natural ecosystems.

HIGHLIGHTS

1. Protoporphyrin IX is necessary for microorganisms and widely distributed in sedimentary environments.

2. PPIX showed a more pronounced spatial rather than seasonal variation.

3. Porphyrins found in brackish sediment samples exhibited distinct characteristics compared with those present in saltwater samples.

4. Environmental factors can further influence the distribution of porphyrins by affecting microorganisms and their interactions.

KEYWORDS:

• Protoporphyrin IX
• marine sediment
• spatial distribution
• microbial community
• interaction pattern

Acknowledgements

We would like to thank the State Key Laboratory of Marine Environmental Science, Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies at Xiamen University for the comprehensive technical and equipment support. We express our thanks to Mr Yang Deyuan for his help in sample collection and the captain and crew members of the R/V Haiyang No.2 for their assistance in sample collection.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

Data will be made available on request.

Additional information

Funding

The work was partly supported by The National Natural Science Foundation of China (U1805242) and the PhD Fellowship of the State Key Laboratory of Marine Environmental Science at Xiamen University.