Iffland-Stettner, A. | bioRxiv Science

bioRxiv2022

A Genome-Scale Metabolic Model of Marine Heterotroph Vibrio splendidus sp. 1A01

While the Vibrio splendidus species is best known as an opportunistic pathogen in oysters, the Vibrio splendidus sp. 1A01 strain was first identified as an early colonizer of synthetic chitin particles incubated in seawater. To gain a better understanding of its metabolism, a genome-scale metabolic model (GSMM) of V. splendidus sp. 1A01 was reconstructed. GSMMs enable us to simulate all metabolic reactions in a bacterial cell using Flux Balance Analysis. A draft model was built using an automated pipeline from BioCyc. Manual curation was then performed based on experimental data, in part by gap-filling metabolic pathways and tailoring the models biomass reaction to V. splendidus sp. 1A01. The challenges of building a metabolic model for a marine microorganism like V. splendidus sp. 1A01 are described.

microbiology↗

bioRxiv2021

Turnover in life strategies recapitulates microbial succession on synthetic marine particles

Particulate organic matter (POM) in the ocean sustains diverse communities of bacteria that mediate the remineralization of organic complex matter. However, the variability of these particles and of the environmental conditions surrounding them present a challenge to the study of the ecological processes shaping particle-associated communities and their function. In this work, we utilise data from experiments in which coastal water communities were grown on synthetic particles to ask which are the most important ecological drivers of their assembly and associated traits. Combining 16S rRNA amplicon sequencing with shotgun metagenomics, together with an analysis of the full genomes of a subset of isolated strains, we were able to identify two-to-three distinct community classes, corresponding to early vs. late colonizers. We show that these classes are shaped by environmental selection (early colonizers) and facilitation (late colonizers), and find distinctive traits associated with each class. While early colonizers have a larger proportion of genes related to uptake of nutrients, motility and environmental sensing with few pathways enriched for metabolism, late colonizers devote a higher proportion of genes for metabolism, comprising a wide array of different pathways including metabolism of carbohydrates, amino acids and xenobiotics We find evidence in selected metabolic pathways for the existence of a trophic-chain topology connecting both classes. The interpretation of these traits suggests a distinction between early and late colonizers analogous to other classifications found in the literature, and we discuss connections with the classical distinction between r- and K-strategists.

microbiology↗