Bacterial Community Composition and Chromophoric Dissolved Organic Matter Differs with Culture Time of Skeletonema dohrnii

Yang Liu,Md Abu Noman,Jun Sun,Jinjun Kan,Jing Yang

doi:10.3390/d13040150

Abstract

Skeletonema dohrnii is a common red tide microalgae occurring in the coastal waters and throughout the world. The associated heterotrophic or autotrophic bacteria play vital roles in regulating algal growth, production, and physiology. In this study, we investigated the detailed bacterial community structure associated with the growth of S. dohrnii’s using high-throughput sequencing-based on 16S rDNA. Our results demonstrated that Bacteroidetes (48.04%) and Proteobacteria (40.66%) in all samples accounted for the majority of bacterial populations. There was a significant linear regression relationship between the abundance of bacterial phyla and culture time. Notable shifts in bacterial community composition were observed during algal growth: Flavobacteriales accounted for the vast majority of sequences at the order level. Furthermore, the relative abundance of Rhodobacterales was gradually reduced during the whole growth process of S. dohrnii (0–12 days). However, beyond that, the relative abundance of Marinobacter was slowly increasing. It is noteworthy that five fluorophores (Peaks T1, T2, I, M, and A) were detected during the growth stage of S. dohrnii. The characteristic indexes (fluorescence index, humification index, and biological index) of chromophoric dissolved organic matter (CDOM) also varied with the culture time. In addition, the taxa of bacteria had certain effects on CDOM and they were inextricably linked to each other.

Highlights

Diatoms are ubiquitous autotrophic eukaryotes in aquatic ecosystems, and they contribute about 20% of the total photosynthesis of the earth [1]
We found that Bacteroidetes, Proteobacteria, and Firmicutes were the most abundant phyla throughout the culture time of Skeletonema dohrnii (Figure 2a)
This study explored the bacterial community associated with Skeletonema dohrnii and chromophoric dissolved organic matter under the 16S rDNA high-throughput sequencing and excitation–emission matrix

Summary

Introduction

Diatoms are ubiquitous autotrophic eukaryotes in aquatic ecosystems, and they contribute about 20% of the total photosynthesis of the earth [1]. In the coastal waters of China, S. dohrnii is a common red tide algae that forms long chains with a shell surface diameter up to 4–12 microns [5]. It is a cold-water species that mainly occurs in winter and spring. S. dohrnii disappears and accumulates in bottom water and shallow sediments [3,6,7] Their occurrence and distribution may be influenced by environmental gradients such as temperature and interactions with other living organisms [2,3,5,8]

Methods

Results

Conclusion