AUTHOR=Li Suheng , Dong Yi , Sun Xiaoxia , Zhao Yuan , Zhao Li , Zhang Wuchang , Xiao Tian 

TITLE=Seasonal and spatial variations of Synechococcus in abundance, pigment types, and genetic diversity in a temperate semi-enclosed bay

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1322548

DOI=10.3389/fmicb.2023.1322548

ISSN=1664-302X

ABSTRACT=<p><italic>Synechococcus</italic> is abundant and globally widespread in various marine environments. Seasonal and spatial variations in <italic>Synechococcus</italic> abundance, pigment types, and genetic diversity were investigated based on flow cytometric analysis and high-throughput sequencing of <italic>cpcBA</italic> operon (encoding phycocyanin) and <italic>rpoC1</italic> gene (encoding RNA polymerase) in a temperate semi-enclosed bay. <italic>Synechococcus</italic> abundance exhibited seasonal variations with the highest value in summer and the lowest value in winter, which was consistent with temperature variation. Three pigment types of <italic>Synechococcus</italic> type 1, type 2, and type 3 were distinguished based on <italic>cpcBA</italic> operon, which displayed obvious variations spatially between the inner and the outer bay. Freshwater discharge and water turbidity played important roles in regulating <italic>Synechococcus</italic> pigment types. <italic>Synechococcus</italic> assemblages were phylogenetically diverse (12 different lineages) based on <italic>rpoC1</italic> gene and dominated by three core lineages S5.1-I, S5.1-IX, and S5.2-CB5 in different seasons. Our study demonstrated that <italic>Synechococcus</italic> abundance, pigment types, and genetic diversity displayed variations seasonally and spatially by different techniques, which were mainly driven by temperature, salinity, nutrients, and turbidity. The combination of more technical means provides more information for studying <italic>Synechococcus</italic> distribution. In this study, three pigment types of <italic>Synechococcus</italic> were discriminated simultaneously by dual lasers flow cytometer for the first time.</p>