Distribution of Dimethylsulfoniopropionate Degradation Genes Reflects Strong Water Current Dependencies in the Sanriku Coastal Region in Japan: From Mesocosm to Field Study

Abstract

Dimethyl sulfide (DMS) is an important component of the global sulfur cycle as it is the most abundant sulfur compound that is emitted via the ocean surface to the atmosphere. Dimethylsulfoniopropionate (DMSP), the precursor of DMS, is mainly produced by phytoplankton and is degraded by marine bacteria. To reveal the role of bacteria in the regulation of DMSP degradation and DMS production, mesocosm and field studies were performed in the Sanriku Coast on the Pacific Ocean in northeast Japan. The responsible bacteria for the transformation of DMSP to DMS and the assimilation of DMSP were monitored, and the genes encoding DMSP lyase ( dddD and dddP ) and DMSP demethylase ( dmdA ) were analyzed. The mesocosm study showed that the dmdA subclade D was the dominant DMSP degradation gene in the free-living (FL) and particle-associated (PA) fractions. The dddD gene was found in higher abundance than the dddP gene in all the tested samples. Most importantly, DMS concentration was positively correlated with the abundance of the dddD gene. These results indicated that bacteria possessing dmdA and dddD genes were the major contributors to the DMSP degradation and DMS production, respectively. The genes dmdA subclade D and dddP were abundant in the Tsugaru Warm (TW) Current, while the dmdA subclade C/2 and dddD genes were dominant in the Oyashio (OY) Current. Functional gene network analysis also showed that the DMSP degradation genes were divided into OY and TW Current-related modules, and genes sharing similar functions were clustered in the same module. Our data suggest that environmental fluctuations resulted in habitat filtering and niche partitioning of bacteria possessing DMSP degradation genes. Overall, our findings provide novel insights into the distribution and abundance of DMSP degradation genes in a coastal region with different water current systems.

Factors regulating the concentration of particulate iodine in coastal seawater

“…The POC, PON, and Chl a concentrations reported previously for coastal seawater in the upper (< 50 m water depth) layer adjacent to northeast Japan range from 1 < to 60 μ mol L −1 , 0.2 < to 10 μ mol L −1 , and 0.1 < to 40 μ g L −1 , respectively (Nakatsuka et al, 2004; Hasegawa et al, 2010; Cui et al, 2020). The datasets of POC, PON, and Chl a in this study contained values that almost fell in the ranges reported in the previous studies.…”

Similar but different: characterization of dddD gene mediated dimethylsulfoniopropionatemetabolism among Coral-Associated Endozoicomonas

“…4c). 34 S was labelled to monitor the DMS emission, and 3 13 C -DMSP was used to monitor DMSP in the cell. At least 37 bacterial cells (regions of interest, ROIs) were analyzed in each ±0.00309mM isotopic treatment.…”

“…Among the eight lyase enzymes, the dddD gene has a higher abundance than dddP (34) and is thought to be the main DMS producer via DMSP cleavage in coastal seawater, particularly when lysed by a member of the order Oceanospirillales (35). However, until now most of the studies related to DMSP have focused on the pelagic SAR11 clades of Alphaproteobacteria and phytoplankton-related Rhodobacterales, which are the main degraders of DMSP via demethylation in the ocean (35).…”

Recent insights into oceanic dimethylsulfoniopropionate biosynthesis and catabolism

“…Studies on the bacterial DMSP‐degrading genes such as dmdA and dddP have been carried out in varied marine environments (Cui et al ., 2015; Kuek et al ., 2016; Zeng et al ., 2016; Liu et al ., 2018; Nowinski et al ., 2019; Cui et al ., 2020; Teng et al ., 2021) and reported that these genes are taxonomically diverse and widespread across almost all major oceans, from tropical waters to the polar sea (Peng et al ., 2012; Cui et al ., 2015; Zeng et al ., 2016; Teng et al ., 2021). In comparison to DMSP catabolism, there were few molecular studies on environmental DMSP production and these showed bacterial DMSP production to be significant in surface coastal sediment, marine sediment and seawater, sea surface microlayer, estuary, and deep‐ocean environments (Williams et al ., 2019; Song et al ., 2020; Sun et al ., 2020; Zheng et al ., 2020; Sun et al ., 2021; Zhang et al ., 2021).…”