On the molecular diversity of dimethylsulphoniopropionate catabolism by marine bacteria

Dimethylsulphoniopropionate (DMSP) is the most abundant organic sulphur molecule in the oceans. Its breakdown by marine organisms is important for the global cycling of sulphur, and as a nutrient source for microbial life. In recent years, the molecular basis of DMSP catabolism by marine bacteria has begun to be unravelled, through the discovery of six different DMSP lyases and a DMSP demethylase, as well as downstream pathways. From these studies, it is becoming evident that there is great diversity in the way bacteria breakdown this important molecule. The work presented here further explores and expands our knowledge of this diversity. I have identified a novel DMSP lyase (DddK), which catalyses the cleavage of DMSP into acrylate and dimethyl sulphide (DMS) in the DMS-producing Candidatus Pelgaibacter ubique HTCC1062 - one of the most prolific bacteria on this planet. I have also shown that the γ-proteobacterium Oceanimonas doudoroffii, which has long been a study species for DMSP catabolism, has no fewer than three functional DMSP lyases - DddD, DddP1 and DddP2 - this being the first example of a species outside of the α-proteobacteria having multiple lyases. Additionally, I have presented a thorough bioinformatics analysis of the occurrence and synteny of genes associated with DMSP catabolism within sequenced members of the abundant Roseobacter clade, revealing some interesting patterns which warrant further experimental investigation. Finally, I have shown that the model marine Roseobacter species Ruegeria pomeroyi DSS-3 is able to use DMSP-derived acrylate as a sole carbon source via a fatty acid biosynthesis route, linked to propionate catabolism.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2015

Author dc:creator

• Fowler, Emily

Language dc:language

en