Polyphosphate dynamics in marine heterotrophic bacteria under phosphorus and organic carbon limitations

Abstract

PolyP has diverse biological functions and is widely distributed in aquatic environments. PolyP metabolisms in marine heterotrophic bacteria may affect bacteria-phytoplankton interaction and strongly impact marine ecology and biogeochemistry. However, while previous research on bacterial polyP has predominantly focused on Escherichia coli and polyP-accumulating bacteria in wastewater treatment plants, little is known about marine heterotrophic bacteria, in which the potential roles of polyP and their ecological significance remain underexplored. In this study, three marine bacteria, Alteromona sp. PM7-2, Photobacterium ganghwense KCTC12328 and Vibrio sp. Mos9 were investigated under phosphorus (P) and organic carbon (OC) limitation conditions (–P and +P conditions, respectively). Results showed that bacteria accumulated polyP through two different mechanisms, luxury uptake under high-P conditions and deficiency response under low-P conditions. Bacteria presented different polyP accumulation capabilities, with Alteromonas sp. PM7-2 demonstrated the highest polyP accumulation among the three studied bacteria, followed by Photobacterium ganghwense KCTC12328, and Vibrio sp. Mos9 exhibited the lowest polyP accumulation ability. Bacteria also responded differently to P and OC limitations. PolyP can support the growth of Alteromona sp. PM7-2 and Photobacterium ganghwense KCTC12328 under P limitation when fresh dissolved organic carbon (i.e., glucose) was available. In Photobacterium ganghwense KCTC12328, when bioavailable P was sufficient, accumulation of polyP also helped the bacteria to survive OC limitation. Accumulation of polyP in Vibrio sp. Mos9, on the other hand, did not support bacterial growth/survival under conditions of either P or OC limitations. These results suggest strong variability in polyP roles in C and P metabolisms of marine heterotrophic bacteria, which should receive more attention in future studies for understanding the ecological and biogeochemical roles of polyP in marine environments.

Date of Award	2024
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Jiying LI (Supervisor)