A Unique Pool of Compatible Solutes on Rhodopirellula baltica, Member of the Deep-Branching Phylum Planctomycetes

Abstract

The intracellular accumulation of small organic solutes was described in the marine bacterium Rhodopirellula baltica, which belongs to the globally distributed phylum Planctomycetes whose members exhibit an intriguing lifestyle and cell morphology. Sucrose, α-glutamate, trehalose and mannosylglucosylglycerate (MGG) are the main solutes involved in the osmoadaptation of R. baltica. The ratio and total intracellular organic solutes varied significantly in response to an increase in salinity, temperature and nitrogen content. R. baltica displayed an initial response to both osmotic and thermal stresses that includes α-glutamate accumulation. This trend was followed by a rather unique and complex osmoadaptation mechanism characterized by a dual response to sub-optimal and supra-optimal salinities. A reduction in the salinity to sub-optimal conditions led primarily to the accumulation of trehalose. In contrast, R. baltica responded to salt stress mostly by increasing the intracellular levels of sucrose. The switch between the accumulation of trehalose and sucrose was by far the most significant effect caused by increasing the salt levels of the medium. Additionally, MGG accumulation was found to be salt- as well as nitrogen-dependent. MGG accumulation was regulated by nitrogen levels replacing α-glutamate as a K+ counterion in nitrogen-poor environments. This is the first report of the accumulation of compatible solutes in the phylum Planctomycetes and of the MGG accumulation in a mesophilic organism.

Vertical organization of microbial communities in Salineta hypersaline wetland, Spain

“…Furthermore, the microbial biomarkers revealed by LEfSe were affiliated with five bacterial OTUs (belonging to the Anaerolineaceae family and the Salinarimonas, Rhodopirellula, Desulfonatronobacter, and Aliifodinibius genera) and two archaeal OTUs (Halorubellus genus and H. formicicum) for the upper layer. Consistent with low ORP observed at the upper layer L1, these OTUs are affiliated with taxa detected in hypersaline ecosystems exhibiting strictly (Anaerolineaceae, Desulfonatronobacter, Aliifodinibius, H. formicicum) or facultative (Salinarimonas, Rhodopirellula) anaerobic metabolisms (Cai et al, 2011;Cui et al, 2012;d'Avó et al, 2013;Sorokin et al, 2015Sorokin et al, , 2017Sugihara et al, 2016). They have also been shown to possess adaptation capacities to sudden environmental changes (Wecker et al, 2009;Cui et al, 2012) that might explain their adaptation to the extreme and fluctuating environmental conditions prevailing at Salineta wetland, especially at the surface soil layer.…”

Effects of Soil Salinity on Sucrose Metabolism in Cotton Fiber

“…Thus, cellulose, sucrose, and β-1,3-glucan are closely associated for ascertaining main fiber quality attributes. Extensive investigations have been conducted on the enzymology of sucrose metabolism in marine planctomycete Rhodopirellula baltica [ 15 ] and Methylotrophic bacteria [ 16 ], under salinity stress. However, there are no previous reports on the relationship between the metabolism of substances involved in fiber development and the fiber quality attributes under salt stress.…”

Mannosylglucosylglycerate biosynthesis in the deep-branching phylum Planctomycetes: characterization of the uncommon enzymes from Rhodopirellula baltica

“…MGG, unexpectedly, was recently shown to accumulate in the mesophilic Rhodopirellula baltica 7 (SH 1 T )7, a pink-colored marine aerobic heterotrophic representative of the Planctomycetes 8. The identification of MGG in this deep-rooted organism17 prompted us to examine the pathway for its synthesis.…”

“…The identification of MGG in this deep-rooted organism17 prompted us to examine the pathway for its synthesis.…”