Project description:Polysaccharides from macroalgae are important bacterial nutrient source and central biogeochemical component in the oceans. To illuminate the cellular mechanisms of polysaccharide degradation by marine bacteria, growth of Alteromonas macleodii 83-1 on a mix of laminarin, alginate and pectin was characterized using transcriptomics, proteomics and exometabolomics. A. macleodii 83-1 showed two distinct growth stages, with exponential growth during laminarin utilization followed by maintenance during simultaneous alginate/pectin utilization. The biphasic growth coincided with major temporal shifts in gene expression and metabolite secretion, enabling to define major/accessory polysaccharide utilization loci, reconstruct the complete degradation pathways for each polysaccharide, as well as identify temporal phenotypes in other relevant traits. FT-ICR-MS revealed a distinct suite of secreted metabolites for each growth phase, with pyrroloquinoline quinone exclusively produced with alginate/pectin. The finding of substrate-unique phenotypes indicates an exquisite adaptation to polysaccharide utilization with probable relevance for the degradation of macroalgal biomass, which comprises a complex mix of polysaccharides. Moreover, substrate-unique exometabolomes possibly influence metabolic interactions with other community members. Overall, the presence of fine-tuned genetic machineries for polysaccharide degradation and the widespread detection of related CAZymes in global locations indicate an ecological relevance of A. macleodii in marine polysaccharide cycling and bacteria-algae interactions.
Project description:Interkingdom Pseudomonas-Candida biofilms is a human pathogen associated with acute and chronic infection. This study examine hoe their structural organization influences their in vivo microenvironment, which in turns affects the interaction of Pseudomonas-Candida biofilms with host immune responses. NCI-H292 grown P. aeruginosa biofilms with and without C. albicans biofilms were used for proteomic analysis. Biofilms were demonstrated in all groups which have 357 proteins from proteomic analysis including i) proteins in PA+CA were higher than PA (76 proteins, such as sigma factor AlgU negative regulatory protein; MucA) and ii) proteins in PA+CA were lower than PA (281 proteins, including alginate genes such as Alginate biosynthesis transcriptional regulatory protein; AlgB). Although most of Pseudomonas proteins in PA+CA were lower than PA due to the lower initial bacteria in preparation of mixed-organism biofilms, mucA overexpressed in PA+CA indicating that high alginate production that transcriptionally controlled by algU-mucABCD genes. These results demonstrated that Pseudomonas-Candida biofilms produced alginate more compared to Pseudomonas biofilms on lungs.
Project description:Polysaccharides from macroalgae are important bacterial nutrient source and central biogeochemical component in the oceans. To illuminate the cellular mechanisms of polysaccharide degradation by marine bacteria, growth of Alteromonas macleodii 83-1 on a mix of laminarin, alginate and pectin was characterized using transcriptomics, proteomics and exometabolomics. A. macleodii 83-1 showed two distinct growth stages, with exponential growth during laminarin utilization followed by maintenance during simultaneous alginate/pectin utilization. The biphasic growth coincided with major temporal shifts in gene expression and metabolite secretion, enabling to define major/accessory polysaccharide utilization loci, reconstruct the complete degradation pathways for each polysaccharide, as well as identify temporal phenotypes in other relevant traits. FT-ICR-MS revealed a distinct suite of secreted metabolites for each growth phase, with pyrroloquinoline quinone exclusively produced with alginate/pectin. The finding of substrate-unique phenotypes indicates an exquisite adaptation to polysaccharide utilization with probable relevance for the degradation of macroalgal biomass, which comprises a complex mix of polysaccharides. Moreover, substrate-unique exometabolomes possibly influence metabolic interactions with other community members. Overall, the presence of fine-tuned genetic machineries for polysaccharide degradation and the widespread detection of related CAZymes in global locations indicate an ecological relevance of A. macleodii in marine polysaccharide cycling and bacteria-algae interactions.
Project description:Alginate, a major exopolysaccharide (EPS) produced by P. putida, is known to create hydrated environments and alleviate the effect of water limitation. In addition to alginate, P. putida is capable of producing cellulose (bcs), putida exopolysaccharide a (pea), and putida exopolysaccharide b (peb). However, unlike alginate, not much is known about their roles under water limitation. Hence, in this study we examined the role of different EPS under water stress. To create environmentally realistic water stress conditions as observed in soil, we used Pressurized Porous Surface Model (PPSM). Our main hypothesis was that under water stress, absence of alginate would be compensated by the other EPS. To test our hypothesis, we investigated colony morphologies and whole genome transcriptomes of P. putida KT2440 WT and its mutants deficient in either alginate or all known EPS