Bacterial consortium proteomics under 4‐chlorosalicylate carbon‐limiting conditions

Abstract

In this study, the stable consortium composed by Pseudomonas reinekei strain MT1 and Achromobacter xylosoxidans strain MT3 (cell numbers in proportion 9:1) was under investigation to reveal bacterial interactions that take place under severe nutrient-limiting conditions. The analysis of steady states in continuous cultures was carried out at the proteome, metabolic profile, and population dynamic levels. Carbon-limiting studies showed a higher metabolic versatility in the community through upregulation of parallel catabolic enzymes (salicylate 5-hydroxylase and 17-fold on 2-keto-4-pentenoate hydratase) indicating a possible alternative carbon routing in the upper degradation pathway highlighting the effect of minor proportions of strain MT3 over the major consortia component strain MT1 with a significant change in the expression levels of the enzymes of the mainly induced biodegradation pathway such as salicylate 1-hydroxylase and catechol 1,2-dioxygenase together with important changes in the outer membrane composition of P. reinekei MT1 under different culture conditions. The study has demonstrated the importance of the outer membrane as a sensing/response protective barrier caused by interspecies interactions highlighting the role of the major outer membrane proteins OprF and porin D in P. reinekei sp. MT1 under the culture conditions tested.

Consortia modulation of the stress response: proteomic analysis of single strain versus mixed culture

“…The initial composition of the culture showed 68% of the community culture cell counts to be specifically stained with strain MT1 probe and 10% with MT3 probe (data not shown). This is similar to previously reported results (Bobadilla Fazzini et al ., 2009). Taken together, 78% closely approximates the 84% live cell counts determined by dead and live staining (Table 1), considering that rRNA targeted FISH gives a strong signal mainly in highly active cells, proportional to the ribosomal content (Zwirglmaier, 2005).…”

“…Proteomics was focused mainly on proteins with significant differential expression (DE) for which new identification (see Tables S1–4) confirmed what was previously reported (Bobadilla Fazzini et al ., 2009). No DE of the enzymes of the main catabolic pathway of 4CS (Nikodem et al ., 2003) was observed.…”

“…The metabolite profile before inoculation of A. xylosoxidans MT3 showed stable micromolar concentrations of cis ‐dienelactone and protoanemonin that were not significantly altered after the addition of strain MT3 as reported before (Bobadilla Fazzini et al ., 2009). After the addition of 4CS, the metabolic profile showed a rather different situation compared with the one observed in the pure strain MT1 culture (Fig.…”

“…The proteomic analysis of the community was initially based on a reference map of the metaproteome previously built from P. reinekei MT1 and A. xylosoxidans MT3 grown in 4CS at the same culture conditions. This includes 41 and 43 different protein spots identified from the strains MT1 and MT3, respectively, including chaperons, central and amino acid metabolism as well as aromatic degradation enzymes and stress response proteins, among others (Bobadilla Fazzini et al ., 2009). The proteomic profile of the P. reinekei MT1 and A. xylosoxidans MT3 consortium culture under 4CS load, restricted to the comparison of initial conditions, showed a very similar proteome pattern to the one observed for strain MT1 (Tables S1–4).…”

“…Finally, a metaproteomic study performed in our laboratory has recently shown a higher metabolic versatility in the mixed culture through the upregulation of parallel catabolic enzymes, indicating an alternative carbon routing in the upper degradation pathway. This highlights the interaction of minor proportions of strain MT3 over the major consortia component strain MT1 under carbon‐limiting conditions (Bobadilla Fazzini et al ., 2009. Following our studies of bacterial interactions in a model community composed of P. reinekei sp.…”