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


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Abstract

SummaryThe high complexity of naturally occurring microbial communities is the major drawback limiting the study of these important biological systems. In this study, a comparison between pure cultures ofPseudomonas reinekeisp. strain MT1 and stable community cultures composed of MT1 plus the addition ofAchromobacter xylosoxidansstrain MT3 (in a steady-state proportion 9:1) was used as a model system to study bacterial interactions that take place under simultaneous chemical and oxidative stress. Both are members of a real community isolated from a polluted sediment by enrichment in 4-chlorosalicylate (4CS). The analysis of dynamic states was carried out at the proteome, metabolic profile and population dynamic level. Differential protein expression was evaluated under exposure to 4CS and high concentrations of toxic intermediates (4-chlorocatechol and protoanemonin), including proteins from several functional groups and particularly enzymes of aromatic degradation pathways and outer membrane proteins. Remarkably, 4CS addition generated a strong oxidative stress response in pure strain MT1 culture led by alkyl hydroperoxide reductase, while the community showed an enhanced central metabolism response, whereA. xylosoxidansMT3 helped to prevent toxic intermediate accumulation. A significant change in the outer membrane composition ofP. reinekeiMT1 was observed during the chemical stress caused by 4CS and in the presence ofA. xylosoxidansMT3, highlighting the expression of the major outer membrane protein OprF, tightly correlated to 4CC concentration profile and its potential detoxification role.

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