Gradual adaptation of facultative anaerobic pathogens to microaerobic and anaerobic conditions

Abstract

Many notable human pathogens are facultative anaerobes. These pathogens exhibit redundant metabolic pathways and a whole array of regulatory systems to adapt to changing oxygen levels. However, our knowledge of facultative anaerobic pathogens is mostly based on fully aerobic or anaerobic cultures, which does not reflect real infection conditions, while the microaerobic range remains understudied. Here, we examine the behavior of pathogenic and nonpathogenic strains of two facultative anaerobes, Escherichia coli and Pseudomonas aeruginosa, during the aerobicanaerobic transition. To do so, we introduce a new technique named AnaeroTrans, in which we allow self-consumption of oxygen by steady-state cultures and monitor the system by measuring the gas-phase oxygen concentration. We explore the different behavior of the studied species toward oxygen and examine how this behavior is associated with the targeted infection sites. As a model, we characterize the adaptation profile of the ribonucleotide reductase network, a complex oxygen-dependent enzymatic system responsible for the generation of the deoxyribonucleotides. We also explore the actions of the most important anaerobic regulators and how these regulators influence bacterial fitness. Our results allow us to classify the different elements that compose the aerobic-anaerobic transition into reproducible stages, thus showing the different adaptation mechanisms of the studied species. K E Y W O R D Sbiofilm, Escherichia, oxygen, Pseudomonas, ribonucleotide

Differential adaptability between reference strains and clinical isolates of Pseudomonas aeruginosa into the lung epithelium intracellular lifestyle

“…It is possible that this increased toxicity may influence the intracellular persistence of the bacterium. However, in addition to the basal oxygenic state of the cells, a common trait among the different infectious conditions was the differential oxygen consumption during the intracellular persistence of the different P. aeruginosa strains within the A549, 16HBE14o-, and CFBE41o-monolayers, which is in agreement with other studies, indicating that pathogen colonization of the lung epithelium exacerbates tissue hypoxia [31] by increasing their own metabolism [18].…”

“…qRT-PCR of nrdA, nrdD, nrdJ genes, in the different infectious conditions and time points was done with 1 μl of cDNA per reaction, using PowerUP Sybr Green Master Mix (ThermoFisher Scientific) and specific primers of P. aeruginosa's nrd genes [18]. The glyceraldehyde 3-phosphate gene (gapA) was used as an internal control.…”

Exploration of Potential Gut Microbiota-Derived Biomarkers to Predict the Success of Fecal Microbiota Transplantation in Ulcerative Colitis: A Prospective Cohort in Korea

“…49 Even though the other five phenotype predictions indicated the moving trends of recipient's microbiome toward donor's, furthermore, we could not assert that the successful engraftment of microbiota guaranteed the prognosis of FMT. For example, the proportion of facultatively anaerobic bacteria and bacteria with mobile elements which were pointed as a potential pathogen in previous study 50,51 were higher in RP group. Additionally, aerobic bacteria represented as a biomarker of colitis 52 was more common in RP compared to NRP.…”

Nitric Oxide Production and Effects in Group B Streptococcus Chorioamnionitis

“…Bifunctional acetaldehyde-alcohol dehydrogenase is an enzyme that converts acetyl-CoA to ethanol under anaerobic conditions [ 83 ]. Although not directly involved in scavenging reactive nitrogen byproducts, activation of anaerobic metabolism during NO exposure may represent an adaptive response that decreases the total burden of harmful radicals by limiting endogenous production of reactive oxygen species [ 84 , 85 , 86 ]. Bifunctional acetaldehyde-alcohol dehydrogenase has also been associated with increased bacterial adherence in Listeria monocytogenes and Streptococcus pneumoniae [ 87 , 88 ].…”