<i><scp>C</scp>omamonas testosteroni</i> uses a chemoreceptor for tricarboxylic acid cycle intermediates to trigger chemotactic responses towards aromatic compounds

Ni, Bin; Huang, Zhou; Fan, Zheng; Jiang, Cheng‐Ying; Liu, Shuang‐Jiang

doi:10.1111/mmi.12400

Cited by 64 publications

(70 citation statements)

References 57 publications

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“…2(a) that significant detectable bacterial chemotaxis was observed towards NaAc and n -hexadecane, but no obvious chemotactic behavior was performed in the presence of hexadecanol or hexadecanoic acid. However, Ni et al 28. showed Comamonas testosteroni used a chemoreceptor for tricarboxylic acid cycle intermediates to trigger chemotactic responses towards aromatic compounds.…”

Section: Resultsmentioning

confidence: 99%

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Long

Bao

et al. 2017

Sci Rep

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Bacteria can use n-hexadecane as a carbon source, but it remains incompletely understood whether n-hexadecane is transformed into metabolic intermediates prior to cellular uptake or not. We newly isolated a strain identified as Pseudomonas synxantha LSH-7′ and conducted chemotaxis experiment of this bacterial strain towards n-hexadecane, hexadecanol and hexadecanoic acid with qualitative assays respectively. Furthermore, we described the identification of extracellular alkane hydroxylase and alcohol dehydrogenase activity; acidification of the culture medium; identification of hexadecanoic acid in the culture medium by the GC-MS analysis; and variation concentration of intracellular n-hexadecane and hexadecanoic acid. A detailed analysis of the experimental data revealed the chemotaxis of this bacterial strain towards n-hexadecane instead of its metabolic intermediates. Our results further suggested that only a fraction of total n-hexadecane followed this path, and alkane hydrolase and hexadecanol dehydrogenase were constitutively expressed when grown in the medium of n-hexadecane. Most strikingly, we quantitatively investigated the concentration of n-hexadecane adsorbed by bacterial chemotaxis. Our findings provided an original insight n-hexadecane might be converted to hexadecanoic acid extracellularly before it was taken up across the cell membrane.Alkanes are found highly abundant constituents of petroleum hydrocarbons are major environmental pollutants as a result of terrestrial and freshwater runoff, refuse from coastal oil refineries, off shore oil production, shipping activities and accidental spills 1,2 . Among the alkanes, n-hexadecane is a major component. The solubility of n-hexadecane in water is 5.21 × 10 −5 mg L −1 at 15 °C and has high partitioning co-efficient 9.1 logKow 3 . Biodegradation of n-hexadecane is believed to be a friendly way to environment as well as human beings. For this, it is necessary to know the metabolic mechanisms of n-hexadecane.Singer and Finnerty 4 observed terminal n-hexadecane degradation by Acinetobacter HO1-N and Pseudomonas putida, and identified five intermediates as n-hexadecylhydroperoxide, n-hexadecanol, n-hexadecyldehyde, n-hexadecanoic acid and n-hexadecylhexadecanoate in degradation process. However, Whyte et al. 5 reported both terminal and sub-terminal oxidation of n-C16 by Rhodococcus strain Q15 producing 1-hexadecanol and 2-hexadecanol. Recently, a new insights into alkane metabolism pathways from alkane sensing, chemotaxis, signal transduction, uptake to degradation was put forward by Wang and shao 6 from the aspect of genes. The underlying mechanisms that control the early responses of bacterial cells to n-hexadecane, such as chemotaxis and uptake, remain largely unexplored.Chemotaxis is defined as the capacity of certain organisms to sense substance concentration gradients and in turn moved towards or away from this gradient 7-9 . Most importantly, alkane chemotaxis had been observed in bacterial isolates of Flavimonas oryzihabitans genus 10 , and even ...

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Section: Resultsmentioning

confidence: 99%

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Long

Bao

et al. 2017

Sci Rep

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“…Microcalorimetric measurements of the binding of iron ions to Psl were performed on a Nano isothermal titration calorimetry (ITC) 2G at 25°C (TA Instruments, USA), as described previously, with modifications (43). Psl was dissolved into deionized water.…”

Section: Methodsmentioning

confidence: 99%

A Survival Strategy for Pseudomonas aeruginosa That Uses Exopolysaccharides To Sequester and Store Iron To Stimulate Psl-Dependent Biofilm Formation

Wei

Zhao

et al. 2016

Appl Environ Microbiol

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Exopolysaccharide Psl is a critical biofilm matrix component in Pseudomonas aeruginosa, which forms a fiber-like matrix to enmesh bacterial communities. Iron is important for P. aeruginosa biofilm development, yet it is not clearly understood how iron contributes to biofilm development. Here, we showed that iron promoted biofilm formation via elevating Psl production in P. aeruginosa. The high level of iron stimulated the synthesis of Psl by reducing rhamnolipid biosynthesis and inhibiting the expression of AmrZ, a repressor of psl genes. Iron-stimulated Psl biosynthesis and biofilm formation held true in mucoid P. aeruginosa strains. Subsequent experiments indicated that iron bound with Psl in vitro and in biofilms, which suggested that Psl fibers functioned as an iron storage channel in P. aeruginosa biofilms. Moreover, among three matrix exopolysaccharides of P. aeruginosa, Psl is the only exopolysaccharide that can bind with both ferrous and ferric ion, yet with higher affinity for ferrous iron. Our data suggest a survival strategy of P. aeruginosa that uses exopolysaccharide to sequester and store iron to stimulate Psl-dependent biofilm formation. IMPORTANCEPseudomonas aeruginosa is an environmental microorganism which is also an opportunistic pathogen that can cause severe infections in immunocompromised individuals. It is the predominant airway pathogen causing morbidity and mortality in individuals affected by the genetic disease cystic fibrosis (CF). Increased airway iron and biofilm formation have been proposed to be the potential factors involved in the persistence of P. aeruginosa in CF patients. Here, we showed that a high level of iron enhanced the production of the key biofilm matrix exopolysaccharide Psl to stimulate Psl-dependent biofilm formation. Our results not only make the link between biofilm formation and iron concentration in CF, but also could guide the administration or use of iron chelators to interfere with biofilm formation in P. aeruginosa in CF patients. Furthermore, our data also imply a survival strategy of P. aeruginosa under high-iron environmental conditions. P seudomonas aeruginosa is a ubiquitous environmental microorganism. It is also an opportunistic pathogen that is often found in the hospital environment. P. aeruginosa can cause severe acute nosocomial infections in immunocompromised individuals or chronic lung infections in cystic fibrosis (CF) patients (1). These infections generally persist despite the use of intensive antimicrobial therapy and have been linked to the formation of antibiotic-resistant biofilms, wherein bacterial cells were encased in an extracellular polymeric substance (EPS) matrix (2, 3). It is generally accepted that the biofilm matrix functions as both a structural scaffold and protective barrier for bacteria in biofilms (4, 5). The iron content of CF sputum is often highly increased compared to that in the sputum of healthy controls, which has also been considered a potential factor in the persistence of P. aeruginosa (6-8). Mineral elem...

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“…ITC was performed as previously described 59 with minimal modifications. Measurements were performed using a NANO ITC 2G at 20°C.…”

Section: Methodsmentioning

confidence: 99%

The long-chain alkane metabolism network of Alcanivorax dieselolei

2014

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Alkane-degrading bacteria are ubiquitous in marine environments, but little is known about how alkane degradation is regulated. Here we investigate alkane sensing, chemotaxis, signal transduction, uptake and pathway regulation in Alcanivorax dieselolei. The outer membrane protein OmpS detects the presence of alkanes and triggers the expression of an alkane chemotaxis complex. The coupling protein CheW2 of the chemotaxis complex, which is induced only by long-chain (LC) alkanes, sends signals to trigger the expression of Cyo, which participates in modulating the expression of the negative regulator protein AlmR. This change in turn leads to the expression of ompT1 and almA, which drive the selective uptake and hydroxylation of LC alkanes, respectively. AlmA is confirmed as a hydroxylase of LC alkanes. Additional factors responsible for the metabolism of medium-chain-length alkanes are also identified, including CheW1, OmpT1 and OmpT2. These results provide new insights into alkane metabolism pathways from alkane sensing to degradation.

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Comamonas testosteroni uses a chemoreceptor for tricarboxylic acid cycle intermediates to trigger chemotactic responses towards aromatic compounds

Cited by 64 publications

References 57 publications

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

Metabolic pathway for a new strain Pseudomonas synxantha LSH-7′: from chemotaxis to uptake of n-hexadecane

A Survival Strategy for Pseudomonas aeruginosa That Uses Exopolysaccharides To Sequester and Store Iron To Stimulate Psl-Dependent Biofilm Formation

The long-chain alkane metabolism network of Alcanivorax dieselolei

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