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Pseudomonas putida
About: Pseudomonas putida is a research topic. Over the lifetime, 6854 publications have been published within this topic receiving 230572 citations.
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TL;DR: In addition to the discovery of a new LOX gene in tomato, this work is the first to show differential induction of LOX isozymes and a more rapid accumulation of 13-hydroperoxy-octadecatrienoic and13-hydroxy- octadecatrianoic acids in rhizobacteria mediated-induced systemic resistance.
Abstract: Some non-pathogenic rhizobacteria called Plant Growth Promoting Rhizobacteria (PGPR) possess the capacity to induce in plant defense mechanisms effective against pathogens. Precedent studies showed the ability of Pseudomonas putida BTP1 to induce PGPR-mediated resistance, termed ISR (Induced Systemic Resistance), in different plant species. Despite extensive works, molecular defense mechanisms involved in ISR are less well understood that in the case of pathogen induced systemic acquired resistance. We analyzed the activities of phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX), key enzymes of the phenylpropanoid and oxylipin pathways respectively, in tomato treated or not with P. putida BTP1. The bacterial treatment did not stimulate PAL activity and linoleate-consuming LOX activities. Linolenate-consuming LOX activity, on the contrary, was significantly stimulated in P. putida BTP1-inoculated plants before and two days after infection by B. cinerea. This stimulation is due to the increase of transcription level of two isoforms of LOX: TomLoxD and TomLoxF, a newly identified LOX gene. We showed that recombinant TomLOXF preferentially consumes linolenic acid and produces 13-derivative of fatty acids. After challenging with B. cinerea, the increase of transcription of these two LOX genes and higher linolenic acid-consuming LOX activity were associated with a more rapid accumulation of free 13-hydroperoxy-octadecatrienoic and 13-hydroxy-octadecatrienoic acids, two antifungal oxylipins, in bacterized plants. In addition to the discovery of a new LOX gene in tomato, this work is the first to show differential induction of LOX isozymes and a more rapid accumulation of 13-hydroperoxy-octadecatrienoic and 13-hydroxy-octadecatrienoic acids in rhizobacteria mediated-induced systemic resistance.
88 citations
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TL;DR: Results indicate that PGPR improve growth parameters in this plant and can help in the biocontrol of pathogen.
Abstract: In this study, antagonistic effects of 6 isolates of Pseudomonas and 6 isolates of Bacillus genera isolated from rhizosphere of chickpea were evaluated against Fusarium oxysporum f. sp. ciceris as potential biocontrol agents in vitro and in vivo. Fungal inhibition tests were performed using plate assay. Each isolate were tested for the production of protease, siderophore, cyanide hydrogen, indole acetic acid, antifungal volatile and extracellular compound. Twelve isolates were selected according to their high antagonistic efficiency in in vitro which was shown as inhibition zones in the dual-culture assay. According to phenotypic properties, selected isolates were identified as Bacillus subtilis (B1, B6, B28, B40, B99, and B108), Pseudomonas putida (P9 and P10) and P. aeuroginosa (P11, P12, P66 and P112). The ability of bacterial isolates was varied in production of cyanide hydrogen, siderophore, protease and indole acetic acid (IAA). Biocontrol activity and plant growth promotion of bacterial strains were evaluated under greenhouse conditions, in which P. aeuroginosa (P10 and P12), B. subtilis (B1, B6, B28 and B99) and P. aeuroginosa (P12 and B28) provided better control (P <= 0.05) than untreated control (15.8-44.8%) in seed treatment and soil-inoculation, respectively. The growth parameters (plant height, fresh and dry weight of plants) were significantly increased by B28, P12 and P112 isolates in both tests compared to the untreated control. Our results indicate that PGPR improve growth parameters in this plant and can help in the biocontrol of pathogen.
88 citations
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TL;DR: The protective role of two rhizobacteria, Pseudomonas putida and Novosphingobium sp.
Abstract: This work reveals the protective role of two rhizobacteria, Pseudomonas putida and Novosphingobium sp., on citrus plants subjected to salt stress conditions. Detrimental salt stress effects on crops are likely to increase due to climate change reducing the quality of irrigation water. Plant growth-promoting rhizobacteria (PGPRs) can mitigate stress-induced damage in plants cultivated under high salinity conditions. In this work, Citrus macrophylla (alemow) plants inoculated with the rhizobacteria Pseudomonas putida KT2440 or Novosphingobium sp. HR1a were subjected to salt stress for 30 days. Results showed that in absence of salt stress, Novosphingobium sp. HR1a induced a decrease of transpiration (E) and stomatal conductance (gs). Both rhizobacteria reduced salt stress-induced damage. Levels of abscisic acid (ABA) and salicylic acid (SA) were lower in inoculated plants under salt stress conditions. Similarly, under stress conditions maximum efficiency of photosystem II (Fv/Fm) in inoculated plants decreased to a lower extent than in non-inoculated ones. In stressed plants, Novosphingobium sp. HR1a also induced leaf accumulation of 3-indole acetic acid (IAA) and a delay in the decrease of quantum yield (ΦPSII). P. putida KT2440 inhibited root chloride and proline accumulation in response to salt stress. Although both bacterial species had beneficial effects on salt-stressed citrus plants, Novosphingobium sp. HR1a induced a better plant performance. Therefore, both strains could be candidates to be used as PGPRs in programs of inoculation for citrus protection against salt stress.
87 citations
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TL;DR: The suitability of Pseudomonas putida GPo1 for large-scale cultivation and production of poly(3-hydroxyoctanoate) (PHO) was investigated in this study and a highly purified PHO was obtained.
Abstract: The suitability of Pseudomonas putida GPo1 for large-scale cultivation and production of poly(3-hydroxyoctanoate) (PHO) was investigated in this study. Three fed-batch cultivations of P. putida GPo1 at the 350- or 400-liter scale in a bioreactor with a capacity of 650 liters were done in mineral salts medium containing initially 20 mM sodium octanoate as the carbon source. The feeding solution included ammonium octanoate, which was fed at a relatively low concentration to promote PHO accumulation under nitrogen-limited conditions. During cultivation, the pH was regulated by addition of NaOH, NH4OH, or octanoic acid, which was used as an additional carbon source. Partial O2 pressure (pO2) was adjusted to 20 to 40% by controlling the airflow and stirrer speed. Under the optimized conditions, P. putida GPo1 was able to grow to cell densities as high as 18, 37, and 53 g cells (dry mass) (CDM) per liter containing 49, 55, and 60% (wt/wt) of PHO, respectively. The resulting 40 kg CDM from these three cultivations was used directly for extraction of PHO. Three different methods of extraction of PHO were applied. From these, only acetone extraction showed better performance and resulted in 94% recovery of the PHO contents of cells. A novel mixture of precipitation solvents composed of 70% (vol/vol) methanol and 70% (vol/vol) ethanol was identified in this study. The ratio of PHO concentrate to the mixture was 0.2:1 (vol/vol) and allowed complete precipitation of PHO as white flakes. However, at a ratio of 1:1 (vol/vol) of the solvent mixture to PHO concentrate, a highly purified PHO was obtained. Precipitation yielded a dough-like polymeric material which was cast into thin layers and then shredded into small strips to allow evaporation of the remaining solvents. Gas chromatographic analysis revealed a purity of about 99% ± 0.2% (wt/wt) of the polymer, which consisted mainly of 3-hydroxyoctanoic acid (96 mol%).
87 citations
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TL;DR: P. putida was found to be the most suitable biocatalyst for further studies as it showed higher reaction rate, lower K m, better growth rate, good yield and ee values and higher stability compared to the other two microorganisms.
Abstract: Several new microorganisms have been isolated with high nitrilase activity against ( RS )-mandelonitrile using the enrichment culture technique. The organisms were cultivated in liquid culture and the enzyme activity was determined at different phases of growth. The organisms having high enzyme titre were further grown and used as catalysts for the transformation of mandelonitrile to mandelic acid. The percentage conversion was checked with RP-HPLC and the enantiomeric excess was determined on a chiral column. Three isolates gave the desired product, ( R )-(−)-mandelic acid with high ee (%) and were identified as Pseudomonas putida , Microbacterium paraoxydans and Microbacterium liquefaciens . All three isolates showed good specific activity (0.33–0.50 U/mg min) with high ee (>93%) and E values. The conversion of racemic mandelonitrile to mandelic acid by these isolates was compared: P. putida was found to be the most suitable biocatalyst for further studies as it showed higher reaction rate ( k Rxn ), lower K m , better growth rate ( μ ), good yield and ee values and higher stability compared to the other two microorganisms.
87 citations