Search

Synthetic genetic circuits have revolutionised our capacity to control cell viability by conferring microorganisms with programmable functionalities to limit survival to specific environmental conditions. Here, we present the GenoMine safeguard, a CRISPR-Cas9-based kill switch for the biotechnological workhorse Pseudomonas putida that employs repetitive genomic elements as cleavage targets to unleash a highly genotoxic response. To regulate the system’s activation, we tested various circuit-based mechanisms including the digitalised version of an inducible expression system that operates at the transcriptional level and different options of post-transcriptional riboregulators. All of them were applied not only to directly control Cas9 and its lethal effects, but also to modulate the expression of two of its inhibitors: the AcrIIA4 anti-CRISPR protein and the transcriptional repressor TetR. Either upon direct induction of the endonuclease or under non-induced conditions of its inhibitors, the presence of Cas9 suppressed cell survival which could be exploited beyond biocontainment in situations where further CRISPR genome editing is undesirable.

Bacterial spot a significant disease that affects tomato crops, despite limited studies and scientific research on this disease, So This study aimed to assess the efficacy of various biological and chemical factors in controlling bacterial spot disease in the field. A field survey was conducted in Najaf Al-Ashraf, specifically in areas such as Al-Haidariya, Al-Rahima, Al-Abbasia, and 20 plastic houses. The disease incidence was observed in these locations, with infection rates from 24% to 60%. Among them, Al-Haidariya had the highest infection rate at 60%, while Al-Abbasia had the lowest at 24%. Regarding to the impact of chemical and biological inducing factors on infection severity, the treatment using nanoscale zinc oxide demonstrated superior effectiveness in reducing the severity of infection caused by Xanthomonas campestris pv. vesicatoria, In reducing the severity of the infection, which amounted to 11.6%, compared with the treatment of X.campestris 2 (control 2) only, which amounted to 74.2%.Field results also indicated that the nanoscale zinc oxide treatment was highly effective in increasing chemical indicators such as chlorophyll content, peroxidase enzyme and catalase enzyme. The values for these indicators were 12.69 mg g-1, 183.25-unit min-1 g -1 FW and 177.84-unit min-1 g -1 FW, respectively, compared to the control treatment, which recorded values of 7.79 mg g-1, 88.3-unit min-1 g -1 FW, and 74.17-unit min-1 g -1 FW, respectively. Furthermore, the treatment using Pseudomonas putida demonstrated superiority in increasing the percentage of TSS, vitamin C content, and acid percentage. The values for these parameters were 8.45%, 20.86 mg g-1, and 0.862%, respectively, compared to the control treatment, which recorded values of 4.78%, 11.09 mg g-1 and 0.462%, respectively. Moreover, the nanoscale zinc oxide treatment exhibited superior effectiveness in increasing the yield per plant, early fruit yield per plant, and total yield. The values for these parameters were 7.54 kg plant-1, 10.261 kg. plant-1 and 8.591 tons plastichouse-1 (500 m²), respectively, compared to the control treatment, which recorded values of 4.15 kg plant-1, 3.752 kg plant-1, and 4.929 tons/plastic house (500 m²), respectively. [ABSTRACT FROM AUTHOR]

For engineered microorganisms, the production of heterologous proteins that are often useless to host cells represents a burden on resources, which have to be shared with normal cellular processes. Within a certain metabolic leeway, this competitive process has no impact on growth. However, once this leeway, or free capacity, is fully utilized, the extra load becomes a metabolic burden that inhibits cellular processes and triggers a broad cellular response, reducing cell growth and often hindering the production of heterologous proteins. In this study, we sought to characterize the metabolic rearrangements occurring in the central metabolism of Pseudomonas putida at different levels of metabolic load. To this end, we constructed a P. putida KT2440 strain that expressed two genes encoding fluorescent proteins, one in the genome under constitutive expression to monitor the free capacity, and the other on an inducible plasmid to probe heterologous protein production. We found that metabolic fluxes are considerably reshuffled, especially at the level of periplasmic pathways, as soon as the metabolic load exceeds the free capacity. Heterologous protein production leads to the decoupling of anabolism and catabolism, resulting in large excess energy production relative to the requirements of protein biosynthesis. Finally, heterologous protein production was found to exert a stronger control on carbon fluxes than on energy fluxes, indicating that the flexible nature of P. putida 's central metabolic network is solicited to sustain energy production. • Heterologous protein production in P. putida reshuffles the periplasmic metabolism. • Increased protein production progressively decouples catabolism from anabolism. • Protein production exerts a stronger control on energy than on carbon fluxes. • Glucose is directed towards ATP production to meet the elevated energy demands. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a destructive disease that causes significant yield losses in wheat production worldwide, including in Egypt. The use of biocontrol agents is among the best eco-friendly management strategies to control this disease, as they are more sustainable and environmentally friendly than traditional chemical control methods. In a comparative analysis, antioxidant enzyme activity and various management approaches were compared with two bacterial biocontrol agents, Bacillus subtilis and Pseudomonas putida. This study showed the remarkable efficacy of endophytic bacteria, B. subtilis and P. putida, in mitigating wheat stripe rust infection across three wheat varieties, namely Misr1, Gimmeiza11, and Sids12. B. subtilis exhibited superior performance compared to P. putida, resulting in infection types of 1 and 2.66, respectively, following inoculation. The highest reduction rate was observed with Tilit fungicide (500 ppm), followed by B. subtilis and Salicylic acid (1000 ppm), respectively. Variations in wheat varieties' response to Pst infection were observed, with Misr1 exhibiting the lowest infection and Sids12 showing high susceptibility. Among the tested inducers, Salicylic acid demonstrated the greatest reduction in disease infection, followed by Indole acetic acid, while Oxalic acid exhibited the lowest decrease. Additionally, the study evaluated the activities of five antioxidant enzymes, including Catalase, Ascorbate peroxidase (APX), glutathione reductase (GR), Superoxide dismutase (SOD), and peroxidase (POX), in the wheat-stripe rust interaction under different integrated management approaches. The wheat variety Misr1 treated with Tilit (500 ppm), B. subtilis, Salicylic acid, Montoro (500 ppm), and P. putida exhibited the highest increase in all enzymatic activities. These findings provide valuable insights into the effectiveness of B. subtilis and P. putida as biocontrol agents for wheat stripe rust control in Egypt, emphasizing their potential role in sustainable, integrated, and environmentally friendly management practices. [ABSTRACT FROM AUTHOR]

As the production of graphene-based nanomaterials such as GO is increasing, it is expected that a large amount of GO waste will be generated. The environment (i.e., soil and aquatic systems) will be amongst the final repositories of these wastes which means important natural microbial communities in such environments will be at risk of GO exposure. However, little is known about how these communities respond to environmental stresses in synergy with the presence of GO. In this study, the effect of three different stress conditions: temperature (5, 25 and 40 °C); pH (5 to 9) and osmotic stress (51, 219 and 320 mM NaCl) in addition to GO treatment was investigated on the viability and physiology of biofilms and planktonic cells of soil bacterium P. putida. It was found that planktonic cells were more resistant to GO alone compared to biofilms. However, the cells were sensitive to GO when exposed to pH or osmotic stresses. Temperature was not found to influence the survival of biofilm with or without exposure to GO. However, low pH caused a reduction in colony-forming units (CFU) at pHs 5 and 6 for the pre-treated samples, while biofilms at pH 7–9 did not show any decrease. Interestingly, the post-treatment of planktonic cells or biofilms with GO showed a significant reduction in CFU at all pH ranges. The effect of higher osmotic stress in combination with GO resulted in a significant reduction in biofilms. These results show that the effect of stresses naturally occurring in the environment can be affected and changed when in combination with GO and can potentially affect the balance of natural biofilms. [ABSTRACT FROM AUTHOR]

Pseudomonas putida is a virulent bacterium that prompts major losses in fish. Recently, there has been a noticeable direction for utilizing nanomaterials in the aquaculture industry for sustaining fish health and performance. Hence, the present study is the first trial to investigate the antibacterial influence of nano titanium dioxide gel (NTG) as a watery addition for combating P. putida infection in Nile tilapia (Oreochromis niloticus). Further, antioxidant-immune capacity, and gene expression in the spleen including antimicrobial peptides and immune-related genes are assessed. Fish (n = 200; 47.50 ± 1.32 g of body weight) were assigned into four groups for 10 days [control, NTG (0.9 mg/L), P. putida , and NTG + P. putida ]. Findings demonstrated that the infection by P. putida induced a decline in antioxidant immune indicators including catalase, glutathione peroxidase, and nitric oxide. Furthermore, a noteworthy rise in lipid peroxide (malondialdehyde), tumor necrosis factor-alpha (TNF-α), and stress indicator (glucose) levels was noticed. P. putida infection induced remarkable alterations in the expression of antimicrobial peptides genes [ tilapia piscidin (TP3 and TP4) , colony-stimulating factor 1 receptor, hepcidin-2, beta-defensin1, and neutrophil cytosolic factor 4] and immune-relevant genes [transforming growth factor beta, tumor necrosis factor receptor-associated factor 6, TNF-α, interleukins (IL-10 and IL-11)]. Notably, applying NTG regenerated all the negative consequences of P. putida infection. Inclusive, this study underscores the crucial role of NTG as a potent antibacterial and immune-antioxidant agent, highlighting its potential in protecting O. niloticus from P. putida infection and improving immune-antioxidant response. • The potential of nano-titanium dioxide gel (NTG) to combat P. putida infections in Nile tilapia is assessed. • Infection with P. putida disruptes antioxidant, immune, and stress indicators, and expression of antimicrobial peptide genes. • Aqueous adition of NTG attenuates the hazardous impacts of P. putida infection on antioxidant and immune markers. • Aqueous NTG supplementation improves antimicrobial peptide gene expression in O. niloticus infected with P. putida. [ABSTRACT FROM AUTHOR]

Chromium is a toxic heavy metal abundantly present in the environment, specifically in groundwater. The groundwater in Saudi Arabia was assessed for heavy metal presence; chromium was detected at a high concentration in Madinah. Many researchers have used various bioprocesses over the last few decades to mitigate Cr(VI) toxicity. The genus Pseudomonas member Pseudomonas putida is widely dispersed in the natural environment. P. putida is chromate-resistant and has a high chromate reduction rate. Bioremediation procedures can eradicate the most potently toxic metal, Cr(VI), in water, air, and soil. Chromate reductase (ChrR) is a bacterial enzyme from P. putida that can be utilized in bioremediation to remove chromate from the environment in a cost-effective and environmentally safe approach. To comprehend the role of ChrR in reducing Cr(VI) to Cr(III), a thorough sequence analysis was followed by constructing models for wild-type and mutants by applying several homology modeling techniques. The protein structure quality of the generated models was evaluated, and the best model was adopted for further optimization by employing an energy minimization technique. Molecular docking studies investigated the intra-molecular interaction between wild-type and mutant ChrR and Cr(VI). Our study is a novel method for determining the 3D structure and interaction of ChrR with Cr(VI) to convert it to a less hazardous form (III). Additionally, it provides stable mutants: Arg83Trp, Gly124Ile, and His127Trp, with a high binding affinity for Cr(VI), which can be considered for protein engineering to produce stable and efficacious enzymes to reduce Cr(VI) to a less toxic form. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a destructive disease that causes significant yield losses in wheat production worldwide, including in Egypt. The use of biocontrol agents is among the best eco-friendly management strategies to control this disease, as they are more sustainable and environmentally friendly than traditional chemical control methods. In a comparative analysis, antioxidant enzyme activity and various management approaches were compared with two bacterial biocontrol agents, Bacillus subtilis and Pseudomonas putida. This study showed the remarkable efficacy of endophytic bacteria, B. subtilis and P. putida, in mitigating wheat stripe rust infection across three wheat varieties, namely Misr1, Gimmeiza11, and Sids12. B. subtilis exhibited superior performance compared to P. putida, resulting in infection types of 1 and 2.66, respectively, following inoculation. The highest reduction rate was observed with Tilit fungicide (500 ppm), followed by B. subtilis and Salicylic acid (1000 ppm), respectively. Variations in wheat varieties’ response to Pst infection were observed, with Misr1 exhibiting the lowest infection and Sids12 showing high susceptibility. Among the tested inducers, Salicylic acid demonstrated the greatest reduction in disease infection, followed by Indole acetic acid, while Oxalic acid exhibited the lowest decrease. Additionally, the study evaluated the activities of five antioxidant enzymes, including Catalase, Ascorbate peroxidase (APX), glutathione reductase (GR), Superoxide dismutase (SOD), and peroxidase (POX), in the wheat-stripe rust interaction under different integrated management approaches. The wheat variety Misr1 treated with Tilit (500 ppm), B. subtilis, Salicylic acid, Montoro (500 ppm), and P. putida exhibited the highest increase in all enzymatic activities. These findings provide valuable insights into the effectiveness of B. subtilis and P. putida as biocontrol agents for wheat stripe rust control in Egypt, emphasizing their potential role in sustainable, integrated, and environmentally friendly management practices.

The proceeding study aimed to isolate glyphosate-degrading bacteria from soil and determine optimal degradation conditions through single-factor experiments and response surface methodology. The detoxifying efficacy of the isolate on glyphosate was assessed using earthworm model. The results indicate that Pseudomonas putida HE exhibited the highest glyphosate degradation rate. Optimal conditions for glyphosate degradation were observed at an inoculation percentage of approximately 5%, a pH of 7, and a temperature of 30 °C. Glyphosate induced notable neurotoxicity and reproductive toxicity in earthworms, evidenced by reduced activity of the neurotoxicity-associated enzyme AChE. Additionally, an increase in the activities of catalase, superoxide dismutase, and lactate dehydrogenase was observed. H&E staining revealed structural disruptions in the earthworm clitellum, with notable atrophy in the structure of spermathecae. Furthermore, glyphosate activation of earthworm immune systems led to increased expression of immune-related genes, specifically coelomic cytolytic factor and lysozyme. Notably, the introduction of strain HE mitigated the glyphosate toxicity to the earthworms mentioned above. P. putida HE was able to increase soil enzyme activities that were reduced due to glyphosate. The isolate P. putida HE, emerged as an effective and cost-efficient remedy for glyphosate degradation and toxicity reduction in natural settings, showcasing potential applications in real ecological settings. [Display omitted] • A novel glyphosate-degrading P. putida strain HE was isolated and characterized. • The optimal conditions for glyphosate degradation by P. putida HE was studied. • Glyphosate was shown to cause neurological, reproductive, and immunological toxicity in earthworms. • P. putida HE alleviates glyphosate-induced toxicity in earthworms. • Glyphosate and P. putida HE affects soil enzyme activities. [ABSTRACT FROM AUTHOR]

As the production of graphene-based nanomaterials such as GO is increasing, it is expected that a large amount of GO waste will be generated. The environment (i.e., soil and aquatic systems) will be amongst the final repositories of these wastes which means important natural microbial communities in such environments will be at risk of GO exposure. However, little is known about how these communities respond to environmental stresses in synergy with the presence of GO. In this study, the effect of three different stress conditions: temperature (5, 25 and 40 °C); pH (5 to 9) and osmotic stress (51, 219 and 320 mM NaCl) in addition to GO treatment was investigated on the viability and physiology of biofilms and planktonic cells of soil bacterium P. putida. It was found that planktonic cells were more resistant to GO alone compared to biofilms. However, the cells were sensitive to GO when exposed to pH or osmotic stresses. Temperature was not found to influence the survival of biofilm with or without exposure to GO. However, low pH caused a reduction in colony-forming units (CFU) at pHs 5 and 6 for the pre-treated samples, while biofilms at pH 7–9 did not show any decrease. Interestingly, the post-treatment of planktonic cells or biofilms with GO showed a significant reduction in CFU at all pH ranges. The effect of higher osmotic stress in combination with GO resulted in a significant reduction in biofilms. These results show that the effect of stresses naturally occurring in the environment can be affected and changed when in combination with GO and can potentially affect the balance of natural biofilms.

Background: Fusarium wilt and Ascochyta blight are the most important diseases of chickpea. The current study was designed to investigate the individual and combined effect of salicylic acid (SA) with Pseudomonas stutzeri and Pseudomonas putida to suppress Fusarium wilt and promote growth of chickpea varieties: Thal-2006 and Punjab-2008. Methods: At the time of sowing, inoculum of Fusarium oxysporum was applied to the soil and the incidence of Fusarium wilt was recorded after 60 days. The seeds were inoculated with Pseudomonas stutzeri and Pseudomonas putida prior to sowing. Chickpea plants were treated with salicylic acid at seedling stage. Results: The combination of P. stutzeri and SA significantly increased root length (166% and 145%), shoot height (50% and 47%) and shoot biomass (300% and 233%) in cv. Thal-2006 and cv. Punjab-2008, respectively, in infected plants. Similarly, the combined treatment of P. putida + SA, also enhanced the plant growth parameters of chickpea varieties. Maximum reduction in disease severity was observed in both P. stutzeri + SA (90% and 84%) and P. putida + SA (79% and 77%) treatments in cv. Thal-2006 and Punjab-2008, respectively. Both P. putida + SA and P. stutzeri + SA treatments resulted in increased leaf relative water and total protein content, peroxidase, superoxide dismutase, phenylalanine ammonia-lyase and polyphenol oxidase activities in both resistant (cv. Thal-2006) and susceptible (cv. Punjab-2008) cultivars. Both treatments also significantly reduced malondialdehyde (MDA) and proline content in cv. Thal-2006 and Punjab-2008. Cultivar Thal-2006 was more effective than cv. Punjab-2008. Conclusions: The results suggested that, in combination, salicylic acid and P. stutzeri may play an important role in controlling Fusarium wilt diseases by inducing systemic resistance in chickpea.

The study was to isolate, characterize and identify bacteria present in the water calyx fluid of the African tulip, Spathodea campanulata P. Beauv. Nutrient agar and nitrogen free malate (Nfb) semi-solid media were used to isolate the bacteria. Bacteria was identified using 16S rDNA sequencing. Pseudomonas putida TS 18 was found to be a new strain based on highest homology during the BLAST. Morphological and biochemical characterization of the identified bacteria was done by routine methods. This is the first study to report bacteria from the water calyx fluid of S. campanulata. Identified bacteria along with fluid content might be playing a unique role in the flower development by showing nitrogen fixing potential under in vitro conditions.

The biodegradation of two halohydrins (1,3-dichloro-2-propanol and 3-chloro-1,2-propanediol) by P. putida DSM 437 was investigated. Intact cells of previously acclimatized P. putida DSM 437 as well as cell-free extracts were used in order to study the degradation kinetics. When whole cells were used, a maximum biodegradation rate of 3-CPD (vmax = 1.28.10–5 mmol mg–1 DCW h–1) was determined, which was more than 4 times higher than that of 1,3-DCP. However, the affinity towards both halohydrins (Km) was practically the same. When using cell-free extract, the apparent vmax and Km values for 1,3-DCP were estimated at 9.61.10–6 mmol mg–1 protein h–1 and 8.00 mM, respectively, while for 3-CPD the corresponding values were 2.42.10–5 mmol mg–1 protein h–1 and 9.07 mM. GC-MS analysis of cell-free extracts samples spiked with 1,3-DCP revealed the presence of 3-CPD and glycerol, intermediates of 1,3-DCP degradation pathway. 3-CPD degradation was strongly inhibited by the presence of epichlorohydrin and to a lesser extent by glycidol, intermediates of dehalogenation pathway.

The study was to isolate, characterize and identify bacteria present in the water calyx fluid of the African tulip, Spathodea campanulata P. Beauv. Nutrient agar and nitrogen free malate (Nfb) semi-solid media were used to isolate the bacteria. Bacteria was identified using 16S rDNA sequencing. Pseudomonas putida TS 18 was found to be a new strain based on highest homology during the BLAST. Morphological and biochemical characterization of the identified bacteria was done by routine methods. This is the first study to report bacteria from the water calyx fluid of S. campanulata. Identified bacteria along with fluid content might be playing a unique role in the flower development by showing nitrogen fixing potential under in vitro conditions. [ABSTRACT FROM AUTHOR]

Chromium in wastewater is classified as one of the dangerous contaminants that require further treatment before being discharged to water body. The concentration of chromium in water body, especially river, has increased as many industries utilize chromium as raw material and then discharge their wastewater without any treatment. Biosorption is one of methods that are widely used to treat heavy metal containing wastewater. Bacteria are the most common microorganisms to be used as heavy metal treatment agent. Azotobacter s8, Bacillus subtilis and Pseudomonas putida had been proven to have a heavy metal resistant capability. The screening test showed that Minimum Inhibitory Concentration (MIC) value of chromium for all bacteria ranged from 100 to 250 mg/L of CrCl3. The chromium biosorption test by bacteria showed that Azotobacter s8 was able to remove 10.53%, and Bacillus subtilis was able to remove 5.68% chromium from 50 mg/L initial concentration, while Pseudomonas putida showed no chromium removal. The chromium biosorption capacity by Azotobacter s8 was 580.08 mg/g and 349.30 mg/g for Bacillus subtilis. [ABSTRACT FROM AUTHOR]

The health of the plant and soil fertility is dependent on the plant–microbes interaction in the rhizosphere. Microbial life tends to endure various rhizosphere plant–microbe interactions. Phytohormones such as auxins, cytokinins, gibberellic acid, ethylene and abscisic acid are termed as the classical group of hormones. Out of the 70 rhizobacterial strains isolated from the Coleus rhizosphere, three different rhizobacterial strains Pseudomonas stutzeri MTP40, Stenotrophomonas maltophilia MTP42 and Pseudomonas putida MTP50 having plant growth-promoting attributes were isolated and characterized for its phytohormone-producing ability. The phytohormones such as indole 3-acetic acid (IAA), gibberellic acid and cytokinin (kinetin and 6-benzyladenosine) were affirmed in culture supernatant of the above isolates. IAA was detected in all the three isolates, where in highest production was found in S. maltophilia MTP42 (240 µg/mL) followed by P. stutzeri MTP40 (250 µg/mL) and P. putida MTP50 (233 µg/mL). Gibberellic acid production was found maximum in MTP40 (34 µg/mL), followed by MTP42 (31 µg/mL) and MTP50 (27 µg/mL). The cytokinin production from the isolates, namely, MTP40, MTP42 and MTP50 were 13, 11 and 7.5 µg/mL, respectively. The isolates showing the production of plant growth enhancing phytohormones can be commercialized as potent bioformulations.

Currently, design and optimisation of biotechnological bioprocesses is performed either through exhaustive experimentation and/or with the use of empirical, unstructured growth kinetics models. Whereas, elaborate systems biology approaches have been recently explored, mixed-substrate utilisation is predominantly ignored despite its significance in enhancing bioprocess performance. Herein, bioprocess optimisation for an industrially-relevant bioremediation process involving a mixture of highly toxic substrates, m -xylene and toluene, was achieved through application of a novel experimental-modelling gene regulatory network – growth kinetic (GRN-GK) hybrid framework. The GRN model described the TOL and ortho -cleavage pathways in Pseudomonas putida mt-2 and captured the transcriptional kinetics expression patterns of the promoters. The GRN model informed the formulation of the growth kinetics model replacing the empirical and unstructured Monod kinetics. The GRN-GK framework's predictive capability and potential as a systematic optimal bioprocess design tool, was demonstrated by effectively predicting bioprocess performance, which was in agreement with experimental values, when compared to four commonly used models that deviated significantly from the experimental values. Significantly, a fed-batch biodegradation process was designed and optimised through the model-based control of TOL Pr promoter expression resulting in 61% and 60% enhanced pollutant removal and biomass formation, respectively, compared to the batch process. This provides strong evidence of model-based bioprocess optimisation at the gene level, rendering the GRN-GK framework as a novel and applicable approach to optimal bioprocess design. Finally, model analysis using global sensitivity analysis (GSA) suggests an alternative, systematic approach for model-driven strain modification for synthetic biology and metabolic engineering applications. [ABSTRACT FROM AUTHOR]

Mercury is one of the toxic element and very harmful. The exposure of the mercury will mainly cause health effect and the exposure can be in term of dose, the age of person exposed, duration exposed route exposed and duration of exposed. In Malaysia, Mercury is one of the heavy metals of concern, found in wastewaters coming from oil refinery and petrochemical industries. Mercury and mercurial compounds are highly toxic contaminants in the aquatic systems and soils. The proper disposal of wastewater should be implemented with the Department of Environment of Malaysia (DOE) which is the concentration of mercury should be 0.05 ppm for standard B in wastewater for the sake of people and environment health. There are many types of mercury removal technology to reduce the concentration of mercury such as chemical treatment, ion exchange, membrane filtration, adsorption as well as bioremediation which used for mercury removal in this study. This paper present the activity of enzyme from Pseudomonas putida (P. putida) is produced in the mercury treatment from petrochemical wastewater at optimum condition. P. putida growth at optimum condition in the different mercury concentration was observed. As a conclusion of optimum condition concentration of mercury and shaker speed at 7 ppm is 41°C and 180 rpm respectively, with able to reduce 92.59% mercury concentration. During the processes of mercury removal, mercuric reductase was produced at a value of 56 kDa. [ABSTRACT FROM AUTHOR]

Chromium (Cr) toxicity affects many physiological processes and inhibits plant growth. Plant growth promoting rhizobacteria (PGPR) have ability to improve plant health in contaminated soil as well as degrade toxic Cr. Present investigation was made to examine the role of Pseudomonas putida (ATCC 39213), to enhancing the plant growth and Cr phytoextraction. Three treatments of Cr (low; 150 ppm, medium; 250 ppm and high; 500 ppm) were applied to the E. sativa seedlings, either inoculated with Pseudomonas putida ( P. putida ) or un-inoculated plants. Results of this study clearly indicate that P. putida inoculation significantly increased plant growth and Cr uptake as compared to un-inoculated plants. Root and shoot length increased 33% and 42%, fresh and dry weight increased 49% and 53% as compared to un-inoculated plants, respectively. However, chlorophyll and proline contents increased 39% and 44%. Physiological parameters of growth indicate that Cr toxicity decreased the plant growth, while inoculation of P. putida overcome the inhibitory effects of Cr and increased growth under Cr stress. Cr uptake by plants was increased 38% with P. putida inoculation. Provision of Indole acetic acid, siderophore and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity by P. putida in the growing media, which may induce the Cr uptake and plant growth under stress condition in E. sativa. The present results offer insight on plant growth promoting rhizobacteria's (PGPRs), such as P. putida , potential to enhance the plant growth by inhibiting the adverse effects of Cr in E. sativa . This study will contribute towards the environmental management of Cr-contaminated areas and enhancing plant growth under Cr stress conditions. [ABSTRACT FROM AUTHOR]

Fluorescent pseudomonads from bean root and rhizosphere in Iran were investigated for biocontrol of the fungal pathogen Rhizoctonia solani . Phylogenetic analysis of concatenated 16S rRNA, gyrB and rpoD sequences for 33 Pseudomonas isolates showed that 15 belonged to four clusters within the ‘ P. fluorescens ’ group, i.e. one corresponding to P. thivervalensis , two others including P. moraviensis or P. baetica , and the last one without closely-related established species. The 18 other isolates belonged to five clusters within the ‘ P. putida ’ group, one including P. mosselii and P. entomophila , another including strains currently described as P. putida , and three without closely-related species described. Ten isolates were selected based on in vitro inhibition of R. solani . Cellulase activity was identified in three pseudomonads, chitinase activity in two pseudomonads, extracellular protease activity in nine pseudomonads and hydrogen cyanide production in two pseudomonads. Genes coding for production of phenazine, pyoluteorin, pyrrolnitrin and 2,4-diacetylphloroglucinol were not found, whereas the 1-aminocyclopropane-1-carboxylate deamination gene acdS was present in three pseudomonads. The antagonistic acdS + strain VKh13 from the ‘ P. putida ’ group effectively protected soil-grown bean from R. solani AG 4-HGI. Results show that pseudomonads from uncharacterized taxa were readily obtained from Iranian soils and displayed biocontrol potential against R. solani . [ABSTRACT FROM AUTHOR]

The biodegradation of two halohydrins (1,3-dichloro-2-propanol and 3-chloro- 1,2- propanediol) by P. putida DSM 437 was investigated. Intact cells of previously acclima- tized P. putida DSM 437 as well as cell-free extracts were used in order to study the degradation kinetics. When whole cells were used, a maximum biodegradation rate of 3-CPD (vmax = 1.28. 10-5 mmol mg-1 DCW h-1 ) was determined, which was more than 4 times higher than that of 1,3-DCP. However, the affinity towards both halohydrins (Km) was practically the same. When using cell-free extract, the apparent vmax and Km values for 1,3-DCP were estimated at 9.61. 10-6 mmol mg-1 protein h-1 and 8.00 mM, respectively, while for 3-CPD the corresponding values were 2.42. 10-5 mmol mg-1 protein h-1 and 9.07 mM. GC-MS analysis of cell-free extracts samples spiked with 1,3-DCP revealed the presence of 3-CPD and glycerol, intermediates of 1,3-DCP degradation pathway. 3-CPD degradation was strongly inhibited by the presence of epichlorohydrin and to a lesser extent by glycidol, intermediates of dehalogenation pathway. [ABSTRACT FROM AUTHOR]

The health of the plant and soil fertility is dependent on the plant–microbes interaction in the rhizosphere. Microbial life tends to endure various rhizosphere plant–microbe interactions. Phytohormones such as auxins, cytokinins, gibberellic acid, ethylene and abscisic acid are termed as the classical group of hormones. Out of the 70 rhizobacterial strains isolated from theColeusrhizosphere, three different rhizobacterial strainsPseudomonas stutzeriMTP40,Stenotrophomonas maltophiliaMTP42 andPseudomonas putidaMTP50 having plant growth-promoting attributes were isolated and characterized for its phytohormone-producing ability. The phytohormones such as indole 3-acetic acid (IAA), gibberellic acid and cytokinin (kinetin and 6-benzyladenosine) were affirmed in culture supernatant of the above isolates. IAA was detected in all the three isolates, where in highest production was found inS. maltophiliaMTP42 (240 µg/mL) followed byP. stutzeriMTP40 (250 µg/mL) andP. putidaMTP50 (233 µg/mL). Gibberellic acid production was found maximum in MTP40 (34 µg/mL), followed by MTP42 (31 µg/mL) and MTP50 (27 µg/mL). The cytokinin production from the isolates, namely, MTP40, MTP42 and MTP50 were 13, 11 and 7.5 µg/mL, respectively. The isolates showing the production of plant growth enhancing phytohormones can be commercialized as potent bioformulations. [ABSTRACT FROM PUBLISHER]

Phosphate solubilizing bacteria (PSB) metabolites are organic acids, phosphomonoesterase enzyme (alkaline phosphatase) and antibiotic, which is able to dissolve insoluble phosphate. Phosphate solubilizing bacteria used in this study was expected to suppress Rhizoctonia solani attacks. This experiment was aimed at (1) identifiying and quantifying PSB metabolites, and (2) examining their capability as biocontrol agent for Rhizoctonia solani in vitro and hydroponics soybean. This study was conducted in three stages. The first stage of this study was culturing two PSB isolates (Pseudomonas putida 27.4B and Pseudomonas diminuta) in the Pikovskaya medium to analyze their metabolites. The second and third stage of this study was testing the antagonist of two bacteria to suppressed R. solani activity, which was conducted in vitro, and in hydroponics medium soybean as indicator plant. The results showed that P. putida 27.4B and P. diminuta produced organic acids i.e.: citrate, formic, succinic, acetic, propionate, butyrate, and oxalate. The totals of organic acids from each bacterium were 70,3 mg.kg-1 and 61,9 mg.kg-1. Production of alkaline phosphatase enzyme in Pikovskaya medium of P. Putida 27.4B was 11,71 ìg pNP .mL-1.h-1 and P. diminuta was 24,04 ìg pNP.mL-1.h-1. Concentration of this enzyme in soil medium was higher than that in Pikovskaya medium with 26,27 ìg pNP.g-1.h-1 and 39,03 ìg pNP.g-1.h-1 respectively. This study also showed that total concentration of antibiotics (tetracycline, oxitetracycline and penicillin) produced by the PSB, were 3,2 ìg.mL-1 (P. putida 27.4B) and 10,96 ìg.m1-1 (P. diminuta), respectively. The results from second stage of this study showed that by using in vitro, the reduced growth of R. solani was observed 58,35% with P. putida 27.4B and 41,96% with P. diminuta. In addition, inoculations of PSB in hydroponics medium reduced the fungal pathogenesis from 10,71% to 21,42% of pre and post emergence damping-off. Visually, the symptom of pathogen attack appeared within the period of 2 untill 14 days after infection.

ABSTRACT The cytochrome P450 monooxygenase CYP154A8 from Nocardia farcinica was previously found to catalyze hydroxylation of linear alkanes (C7-C9) with a high regio- and stereoselectivity. The objective of this study was to integrate CYP154A8 along with suitable redox partners into a whole-cell system for the production of chiral 2-alkanols starting from alkanes. Both recombinant Escherichia coli and Pseudomonas putida whole-cell biocatalysts tested for this purpose showed the ability to produce chiral alkanols, but a solvent tolerant P. putida strain demonstrated several advantages in the applied biphasic reaction system. The optimized P. putida whole-cell system produced ∼16 mM ( S)-2-octanol with 87% ee from octane, which is more than sevenfold higher than the previously described system with isolated enzymes. The achieved enantiopurity of the product could further be increased up to 99% ee by adding an alcohol dehydrogenase (ADH) to the alkane-oxidizing P. putida whole-cell systems. By using this setup for the individual conversions of heptane, octane or nonane, 2.6 mM ( S)-2-heptanol with 91% ee, 5.4 mM ( S)-2-octanol with 97% ee, or 5.5 mM ( S)-2-nonanol with 97% ee were produced, respectively. The achieved concentrations of chiral 2-alkanols are the highest reported for a P450-based whole-cell system so far. Biotechnol. Bioeng. 2016;113: 1845-1852. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Environmental contamination of mercury (Hg) has caused public health concerns with focuses on the neurotoxic substance methylmercury, due to its bioaccumulation and biomagnification in food chains. The goals of the present study were to examine: (i) the transformation of methylmercury, thimerosal, phenylmercuric acetate and mercuric chloride by cultures of Pseudomonas putida V1, (ii) the presence of the genes mer A and mer B in P. putida V1, and (iii) the degradation pathways of methylmercury by P. putida V1. Strain V1 cultures readily degraded methylmercury, thimerosal, phenylmercury acetate, and reduced mercuric chloride into gaseous Hg(0). However, the Hg transformation in LB broth by P. putida V1 was influenced by the type of Hg compounds. The mer A gene was detected in P. putida V1, on the other hand, the merB gene was not detected. The sequencing of this gene, showed high similarity (100%) to the mercuric reductase gene of other Pseudomonas spp. Furthermore, tests using radioactive 14 C-methylmercury indicated an uncommon release of 14 CO 2 concomitant with the production of Hg 0 . The results of the present work suggest that P. putida V1 has the potential to remove methylmercury from contaminated sites. More studies are warranted to determine the mechanism of removal of methylmercury by P. putida V1. [ABSTRACT FROM AUTHOR]

Textile industry is considered as one of the important factors of the economic growth in Tunisia. However, this prominent role has certainly some drawbacks mainly represented by the huge amounts of textile wastewaters generated that become a real menace to nature. Many previous studies showed the purifying potential of some activated sludge and bacteria ( Pseudomonas putida) to decolourize textile effluents. However, in many cases, decolourization of wastewaters is not necessary associated with detoxification, generating a real risk for the ecosystem in general. We evaluated in this work the induced toxicity of a textile effluent before and after its treatment with activated sludge followed by P. putida, using a battery of biotests. This study proved the detoxifying power of the activated sludge according to most of ecotoxicity tests. The treatment with P. putida did not improve the quality of the effluent; on the contrary, it could increase its toxicity. Daphnia magna and Raphidocelis subcapitata appear to be the most sensitive organisms in assessing eventual toxicity caused by this kind of wastewaters. [ABSTRACT FROM AUTHOR]

Participation of Pseudomonas putida -derived methyl phenol ( dmp ) operon and DmpR protein in the biodegradation of phenol or other harmful, organic, toxic pollutants was investigated at a molecular level. Documentation documents that P. putida has DmpR protein which positively regulates dmp operon in the presence of inducers; like phenols. From the operon, phenol hydroxylase encoded by dmpN gene, participates in degrading phenols after dmp operon is expressed. For the purpose, the 3-D models of the four domains from DmpR protein and of the DNA sequences from the two Upstream Activation Sequences (UAS) present at the promoter region of the operon were demonstrated using discrete molecular modeling techniques. The best modeled structures satisfying their stereo-chemical properties were selected in each of the cases. To stabilize the individual structures, energy optimization was performed. In the presence of inducers, probable interactions among domains and then the two independent DNA structures with the fourth domain were perused by manifold molecular docking simulations. The complex structures were made to be stable by minimizing their overall energy. Responsible amino acid residues, nucleotide bases and binding patterns for the biodegradation, were examined. In the presence of the inducers, the biodegradation process is initiated by the interaction of phe50 from the first protein domain with the inducers. Only after the interaction of the last domain with the DNA sequences individually, the operon is expressed. This novel residue level study is paramount for initiating transcription in the operon; thereby leading to expression of phenol hydroxylase followed by phenol biodegradation. [ABSTRACT FROM AUTHOR]

Pseudomonas putida N, a poly-3-hydroxyalkonate (PHA)-producing bacterium, showing ampicillin resistance, is an unusual strain. In the presence of this antibiotic, it grows as giant cells (25–50 μm) forming complex networks inter-connected by micro-tubular structures. The transformation of this bacterium with a plasmid containing the gene phaF , which encodes a phasin involved in the molecular architecture of the PHA-granules, (i) restores the wild-type phenotype by reducing both bacterial size and length (coco-bacilli ranging between 0.5 and 3 μm), and (ii) increases ampicillin resistance by more than 100-fold. [ABSTRACT FROM AUTHOR]

Abstract: The mechanisms by which Pseudomonas putida causes fouling on a microfiltration membrane have been studied. For an initial P. putida concentration of 0.77g/L (5.1×108 cfu/mL) stirred dead-end tests indicated that approximately 70% of the permeability was lost during the first minute of filtration and only 15% more was lost during the following 24min. SEM observations showed the presence of aggregates within the most external part of the membrane pores, partially blocking these pores and leading to more or less regular surface deposits and consequently, an intermediate blocking model was proposed and successfully fitted. The analysis of fouling resistance-in-series indicated that the selection of a high TMP during the microfiltration of P. putida had no effect on the final permeate flux but provoked an increase in external in comparison to internal fouling. On the other hand, the selection of a lower TMP led to a low rate of accumulation of P. putida on the membrane, reducing the total membrane resistance and allowing a deeper penetration of the bacteria into the pore. Studies on the cleanability of the membrane using sonication showed how this technique was more effective when membrane was fouled at higher TMP, achieving permeability recoveries of around 80% in the best cases. [Copyright &y& Elsevier]

Effects of cultural filtrates of six bio-control agents i.e. Pseudomonas fluorescens, P. putida, Streptomyces aureofaciens, Trichoderma harzianum, T. viride and Bacillus subtilis, as standard solution and dilutions (S/20, S/40 and S/80) on the development and reproduction of root knot nematode, Meloidogyne incognita and plant growth of infected grape seedlings cv. Early Sweet was evaluated under laboratory and greenhouse conditions. Also, their potential to control nematodes was compared with that achieved by using the chemical control agent, Ragby. In vitro tests, all bio-control agents were found to be highly nematicidical effects against infective juveniles of nematode. Pseudomonas putida at all concentrations was more effective which causedlOO, 95, 90 and 74% nematode mortality, since was Pseudomonas fluorescens, Trichoderma harzianum, Streptomyces aureofaciens, Bacillus subtilis and Trichoderma viride. In greenhouse, all tested biofiltrates significantly controlled nematode population by reduced number of all nematode parameters compared to the control, and enhanced plant growth. Recommended dose of Ragby and standard solution of P. putida and T. harzianum has surpassed in reducing M. incognita population the others through successive four months . However, T. viride, P. fluorescens and B. subtilis was mostly effective .While, the least effective treatment was S. aureofaciens that gave the minmum of the percentage efficacy in reducing of all nematode parameters. [ABSTRACT FROM AUTHOR]

Summary: Objectives: An outbreak of bacteremia caused by Pseudomonas spp (P. fulva and P. putida) was first identified in our hospital in the summer of 2010 and reoccurred in the following year. Based on the epidemiological data collected in these 2 years, we initiated an investigation on the source of the outbreak. The aim of this study was to report the results of the investigation, as well as the intervention strategies that resulted in successful control of the outbreak. Methods: An infection control team was set up consisting of infectious disease specialists, microbiologists, infection control practitioners, and head nurses. The microbiology and medical records of case-patients with P. fulva or P. putida bloodstream infections were reviewed. Environmental samples and intravenous (IV) solutions from the wards and the pharmacy center were collected for culturing. The molecular characteristics of the bacterial isolates were studied by pulsed-field gel electrophoresis (PFGE). Strict infection control strategies were implemented. Results: A total of 20 case-patients from five inpatient wards were identified during three summer seasons from 2010 to 2012. Nineteen of them recovered with proper antibiotics. Unfortunately one died from complications of heart failure. A total of 19 isolates of P. fulva and four of P. putida were identified, of which 20 were from blood, two from environmental surface samples from the hospital pharmacy, and one from an in-use compounded solution from a case-patient in the cardiology ward. Molecular analysis revealed that the P. fulva isolated from the in-use compounded solution (5% glucose solution containing insulin, isosorbide dinitrate, and potassium magnesium aspartate) and the environmental samples had the same PFGE type as the clinical isolates. Conclusions: The investigation identified that contaminated IV solution was the source of the P. fulva bacteremia, which prompted us to implement intensified control measures that resulted in successful control of the outbreak. [ABSTRACT FROM AUTHOR]

Highlights: [•] Copolymer Polyacrylate alcohol was used for the first time in this research work. [•] Polyacrylate polyalcohol induced pH neutralisation of the cultivation medium. [•] C. vulgaris cultivation yielded in photosynthetic oxygenation of 11mgl−1 d−1. [•] Immobilised C. vulgaris cultivation resulted in 89% removal of COD in 96h. [ABSTRACT FROM AUTHOR]

Highlights: [•] MBR under feed-induced stress conditions: starvation and changing feeding conditions. [•] High capacity of MBR to withstand high variations in feed loads. [•] Slow biofilm formation under starvation conditions during the first days. [•] Observed growth of P. putida for substrate to microorganism ratio higher than 0.6g/g. [•] Maximum specific growth rate and growth yield values of around 37.5h−1 and 0.5g/g. [ABSTRACT FROM AUTHOR]

Abstract: Characteristics and mechanisms of the fouling of microfiltration pleated cartridges (10-inch, PES, pore size of 0.2µm) in biotechnical applications were analyzed, in order to obtain information about strategies that allow increasing their lifespan. Specifically, fouling experiments were carried out using the biodegradation of salicylic acid by means of Pseudomona putida as model of cellular media. A complete blocking mechanism with non-uniform distribution of the fouling along the pleated structure was proposed. Main accumulation of solids was located into the space between pleats near to the external perimeter of the filter, whereas the base of the pleats remained relatively clean, only fouled by small particles that can cause a small standard blocking of the pores. Concerning fouling cures, air scouring only provoked moderate recoveries of permeability after relaxation periods of days when spaces between pleats are completely filled and the biomass began to accumulate over the pleated structure. Backflushing (30s) effectiveness tended to decrease with operation time and consecutive applications, but improved the effect of a subsequent relaxation on the permeability recovery. After chemical cleaning, permeability recovery (R) of 87.8% was observed, which implies a considerable increase of the lifespan of the cartridge. [Copyright &y& Elsevier]

Antagonistic activities of 120 epiphytic bacterial isolates against Erwinia amylovora were evaluated under laboratory and orchard conditions. Samples were collected at three stages of plant growth during 2009. The hosts were chosen from diseased and healthy pome fruit and stone fruit trees in Alborz, Isfahan and Neishabur regions of Iran. Two in vitro tests including antibiosis and immature fruit assay were performed to identify effective bacterial antagonists. Out of 21 strains, four representative strains encoded Kgh1, Abp2, E11 and E10 showed maximum growth inhibition, growth rate and stability in inhibition. Identification of four bacterial antagonists was confirmed by sequencing their 16S rDNA and performing common biochemical tests. These strains were identified as Pseudomonas fluorescens (E10), Pantoea agglomerans (Abp2), Pseudomonas putida (E11) and Serratia marcescens (Kgh1). Some complementary tests were then conducted to check their antagonistic activity against Erwinia amylovora on pear blossom. In all evaluation procedures, biocontrol effects of Pantoea agglomerans Abp2 and Pseudomonas fluorescens E10 were more promising than those afforded by Pseudomonas putida E11 and Serratia marcescens Kgh1. A one-year field experiment was also carried out on a partially susceptible domestic pear cultivar in an infested orchard in the Karaj region of Iran. The selected bacteria were applied twice at 20% and 80% of blooming. The results showed 46.9% disease occurrence in control plants, while the antagonistic bacteria reduced the disease between 23 and 60%. In the orchard trial the most effective antagonist was P. agglomerans Abp2, while the least effective was S. marcescens Kgh1. [ABSTRACT FROM AUTHOR]

Abstract: We report the study of phage AF, the first member of the canonical lambdoid phage group infecting Pseudomonas putida. Its 42.6kb genome is related to the “epsilon15-like viruses” and the “BPP-1-like viruses”, a clade of bacteriophages shaped by extensive horizontal gene transfer. The AF virions display exopolysaccharide (EPS)-degrading activity, which originates from the action of the C-terminal domain of the tail spike (Gp19). This protein shows high similarity to the tail spike of the T7-like P. putida-infecting phage φ15. These unrelated phages have an identical host spectrum and EPS degradation characteristics, designating the C-terminal part of Gp19 as sole determinant for these functions. While intact AF particles have biofilm-degrading properties, Gp19 and non-infectious AF particles do not, emphasizing the role of phage amplification in biofilm degradation. [Copyright &y& Elsevier]

Abstract: Highly sensitive calorimetry was evaluated for its potential for the monitoring of the bacterial contamination of drinking water. For that purpose, water samples were added to different media and bacterial growth was followed microcalorimetrically. Drinking water samples were either tested untreated or after artificial contamination with selected bacterial strains. Two bacteria, two growth media and two growth conditions (i.e. aerobic and anaerobic) were applied. Even minor initial bacterial contamination (1–100 cells mL−1) gave rise to calorimetric signals after 5–17 h growth. Calorimetry was thus faster than detection of bacterial contamination by plating on agar and inspection of colony formation, which was performed for comparison. It was further demonstrated theoretically that calorimetric detection is superior to colony detection. The heat production curves were characteristic for the strain, the medium and the growth conditions. It is hypothesized that a further refinement of the microcalorimetric method via the application of sets of specific media in combination with selective growth conditions should allow delimiting the identity of the contaminant. [Copyright &y& Elsevier]

This study describes the biodegradation of phenanthrene in aqueous media in the presence and in the absence of a surfactant, Brij 30. Biodegradations were performed using either Pseudomonas putida DSMZ 8368 or a bacterial consortium Pyr01 isolated from one PAHs-polluted site. P. putida degraded phenanthrene to form 1-hydroxy-2-naphthoic acid (1H2Na) as the major metabolite. LC-MS analysis revealed the production of complementary intermediates in the presence of Brij 30, showing intense ions at mass-to-charge ratios ( m/z) 97 and 195. Higher phenanthrene biodegradation rate was obtained in the presence of Brij 30. Conversely, in the case of Pyr01consortium, the addition of Brij 30 (0.5 g L) had a negative effect on biodegradation: no phenanthrene biodegradation products were detected in the medium, whereas a production of several intermediates ( m/z 97, 195 and 293) was obtained without surfactant. New results on phenanthrene metabolism by P. putida DSMZ 8368 and Pyr01 consortium in the presence and in the absence of Brij 30 we obtained. They confirm that the knowledge of the effect of a surfactant on bacterial cultures is crucial for the optimization of surfactant-enhanced PAHs biodegradation. [ABSTRACT FROM AUTHOR]

With the growing interest in using surfactants to improve microbial cell performance for whole-cell biocatalysis and bioremediation, understanding the interactions between surfactants and bacteria is of great importance. By using cyanine fluorescent protein (CFP) and bacterial luciferase (LUX) as dual bioreporters, the effects of n-dodecyltrimethylammonium bromide (DTAB) on the whole cells and intracellular proteins in Pseudomonas putida cultures were quantitatively and systematically studied. The dual reporter system was shown to be a useful indicator to assess the effect of DTAB treatment on whole-cell metabolic activity, membrane permeability, and cellular enzyme activity. CFP was useful to assess the leakage of intracellular enzymes and the lysis of cells and was able to reflect the activities of most cellular enzymes, while LUX reflected the permeability of cell membranes and cellular metabolic activity. The validity of CFP-LUX dual bioreporters was further confirmed by detecting changes in extracellular proteins, membrane potential, oxygen consumption rate (OUR), and intracellular catechol 2,3-dioxygenase (C23O) activity with the addition of DTAB. The dual LUX-CFP bioreporter is a useful tool for analyzing the surfactant-bacterium interactions for biotechnological applications. [ABSTRACT FROM AUTHOR]

Abstract: An endophytic bacterium named Pseudomonas putida MGY2 was isolated from papaya fruit. The effect of MGY2 on reducing anthracnose caused by Colletotrichum gloeosporioides infection in harvested papaya fruit and the possible mechanisms involved were investigated. Fruit treated with MGY2 showed a significant lower disease index, disease incidence, and lesion diameter than the control. MGY2 reduced the decrease in firmness and delayed the peak of ethylene production of harvested papaya fruit stored at 25°C. MGY2 also significantly enhanced the activities of phenylalanine ammonia-lyase (PAL), catalase (CAT), and peroxidase (POD) and increased the phenolic content. The expression levels of PAL1, CAT1, and POD genes were obviously elevated in MGY2-treated fruit. These results suggested that papaya fruit is capable of responding to the endophyte P. putida MGY2, which could activate defensive enzymes and genes and thereby induce host disease resistance. [ABSTRACT FROM AUTHOR]

Abstract: Fertilizer costs are a major component of corn production. The use of biofertilizers may be one way of reducing production costs. In this study we present isolation and identification of three plant growth promoting bacteria that were identified as Enterobacter cloacae (CR1), Pseudomonas putida (CR7) and Stenotrophomonas maltophilia (CR3). All bacterial strains produced IAA in the presence of 100mgl−1 of tryptophan and antifungal metabolites to several soilborne pathogens. S. maltophilia and E. cloacae had broad spectrum activity against most Fusarium species. The only strain that was positive for nitrogen fixation was E. cloacae and it, and P. putida, were also positive for phosphate solubilization. These bacteria and the corn isolate Sphingobacterium canadense CR11, and known plant growth promoting bacterium Burkholderia phytofirmans E24 were used to inoculate corn seed to examine growth promotion of two lines of corn, varieties 39D82 and 39M27 under greenhouse conditions. When grown in sterilized sand varieties 39M27 and 39D82 showed significant increases in total dry weights of root and shoot of 10–20% and 13–28% and 17–32% and 21–31% respectively. Plants of the two varieties grown in soil collected from a corn field had respective increases in dry weights of root and shoot of 10–30% and 12–35% and 11–19% and 10–18%. In sand, a bacterial mixture was highly effective whereas in soil individual bacteria namely P. putida CR7 and E. cloacae CR1 gave the best results with 39M27 and 39D82 respectively. These isolates and another corn isolate, Azospirillum zeae N7, were tested in a sandy soil with a 55 and 110kgha−1 of nitrogen fertility at the Delhi research Station of Agriculture and Agri-Food Canada over two years. Although out of seven bacterial treatments, no treatment provided a statistically significant yield increase over control plots but S. canadense CR11 and A. zeae N7 provided statistically significant yield increase as compared to other bacteria. The 110kg rate of nitrogen provided significant yield increase compared to the 55kg rate in both years. [Copyright &y& Elsevier]

Abstract: Metabolites, substrates and substrate impurities may be toxic to cells by damaging biological molecules, organelles, membranes or disrupting biological processes. Chemical stress is routinely encountered in bioprocessing to produce chemicals or fuels from renewable substrates, in whole-cell biocatalysis and bioremediation. Cells respond, adapt and may develop tolerance to chemicals by mechanisms only partially explored, especially for multiple simultaneous stresses. More is known about how cells respond to chemicals, but less about how to develop tolerant strains. Aiming to stimulate new metabolic engineering and synthetic-biology approaches for tolerant-strain development, this review takes a holistic, comparative and modular approach in bringing together the large literature on genes, programs, mechanisms, processes and molecules involved in chemical stress or imparting tolerance. These include stress proteins and transcription factors, efflux pumps, altered membrane composition, stress-adapted energy metabolism, chemical detoxification, and accumulation of small-molecule chaperons and compatible solutes. The modular organization (by chemicals, mechanism, organism, and methods used) imparts flexibility in exploring this complex literature, while comparative analyses point to hidden commonalities, such as an oxidative stress response underlying some solvent and carboxylic-acid stress. Successes involving one or a few genes, as well as global genomic approaches are reviewed with an eye to future developments that would engage novel genomic and systems-biology tools to create altered or semi-synthetic strains with superior tolerance characteristics for bioprocessing. [Copyright &y& Elsevier]