Pseudomonas Fluorescens Research Articles

Compatibility of Bacillus thuringiensis var. kurstaki and Pseudomonas fluorescens with pesticides recommended for rice pest management at drone and taiwan spraying concentrations

In vitro studies were carried out at Institute of Rice Research, PJTSAU, Rajendranagar, Hyderabad, in 2023 to assess the compatibility of biopesticides with chemical pesticides applied at drone and Taiwan sprayer concentrations. The possibility of utilizing both biopesticides and chemical pesticides together with drone for managing major rice insect-pests and diseases was explored. The compatibility of Bacillus thuringiensis var. kurstaki with four insecticides (flubendiamide 39.35% SC, chlorantraniliprole 18.50% SC, cartap hydrochloride 50% SP and tetraniliprole 18.18% SC) and Pseudomonas fluorescens with three fungicides (propiconazole 10.7% + tricyclazole 34.2% SE, tebuconazole 50% + trifloxystrobin 25% WG and propiconazole 25% EC) was determined by following the inhibition zone technique on suitable media with sterile filter paper discs. Bacillus thuringiensis var. kurstaki combinations tested with flubendiamide 39.35% SC, chlorantraniliprole 18.50% SC, cartap hydrochloride 50% SP exhibited slight inhibition over control while, tetraniliprole 18.18% SC exhibited high compatibility with B. thuringiensis var. kurstaki without any growth inhibition at both drone and Taiwan sprayer concentrations. Similarly, all the tested fungicides were found compatible with P. fluorescens, displaying negligible growth inhibition compared to the control. Notably, tebuconazole 50% + trifloxystrobin 25% WG showed cent per cent compatibility with no growth inhibition at both drone and Taiwan sprayer concentrations. These findings underscore the potential for seamlessly integrating biopesticides with chemical pesticides, paving the way for effective management of pests and diseases without compromising efficacy, particularly as a pesticide resistance management strategy.

Soil microbiome bacteria protect plants against filamentous fungal infections via intercellular contacts

Bacterial-fungal interaction (BFI) has significant implications for the health of host plants. While the diffusible antibiotic metabolite-mediated competition in BFI has been extensively characterized, the impact of intercellular contact remains largely elusive. Here, we demonstrate that the intercellular contact is a prevalent mode of interaction between beneficial soil bacteria and pathogenic filamentous fungi. By generating antibiotics-deficient mutants in two common soil bacteria, Lysobacter enzymogenes and Pseudomonas fluorescens, we show that antibiotics-independent BFI effectively inhibits pathogenic fungi. Furthermore, transcriptional and genetic evidence revealed that this antibiotics-independent BFI relies on intercellular contact mediated by the type VI secretion system (T6SS), which may facilitate the translocation of bacterial toxic effectors into fungal cells. Finally, by using a "conidia enrichment" platform, we found that T6SS-mediated fungal inhibition resulting from intercellular contact naturally occurs within the soil microbiome, particularly represented by Pseudomonas fulva. Overall, these results demonstrate that bacteria from the soil microbiome can protect host plants from fungal infection through antibiotics-independent intercellular contacts, thus revealing a naturally occurring and ecologically important mode of BFI in agricultural contexts.

Management of Leaf Blight and Node Blight Diseases Indian Barnyard Millet (Echinochloa frumentacea (Roxb)

A study on the management of important diseases of rainfed kuthiraivali was carried out through biological control and fungicides in combination with seed treatment and foliar application methods and different intervals of diseases incidence. The leaf blight pathogen was isolated from the affected leaf; the isolated fungus's dark grayish-colored, fluffy mycelia were observed on the PDA medium. The mycelium was grey to olivaceous green, profusely branched, and septate. Conidiophores were single or in small groups, straight to flexuous, septate, smooth, and dark brown. Measuring 3.5 µm x 0.865 µm (1 µm), The disease incidence was observed at 15-day intervals using the percent disease index. Among three years, the seed treatment (10gm/kg) of Pseudomonas fluorescens (TNAU Pf1) followed by foliar application of Carbendazim + Mancozeb 2 gm/lit decreases the leaf blight diseases (63.63% reduction over control) and also recorded an increased yield of 1075 kg/ha of kuthiraivali. Seed treatment with Pseudomonas fluorescens Pf1 combined with foliar fungicide sprays significantly enhances yield and cost-benefit ratio under rainfed conditions while effectively managing seed-borne and foliar diseases.

Enhancing Vigna radiata Growth and Reducing Metal Toxicity with Pseudomonas spp. in Hydroponic Systems

Heavy metals in the environment originate from both natural sources and human activity, such as industrial waste and mining. Metals like cadmium, lead, and mercury accumulate in soil, water, and air, which can result in substantial threats to plants and ecosystems. Overexposure to heavy metals in plants leads to regeneration of reactive oxygen species (ROS), causing oxidative stress and disrupting many metabolic pathways, eventually impacting plant growth and productivity. Microbial bioremediation is an approach used to address this issue. This study investigates the effectiveness of the Pseudomonas family, specifically Pseudomonas aeruginosa and Pseudomonas fluorescens, in reducing heavy metal toxicity in non-circulating hydroponic systems. The objective is to observe the impact of zinc and cadmium stress on the growth of Vigna radiata (mung bean) seedlings. The results indicate that Pseudomonas aeruginosa promotes the development of seedlings up to a concentration of 1000 parts per million (ppm) of zinc, as well as cadmium. Pseudomonas fluorescens, on the other hand, supports plant growth under cadmium stress of up to 300 ppm and zinc stress of up to 1000 ppm. The results demonstrate the potential of the Pseudomonas family, which can serve as an effective method for reducing the presence of heavy metals in soil. Consequently, these bacteria could potentially serve as biofertilizers in heavy metal-contaminated regions, enhancing production while also mitigating the presence of heavy metals in the soil.

Complete genome of a fluorescent Pseudomonas sp. isolated from a PFAS groundwater treatment site.

Pseudomonas sp. CBR-F is a bacterial species isolated from a water treatment plant targeting for per- and poly-fluoroalkyl substances, a difficult-to-degrade family of anthropogenic compounds. Here, we report a complete genome for Pseudomonas sp. CBR-F, sequenced with Oxford Nanopore Technology. The genome consists of one 6.91 Mbp chromosome.

Ultrasensitive Characterization of Native Bacterial Biofilms via Dynamic Nuclear Polarization-Enhanced Solid-State NMR.

Bacterial biofilms are major contributors to persistent infections and antimicrobial resistance, posing significant challenges to treatment. However, obtaining high-resolution structural information on native bacterial biofilms has remained elusive due to the methodological limitations associated with analyzing complex biological samples. Solid-state NMR (ssNMR) has shown promise in this regard, but its conventional application is hindered by sensitivity constraints for unlabeled native samples . In this study, we utilized high-sensitivity Dynamic Nuclear Polarization (DNP) ssNMR to characterize native Pseudomonas fluorescens colony biofilms. The ~75-fold sensitivity enhancement provided by DNP enabled structural characterization without the need for isotope labeling or chemical/physical modification. We successfully collected 1D 13C/15N, and 2D 1H-13C, 1H-15N and 13C-13C ssNMR spectra within seconds, minutes or hours, facilitating the identification and quantification of biofilm extracellular matrix (ECM) components. Additionally, DNP ssNMR allowed quantitative detection of both flexible and rigid biofilm components by favorable freezing conditions. This study represents the first application of ultrasensitive DNP ssNMR to characterize a native bacterial biofilm, significantly expanding the capabilities of ssNMR for analyzing the composition and structure of a wide array of in vitro and ex vivo biofilms. The versatility of this approach will accelerate structure-guided efforts to combat infections caused by biofilm-forming microbes.

Assessment of the efficacy of Bacillus thuringiensis and Pseudomonas fluorescens in the biological control of Hypera postica larvae and adults

The research aimed to assess the impact of two bacterial isolates, Bacillus thuringiensis and Pseudomonas fluorescens, on the larvae and adults of Hypera postica in a laboratory setting, utilising three concentrations (1×10², 1×10⁴, and 1×10⁶) CFU / ml for both bacterial kinds under investigation. The study's results indicated that the quantities employed varied in their efficacy in exterminating larvae and adults of the clover weevil H. postica in a laboratory setting. The findings indicated that the rates of mortality escalate with higher concentrations and prolonged feeding durations. The concentration of 1×106 CFU / ml of the B. thuringiensis exhibited the highest mortality rates after 96 hours of treatment, with rates of (75.8%, 73.9%, 69.7%, 68.2%, and 43.5%) for the first, second, third, fourth larval stages, and adults, respectively. In contrast, the lowest mortality rate was observed with the bacterium P. fluorescens at a concentration of 1×102 CFU / ml after 48 hours, yielding rates of (13.5%, 28.4%, 27.7%, 27.0%, and 6.6%) Subsequent to the aforementioned stages.

Antibacterial mechanism of vitamin K3-mediated photodynamic inactivation against Pseudomonas fluorescens and its influences on blunt bream (Megalobrama amblycephala) quality

Photodynamic inactivation (PDI) has emerged as a novel non-thermal process technology for inactivating microorganisms due to its low cost, safety, and efficiency. This study aimed to investigate the antimicrobial effect of VK3-mediated PDI against Pseudomonas fluorescens (P. fluorescens) and to assess its impact on the quality of the blunt bream contaminated with P. fluorescens. The inhibition efficiency and photosensitization mechanism were investigated under different VK3 concentrations and UV-A light time conditions. The results showed that PDI could significantly inactivate P. fluorescens >7.0 log10 cfu/ml with 1 mM VK3 and 45 min of UV-A irradiation. Type I and type II photoresponses could co-occur in VK3-mediated PDI by quantitatively analyzing the photoresponse product ROS (OH, H2O2, 1O2). It was observed by SEM and TEM that the combined treatment of VK3 and UV-A disrupted the cellular integrity of P. fluorescens, leading to leakage of cell contents. Meanwhile, it degraded intracellular proteins and destroys genomic DNA, ultimately leading to bacterial death. In addition, the PDI system slowed down P. fluorescens’ proliferation during the blunt bream storage at 4 °C. The PDI system effectively killed 59 % of P. fluorescens on the blunt bream fillets under 1.5 mM VK3 and 60 min of UV-A irradiation. The VK3-mediated PDI delayed pH change and TVB-N production, inhibited protein degradation and fat oxidation, and ultimately maintained the quality of fish fillets. This study provides a promising PDI system for controlling food microbial contamination and maintaining the storage quality of aquatic products.

Enhancement of curcumin-mediated photodynamic inactivation against Pseudomonas fluorescens on fish fillets combined with ε-polylysine hydrochloride

Enhancement of curcumin-mediated photodynamic inactivation against Pseudomonas fluorescens on fish fillets combined with ε-polylysine hydrochloride

Synergistic antimicrobial effects of allyl isothiocyanate and cinnamaldehyde on Pseudomonas fluorescens and their application in chilled beef

Synergistic antimicrobial effects of allyl isothiocyanate and cinnamaldehyde on Pseudomonas fluorescens and their application in chilled beef

Field efficacy of Trichoderma viride, Pseudomonas fluorescens, and consortia of microbial agents against tomato late blight, Phytophthora infestans (Mont.) de Bary in Indo-Gangetic Plain of Bihar

Field efficacy of Trichoderma viride, Pseudomonas fluorescens, and consortia of microbial agents against tomato late blight, Phytophthora infestans (Mont.) de Bary in Indo-Gangetic Plain of Bihar

Effect of Seed Biopriming with Pseudomonas fluorescens for Increasing Seed Quality of Kenaf (Hibiscus cannabinus L.) Cultivar KR 14

Abstract Kenaf is a seasonal plant that produces fiber with biomass that has the potential to be developed as animal feed at the Animal Feed Tefa of Jember State Polytechnic. The quality of seed that planted can affect crop yield and quality. Seed priming can stimulate germination to overcome the problem of low physiological quality of kenaf seeds due to storage. Trichoderma is one of the biological agents that can be used as a seed priming material. This study aims to determine the effect of biological agents for seed priming on increasing the quality of kenaf seeds. The research was conducted from June to August 2024 at Seed Technology Laboratory of Jember State Polytechnic. The research was arranged using a nonfactorial completely randomized design. The treatment applied was control (without soaking agent), 1 hour seed soaking with Pseudomonas fluorescens isolate, 2 hours seed soaking with P. fluorescens isolate, and 3 hours seed soaking with P. fluorescens isolate. The observations made were Seed Germination (%), Growth Rate (%), Vigor Index (%), sprout shoot length (cm) and root length (cm). The results showed that seed biopriming using P. fluorescens increasing seed germination and seed vigor percentage. The recommended seed soaking treatment for seed priming kenaf seeds with low initial viability is soaking for 1 hour.

Prevention and control strategies for psychrophilic Pseudomonas fluorescens in food: A review.

Psychrophilic Pseudomonas fluorescens can secrete extracellular enzymes, biofilms, and other substances even under refrigeration conditions, which have a negative impact on the quality of dairy products, aquatic products, meat products, produce, and other foods, causing food spoilage and huge economic losses. Therefore, strengthening the prevention and control of psychrophilic P. fluorescens in food is of great significance. Although some reviews have introduced information on P. fluorescens, there are few reviews that provide detailed information on the psychrophilic mechanism, detection, prevention, and control methods of psychrophilic P. fluorescens. Therefore, to comprehensively address the shortcomings of previous reviews, this review provides a detailed overview of the physiological characteristics, secreted spoilage factors, psychrophilic mechanisms, and prevention and control methods, such as bacteriophages, quorum sensing inhibitors, and nanomaterials of P. fluorescens. And future research directions for the prevention and control strategies of P. fluorescens are discussed. The future research focus will be on strengthening the detection of P. fluorescens and adopting a combination of multiple technologies to prevent and control P. fluorescens without affecting food nutrition and quality while preventing the occurrence of drug resistance. This article aims to provide references for improving the quality and safety of refrigerated food and extending its shelf life.

The Pseudomonas aeruginosa sphBC genes are important for growth in the presence of sphingosine by promoting sphingosine metabolism.

Sphingoid bases, including sphingosine, are important components of the antimicrobial barrier at epithelial surfaces where they can cause growth inhibition and killing of susceptible bacteria. Pseudomonas aeruginosa is a common opportunistic pathogen that is less susceptible to sphingosine than many Gram-negative bacteria. Here, we determined that the deletion of the sphBCD operon reduced growth in the presence of sphingosine. Using deletion mutants, complementation and growth assays in P. aeruginosa PAO1, we determined that the sphC and sphB genes, encoding a periplasmic oxidase and periplasmic cytochrome c, respectively, were important for growth on sphingosine, while sphD was dispensable under these conditions. Deletion of sphBCD in P. aeruginosa PA14, Pseudomonas protegens Pf-5 and Pseudomonas fluorescens Pf01 also showed reduced growth in the presence of sphingosine. The P. aeruginosa sphBC genes were also important for growth in the presence of two other sphingoid bases, phytosphingosine and sphinganine. In WT P. aeruginosa, sphingosine is metabolized to an unknown non-inhibitory product, as sphingosine concentrations drop in the culture. However, in the absence of sphBC, sphingosine accumulates, pointing to SphC and SphB as having a role in sphingosine metabolism. Finally, the metabolism of sphingosine by WT P. aeruginosa protected susceptible cells from full growth inhibition by sphingosine, pointing to a role for sphingosine metabolism as a public good. This work shows that the metabolism of sphingosine by P. aeruginosa presents a novel pathway by which bacteria can alter host-derived sphingolipids, but it remains an open question whether SphB and SphC act directly on sphingosine.

Isolation and Identification of Bacillus Subtilis and Pseudomonas Fluorescens from Wheat Rhizosphere and Their Use as Biocontrol Agents

Isolation and Identification of Bacillus Subtilis and Pseudomonas Fluorescens from Wheat Rhizosphere and Their Use as Biocontrol Agents

Reduction of fungal spoilage in Amélie variety mango (Mangifera indica L.) using biocontrol agents

The mango is today one of the five most produced and consumed fruits in the world after the orange, the banana, the grape and the apple. It is one of the three most exported fruits from Côte d’Ivoire with banana and pineapple. However, the mango sector faces enormous post-harvest losses due to diseases and handling activities. It is in this context that the objective of this work is to reduce post-harvest losses of the Amélie variety mango, using formulations based on biocontrol agents (Pseudomonas fluorescens and Bacillus subtilis) against fungal germs spoilage. To do this, isolation and identification of spoilage fungal strains on 50 spoiled Amélie variety mangoes were carried out. Two liquid formulations based on the two biocontrol agents were produced and tested on the isolated fungal strains. The results of this study showed that Colletotrichum and Lasiodiplodia were identified as genera responsible for mango spoilage. In vitro antagonist tests carried out with the formulations inhibited the growth of Colletotrichum and Lasiodiplodia. The inhibition rates of the Bacillus subtilis formulation were between 76.63% and 89.06% and those of Pseudomonas fluorescens were 78.21% to 83.57%. For the consortium (Bacillus subtilis + Pseudomonas fluorescens), the inhibition rates of the formulations were between 87.73% and 88.97%. Therefore, Bacillus subtilis and Pseudomonas fluorescens could be used as biocontrol agents in the fight against fungal spoilage of mango in Côte d'Ivoire.

Influence of plant growth promoting rhizobacteria And organic manures on yield of okra (abelmoschus esculentus (l.) Moench)

The investigation revealed that different growth and yield parameters viz., minimum days to first flowering, earliest first flowering node, minimum days to first fruit harvest and maximum plant height, average fruit weight, fruit length, fruit breadth, fruit yield per plant, fruit yield per plot and harvest duration were recorded in treatment combination of FYM + Vermicompost + Jeevamrit + Pseudomonas fluorescens. Therefore, supply of plant nutrients through organic sources like vermicompost, FYM, jeevamrit and Pseudomonas fluorescens enhance plant growth and development, increase soil nutrient status and maintain sustainable crop production. Bangladesh J. Bot. 53(4): 1021-1025, 2024 (December)

Integrated management of tomato gray mold disease using selective plant extracts and rhizobacteria

Botrytis cinerea is one of the most significant plant pathogens globally, causing extensive damage to fruits and vegetables. Botrycides remain a widely used method of plant protection; however, the introduction of plant-beneficial bacteria offers a promising and agroecologically sustainable alternative. The current study evaluated the effectiveness of plant extracts and rhizobacteria in controlling diseases caused by B. cinerea in tomatoes. Neem (Azadirachta indica), garlic (Allium sativum), and turmeric (Curcuma longa) extracts were tested alongside rhizobacterial strains (Bacillus subtilis, Pseudomonas fluorescens, and Trichoderma harzianum). In vitro experiments showed that, at a 15% extract concentration, neem and garlic inhibited fungal growth by 78% and 72%, respectively, while B. subtilis suppressed mycelial growth by 62%. Synergistic treatments, particularly neem combined with B. subtilis, exhibited the highest inhibition zone (22 mm) and an 85% synergy effect. Greenhouse trials demonstrated that neem extract combined with B. subtilis significantly reduced disease severity, achieving a disease severity index (DSI) of 1.3 and a 75% disease reduction compared to controls, which had a DSI of 4.8. Neem extract and B. subtilis alone reduced disease by 52.1% and 58.3%, respectively. The combination of neem extract and B. subtilis proved more effective in managing grey mold, promoting healthier plants, and providing a potential chemical-free alternative to fungicides. Further field trials are recommended to develop scalable, eco-friendly solutions for sustainable tomato disease management.

Impact of the UV/H2O2 Process on Assimilable Organic Carbon and Trihalomethane Formation in Cyanobacteria-Contaminated Waters

The organic material from cyanobacteria is a significant precursor to the generation of disinfection byproducts. This study’s aim was to evaluate the formation of assimilable organic carbon (AOC) in water contaminated with cyanobacteria. Furthermore, the formation of AOC was related to the generation of trihalomethanes (THMs) and dissolved organic carbon (DOC). The advanced oxidation process was caISOrried out by exposing Microcystis aeruginosa cells (250,000 cells mL−1) to different peroxide dosages (10 to 100 mg L−1) under ultraviolet radiation. Pseudomonas fluorescens (P-17), Spirillum sp. (NOX), and flow cytometry were used to determine the AOC concentration. The formation of AOC and THMs during the UV/H2O2 process was not directly related. The AOC concentration increased with low H2O2 doses and decreased at higher concentrations, while the levels of THMs decreased regardless of the AOC formed. After oxidation, the DOC concentration decreased, along with the concentration of THMs. Additionally, it was observed that the behavior of DOC and AOC is inversely proportional. These results suggest that the oxidation process has a complex effect on organic matter, influencing byproduct formation and AOC availability. Moreover, these findings highlight the importance of carefully monitoring and controlling the oxidation processes to better understand their impact on water treatment and byproduct formation.

Pseudomonas fluorescens and Listeria monocytogenes Planktonic Cells and Biofilms Are Inhibited by Surfactin from Bacillus velezensis H2O-1

Biofilms are highly important to be controlled in food industries for two major reasons: (i) pathogenic microorganisms can impact public health causing foodborne illness outbreaks, and (ii) food-spoilage microorganisms can cause economic impacts due to the loss of organoleptic quality. Listeria monocytogenes and Pseudomonas fluorescens are ubiquitous and highly representative of both problems. The presence of these bacteria in biofilms must be controlled, and new strategies need to be implemented. Among those strategies, the use of biosurfactants is promising. The present work studied the application of a surfactin produced by Bacillus velezensis H2O-1 to inhibit corrosion, planktonic growth, microbial adhesion, and biofilm formation by two strains of L. monocytogenes and one strain of P. fluorescens. For that purpose, scanning electron microscopy, epifluorescence microscopy, and the determination of the physicochemical characteristics of different surfaces, microorganisms and biofilms were performed. Biofilm reduction on conditioned surfaces reached up to 75%. When the surfactin was added to the media, the planktonic inhibition values reached 87%, and biofilms were inhibited by up to 100%. The analyzed images suggest that this molecule has great potential to postpone steel corrosion. The results demonstrated the great potential of this biomolecule in the food industry against both microorganisms, thus enhancing food safety and shelf-life.