Bacterium Pseudomonas Fluorescens Research Articles

Effectiveness of Essential Oil Component Cocrystals Against Food Spoilage Bacteria

AbstractImproving food preservation technologies is a key aspect in the struggle to reduce global food waste, and natural antimicrobial substances, such as essential oil (EO) components represent very promising food preserving agent. However, their intrinsic chemico‐physical properties, such as the low melting point, low water solubility and high volatility, pose some practical difficulties in exploiting them for practical applications. Cocrystallization is used to stabilize liquid or volatile EO components providing them whit a crystalline environment, thus improving their potential application as antibacterial agents. Five EO active ingredients (THY = thymol, CAR = carvacrol, EUG = eugenol, CAD = trans‐cinnamaldehyde, and VAN = o‐vanillin) and two coformers (INA = Isonicotinamide, and HBA = 4‐hydroxybenzoic acid) have been combined and the corresponding cocrystals have been studied for their potential inhibiting effect against four food spoilage bacteria (Bacillus thuringiensis, Enterobacter cloacae, Pseudomonas fluorescens, and Serratia marcescens). The structures of the five cocrystals have been used to derive structure‐activity relationships in terms of release energy of the active ingredients form the crystalline environment, and a correlation has been derived with the Intermolecular Interaction Energies of the EO molecules.

Nitrogen uptake, grain yield, and oil concentration of dwarf castor beans under nitrogen rates and inoculation of rhizobacteria in grasses-legumes rotation.

Plant growth-promoting bacteria (PGPB) have been primarily studied for atmospheric nitrogen (N) fixation but they also have the capacity to improve nutrition and yield of crop plants. Therefore, the objective of this research was to investigate the effects of inoculation with PGPB in association with different N rates on N uptake, grain yield, and oil concentration of dwarf castor beans in succession to legumes and grasses in Ilha Solteira, Brazil. The treatments consisted of N rates (0 to 180 kg ha-1 of N) and inoculation with three plant growth-promoting bacteria (Azospirillum brasiliense, Bacillus subtilis, and Pseudomonas fluorescens, applied by leaf) and a control with no-inoculation. The grain and oil yields of castor beans were increased by 20 and 40% at a rate of 103 kg ha-1 of N in succession to grasses as compared to without N application. In addition, the grain yield of castor bean after legumes was increased by 28, 64, and 40% with estimated rates of 97, 113, and 92 kg ha-1 of N in combination with inoculations of A. brasilense, B. subtilis, and P. fluorescens as compared to without N application, respectively. Shoot, grain, and total N uptake were improved with foliar inoculation of A. brasilense, B. subtilis, and P. fluorescens at the N rates of 45, 90, and 135 kg ha-1, respectively. Topdressing of N at the rate of 103 kg ha-1 and foliar inoculation in succession to grasses and 180 kg ha-1 of N without the effect of foliar inoculation in succession to legumes are recommended for higher grain and oil yield of castor beans. Foliar inoculations with A. brasilense, B. subtilis, and P. fluorescens increased grain yield under reduced use of N fertilizer by 44, 37, and 49% in dwarf castor cultivation in succession to legumes, potentially contributing to sustainable agriculture.

Effect of Effective Microorganisms on Vegetative Growth of Wheat

Background: environmental pollution has led to climate change and agriculture is an aspect of this pollution, Pesticides, fertilizers and plant growth regulators are pollutants in soil and water. Therefore, beneficial microorganisms found in nature to provide plants with nutrients, resist pests and reduce mineral fertilizers is an ambitious goal for researchers. On the environment. Pseudomonas bacteria, baker’s yeast and mycorrhizal fungi are known for their ability to increase a group of nutrients’ organic and amino acids, as well as plant hormones that stimulate growth. Methods: A field experiment was conducted at University of Baghdad to assess the impact of beneficial microorganisms on wheat growth traits during winter Of 2019-2020., using a randomized complete block design (RCBD) with eight treatments.: Pseudomonas fluorescens bacteria (Pse), Mycorrhizae Glomusspp. (Gl.), Saccharomyces cerevisiae yeast (Sa.), Ps+Gl, Gl+Sa, Ps+Sa, Ps+Sa+Gl and control. Result: Experimental indicated that treatments significantly outperformed in plant height, tiller number, CGR (crop growth rate) and total dry weight. Additionally, the Ps+Sa+Gl treatment demonstrated a significant superiority over all other treatments in terms of plant height and tiller number. These observations suggest that the combination of biological factors within a single treatment resulted in a synergistic interaction, that led to enhancement of the vegetative growth indices in wheat plants.

Effect of Specific Spoilage Organisms on the Degradation of ATP-Related Compounds in Vacuum-Packed Refrigerated Large Yellow Croaker (Larimichthys crocea).

This study examined the spoilage potential of specific spoilage organisms on the degradation of adenosine triphosphate (ATP)-related compounds in vacuum-packed refrigerated large yellow croaker. The total viable count (TVC), ATP-related compounds and related enzymes of vacuum-packed refrigerated large yellow croaker inoculated with different bacteria (Pseudomonas fluorescens and Shewanella putrefaciens) were characterized using the spread plate method, high-performance liquid chromatography and assay kits, respectively. Results indicated that the TVC for both control and Shewanella putrefaciens groups reached spoilage levels at days 9 and 15, respectively. The changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and adenosine deaminase activity across all groups showed no significant difference attributable to microbial growth. The results suggested that ATP to inosine monophosphate (IMP) degradation primarily occurs via fish's endogenous enzymes, with minimal microbial involvement. On day 12, the IMP content in fillets inoculated with Pseudomonas fluorescens (0.93 μmol/g) was half higher than in those inoculated with Shewanella putrefaciens (0.57 μmol/g). Both spoilage organisms facilitated IMP degradation, with Shewanella putrefaciens making a more substantial contribution. Analysis of K values and correlation coefficients revealed that Shewanella putrefaciens was the primary factor in the freshness loss of refrigerated vacuum-packed large yellow croaker. These findings offer a reference for understanding quality changes in refrigerated large yellow croaker, especially regarding umami degradation at the microbial level.

Biological Control of Tomato Bacterial Leaf Spots and Its Impact on Some Antioxidant Enzymes, Phenolic Compounds, and Pigment Content.

Tomato bacterial spots, caused by Xanthomonas campestris pv. vesicatoria (Xcv1) and X. euvesicatoria (Xe2), as well as bacterial specks, caused by two strains of Pseudomonas syringae pv. tomato (Pst1 and Pst2), represent significant threats to tomato production in the El-Sharkia governorate, often resulting in substantial yield losses. The objective of this study was to evaluate the efficacy of various biocontrol culture filtrates, including bacteria and fungi agents, in managing the occurrence and severity of these diseases, while also monitoring physiological changes in tomato leaves, including antioxidant enzymes, phenolics, and pigment content. The culture filtrates from examined Trichoderma species (T. viride, T. harzianum, and T. album), as well as the tested bacteria (Bacillus subtilis, Pseudomonas fluorescens, and Serratia marcescens) at concentrations of 25%, 50%, and 100%, significantly inhibited the proliferation of pathogenic bacteria In vitro. For the In vivo experiments, we used specific doses of 5 mL of spore suspension per plant for the fungal bioagents at a concentration of 2.5 × 107 spores/mL. The bacterial bioagents were applied as a 10 mL suspension per plant at a concentration of 1 × 108 CFU/mL. Spraying the culture filtrates of the tested bioagents two days before infection In vivo significantly reduced disease incidence and severity. Trichoderma viride exhibited the highest efficacy among the fungal bioagents, followed by T. harzianum and T. album. Meanwhile, the culture filtrate of B. subtilis emerged as the most potent among the bacterial bioagents, followed by P. fluorescens. Furthermore, applying these culture filtrates resulted in elevated levels of chitinase, peroxidase, and polyphenol oxidase activity. This effect extended to increased phenol contents, as well as chlorophyll a, chlorophyll b, and carotenoids in sprayed tomato plants compared to the control treatment. Overall, these findings underscore the potential of these biocontrol strategies to effectively mitigate disease incidence and severity while enhancing plant defense mechanisms and physiological parameters, thus offering promising avenues for sustainable disease management in tomato production.

Residual Soil Fertility and Yield of Okra as Affected by Bio-inoculants and Bio-organic Nutrient Sources

Over the course of two kharif seasons in 2020 and 2021, a study was conducted to explore the impact of bi-inoculants (Pseudomonas fluorescens and Pseudomonas lactis) and bio-organic nutrient sources (farmyard manure, vermicompost, Beejamrit and Jeevamrit) over the fruit yield and residual soil fertility of okra in the Entisols of Himachal Pradesh. The study was structured around seventeen treatments with different combinations of bio-inoculants, bio-formulations and nutrient sources. The investigation revealed that minimum soil pH (6.96), maximum soil organic carbon (0.76 %), available nitrogen (259.36 kg/ha) and available phosphorus (26.98 kg/ha) were obtained with treatment T16 [FYM (50 q/ha) + Vermicompost (25 q/ha) + Jeevamrit + Pseudomonas fluorescens]. The maximum soil electrical conductivity (0.208 dSm-1) and available potassium (174.65 kg/ha) was obtained in treatment T17 [Recommended Dose of Fertilizer (78N:50P:54K kg/ha)]. The highest gross income (₹2,58,760 /ha), net income (₹1,60,620 /ha) were observed in treatment T16 [FYM (50 q/ha) + Vermicompost (25q/ha) + Jeevamrit + Pseudomonas fluorescens] and the highest benefit: cost ratio (1.69) was observed in treatment T10 [Jeevamrit + Pseudomonas fluorescens]. Therefore, it is evident that using bio-organic nutrients such as farmyard manure, vermicompost, and Jeevamrit, in conjunction with the bacterium Pseudomonas fluorescens, is advantageous for enhancing the residual fertility of the soil and achieving sustainable cultivation of okra, while also allowing for a complete savings of 100% on fertilizers.

Efficiency of application of the complex based on pseudomonas fluorescens bacteria on potato plantations in the Western Forest Steppe of Ukraine

Goal. To form effective complexes based upon bacterium Pseudomonas fluorenscens in combination with stimulation growth preparations and microelements with their efficiency study on potato plantations.
 Methods. The researches conducted during 2021—2022 in breeding- seeding rotation on the base Ukrainian Research Plant Quarantine Station of Institute of Plant Protection of NAAS. The experiment conducted on variety Slovyanka. The preparations efficiency determined in different rates against fungi diseases. Records conducted as per generally approved techniques with experimental methods in plant pathology and plant protection.
 Results. The efficiency of complex based upon Pseudomonas fluorescens АР-33 with stimulating matter nature and chelated microelementson potato plantations in growing period. The yield increased in 1.1—1.5 times during chelate 1 adding to preparation based upon bacterium Pseudomonas fluоrescens, and it increased in 1.3—1.6 times during chelate 2 addition. All biocomplexes combinations showed the preparation efficiency against Alternaria blight in scope 41.5—66.8%, but for late blight it had the following indexes 65.6—85.2.
 Conclusions. Combinations with chelates № 2 (Fe + Mn + Zn + Mo + Co + B) provided best growing results and yield. The combination Pseudomonas fluоrescens + xymedon + accinic acid + DMAE2ml/l + DМSО2 ml/l chelate (3.6%) showed the best result against potato Alternaria blight. It’s efficiency consisted of 66.8%.The combination Pseudomonas fluоrescens + xymedon + accinic acid + DMAE2ml/l + DМSО2 ml/l chelate(3.6%) showed 85.2% against late blight. It was the best index.

Large-scale duplication events underpin population-level flexibility in tRNA gene copy number in Pseudomonas fluorescens SBW25.

The complement of tRNA genes within a genome is typically considered to be a (relatively) stable characteristic of an organism. Here, we demonstrate that bacterial tRNA gene set composition can be more flexible than previously appreciated, particularly regarding tRNA gene copy number. We report the high-rate occurrence of spontaneous, large-scale, tandem duplication events in laboratory populations of the bacterium Pseudomonas fluorescens SBW25. The identified duplications are up to ∼1 Mb in size (∼15% of the wildtype genome) and are predicted to change the copy number of up to 917 genes, including several tRNA genes. The observed duplications are inherently unstable: they occur, and are subsequently lost, at extremely high rates. We propose that this unusually plastic type of mutation provides a mechanism by which tRNA gene set diversity can be rapidly generated, while simultaneously preserving the underlying tRNA gene set in the absence of continued selection. That is, if a tRNA set variant provides no fitness advantage, then high-rate segregation of the duplication ensures the maintenance of the original tRNA gene set. However, if a tRNA gene set variant is beneficial, the underlying duplication fragment(s) may persist for longer and provide raw material for further, more stable, evolutionary change.

Digest: The detrimental effects of abrupt environmental stress on diversity and fitness.

Does the rate of environmental deterioration influence diversity and fitness in a population? Zhou and Zhang 2024 found that, compared with gradual stress, abrupt stress led to a larger decrease in fitness and diversity in the bacterium, Pseudomonas fluorescens. These findings help explain the relationship between species evolution and antimicrobial resistance.

Effect of Type and Concentration of Organic Acids on Soil Bacteria Growth

The study was carried out at the University of Kufa - College of Agriculture for the season 2023-2022 to study the effect of the type and concentration of organic acids on the growth of soil bacteria, the first experiment includes the cultivation of bacteria on optional, broth, four types of organic acids were used (Citric acid, Acetic acid, Oxalic acid, Propionic acid) in concentrations (0,25.50.75.100.150) mM factor included four types of bacteria (Pseudomonas fluorescens, Acinetobacter calcoaceticus, Bacillus subtilis, Enterobacter cloacae). During this experiment, the minimum inhibitory concentration of these organic acids was determined, the second experiment included planting wheat seeds of a local variety by 4-2seeds per pot and used two types of organic acids (Acetic acid, Oxalic acid) and two types of pathogenic bacteria and biological resistance (Enterobacter cloacae and Bacillus subtilis). The results of the laboratory experiment showed a significant effect of organic acids in reducing the growth of bacteria, the addition of organic acids to the soil had a significant effect on the values of (Ec, PH) in the soil as oxalic acid obtained the highest rate of 6.370 dc m-1 At a concentration of 50 mM, oxalic acid obtained the highest rate of soil reaction score of 6.300 at a concentration of 75.50mM. The results indicate the significant effect of organic acids in inhibiting the total bacteria population in the soil, as oxalic acid obtained the highest rate of 106×114.3 g-1 dry soil at 50mM concentration.

Replacing Part of the Mineral Fertilizer by using Organic and Biological Fertilizers in the Sunflower

A field experiment was conducted in one of the fields of the College of Agricultural Engineering Sciences - University of Baghdad - Jadriya during the spring season of 2022, with the aim of assessing the possibility of replacing chemical fertilizers with organic and biological fertilizers as an alternative for a portion of the chemical fertilizers and their impact on the yield and quality of sunflower seeds. Randomized Complete Bock Design (RCBD) with three replications was used, using split plot arrangement. The main plots included four fertilizer treatments: (100% mineral fertilizers (recommended), 50% recommended mineral fertilizers + organic fertilizer represented by Trichoderma harzianum fungus and Pseudomonas fluorescens bacteria, 50% recommended mineral fertilizers + organic fertilizer represented by Trichoderma harzianum fungus and Azotobacter chroccocum bacteria, and 50% recommended mineral fertilizers + organic fertilizer represented by Orgevit poultry waste supplemented with macro and micronutrients). The sub-plots included three cultivars (Ishaqi1, Flami, and Lilo). The results showed that the Ishaqi1 cultivar outperformed and gave the highest fertility percentage (75.22%) and number of seeds per head (757.78 seeds head -1), and weight of 300 seeds (15.80 grams) and a total seed yield (2.942 tons ha-1), and an oil content percentage of 41.00%. On the other hand, the Flami cultivar excelled in the percentage of filling (47.115%). The fertilizer treatment of 50% recommended mineral fertilizers + organic fertilizer represented by (Trichoderma harzianum fungus and Pseudomonas fluorescens bacteria) showed superiority in fertility percentage (79.69%), number of seeds per head (771.20 seeds head -1), filling percentage (47.397%), total seed yield (3.041 tons ha-1), and oil content percentage (42.17%).

Evolutionary innovation through transcription factor rewiring in microbes is shaped by levels of transcription factor activity, expression, and existing connectivit.

The survival of a population during environmental shifts depends on whether the rate of phenotypic adaptation keeps up with the rate of changing conditions. A common way to achieve this is via change to gene regulatory network (GRN) connections-known as rewiring-that facilitate novel interactions and innovation of transcription factors. To understand the success of rapidly adapting organisms, we therefore need to determine the rules that create and constrain opportunities for GRN rewiring. Here, using an experimental microbial model system with the soil bacterium Pseudomonas fluorescens, we reveal a hierarchy among transcription factors that are rewired to rescue lost function, with alternative rewiring pathways only unmasked after the preferred pathway is eliminated. We identify 3 key properties-high activation, high expression, and preexisting low-level affinity for novel target genes-that facilitate transcription factor innovation. Ease of acquiring these properties is constrained by preexisting GRN architecture, which was overcome in our experimental system by both targeted and global network alterations. This work reveals the key properties that determine transcription factor evolvability, and as such, the evolution of GRNs.

Community composition drives siderophore dynamics in multispecies bacterial communities

BackgroundIntraspecific public goods are commonly shared within microbial populations, where the benefits of public goods are largely limited to closely related conspecifics. One example is the production of iron-scavenging siderophores that deliver iron to cells via specific cell envelope receptor and transport systems. Intraspecific social exploitation of siderophore producers is common, since non-producers avoid the costs of production but retain the cell envelope machinery for siderophore uptake. However, little is known about how interactions between species (i.e., interspecific interactions) can shape intraspecific public goods exploitation. Here, we predicted that strong competition for iron between species in diverse communities will increase costs of siderophore cooperation, and hence drive intraspecific exploitation. We examined how increasing microbial community species diversity shapes intraspecific social dynamics by monitoring the growth of siderophore producers and non-producers of the plant-growth promoting bacterium Pseudomonas fluorescens, embedded within tree-hole microbial communities ranging from 2 to 15 species.ResultsWe find, contrary to our prediction, that siderophore production is favoured at higher levels of community species richness, driven by increased likelihood of encountering key species that reduce the growth of siderophore non-producing (but not producing) strains of P. fluorescens.ConclusionsOur results suggest that maintaining a diverse soil microbiota could partly contribute to the maintenance of siderophore production in natural communities.

Biocontrol of Bacterial Fruit Blotch by Seed Priming with Bacillus Amyloliquefaciens and Pseudomonas Fluorescens

Bacterial fruit blotch (BFB), caused by the seed-transmitted pathogen Acidovorax citrulli, poses a serious threat to cucurbitaceous crops worldwide. In this study, two biocontrol bacteria strains, Bacillus amyloliquefaciens (Ba- 2) and Pseudomonas fluorescens (2P24), with significant antagonistic activity against A. citrulli were and applied by seed priming to control BFB seed transmission. Artificially infested watermelon and melon seeds were treated with the biocontrol strains by liquid or solid matrix seed priming. The seed bio-priming effects were evaluated under greenhouse conditions. Germination percentages were improved by seed priming treatments for melon, and seedling uniformity was higher for seeds primed with Ba-2 than for seeds from the other treatments for watermelon. Seedling disease incidence of untreated seeds were 6.5% for watermelon and 16.0% for melon, and water-priming resulted in similar disease progress curves as the untreated control. Seed priming with Ba-2 and 2P24 significantly reduced seedling BFB incidence for both watermelon and melon. Evaluation with naturally infested watermelon seeds primed with biocontrol strains indicated that 2P24 seed priming was more effective than Ba-2 ( P < 0.05) and 2P24 solid matrix priming, reducing the seedling disease incidence to 1.3%. Seed bio-priming has potential as an effective and eco-friendly approach for suppressing bacterial fruit blotch seed-to-seedling transmission.

Citrate Synthase GltA Modulates the 2,4-Diacetylphloroglucinol Biosynthesis of Pseudomonas fluorescens 2P24 and is Essential for the Biocontrol Capacity.

Carbon metabolism is critical for microbial physiology and remarkably affects the outcome of secondary metabolite production. The production of 2,4-diacetylphloroglucinol (2,4-DAPG), a bacterial secondary metabolite with a broad spectrum of antibiotic activity, is a major mechanism used by the soil bacterium Pseudomonas fluorescens 2P24 to inhibit the growth of plant pathogens and control disease occurrence. Strain 2P24 has evolved a complex signaling cascade to regulate the production of 2,4-DAPG. However, the role of the central carbon metabolism in modulating 2,4-DAPG production has not been fully determined. In this study, we report that the gltA gene, which encodes citrate synthase, affects the expression of the 2,4-DAPG biosynthesis gene and is essential for the biocontrol capacity of strain 2P24. Our data showed that the mutation of gltA remarkably decreased the biosynthesis of 2,4-DAPG. Consistent with this result, the addition of citrate in strain 2P24 resulted in increased 2,4-DAPG production and decreased levels of RsmA and RsmE. In comparison with the wild-type strain, the gltA mutant was severely impaired in terms of biocontrol activity against the bacterial wilt disease of tomato plants caused by Ralstonia solanacearum. Moreover, the gltA mutant exhibited increased antioxidant activity, and the expression of oxidative, stress-associated genes, including ahpB, katB, and oxyR, was significantly upregulated in the gltA mutant compared to the wild-type strain. Overall, our data indicate that the citrate synthase GltA plays an important role in the production of 2,4-DAPG and oxidative stress and is required for biocontrol capacity.

Corrosive Activity of Microorganisms Isolated from Fouling of Structural Materials in the Coastal Zone of the Barents Sea

Potentially corrosive active microorganisms isolated from structural materials with signs of biofouling on the coast of Kislaya Bay (Barents Sea, Russia) were studied: sulfate-reducing, iron-oxidizing and sulfur-oxidizing bacteria. Cultures of sulfate-reducing bacteria (Desulfovibrio sp., Halodesulfovibrio sp.), sulfur-oxidizing bacteria (Dietzia sp.), and iron-oxidizing bacteria (Pseudomonas fluorescens, Bacillus sp.) were identified on the basic of the determining the nucleotide sequences of the 16S rRNA gene. The methods of scanning electron microscopy, energy dispersive microanalysis of the chemical composition and X-ray phase analysis revealed significant changes in the structure and chemical composition of the surface layer of steel reinforcement samples exposed for 28 days in the presence of isolated microorganisms that demonstrated their active participation in corrosion processes. It has been shown that the formation of mineral analogues in corrosion products depends on the strains of studied bacteria and peculiarities of their metabolism. Sulfate-reducing bacteria isolated from the littoral zone of the Barents Sea showed the highest activity in the development of corrosion processes.

Element dissolution from Zn-bearing rocks treated with chemical and biotic agents: A prospective circular economy strategy for metal recovery from secondary resources

Calamine susceptibility to dissolution requires a detailed experimental evaluation to uncover an alternative management option for these materials. This study aimed to investigate the (bio)leaching behaviours of Zn/Pb-bearing calamines to quantify their potential as a Zn resource. Chemical treatments, including the application of mineral (H2SO4, HCl and HNO3) and organic acids (citric and oxalic acids), along with biotic treatments involving the bacteria Acidithiobacillus thiooxidans and Pseudomonas fluorescens, were used to analyse the mobilisation mechanisms, namely acidification and complexation. The results showed that HCl and HNO3 were the most efficient chemical agents, with an extraction efficiency as high as 39 % (Zn). A. thiooxidans extracted the largest amount of Zn (40 %), which proves that the efficiency of the biotic process can be nearly the same as that of the chemical process. However, the main mechanism governing element mobility was the pH factor. This study shows the potential of calamines as prospective materials for the recovery of Zn and other elements (Ge, Tl), even in those treatment conditions that require further optimisation.

Source-sink migration of natural enemies drives maladaptation of victim populations in sink habitats.

Natural enemies are critical drivers of species biogeography, and they may often limit the evolutionary adaptation and persistence of victim populations in sink habitats. Source-sink migration is also a major determinant of adaptation in sink habitats. Here we specifically suggest that source-sink migration of enemies reduces evolutionary adaptation of victim populations in sink habitats. The underlying mechanisms may include depressed population size (which limits the supply of genetic variation) and enforced resistance evolution in victims (which shows a trade-off with growth performance). We experimentally tested this hypothesis using a model microbial system, bacterium Pseudomonas fluorescens (victim) and its lytic bacteriophage (enemy). The ancestral bacterial strain had lower growth performance at a cold temperature (10°C, considered as sink habitat) than at its optimal temperature (28°C, source habitat). Evolutionary adaptation took place in bacterial populations that evolved alone in the cold environment. When phages were present, no significant abiotic adaptation was observed. Crucially, phage immigration from source populations caused maladaptation, i.e., decreased growth performance relative to the ancestral genotype, although this was not the case when there was simultaneous immigration of phage and bacteria. Therefore, enemy-mediated intraspecific apparent competition could lead to prosperity in core habitats causing hardship in edge habitats.

Self-healing of cement mortar with partial replacement of cement with silica fume

Many attempts are being made to use alternative building materials for sustainable construction practices. Huge research work being conducted to identify materials which can be partially replaced by cement. Here we tried to use silica fume & pseudomonas fluorescens as a partial replacement of cement which is having capability of self-healing in cement mortar. Efforts has been made to develop resources with minimal use of fossil fuel based on non-renewable resources which has negative impact on environment. Hence reducing ecological disturbances making biologically efficient. Many industries have been exploring way for variety of bacterial properties to introduce in construction line. Cracks occurring in cement mortar will result into the decrease in its durability property. Hence there is a great demand for effective yet eco-friendly alternative technique for reducing cracks in cement mortar. Reduction of cost can be achieved by bacterial self-healing cement mortar in terms of damage spotting and maintenance of cement mortar. This project presents effect of the bacteria (pseudomonas fluorescens) on strength and durability properties of sustainable cement mortar. Optimized bacterial concentrations of 107 cells/ml and 108 cells/ml were used for designing of mortar mix proportions. Silica fume is added at 5%, 10%, 15%, 20%, and 25% by weight of cement for replacing of cement in the 1:3 cement mortar mix. Compressive strength, split tensile strength and flexural strength tests were performed on mortar cubes at the age of 7 & 28 days. The obtained results are evident that, addition of pseudomonas fluorescens bacteria in mortar mix will enhance the mechanical and durability properties in cement mortar.

Barcoding Populations of Pseudomonas fluorescens SBW25

In recent years, evolutionary biologists have developed an increasing interest in the use of barcoding strategies to study eco-evolutionary dynamics of lineages within evolving populations and communities. Although barcoded populations can deliver unprecedented insight into evolutionary change, barcoding microbes presents specific technical challenges. Here, strategies are described for barcoding populations of the model bacterium Pseudomonas fluorescens SBW25, including the design and cloning of barcoded regions, preparation of libraries for amplicon sequencing, and quantification of resulting barcoded lineages. In so doing, we hope to aid the design and implementation of barcoding methodologies in a broad range of model and non-model organisms.