Pseudomonas Fluorescens Isolates Research Articles

Biopriming of cayenne seed (Capsicum frutescens L.) using Indole Acetic Acid (IAA) - producing fluorescent pseudomonads to increase germination and growth of seeds

Capsicum frutescens L. is one of the horticultural commodities that plays an important role as food and industrial raw materials. The amount of chili consumption continues to increase, so its production requires quality seeds. The physiological quality of seeds can be improved, one of which is by using fluorescent pseudomonads as biopriming. The fluorescent pseudomonads LAHLS1, LAHT1, LAHCS2, and PfPb3 produced Indole Acetic Acid (IAA) with concentrations between 5.37 to 20.31 ppm, and were significantly different. Biopriming of C. frutescens L. seeds using different fluorescent pseudomonad isolates affected the percentage of germination, wet weight and dry weight of C. frutescens L. seedlings. Fluorescent pseudomonads LAHLS1, LAHT1, LAHCS2, and PfPb3 can increase the percentage of C. frutescens L. seed germination up to 100%. The highest seedling wet weight (43.52 mg) was found in seed biopriming using fluorescent pseudomonad LAHLS1 and the lowest was control (12.33 mg). The highest seedling dry weight (4.40 mg) was found in seed biopriming using fluorescent pseudomonad LAHLS1, and the lowest was control (0.93 mg). The results showed the potential use of IAA-producing fluorescent pseudomonads in increasing the percentage of seed germination and influencing the growth of C. frutescens L. seedlings based on observations of wet weight and dry weight of seeds.

Compatibility study of bio control agents with agro chemicals

Agrochemicals were tested for their compatibility with Trichoderma harzianum and Pseudomonas fluorescens under in vitro. Carbendazim @ 50, 100, 250 and 500 ppm, and copper oxychloride @ 1000, 1500, 2000and 2500 ppm concentrations, completely inhibited growth of T. harzianum. However, chlorpyrifos and cartap hydrochloride @ 250 and 500 ppm were moderately compatible. At initial two lower concentrations, pendimethalin@ 500 and 1000 ppm and fenoxyprop-p-ethyl @ 50 and 100 ppm were compatible with T. harzianum. All the fungicides/combination of fungicides, insecticides and herbicides tested at all their concentrations were completelycompatible with Pseudomonas fluorescens isolate-.

Characterization of Native Fluorescent Pseudomonads against Sclerotinia Blight of Brinjal (Solanum melongena L.)

Brinjal (Solanum melongena L.) is one of the most common and known rich source of vitamin B1 (Thiamin), dietary fibre, manganese, niacin (vitamin B3), copper, vitamin B6 (pyridoxine), folate (vitamin B9), potassium, Vitamin K. Brinjal cultivation is affected by several pests and diseases. Sclerotinia blight is one of the most destructive diseases of brinjal caused by Sclerotinia sclerotiorum (Lib) de Bary. Under the present investigation two isolates of Fluorescent Pseudomonads (FLPs) viz., FLP-Brinjal 2020-1 and FLP-Brinjal 2020-2, were evaluated against Sclerotinia sclerotiorum (SCL)under in vivo and in vitro conditions using dual culture, inverted plate assay. FLP-Brinjal 2020-2 gave maximum inhibition over the control followed by FLP-Brinjal 2020-1 against the pathogen in in vitro condition. Experiments conducted in pluck trays indicated that FLP-Brinjal 2020-2 was superior with least sclerotinia blight incidence (20.53%).The identity and diversity among the FLP isolates were examined by sequence analysis of 16s rRNA gene. The gene was amplified by PCR using primers pair, 27 F/1492 R. Amplified DNA products were sequenced and analysed by BLAST (BLASTn) programme at NCBI database for species identification. Among the 10 FLPs isolates assessed 9 were found to have maximum similarity with Pseudomonas aeruginosa. FLP 2020-2 and FLP 2020-1 were found to be Pseudomonas fluorescence which is in confirmation with the morphological observations. Significant diversity among the isolates was observed when dendrogram of the sequence was plotted using CLUSTAL W.

Characterization of Florescent Pseudomonads for Biological control Efficacy, Plant Growth Promotion and Antibiotic Tolerance

A collection of fourteen indigenous Fluorescent Pseudomonads (FLPs) was isolated from diverse crop rhizospheres across different regions of Bihar, and their distinctive characteristics were documented. The differentiation between Pseudomonas aeruginosa and Pseudomonas fluorescens was achieved through pigmentation, fluorescence assessment on King's A media, and growth analysis at 42°C. Among the isolates, nine were identified as P. aeruginosa: FLP strains associated with Rice, Turmeric, Mustard-1, Mustard-2, Okra-G, Pea, Barley, Brinjal, and Chickpea. Meanwhile, five isolates - FLP Wheat, FLP Bean, FLP Mango, FLP Brinjal New, and FLP Cauliflower - were classified as P. fluorescens. Confirmation of these classifications was established through DNA sequencing of the 16s RNA region. These FLP isolates were evaluated against prevalent phytopathogens, including Macrophomina phaseolina, Colletotrichum musae, Fusarium oxysporum f. sp. cubense, and Xanthomonas oryzae pv. oryzae. Notable performance was exhibited by FLP Barley (70.55%) against Macrophomina phaseolina, FLP Okra-G (53.82%) against Colletotrichum musae, FLP Rice (38.58%) against Fusarium oxysporum f. sp. cubense, and FLP Okra-G against Xanthomonas oryzae pv. oryzae. In the context of biocontrol efficacy, FLP Turmeric, FLP Pea, FLP Okra-G, and FLP Mustard-1 showcased superior performance in combatting phytopathogens. Additionally, all FLP isolates, except FLP Cauliflower, exhibited phosphate-solubilizing capabilities, with FLP Brinjal demonstrating the highest solubilization (Phosphate Solubilizing Index of 2.89). Siderophore production was a common trait among the isolates. Compatibility with antibiotics, namely Streptocycline at concentrations of 0.025% and 0.10%, as well as Copper oxychloride at 0.25%, 0.30%, and 0.50%, was assessed. Only FLP Cauliflower exhibited compatibility with both antibiotics across all concentrations. Notably, FLP Rice, FLP Turmeric, and FLP Barley demonstrated positive antibiotic compatibility alongside effective biocontrol potential. In summation, this study unveils the distinct attributes and potential applications of indigenous Fluorescent Pseudomonads (FLPs) isolated from the rhizospheres of diverse crops in Bihar. The identified isolates exhibit promising traits such as disease control, phosphate solubilization, siderophore production, and antibiotic compatibility, thus presenting valuable options for sustainable agricultural practices and disease management.

Isolation and screening of Pseudomonas fluorescens isolates against Fusarium oxysporum f. sp. radicis-lycopersici and their effects on seedling growth of Paraserianthes falcataria

Abstract. Yusran Y. 2023. Isolation and screening of Pseudomonas fluorescens isolates against Fusarium oxysporum f.sp. radicis-lycopersici and their effects on seedling growth of Paraserianthes falcataria. Biodiversitas 24: 2294-2301. Pseudomonas fluorescens plays a major role in biological control of pathogens and plant growth promotion as well with various mechanisms. The aim of the present study was to determine the biochemical characteristics of several Pseudomonas spp. isolates and to screen them against root pathogenic fungus Fusarium oxysporum f.sp radicis-lycopersici (FORL) and to evaluate their effect on the growth enhancement of Paraserianthes falcataria (L.) I.C. Nielsen seedlings. About 28 Pseudomonas fluorescens isolates were isolated from the rhizosphere of several plants and identified based on their physiological and morphological characters as well as their biochemical reactions. All isolates were tested for their ability to suppress FORL growth in vitro. All isolates inhibited FORL growth with varying inhibition zones. Six P. fluorescens isolates showed highest inhibition zones, namely TMTP4, TMTP5, TMTP6, SCPA1, SCPB3 and Proradix. The results showed that eight Pseudomonas isolates, namely TMTP4, TMTP5, TMTP6, SCPA1, SCPB3, SMPB3, TMTA2 and Proradix had a significantly different effect compared to the control treatment in increasing the growth of Paraserianthes seedlings. Based on our findings, it was confirmed that some P. fluorescens isolates could be used as potential bio-inoculants for controlling plant diseases caused by FORL and as a biological fertilizer to increase plant growth.

Genome Update for Pseudomonas fluorescens Isolate SBW25.

We report a genome update for Pseudomonas fluorescens isolate SBW25. The updated genome assembly, which was derived from the original isolate, is based on PacBio long-read sequence data. It shows three minor differences, compared with the previously published genome sequence. Original annotations were merged with recent automated annotations to preserve information.

Impact of soil temperature, pH and carbon dioxide on the population and efficiency of fluorescent pseudomonad in the rhizosphere soil of Pokkali rice

The present study was aimed at the evaluation of soil temperature, pH and carbon dioxide evolution on the number and efficiency of fluorescent pseudomonads around the root system of Pokkali rice at Vytilla in Ernakulam district of Kerala. Two plots (40 m2) comprising control (without application of Pseudomonas fluorescens) and P. fluorescens treated plants were used for the field experiment. The isolates of fluorescent Pseudomonads or Pseudomonas fluorescence were counted and their efficiency was assessed for IAA, ammonia, HCN and siderophore production. Simultaneously, soil temperature, pH, and carbon dioxide evolution were also recorded. A total of 6 fluorescent pseudomonads (VPJU, VPJL, VPAU1, VPAU2, VPAU3 and VPAU4) were found during the crop period. All the isolates produced IAA and ammonia with varying degrees of intensity. Three isolates (VPAU1, VPAU3 and VPAU4) produced HCN, and no microbial isolates produced siderophore. The effect of soil temperature, pH, EC and carbon dioxide evolution was correlated with the number of fluorescent pseudomonads in the soil. The bacteria were significantly afflicted by pH and EC, whereas soil temperature and CO2 evolution did not show any effect on the number of fluorescent pseudomonads. There was no significant influence of soil temperature, pH, EC and carbon dioxide evolution on indole acetic acid production, ammonia, and HCN production. Inoculated Pseudomonas fluorescence did not survive in Pokkali rice fields. However, further studies are needed for at least three seasons in Pokkali soils to confirm the results of the present study.

Evaluation of compatibility of native plant growth promoting rhizobacterial isolates against chemical pesticides

Conventional agriculture relies heavily on chemical fertilizers, pesticides and weedicides to control plant diseases, pests and weeds to improve production. Consequently, the soil receives the bulk of complex agrochemical compounds many of which are poisonous to the activity of non-target beneficial soil microorganisms. There is a need to check the tolerance of biocontrol agents like Plant Growth Promoting Rhizobacterial (PGPR) to various pesticides before their practical application. Taking this into account, the investigation was conducted for the screening of the PGPR isolates against chemical pesticide degradation potentialities in Plant Bacteriological Laboratory, Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal during 2021-22. All the native rhizobacterial, Bacillus and Fluorescent pseudomonad isolates tested had good potentiality to tolerate Carbendazim and Glyphosate. Among native Bacillus isolates, BRB89, BRB42, PR 19, PR 20, BRB 52, BRB 56, BRB 74, and SM 9 showed moderate tolerance, whereas among all the native Fluorescent pseudomonads, all except GP2 showed high tolerance against Paraquat. All native Bacillus isolates except PR16 were highly sensitive against Chorpyriphos. However, all the native fluorescent pseudomonads showed tolerance against Chorpyriphos even at 2000 ppm concentration.

Potential of Pseudomonas and Trichoderma from the Brazilian Amazon as Biocontrol Agents against the Wheat Blast Disease

Blast is one of the most significant wheat diseases, causing high yield losses in susceptible varieties under favorable conditions in Latin America, Southeastern Asia and Eastern Africa. The disease is caused by the ascomycetous fungal pathogen Pyricularia oryzae Triticum lineage (PoTl). Chemical control with fungicides has been used as a management strategy; however, the effectiveness of the major classes of high-risk site-specific systemic fungicides has been reduced due to the widespread prevalence of resistance, especially in Brazil. Biological control is seen as a highly important and sustainable strategy to minimize the impact of yield losses associated with wheat blast in areas where fungicides are ineffective. In our study, we specifically aimed to determine the biological control potential of the three isolates of fluorescent Pseudomonas and three of Trichoderma as the antagonists of PoTl, both in in vitro and under greenhouse conditions. Additionally, we aimed to describe the ultrastructural interactions among the biocontrol agents and the pathogen in vitro by means of scanning electron microscopy (SEM). Fluorescent P. wayambapalatensis ‘Amana’ or Pseudomonas sp. nov. ‘Yara’, both from the P. putida group, and Trichoderma koningiopsis ‘Cachara’ significantly reduced PoTl in vitro mycelial growth and the blast disease severity on wheat plants. The SEM analyses revealed ultrastructural antagonistic mechanisms: biofilm formation, direct antagonism and mycoparasitism. Further research on the topic should include the development of stable formulations of the Pseudomonas- and Trichoderma-based biocontrol agents selected in our study for managing the wheat blast disease and the field tests of the biofungicide formulations obtained thereafter.

Compatibilty Of Pseudomonas Fluorescens With Different Fungicides Used In Management Of Citrus Diseases

An experiment was conducted to study the compatibility of fungicides with bacterial biocontrol agents Pseudomonas fluorescens under in vitro conditions with five fungicides commonly used in management of Citrus diseases by employing poisoned food technique. Each fungicide was tested at diffrent concentrations from(Trace), 0.05%, 0.1%, 0.2%,0.3%, 0.4% and 0.5% in case of Bordeaux mixture upto 2.0%. For that purpose four Pseudomonas fluorescens isolates i.e. Pf 1, Pf2, Pf 7 and Pf 26 used. The results of the study proved that, Out of five fungicides, P. fluorescens showed good adaptation with Metalaxyl, Fosetyl-Al and Bordeaux mixture.

Method to evaluate disease supression against Pythium debaryanum and alfalfa growth promotion by fluorescent Pseudomonas

Fluorescent Pseudomonas have been extensively reported as effective biocontrol agents and can be used to manage Pythium seedling diseases in alfalfa. An in vivo methodology was developed to evaluate fluorescent Pseudomonas isolates for their ability to suppress disease and promote plant growth in the alfalfa-Pythium pathosystem. The standard method consists of a bioassay performed in growth chamber under controlled conditions of temperature and photoperiod. Alfalfa seeds were sown in commercial substrate and subsequently treated as follows: no Pseudomonas, no Pythium debaryanum (germination control); inoculated only with P. debaryanum (disease control); each one of the Pseudomonas isolates co-inoculated with P. debaryanum. An augmented experiment design was obtained by selecting a random complete blocks design for four checks systematically evaluated on 12 bioassays, and enlarging the blocks to accommodate up to 16 treatments per assay. Disease control recorded an emergence of 33.2% on day 15 after sowing date, as compared with germination control (100%). The 101 fluorescent Pseudomonas isolates showed a wide response on disease suppression ability. Twelve percent of tested isolates reasonably protected alfalfa plants against P. debaryanum, recording an emergence of over 60%. A similar procedure, in the absence of the pathogen, was used to evaluate alfalfa growth-promoting ability of selected Pseudomonas isolates. Five isolates exhibited a significant biocontrol activity against P. debaryanum and four of them also recorded a significant plant growth-promoting effect. Both bioassays were appropriate to identify candidate Pseudomonas isolates to be further tested under field conditions.

Potential of some Rhizobacteria Isolates Antagonists in Various Formulation to Control Sheat Root Disease (Sarocladium oryzae) on Rice Plants

The reserach aims to determine the potential of antagonistic rhizobacteria and is appropriate formulations used to control sheat root disease (Sarocladium oryzae). This research was carried out in July to December 2019 in the Plant and Disease Laboratory and the Greean House Faculty of Agriculture Jember University. The experiment was conducted using a completely randomized design (CRD) 2 factors, namely isolates and formulation. Isolates factors have 4 factors levels; control, Bacillus sp. isolate, Pseudomonas fluorescens isolate, and Bacillus sp. + Pseudomonas fluorescens isolate. The formulation factors has 4 factors levels; glucose 10% + potato water 70% + bacterial starter 20%, Fructose 20% + coconut water 60% + bacteria; starter 20%, glucose 10% + CMC 2% + monmorilonite 68% + bacterial starter 20%, fructose 20% + CMC 2% + kaolin 58% + bacterial starter 20%. The result showed that the treatment of Bacillus sp. with formulation glucose 10% + CMC 2% + monmorilonite 68% + bacterial starter 20%, showed the best result, with a control effectiveness of 78.31%.Key word; Formulation, Rhizobacteria antagonist, Sarocladium oryzae

Bioprospecting Fluorescent Pseudomonas from the Brazilian Amazon for the Biocontrol of Signal Grass Foliar Blight

Biological control is considered the only viable integrated disease management practice for controlling the widely distributed and destructive foliar blight and sudden death disease caused by the fungus Rhizoctonia solani AG-1 IA on signal grass (Urochloa brizantha) pastures. Since major signal grass varieties are highly susceptible and fungicide sprays are not labeled for grass pasture cropping systems, biological control is sought as an alternative for managing this fungal disease. In this study, 24 fluorescent Pseudomonas isolates obtained from naturally suppressive soils from the Amazon biome were bio-prospected for their role as biocontrol agents against R. solani AG-1 IA. Based on in vitro antagonism, three isolates (Amana, Poti, and Yara) were selected for further in vivo assays. Multilocus phylogenetic analysis indicated that Amana and Yara were grouped into the Pseudomonas putida group while Poti was grouped into the Pseudomonas asplenii group, and could well constitute a new Pseudomonas species. For in vivo biocontrol assays, the biocontrol agents were applied either via seed-treatment or via foliar spray. All three isolates produced siderophores and solubilized phosphate, while Amana and Poti showed protease and chitinase in vitro activity. Foliar application of P. putida Amana from Amazonian suppressive soils resulted in a significant reduction of the foliar blight disease severity on signal grass. We discuss further steps for the development and labeling of Pseudomonas-based biofungicides for managing the foliar blight disease on signal grass pastures in Brazil.

Application of Secondary Metabolites of Two Pseudomonas fluorescens Isolates to Control Bacterial Wilt of Potato

The focus of this research was to determine how secondary metabolites from two isolates of Pseudomonas fluorescens (P8 and P60) affected potato plant resistance to bacterial wilt (Ralstonia solanacearum) as well as potato growth and productivity. For four months, this experiment was carried out at Serang Village’s potato field, in Karangreja District, Purbalingga Regency, at an altitude of 1285 m above sea level, with Andisol soils, an average temperature of 22.31 C, and relative humidity of 84.09%. A randomized block design was used with a control treatment, drenching with 1.5 g/L bactericide (20% streptomicin sulphate) administered six times, and drenching with secondary metabolites of P. fluorescens P8 or P. fluorescens P60 administered three, six, nine, and 12 times. Each treatment was carried out five times. Each treatment resulted in a different incubation period, disease intensity, infection rate, plant height, number of tubers, tuber weight per plant, wet and dry weight of crop, fresh and dry weight of root, number of branches, and phenolic compound analysis. The results showed that applying P. fluorescens P8 and P. fluorescens P60 secondary metabolites to potato plants can induce resistance by increasing the content of phenolic compounds in the plants. Drenching with secondary metabolites from P. fluorescens P8 or P. fluorescens P60 12 times can reduce the incubation period by 9.23%, the intensity of disease by 75%, and the incidence of disease by 53.57%. Plant height, crop dry weight, root fresh weight, root dry weight, number of tubers, and tuber weight per plant can all be increased by using secondary metabolites.
 Keywords: bacterial wilt, potato, Pseudomonas fluorescens, secondary metabolites.

“Pseudomonas fluorescens” as an Antagonist to Control Okra Root Rotting Fungi Disease in Plants

The common bacteria found in fruit and vegetables are Pseudomonas fluorescens which is Germ-negative and is rod-shaped. Pseudomonas fluorescens has been originated from the rhizosphere of Roorkee-grown okra. The presented work involves recognizing and controlling the isolates of Pseudomonas fluorescens. The scope of the proposed work is that the technique used here is a unique strategy to plant protection and control of rotting fungus diseases based on the recognition and management of Pseudomonas fluorescens isolates. Antagonist effect occurs commonly in vegetable and fruit plants. The main goal of this study is to isolate, identify, and evaluate the development of these bacteria which effects on plant growth. In this research work, five isolates have been chosen for further research based on their morphological, biochemical, and physiological characteristics. All five isolates have been identified as Pseudomonas fluorescens from Bergey’s Manual for the determination of bacteriology. Catalase, urease, amylase, and citrate utilization test were all positive in all of the isolates. PFTT4 was identified to be a likely strain for all plant growth promoting exercises such as age of IAA, HCN, ammonia, and phosphate solubilization subsequent to being assessed for their plant development advancing properties. Further, in vitro exploring uncovered that PFTT4 diminished the development of phytopathogens such as Fusarium solani and extraordinarily further developed seed germination just as all development boundaries like shoot and root length. Furthermore, Pseudomonas sp. PFTT4’s plant growth promoting and antifungal activities put forward to it could be there used because of bioinoculant agents for Abelmoschus esculentus.

Pseudomonas fluorescens VSMKU3054 mediated induced systemic resistance in tomato against Ralstonia solanacearum

Plant growth-promoting rhizobacteria (PGPR) are potential bio agents for the suppression of various soil-borne diseases in crop plants and considered as viable alternative to chemical pesticides. The selected Pseudomonas fluorescens isolate VSMKU3054 is an effective biological control inoculum for the suppression of wilt disease of tomato incited by Ralstonia solanacearum by inducing plant defense enzymes viz., peroxidase (POX), polyphenol oxidase (PPO), lipoxygenase (LOX), phenylalanine ammonia-lyase (PAL) and total phenol content. The highest level of defense enzymes viz., POX, PAL, PPO, LOX and total phenol contents were observed in tomato seedlings treated with P. fluorescens at 24h, 36h, 36h, 48h and 24h after challenge inoculation of R. solanacearum, respectively. Whereas application of P. fluorescens alone in tomato plants also brought about induction of higher levels of POX, PAL, LOX and total phenol contents, and a moderate level of PPO activity compared to pathogen inoculated plants and control plants. The maximum induction of four prominent PPO isoforms was observed in tomato plants upon the treatment of P. fluorescens VSMKU3054 and challenged with R. solanacearum. Thus, this study showed that induction of defense-related genes by P. fluorescens plays an important role against R. solanacearum.

Differential response of native fluorescent pseudomonads isolates in plant growth promotion and biocontrol activity in Eleusine coracana (L.) gaertn

In the present study, different fluorescent pseudomonads isolates from agricultural soil were characterized and identified as plant growth promoting bacteria. On the basis of specific biochemical tests, 42 were confirmed as fluorescent Pseudomonas spp. Simultaneously, when all isolates were evaluated for their biocontrol traits, 21 isolates were good HCN producers, 23 isolates were siderophore producers and 28 isolates were also identified as phosphate solubilizers. Further, all the 42 isolates were evaluated for their antagonistic activity against the four major pathogens using dual culture assay viz., Sclerotium rolfsii, Rhizoctonia solani, Pyricularia grisea and Helminthosporium nodulosum, of which 10 isolates viz., UUHF Psf-4, 11, 12, 15, 17, 20, 28, 35, 40 and 41 showed maximum per cent inhibition against all the four tested pathogens. Among all the isolates, UUHF Psf-4 exhibited maximum per cent inhibition with 83.75% towards S. rolfsii, 85.00% inhibition towards R. solani, 80.00% inhibition towards P. grisea and 78.57% inhibition towards H. nodulosum, respectively. Results of plant growth-promoting (PGP) activities in finger millet, under laboratory and glass house conditions, revealed that all the 10 putative candidates were found effective in significantly increasing most of the planting value parameters (first count, germination per cent, root length, shoot length, seedling length, fresh and dry weight, vigour index I and II) under both laboratory and glass house conditions. UUHF Psf-4 was found to be best followed by UUHF Psf-15 and UUHF Psf-41 in most of the characters studied, all being superior to control.

Genetic diversity of Pseudomonas fluorescens isolates collected from basmati rice and saffron crops of north-western Himalayan region

Pseudomonas fluorescens is ubiquitous in nature and having diverse mechanism of action which ameliorates the biotic and abiotic stresses and possess plant growth promotion activities in agricultural crops. Out of fifty isolates of fluorescent pseudomonads collected from saffron and paddy crops, thirty-five isolates were identified as P. fluorescens on the basis of phenotypic test and species-specific PCR. Species-specific-PCR assay provided a rapid, specific and sensitive alternative to conventional culture methods for the identification of P. fluorescens. Cluster analysis of the collected thirty-five isolates of P. fluorescens by rep-PCR showed considerable genetic diversity. Twenty and twenty-one banding patterns were obtained for both the BOX and REP primers. The present study shall be useful to correlate the genetic diversity with functional diversity of P. fluorescens to explore the possibilities of suitable disease management strategies for a particular crop in sustainable agriculture.

Antagonism of Siderophore Producing Bacteria Against Blood Disease Bacteria

Siderophore is a chemical compound of Fe chelating. This compound is produced by several microorganisms that grow under iron-limiting conditions. Siderophore can facilitate the transfer of Fe from the environment to become available to plants. The siderophore ability to bind Fe as a competitor against other microorganisms, so that in the agricultural system it can be used as a plant disease controller. This study aims to determine the production of siderophore produced by several fluorescent pseudomonad isolates and its antagonistic tests against Blood Disease Bacteria (BDB). Siderohore detection is determined by the absorbance value obtained, and measured using a spectrophotometer at a wavelength of 410 nm. The antagonist test used a completely randomized designwith 7 treatments and 3 replications. The treatment is fluorescent pseudomonads isolates PfLAHP2, PfPb1, PfCas3, PfKd7, PfCas, PfPj1, and PfPj2. PfLAHP2 isolates produced the highest siderophore, which was 1.027, and the lowest isolate PfCas was 0.148. The antagonistic test of fluorescent pseudomonad against BDB showed that PfLAHP2 isolate produced the largest inhibitory zone, which was 1.042 cm.

A novel bacterial infection in cultured Nile tilapia, Oreochromis niloticus in New Valley, Egypt

Pseudomonas and micrococcus (Pseudomonas fluorescens and M. luteus) are an emerging opportunistic fish pathogens that results in considerable economic losses among the infected fish. In the present study, a total number of 150 cultured Nile tilapia, Oreochromis niloticus were collected from concrete ponds farms in Alkharga oases, New Valley governorate during the period from March to July 2019 and subject to clinical and bacteriological examination. including excessive black colouration of skin, scales loss, skin ulcer and focal hemorrhages, exophthalmia, fin congestion and rot. Internally, the diseased fish had congested internal organs including liver, spleen, and kidney., The prevalence of Pseudomonas fluorescens and M. luteus infection was 6.7 % withe a total number of 10 isolates and 11.3% withe a total number of 17 isolates respectively. Were recovered from infected fish. The suspected Pseudomonas fluorescens isolates were biochemically similar while The suspected M. luteus isolates were biochemically similar, except for Arginine hydrolysis, Vogus-Proskauer and Urease tests. The isolation and biochemical characterizations suggested that the isolates belong to the genus Pseudomonas. And genus micrococcus. The recovered M. luteus isolates were pathogenic to O. niloticus, this is the first report of M. luteus infection in O. niloticus in Egypt.