Pseudomonas Isolates Research Articles

Effect of selected bacteria of the genus Pseudomonas on the quality of raw cow’s milk

Pseudomonas spp. are a psychrotrophic species associated with milk spoilage caused by its enzymatic activities. The aim of this study was to identify Pseudomonas spp. in raw cow’s milk and to investigate their associated enzymatic properties and the ability to produce pyoverdine pigment. For microbiological analysis, 2 ml of milk samples was taken in sterile sample boxes. Milk sampling was carried out according to the principles of STN EN ISO 707. By identification using the PCR method, of n=320 samples of raw cow milk a total of 73 isolates of Pseudomonas spp. were identified as P. putida (34.25%); P. fragi (13.70%); P. lundensis (9.59%) and Pseudomonas spp. (42.47%). Proteolytic activity determined at a temperature of 7°C was positive from n=20 selected isolates of Pseudomonas spp. (60%) isolates and a temperature of 25°C was positively detected (85%). Lipolytic activity determined at a temperature of 7°C was confirmed in 35% of isolates and a temperature of 25°C it was confirmed in 70% isolates. Pyoverdine pigment production was detected in 65% of isolates. The results reveal the enzymatic activity of Pseudomonas spp. present in raw cow’s milk and its spoilage potential at different temperatures in relation to pigment production.

Antagonistic potential and biological control mechanisms of Pseudomonas strains against banded leaf and sheath blight disease of maize

Rhizoctonia solani, the causal agent of banded leaf and sheath blight (BL&SB), poses a significant threat to maize and various crops globally. The increasing concerns surrounding the environmental and health impacts of chemical fungicides have encouraged intensified concern in the development of biological control agents (BCAs) as eco-friendly alternatives. In this study, we explored the potential of 22 rhizobacteria strains (AS1–AS22) isolates, recovered from the grasslands of the Pithoragarh region in the Central Himalayas, as effective BCAs against BL&SB disease. Among these strains, two Pseudomonas isolates, AS19 and AS21, exhibited pronounced inhibition of fungal mycelium growth in vitro, with respective inhibition rates of 57.04% and 54.15% in cell cultures and 66.56% and 65.60% in cell-free culture filtrates. Additionally, both strains demonstrated effective suppression of sclerotium growth. The strains AS19 and AS21 were identified as Pseudomonas sp. by 16S rDNA phylogeny and deposited under accession numbers NAIMCC-B-02303 and NAIMCC-B-02304, respectively. Further investigations revealed the mechanisms of action of AS19 and AS21, demonstrating their ability to induce systemic resistance (ISR) and exhibit broad-spectrum antifungal activity against Alternaria triticina, Bipolaris sorokiniana, Rhizoctonia maydis, and Fusarium oxysporum f. sp. lentis. Pot trials demonstrated significant reductions in BL&SB disease incidence (DI) following foliar applications of AS19 and AS21, with reductions ranging from 25 to 38.33% compared to control treatments. Scanning electron microscopy revealed substantial degradation of fungal mycelium by the strains, accompanied by the production of hydrolytic enzymes. These findings suggest the potential of Pseudomonas strains AS19 and AS21 as promising BCAs against BL&SB and other fungal pathogens. However, further field trials are warranted to validate their efficacy under natural conditions and elucidate the specific bacterial metabolites responsible for inducing systemic resistance. This study contributes to the advancement of sustainable disease management strategies and emphasizes the potential of Pseudomonas strains AS19 and AS21 in combating BL&SB and other fungal diseases affecting agricultural crops.

Indole Acetic Acid (IAA) Mediated Plant Growth Promotion Activity of Fluorescent Pseudomonads and Bacillus spp.

This investigation was made to study the involvement of IAA in plant growth promotion and vigor of wheat plants induced with plant growth promoting rhizobacteria. Nineteen isolates of fluorescent pseudomonads and 11 isolates of Bacillus spp. were subjected to germination percentage and seedling vigor index test. These parameters were determined according to recommended methods by ISTA (1985). The IAA production from selected bacterial isolates, which were showing the potential function of plant growth promotion were further subjected to quantitative analysis using Salkowski’s reagent (2% of 0.5 M FeCl3 in 34% HClO4) for Colorimetric detection. The vigor index and plant growth were significantly increased in Pfa-65 (43.36%) followed by B-18 (42.58%), Pfa-77 (40.83%), B-24 (40.68), Pfa-37(38.82%) and B-38 (38.52). The maximum concentration of IAA was detected in the isolate B-24(36.66 µg/ml) followed by Pfa-65(36.16 µg/ml), B-18(35.98 µg/ml) and Pfa-77(35.72 µg/ml). A positive correlation was observed between concentration of IAA produced and germination percentage with PGPR treatments (correlation coefficient was 0.94). The correlation coefficient was 0.96 between IAA produced and percent increase in vigor index with the treatments. Our data suggests that IAA, a growth promoting hormone, might be the key factor to promote the plant growth directed by the rhizobacteria

Acquired Bartter-like syndrome associated with colistin use in an adult patient: a case report.

Colistin is an effective antibiotic utilized for the treatment of Gram-negative bacterial infections with coverage against a broad spectrum of bacteria. Despite the broad antibacterial coverage, this antibiotic can have serious complications such as acute kidney injury. Colistin also can have a toxic effect on the loop of Henle, causing tubulopathy, electrolyte imbalances, and the occurrence of Bartter-like syndrome (BLS) which is characterized by magnesium and calcium disturbances, polyuria, and metabolic alkalosis. We here report a 32-year-old male with a history of multiple trauma due to an accident that received colistin therapy for Pseudomonas isolation from wound culture on the 5th day of hospitalization. Polyuria, hypokalemic metabolic alkalosis, hypomagnesemia, and hypocalcemia were developed on the first week of colistin administration. The patient received colistin until the 21st day of hospitalization. Serum calcium and magnesium levels became normal 1 day after stopping colistin, while urine volume and metabolic alkalosis resolved 6 days after colistin discontinuing. Therefore, it is crucial to adjust the dose of colistin to minimize its toxicity.

Characterization and Field Evaluation of Potential Fluorescent Pseudomonas Isolates on Growth and Yield Attributing Characters in Chickpea

The present investigation was conducted at the research and instructional farm, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh, India during rabi (October–December 2019) to evaluate the influence of fluorescent Pseudomonas isolates on chickpeas through characterization and field evaluation. Eighty-eight rhizosphere soil samples were derived from different locations in Bastar and Bilaspur districts of Chhattisgarh, India. Potential isolates were required for fundamental research and practical application of plant growth-promoting rhizobacterial strains on different crops. Among eighty-eight isolates, ten fluorescent Pseudomonas (visible under UV light at 360 nm) emitting strong fluorescence were selected for the course of the investigation and characterized for the production of siderophores, phosphate solubilization, indole acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase, and analysis of antagonistic potential. Of the 10 Pseudomonas isolates, 9704 was identified as the highest phosphate solubilizer, BSP-23 was identified as the highest indole acetic acid producer, and BSP-19 was the highest siderophore producer. Fluorescent Pseudomonas isolates BS-1, BS-4, 9809, BSP-14, and BSP-19 were identified to possess 1-aminocyclopropane-1-carboxylic acid deaminase-producing ability following qualitative analysis. Our present investigation indicates that beneficial effects of fluorescent Pseudomonas could be achieved through simple and cost-effective seed treatment. Three fluorescent Pseudomonas strains, 9704, BS-14, and 9829, consistently increased seed germination and improved plant growth and yield (BS-37.9% and 9704-35.7%) attributes in chickpeas. Besides, confrontation assays performed against R. bataticola expressed varying levels of inhibition. The phylogenetic affinities of 16S rRNA gene sequencing resolved the species identities of selected isolates.

Colonization of Solanaceous crops by endophytic and rhizospheric plant growth-promoting bacteria from the native Solanaceae Solanum hindsianum Benth

Plant-associated bacteria are an important tool for sustainable agriculture since the have been shown to play a significant role in the health and productivity of plants through various mechanisms. However, commercial inoculants often fail to produce desired effects due to colonization issues and lack of adaptation to local conditions. In this study, we aimed to evaluate the potential of plant growth-promoting bacteria (PGPB) isolated from Solanum hindsianum, a native plant from the Sonoran Desert, to colonize and promote growth in Solanaceae crops under different irrigation conditions. First, endophytic bacteria were screened for various plant growth-promoting traits, and selected strains were identified as Bacillus, Brevibacillus, Pseudomonas, Acinetobacter, and Siccibacter. Then, endophytic and rhizospheric Pseudomonas isolates, were tested for their tolerance to salinity and osmotic stress and for their ability to induce auxin-responsive gene expression and promote plant development in Arabidopsis. All strains induced strong expression of an auxin reporter gene, while significantly improving root and plant morphology, and showed tolerance to osmotic and salinity stress. In colonization experiments, these strains successfully colonized the root crown and rhizosphere of chili, tomatillo, and tomato plants. However, the endophytic strain showed better colonization ability, especially under low irrigation conditions. Overall, this study demonstrates the potential of native PGPR strains to colonize and promote growth in Solanaceae crops under specific environmental conditions.

Environmental reservoirs of multidrug-resistant pseudomonads in a geographical location in Kenya with high community-acquired infections

Background Pseudomonads are gram negative bacteria and readily form biofilms in the environment, allowing long-term colonization and persistence in sinks, water systems. They pose a risk of life-threatening opportunistic infections in immune-compromised individuals. MDR strains, make treatment increasingly difficult. Environmentally persistent MDR strains are typically problematic within healthcare facilities, however, data on MDR pseudomonad reservoirs in settings with community-acquired infections to inform preventive interventions, in resource-constrained settings is scarce. Here, we determined reservoirs and antibiotic susceptibility of Pseudomonas species in water sources in Kisumu County, Kenya with reported high levels of community acquired pseudomonad infections. Methods We adopted a cross-sectional design, randomly collecting 297 samples from tap heads, sinks, tanks, vendor and household storage containers in six selected sub-locations and one hospital (KCRH). Standard microbiological procedures were used for identification and AST of the isolates. Results We isolated Pseudomonads from 14.1% of the samples collected, predominantly from the community 10.4%. Seven different pseudomonads were identified, with Pseudomonas aeruginosa predominating 6.7% overall, in the community samples 5.7%, and among isolates from water tanks 21.4%. Pseudomonad isolates were 62% non-susceptible to piperacillin, 57% to tigecycline, 24% meropenem, 21% cefepime, 19% levofloxacin and 14% colistin. Carbapenem resistance was mainly detected in P. aeruginosa 80% (8/10) from Milimani sub-location 75% (6/8). 45% of the isolates recovered were MDR, mainly community-associated carbapenem-resistant P. aeruginosa (CRPA) 42%, strains susceptible to colistin. The MDR pseudomonads exhibited high multiple antibiotic resistance indices, ranging from 0.43 to 1. Conclusion This study reveals a higher prevalence of MDR pseudomonads, including CRPA strains in community water sources. These potential conduits of drug resistance present a critical public health threat, especially among immunocompromised. Regular cleaning of water storage facilities, water treatment and implementation of antimicrobial stewardship programs, are required to prevent a rise in AMR and eliminate the environmental reservoirs that put the vulnerable populations at risk.

Molecular identification and characterizations of rhizobacterial isolates collected from lentil rhizosphere of Indo-gangetic plains.

Plant growth promoting rhizobacteria (PGPR) are also known to colonize in the soil rhizosphere and prevent the development of other soil borne pathogens residing in the root surface. These microorganisms play a vital role in growth and development of the plant and also enhances the soil fertility by enriching the soil with different beneficial nutrients. This study was aimed at isolation of different rhizobacteria and their molecular characterization in search of efficient bacterial strains with multiple growth regulating activities. A total 36 bacteria were isolated from lentil root nodule as well as soil from different lentil growing fields with a view to screen/evaluate their plant growth promoting potential. Morphological characterization of isolated rhizobacterial candidates were done by observing the colonies on YEMA and nutrient agar media. Determination of CFU, Congo red test and gram staining tests were done to further screen them according to their morphology. All the isolates were then undergone molecular phylogenetic analysis using the partial sequences of the 16S rDNA. Based upon the Gram staining test, all the isolates were negative in gram reaction except six Bacillus isolates, PSB2 and AB3. Results of Ribosomal Database Project (RDP) and Basic Local Alignment Search Tool for Nucleotide Sequences (BLASTn) from 16S rDNA gene sequences showed that these isolates are genetically diverse. A total of 15 isolates of Rhizobium, 6 isolates of Bacillus, 3 isolates of Pseudomonas, 2 isolates of Phosphate Solubilizing Bacteria, 4 isolates of actinomycetes were identified by molecular sequencing of their 16S rDNA region and comparing them with the other isolates enlisted in the database of NCBI for the similarity percentage, query coverage. The purpose of the present study was to select native rhizosphere bacteria from the lentil nodule and soil of Lentil field and to evaluate their plant growth promoting potential as an alternative of chemical fertilizer for sustainable, environment friendly agriculture and assessment of their phylogenetic characterization.

Phosphate solubilizing Pseudomonas and Bacillus combined with rock phosphates promoting tomato growth and reducing bacterial canker disease.

Nowadays, sustainable agriculture approaches are based on the use of biofertilizers and biopesticides. Tomato (Solanum lycopersicum L.) rhizosphere could provide rhizobacteria with biofertilizing and biopesticide properties. In this study, bacteria from the rhizosphere of tomato were evaluated in vitro for plant growth promotion (PGP) properties. Five Pseudomonas isolates (PsT-04c, PsT-94s, PsT-116, PsT-124, and PsT-130) and one Bacillus isolate (BaT-68s), with the highest ability to solubilize tricalcium phosphate (TCP) were selected for further molecular identification and characterization. Isolates showed phosphate solubilization up to 195.42 μg mL-1. All isolates showed phosphate solubilization by organic acid production. The six isolates improved seed germination and showed effective root colonization when tomato seeds were coated with isolates at 106 cfu g-1 in axenic soil conditions. Furthermore, the selected isolates were tested for beneficial effects on tomato growth and nutrient status in greenhouse experiments with natural rock phosphate (RP). The results showed that inoculated tomato plants in the presence of RP have a higher shoot and root lengths and weights compared with the control. After 60 days, significant increases in plant Ca, Na, P, protein, and sugar contents were also observed in inoculated seedlings. In addition, inoculated tomato seedlings showed an increase in foliar chlorophyll a and b and total chlorophyll, while no significant changes were observed in chlorophyll fluorescence. In greenhouse, two Pseudomonas isolates, PsT-04c and PsT-130, showed ability to trigger induced systemic resistance in inoculated tomato seedlings when subsequently challenged by Clavibacter michiganensis subsp. michiganensis, the causal agent of tomato bacterial canker. High protection rate (75%) was concomitant to an increase in the resistance indicators: total soluble phenolic compounds, phenylalanine-ammonia lyase, and H2O2. The results strongly demonstrated the effectiveness of phosphate-solubilizing bacteria adapted to rhizosphere as biofertilizers for tomato crops and biopesticides by inducing systemic resistance to the causal agent of tomato bacterial canker disease.

Widespread and active piezotolerant microorganisms mediate phenolic compound degradation under high hydrostatic pressure in hadal trenches

Phenolic compounds, as well as other aromatic compounds, have been reported to be abundant in hadal trenches. Although high-throughput sequencing studies have hinted at the potential of hadal microbes to degrade these compounds, direct microbiological, genetic and biochemical evidence under in situ pressures remain absent. Here, a microbial consortium and a pure culture of Pseudomonas, newly isolated from Mariana Trench sediments, efficiently degraded phenol under pressures up to 70 and 60 MPa, respectively, with concomitant increase in biomass. By analyzing a high-pressure (70 MPa) culture metatranscriptome, not only was the entire range of metabolic processes under high pressure generated, but also genes encoding complete phenol degradation via ortho- and meta-cleavage pathways were revealed. The isolate of Pseudomonas also contained genes encoding the complete degradation pathway. Six transcribed genes (dmpKLMNOPsed) were functionally identified to encode a multicomponent hydroxylase catalyzing the hydroxylation of phenol and its methylated derivatives by heterogeneous expression. In addition, key catabolic genes identified in the metatranscriptome of the high-pressure cultures and genomes of bacterial isolates were found to be all widely distributed in 22 published hadal microbial metagenomes. At microbiological, genetic, bioinformatics, and biochemical levels, this study found that microorganisms widely found in hadal trenches were able to effectively drive phenolic compound degradation under high hydrostatic pressures. This information will bridge a knowledge gap concerning the microbial aromatics degradation within hadal trenches.

Evaluation of antagonistic activity of DAPG‐producing fluorescent pseudomonads from rhizospheres of Solanaceous crops for biocontrol of bacterial wilt

AbstractPseudomonads produce a wide array of antimicrobial compounds including 2,4‐diacetylphloroglucinol (DAPG), which possess a broad‐spectrum antagonistic effect against phytopathogens. Rhizospheric soil samples were collected from the Solanaceous crops for isolation of fluorescent pseudomonads (FPs). Out of the 32 fluorescent bacterial isolates, 21 showed antagonistic activity against Ralstonia solanacearum (NAIMCC‐B‐01630) with the highest zone of inhibition at 38.33 mm. Among them, 11 bacterial isolates depicted the production of DAPG in Kings' B medium. DAPG production was detected by TLC and quantified through HPLC analysis. Moreover, the bacterial isolate OD13 exhibited higher DAPG production. Further, the presence of the DAPG‐encoding phlD gene within the size of 629 bp and 725 bp was also validated through amplification. These bacterial isolates belonged to the genera Pseudomonas as confirmed by morpho‐physiological characterization using the VITEK 2 system. The higher DAPG‐producing bacterial isolate was identified as Pseudomonas aeruginosa by polyphasic approach with GenBank accession number OQ781265. Thus, the DAPG‐producing rhizospheric Pseudomonas strains can be used as biocontrol agents for bacterial wilt. However, field study is highly essential before its successful application.

Loss of AC10 Impairs Neutrophil Recruitment and Alters Bacterial Colonization in the Lung During Bacterial Pneumonia

Rationale: Pseudomonas aeruginosa is a gram-negative bacterium and a common cause of nosocomial pneumonia that can progress to acute respiratory distress syndrome (ARDS), characterized by hypoxia, pulmonary edema, elevated bicarbonate, and widespread inflammation. Neutrophil recruitment is a critical line of defense against P. aeruginosa; however, excessive, or dysregulated neutrophil infiltration can exacerbate tissue damage and contribute to the severity of ARDS. Recently, AC10 has been implicated in neutrophil transendothelial migration via CD99. Despite the growing recognition and significance of AC10 in various physiological processes, its role in neutrophil recruitment during ARDS remains poorly understood. Thus, herein we hypothesize that loss of AC10 attenuates neutrophil recruitment during pneumonia and increase bacterial colonization in the lung. Methods: Wild-type and AC10 knockout mice were intratracheally inoculated with increasing doses of P. aeruginosa. Twenty fours after infection, bronchoalveolar lavage fluid (BALF) was collected and the percent of PMNs in the BALF determined. In separate experiments, mice were intratracheally inoculated with P. aeruginosa for 6 or 24 hours and organs (lungs, kidney, liver, spleen and brain) harvested, homogenized and the homogenate cultured overnight on Pseudomonas isolation agar for quantification of colony forming units (CFUs). Results: Our data confirmed CD99 expression in rat pulmonary microvascular endothelial cells and whole lung of both wild type and AC10 knockout mice. While there was no difference in the percentage of PMNs in the BALF between male wild type and knockout animals at any of the bacterial doses tested, in the female AC10 knockout mice, there was a decrease in the percentage of cells PMNs in the BALF compared to female wild type litter mates at several doses tested (1x103 up to 1x105, p<0.05). At a higher dose of P. aeruginosa (2.5x106), there was no difference in bacterial clearance between male WT and AC10 knockout mice, but a trend toward an increase in the CFU harvested from lung tissue 6 hours post infection in female KO mice. Conclusion: Thus, CD99 is expressed in the pulmonary endothelium. Further, in female mice, AC10 plays a role in neutrophil recruitment into the airspace. Further studies are required to resolve whether AC10 plays a role in bacterial clearance in female mice in a model of P. aeruginosa pneumonia. HL121513. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Purines enrich root-associated Pseudomonas and improve wild soybean growth under salt stress

The root-associated microbiota plays an important role in the response to environmental stress. However, the underlying mechanisms controlling the interaction between salt-stressed plants and microbiota are poorly understood. Here, by focusing on a salt-tolerant plant wild soybean (Glycine soja), we demonstrate that highly conserved microbes dominated by Pseudomonas are enriched in the root and rhizosphere microbiota of salt-stressed plant. Two corresponding Pseudomonas isolates are confirmed to enhance the salt tolerance of wild soybean. Shotgun metagenomic and metatranscriptomic sequencing reveal that motility-associated genes, mainly chemotaxis and flagellar assembly, are significantly enriched and expressed in salt-treated samples. We further find that roots of salt stressed plants secreted purines, especially xanthine, which induce motility of the Pseudomonas isolates. Moreover, exogenous application for xanthine to non-stressed plants results in Pseudomonas enrichment, reproducing the microbiota shift in salt-stressed root. Finally, Pseudomonas mutant analysis shows that the motility related gene cheW is required for chemotaxis toward xanthine and for enhancing plant salt tolerance. Our study proposes that wild soybean recruits beneficial Pseudomonas species by exudating key metabolites (i.e., purine) against salt stress.

The genotype of barley cultivars influences multiple aspects of their associated microbiota via differential root exudate secretion.

Plant-associated microbes play vital roles in promoting plant growth and health, with plants secreting root exudates into the rhizosphere to attract beneficial microbes. Exudate composition defines the nature of microbial recruitment, with different plant species attracting distinct microbiota to enable optimal adaptation to the soil environment. To more closely examine the relationship between plant genotype and microbial recruitment, we analysed the rhizosphere microbiomes of landrace (Chevallier) and modern (NFC Tipple) barley (Hordeum vulgare) cultivars. Distinct differences were observed between the plant-associated microbiomes of the 2 cultivars, with the plant-growth promoting rhizobacterial genus Pseudomonas substantially more abundant in the Tipple rhizosphere. Striking differences were also observed between the phenotypes of recruited Pseudomonas populations, alongside distinct genotypic clustering by cultivar. Cultivar-driven Pseudomonas selection was driven by root exudate composition, with the greater abundance of hexose sugars secreted from Tipple roots attracting microbes better adapted to growth on these metabolites and vice versa. Cultivar-driven selection also operates at the molecular level, with both gene expression and the abundance of ecologically relevant loci differing between Tipple and Chevallier Pseudomonas isolates. Finally, cultivar-driven selection is important for plant health, with both cultivars showing a distinct preference for microbes selected by their genetic siblings in rhizosphere transplantation assays.

Identification of microbial communities and multi-species biofilms contamination in seafood processing environments with different hygiene conditions

Biofilms formed by spoilage and pathogenic bacteria increase microbial persistence, causing an adverse influence on the quality of seafood. The mono-species biofilms are widely reported, however, the contamination of multi-species biofilms and their matrix in food environments are still not fully understood. Here, we assessed the contamination of multi-species biofilms in three seafood processing environments with different hygiene levels by detecting bacterial number and three biofilm matrix components (carbohydrates, extracellular DNA (eDNA), and proteins). Samples comprising seven food matrix surfaces and eight food processing equipment surfaces were collected from two seafood processing plants (XY and XC) and one seafood market (CC). The results showed that the bacterial counts ranged from 1.89 to 4.91 CFU/cm2 and 5.68 to 9.15 BCE/cm2 in these surfaces by cultivation and real-time PCR, respectively. Six biofilm hotspots were identified, including four in CC and two in XY. Among the three processing environments, the amplicon sequence variants (ASVs) of Proteobacteria, Bacteroidetes, and Actinobacteria decreased with improved processing hygiene, while Firmicutes showed a decrease in the four most abundant phyla. The most prevalent bacteria belonged to genera Psychrobacter, Acinetobacter, and Pseudomonas, demonstrating the significant differences and alteration in bacterial community composition during different environments. From the biofilm hotspots, 15 isolates with strong biofilm forming ability were identified, including 7 Pseudomonas, 7 Acinetobacter, and 1 Psychrobacter. The Pseudomonas isolates exhibited the highest production of EPS components and three strong motilities, whose characteristics were positively correlated. Thus, this study verified the presence of multi-species biofilms in seafood processing environments, offering preliminary insights into the diversity of microbial communities during processing. It highlights potential contamination sources and emphasizes the importance of understanding biofilms composition to control biofilms formation in seafood processing environments.

Characterization of β-lactamase and virulence genes in Pseudomonas aeruginosa isolated from clinical, environmental and poultry sources in Bangladesh.

The emergence and spread of multidrug-resistant pathogens like Pseudomonas aeruginosa are major concerns for public health worldwide. This study aimed to assess the prevalence of P. aeruginosa in clinical, environmental, and poultry sources in Bangladesh, along with their antibiotic susceptibility and the profiling of β-lactamase and virulence genes using standard molecular and microbiology techniques. We collected 110 samples from five different locations, viz., BAU residential area (BAURA; n = 15), BAU Healthcare Center (BAUHCC; n = 20), BAU Veterinary Teaching Hospital (BAUVTH; n = 22), Poultry Market (PM; n = 30) and Mymensingh Medical College Hospital (MCCH; n = 23). After overnight enrichment in nutrient broth, 89 probable Pseudomonas isolates (80.90%) were screened through selective culture, gram-staining and biochemical tests. Using genus- and species-specific PCR, we confirmed 22 isolates (20.0%) as P. aeruginosa from these samples. Antibiogram profiling revealed that 100.0% P. aeruginosa isolates (n = 22) were multidrug-resistant isolates, showing resistance against Doripenem, Penicillin, Ceftazidime, Cefepime, and Imipenem. Furthermore, resistance to aztreonam was observed in 95.45% isolates. However, P. aeruginosa isolates showed a varying degree of sensitivity against Amikacin, Gentamicin, and Ciprofloxacin. The blaTEM gene was detected in 86.0% isolates, while blaCMY, blaSHV and blaOXA, were detected in 27.0%, 18.0% and 5.0% of the P. aeruginosa isolates, respectively. The algD gene was detected in 32.0% isolates, whereas lasB and exoA genes were identified in 9.0% and 5.0% P. aeruginosa isolates. However, none of the P. aeruginosa isolates harbored exoS gene. Hence, this study provides valuable and novel insights on the resistance and virulence of circulating P. aeruginosa within the clinical, environmental, and poultry environments of Bangladesh. These findings are crucial for understanding the emergence of β-lactamase resistance in P. aeruginosa, highlighting its usefulness in the treatment and control of P. aeruginosa infections in both human and animal populations.

Selection of the Dominant Endophytes Based on Illumina Sequencing Analysis for Controlling Bacterial Wilt of Patchouli Caused by Ralstonia solanacearum.

Bacterial wilt caused by Ralstonia solanacearum (RS) is one of the most devastating diseases in patchouli (Pogostemon cablin [Blanco] Benth.), which results in low yield and quality of patchouli. However, no stable and effective control methods have been developed yet. To evaluate the potential of dominant bacterial endophytes in biocontrol, the endophytic bacterial diversity of patchouli was investigated based on Illumina sequencing analysis, and the ability of isolates belonging to the dominant bacterial genera to control RS wilt of patchouli was explored in pot experiments. A total of 245 bacterial genera were detected in patchouli plants, with the highest relative abundance of operational taxonomic units belonging to the genus Pseudomonas detected in roots, leaves, and stems. The Pseudomonas isolates S02, S09, and S26 showed antagonistic activity against RS in vitro and displayed many plant growth-promoting characteristics, including production of indole-3-acetic acid, siderophores, and 1-aminocyclopropane-1-carboxylic acid deaminase and phosphate- and potassium-solubilizing capability. Inoculation of patchouli plants with the isolates S02, S09, and S26 significantly improved shoot growth and decreased the incidence of bacterial wilt caused by RS. The results suggest that screening of dominant bacterial endophytes for effective biocontrol agents based on Illumina sequencing analysis is more efficient than random isolation and screening procedures.

Etiologies, risk factors, and antibiotic pattern of lower respiratory tract infection in patients coming to Deccan College of Medical Sciences, Hyderabad, South India

Background. Lower Respiratory Tract Infections (LRTI) impose a huge problem on society due to their tenacious and unescapable health problems, and they were the reasons for consultation and hospitalization. Patients with LRTI were present with a wide spectrum of diseases that range from life-threatening infections to minor self-limiting illnesses. Materials and methods. Sputum samples from 310 patients with complaints of lower respiratory tract infections were collected and analyzed. After microscopic analysis, 30 were excluded from the study. Of the 280 that were included in the study, 171 were males and 109 were females. The age group between 56 and 65 years comprised the highest number of patients in the study. Different antibiotics were used to check antibiotic sensitivity patterns against isolated Gram-positive and negative bacteria. Results. Of the 280 samples processed, 122 (43.5%) were culture-positive. Among the 122 bacterial isolates, the predominant organism was Klebsiella pneumoniae 55 (45%). The most common predisposing factor identified in 115 (37%) patients was smoking. Using the Double Disk Synergy Test, 11 (20%) out of a total of 55 K. pneumoniae isolates and 4 (30.7%) out of 13 Pseudomonas isolates showed Extended Spectrum Beta Lactamases (ESBL). The Klebsiella and Pseudomonas isolates showed resistance to 2nd and 3rd generation Cephalosporins. Conclusion. Because of different geographical regions and conditions, the etiology and the antibiotic sensitivity patterns of LRTI vary, so the etiology, predisposing factors, and the antibiotic sensitivity pattern of LRTI need to be updated regularly. The diagnostic facilities for early and rapid identification of LRTI also need to be improved.

Comparison of alternative media from organic waste as a growth media for the biological agent bacteria Pseudomonas spp

Introduction: Pseudomonas spp is one of the biological agents that has many abilities. With the high cost of synthetic media used as a medium for the propagation and growth of this bacteria, it is necessary to have alternative media that are cheap and environmentally friendly, one of which is by utilizing organic waste. This study aims to determine the comparison of the growth of Pseudomonas spp on alternative media from organic waste. Method: The design used was a non-factorial Completely Randomized Design (CRD) with 3 (three) treatments using types of bacteria propagation media, namely P0 = selective media formulation (Pseudomonas Isolation Agar), P1 = soybean water stew waste, and P2 = coconut water waste and repeated 6 times. Result: The results showed that the bacteria tested were Pseudomonas spp based on the Gram staining test and the pendar fluorescence test. The highest number of colonies on day 5 was found in coconut water media as well as the results of the absorbance test and the Pseudomonas spp had antagonistic properties against Xanthomonas sp. Conclusion: Alternative media from organic waste coconut water are the best media for the growth of Pseudomonas spp which have antagonistic properties against Xanthomonas sp.

Long-duration environmental biosensing by recording analyte detection in DNA using recombinase memory.

Microbial biosensors that convert environmental information into real-time visual outputs are limited in their sensing abilities in complex environments, such as soil and wastewater, due to optical inaccessibility. Biosensors that could record transient exposure to analytes within a large time window for later retrieval represent a promising approach to solve the accessibility problem. Here, we test the performance of recombinase-memory biosensors that sense a sugar (arabinose) and a microbial communication molecule (3-oxo-C12-L-homoserine lactone) over 8 days (~70 generations) following analyte exposure. These biosensors sense the analyte and trigger the expression of a recombinase enzyme which flips a segment of DNA, creating a genetic memory, and initiates fluorescent protein expression. The initial designs failed over time due to unintended DNA flipping in the absence of the analyte and loss of the flipped state after exposure to the analyte. Biosensor performance was improved by decreasing recombinase expression, removing the fluorescent protein output, and using quantitative PCR to read out stored information. Application of memory biosensors in wastewater isolates achieved memory of analyte exposure in an uncharacterized Pseudomonas isolate. By returning these engineered isolates to their native environments, recombinase-memory systems are expected to enable longer duration and in situ investigation of microbial signaling, cross-feeding, community shifts, and gene transfer beyond the reach of traditional environmental biosensors.IMPORTANCEMicrobes mediate ecological processes over timescales that can far exceed the half-lives of transient metabolites and signals that drive their collective behaviors. We investigated strategies for engineering microbes to stably record their transient exposure to a chemical over many generations through DNA rearrangements. We identify genetic architectures that improve memory biosensor performance and characterize these in wastewater isolates. Memory biosensors are expected to be useful for monitoring cell-cell signals in biofilms, detecting transient exposure to chemical pollutants, and observing microbial cross-feeding through short-lived metabolites within cryptic methane, nitrogen, and sulfur cycling processes. They will also enable in situ studies of microbial responses to ephemeral environmental changes, or other ecological processes that are currently challenging to monitor non-destructively using real-time biosensors and analytical instruments.